Patent Publication Number: US-2023163035-A1

Title: Substrate for light emitting elements, light emitting device including substrate for light emitting elements, and method of producing substrate for light emitting elements

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority to Japanese Patent Application No. 2021-188538, filed on Nov. 19, 2021, the entire contents of which are hereby incorporated by reference. 
     BACKGROUND 
     The present application relates to a substrate for light emitting elements, a light emitting device including a substrate for light emitting elements, and a method of producing a substrate for light emitting elements. 
     Light emitting devices that include light emitting elements, such as LED (Light Emitting Diode), mounted on a substrate have been known. In such light emitting devices, the substrate on which the light emitting elements are to be mounted (hereinafter, referred to as “substrate for light emitting elements”) includes, for example, a plurality of electrically-conductive layers on a surface opposite to the front surface of the substrate on which the light emitting elements are to be mounted such that the electrically-conductive layers can be electrically connected to the positive and negative electrodes of the light emitting elements. (See, for example, Japanese Patent Publication No. 2010-040801.) 
     SUMMARY 
     As the distance between the plurality of electrically-conductive layers provided in the substrate for light emitting elements decreases, ion migration is more likely to occur between the electrically-conductive layers. Occurrence of ion migration can cause a short circuit between the electrically-conductive layers, which can cause the light emitting elements to erroneously operate or fail to emit light. 
     An object of the present disclosure is to provide a substrate for light emitting elements in which a short circuit due to ion migration between electrically-conductive layers is suppressed, a light emitting device including such a substrate for light emitting elements, and a method of producing such a substrate for light emitting elements. 
     According to one aspect of the present disclosure, a substrate for light emitting elements includes: a resin layer, a first electrically-conductive layer, a second electrically-conductive layer. The resin layer has a sheet shape, a first surface, and a second surface located opposite to the first surface. The second surface has one or more groove portions. The second surface is divided by the first groove portion into a plurality of regions that include the first region and the second region. The resin layer includes a plurality of fiber bundles and a resin. The first electrically-conductive layer is located in the first region of the resin layer. The second electrically-conductive layer is located in the second region of the resin layer. In a cross-sectional view including the first electrically-conductive layer, the first groove portion, and the second electrically-conductive layer, at least one continuous fiber bundle included in the plurality of fiber bundles includes a portion that is located at a position shallower than a bottom of the first groove portion. In a plan view, the at least one continuous fiber bundle extends inside the resin layer across the first region, a portion below the first groove portion, and the second region in a plan view. 
     According to another aspect of the present disclosure, a light emitting device includes: the substrate as set forth in the foregoing paragraph, the first electrically-conductive layer being a first lower electrically-conductive layer, the second electrically-conductive layer being a second lower electrically-conductive layer, the substrate further including a first upper electrically-conductive layer and a second upper electrically-conductive layer on the first surface side of the resin layer, the first upper electrically-conductive layer and the second upper electrically-conductive layer being spaced away from each other, and the first upper electrically-conductive layer being electrically connected to the first lower electrically-conductive layer, and the second upper electrically-conductive layer being electrically connected to the second lower electrically-conductive layer; and at least one light emitting element provided on the first surface side of the resin layer, wherein the at least one light emitting element includes a first light emitting element, the first light emitting element including a first electrode electrically connected to the first upper electrically-conductive layer and a second electrode electrically connected to the second upper electrically-conductive layer. 
     According to still another aspect of the present disclosure, a method of producing a substrate for light emitting elements, includes: providing a sheet-like metal plate and a pre-preg, the metal plate having a first surface and one or more raised portions at the first surface, the pre-preg including a plurality of fiber bundles and a resin; binding together the first surface of the metal plate and the pre-preg; forming a resin layer that includes curing the pre-preg; forming a resist on the metal plate; etching away the one or more raised portions of the metal plate; and removing the resist. The etching includes dividing the metal plate by the one or more groove portions into two or more parts that includes a first region and a second region. 
     According to certain embodiments of the present disclosure, a substrate for light emitting elements in which a short circuit due to ion migration between electrically-conductive layers is suppressed, a light emitting device including such a substrate for light emitting elements, and a method of producing such a substrate for light emitting elements can be provided. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1 A  is a schematic top view of a substrate for light emitting elements according to an embodiment of the present disclosure. 
         FIG.  1 B  is a schematic bottom view of the substrate shown in  FIG.  1 A . 
         FIG.  1 C  is a schematic cross-sectional view of the substrate taken along line  1 C- 1 C shown in  FIG.  1 A  and  FIG.  1 B . 
         FIG.  1 D  is an enlarged schematic cross-sectional view showing a part of  FIG.  1 C . 
         FIG.  2 A  is a schematic top view of a light emitting device according to an embodiment of the present disclosure. 
         FIG.  2 B  is a schematic cross-sectional view of the light emitting device taken along line  2 B- 2 B shown in  FIG.  2 A . 
         FIG.  3 A  is an enlarged schematic cross-sectional view showing a part of a resin layer according to an embodiment. 
         FIG.  3 B  is an enlarged schematic top view showing an example of a fiber layer. 
         FIG.  3 C  is an enlarged schematic bottom view showing a part of the substrate for light emitting elements for illustrating the arrangement of the first fiber bundle. 
         FIG.  4 A  is a schematic bottom view showing a first substrate according to an embodiment. 
         FIG.  4 B  is an enlarged schematic bottom view showing a part of the first substrate shown in  FIG.  4 A . 
         FIG.  4 C  is a schematic cross-sectional view of the first substrate taken along line  4 C- 4 C shown in  FIG.  4 B . 
         FIG.  5    is an enlarged schematic bottom view showing a part of an alternative first substrate according to an embodiment. 
         FIG.  6    is a cross-sectional view showing another example of a light source section. 
         FIG.  7 A  is a schematic top view showing a light emitting device according to an embodiment. 
         FIG.  7 B  is a schematic bottom view of the light emitting device shown in  FIG.  7 A . 
         FIG.  7 C  is a schematic cross-sectional view of the light emitting device taken along line  7 C- 7 C shown in  FIG.  7 A  and  FIG.  7 B . 
         FIG.  7 D  is a schematic lateral side view of the light emitting device shown in  FIG.  7 A . 
         FIG.  8 A  is an enlarged schematic top view showing a part of a metal plate for use in production of the substrate for light emitting elements according to an embodiment. 
         FIG.  8 B  is a schematic cross-sectional view of the metal plate taken along line  8 B- 8 B shown in  FIG.  8 A . 
         FIG.  8 C  is an enlarged schematic cross-sectional view showing a part of a pre-preg for use in production of the substrate for light emitting elements according to an embodiment. 
         FIG.  9 A  is a cross-sectional view showing a production step of the substrate for light emitting elements according to an embodiment. 
         FIG.  9 B  is a cross-sectional view showing a production step of the substrate for light emitting elements according to an embodiment. 
         FIG.  9 C  is a cross-sectional view showing a production step of the substrate for light emitting elements according to an embodiment. 
         FIG.  9 D  is a cross-sectional view showing a production step of the substrate for light emitting elements according to an embodiment. 
         FIG.  9 E  is a cross-sectional view showing a production step of the substrate for light emitting elements according to an embodiment. 
         FIG.  9 F  is a cross-sectional view showing a production step of the substrate for light emitting elements according to an embodiment. 
         FIG.  9 G  is a cross-sectional view showing a production step of the substrate for light emitting elements according to an embodiment. 
         FIG.  10 A  is a schematic top view of a substrate for light emitting elements according to Variant Example 1. 
         FIG.  10 B  is a schematic bottom view of the substrate shown in  FIG.  10 A . 
         FIG.  10 C  is a schematic cross-sectional view of the substrate taken along line  10 C- 10 C shown in  FIG.  10 A  and  FIG.  10 B . 
         FIG.  11    is an enlarged schematic bottom view showing a part of the first substrate of Variant Example 1. 
         FIG.  12 A  is a schematic top view showing a light emitting device of Variant Example 1. 
         FIG.  12 B  is a schematic bottom view of the light emitting device shown in  FIG.  12 A . 
         FIG.  12 C  is a schematic cross-sectional view of the light emitting device taken along line  12 C- 12 C shown in  FIG.  12 A  and  FIG.  12 B . 
         FIG.  13    is a cross-sectional view of a structure equivalent to the light emitting device shown in  FIG.  12 C  from which a lens has been removed. 
         FIG.  14 A  is a schematic top view of a substrate for light emitting elements according to Variant Example 2. 
         FIG.  14 B  is a schematic bottom view of the substrate shown in  FIG.  14 A . 
         FIG.  14 C  is a schematic cross-sectional view of the substrate taken along line  14 C- 14 C shown in  FIG.  14 A  and  FIG.  14 B . 
         FIG.  15    is an enlarged schematic bottom view showing a part of the first substrate of Variant Example 2. 
         FIG.  16    is a schematic bottom view showing an alternative substrate for light emitting elements according to Variant Example 2. 
         FIG.  17 A  is a schematic bottom view of a substrate for light emitting elements according to Variant Example 3. 
         FIG.  17 B  is a schematic bottom view of an alternative substrate for light emitting elements according to Variant Example 3. 
         FIG.  18    is a schematic bottom view of a still alternative substrate for light emitting elements according to Variant Example 3. 
         FIG.  19 A  is a schematic cross-sectional view of a substrate for light emitting elements according to Variant Example 4. 
         FIG.  19 B  is a schematic cross-sectional view of an alternative substrate for light emitting elements according to Variant Example 4. 
         FIG.  19 C  is a schematic cross-sectional view of an alternative substrate for light emitting elements according to Variant Example 4. 
         FIG.  20    is a schematic bottom view of an alternative substrate for light emitting elements according to Variant Example 4. 
         FIG.  21    is an enlarged schematic cross-sectional view illustrating a reference example processing method of forming a groove portion in a resin layer. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, embodiments of the present invention are described with appropriate reference to the drawings. A substrate for light emitting elements and a light emitting device that will be described below are provided as examples for giving a concrete form to the technical concepts of the present invention. However, the present invention is not limited to the description below unless specified otherwise. The description provided for one embodiment is also applicable to other embodiments and variations. The sizes, relative positions, etc., of members shown in the drawings are sometimes exaggerated for clear description. 
     In the following description, components of like functions may be denoted by like reference signs and may not be described redundantly. Sometimes, components that are not referred to in the description may not be accompanied with reference characters. Terms indicating specific directions and positions (e.g., “upper,” “lower,” “right,” “left,” and other terms including or related such terms) may be used in the following description. Note however that these terms are used merely for the ease of understanding relative directions or positions in the figure being referred to. The arrangement of components in figures from documents other than the present disclosure, actual products, actual manufacturing apparatuses, etc., does not need to be equal to that shown in the figure being referred to, as long as it conforms with the directional or positional relationship as indicated by terms such as “upper” and “lower” in the figure being referred to. In the present disclosure, the term “parallel” encompasses cases where two straight lines, sides, planes, etc., are in the range of about 0±5°, unless otherwise specified. In the present disclosure, the terms “perpendicular” and “orthogonal” encompass cases where two straight lines, sides, planes, etc., are in the range of about 90±5°, unless otherwise specified. 
     The drawings described below also show arrows representative of the X, Y and Z axes that are perpendicular to one another. The forward direction of the arrow in the x direction is denoted as +x direction, and the direction opposite to the +x direction is denoted as −x direction. The forward direction of the arrow in the y direction is denoted as +y direction, and the direction opposite to the +y direction is denoted as −y direction. The forward direction of the arrow in the z direction is denoted as +z direction, and the direction opposite to the +z direction is denoted as −z direction. In the embodiments, according to an example, light emitting elements are to emit light to the +z direction side. Note that, however, this does not limit the orientation of a light emitting device or light emitting element when used. The orientation of the light emitting device or light emitting element is discretionary. In the claims and the specification, the phrase “plan view” or “viewed in plan” means viewing an object from the +z direction or the −z direction, and the term “planar shape” means the shape of an object as viewed in the z direction. 
     In the present specification and claims, when there are a plurality of items of a certain component and these items are described as being distinct from one another, these items may be preceded by ordinal numerals (e.g., first, second) for distinction. Between the present specification and the claims, objects to be distinguished may be different. Thus, if a component recited in a claim is preceded by the same ordinal numeral as that of a component described in the specification, an object specified by the component recited in the claim may not be identical with an object specified by the component described in the specification. 
     For example, consider that there are three items of a component in the present specification, which are distinguished by ordinal numerals, “first,” “second” and “third.” When the “first” and “third” items of the component in the specification are recited in the claims, they may be referred to as the “first” and “second” items in the claims for the sake of readability. In this case, the items of the component preceded by “first” and “second” in the claims correspond to the “first” and “third” items of the component in the specification. Note that this rule applies not only to components but also rationally and flexibly to other objects. 
     Embodiments 
       FIG.  1 A ,  FIG.  1 B ,  FIG.  1 C  and  FIG.  1 D  are diagrams showing a substrate  100  for light emitting elements (hereinafter, sometimes simply referred to as “substrate”) according to an embodiment of the present disclosure.  FIG.  1 A  is a schematic top view of the substrate  100 .  FIG.  1 B  is a schematic bottom view of the substrate  100 .  FIG.  1 C  is a schematic cross-sectional view of the substrate  100  taken along line  1 C- 1 C shown in  FIG.  1 A  and  FIG.  1 B .  FIG.  1 D  is an enlarged cross-sectional view showing a part of  FIG.  1 C . 
     The substrate  100  includes a sheet-like resin layer  10 , and a plurality of electrically-conductive layers  20  that include a first electrically-conductive layer  21  and a second electrically-conductive layer  22 . The resin layer  10  has a first surface  10   a  and a second surface  10   b  located opposite to the first surface  10   a . The second surface  10   b  has at least one groove portion  30 , which includes the first groove portion  31 , and a first region R 1  and a second region R 2  such that the first groove portion  31  is interposed therebetween. The resin layer  10  at least includes a plurality of fiber bundles and a resin. In the resin layer  10 , at least one continuous first fiber bundle included in the plurality of fiber bundles that is located at a position shallower than the bottom P of the first groove portion  31  in a cross-sectional view including the first electrically-conductive layer  21 , the first groove portion  31  and the second electrically-conductive layer  22  is provided so as to extend across the first region R 1 , the first groove portion  31  and the second region R 2  in a plan view. 
     The substrate  100  has the upper surface  100   a  and the lower surface  100   b  located opposite to the upper surface  100   a . The first surface  10   a  of the resin layer  10  is located on the same side as the upper surface  100   a  of the substrate  100 . The second surface  10   b  is located on the same side as the lower surface  100   b  of the substrate  100 . 
     The plurality of electrically-conductive layers  20 , which includes the first electrically-conductive layer  21  and the second electrically-conductive layer  22 , are provided on the second surface  10   b  of the resin layer  10 . The first electrically-conductive layer  21  is located in the first region R 1  of the resin layer  10 . The second electrically-conductive layer  22  is located in the second region R 2  of the resin layer  10 . In the present specification, an electrically-conductive layer  20  provided on the second surface  10   b  of the resin layer  10  may be referred to as “lower electrically-conductive layer.” 
     In the substrate  100  of the present embodiment, the first groove portion  31  is provided in the second surface  10   b  of the resin layer  10 , so that the distance measured along the second surface  10   b  of the resin layer  10  between the first electrically-conductive layer  21  and the second electrically-conductive layer  22  (hereinafter, sometimes referred to as “creepage distance of insulation”) can be large. Thus, occurrence of a short circuit due to ion migration between the first electrically-conductive layer  21  and the second electrically-conductive layer  22  can be suppressed. 
       FIG.  2 A  is a schematic top view of a light emitting device according to an embodiment of the present disclosure.  FIG.  2 B  is a schematic cross-sectional view of the light emitting device taken along line  2 B- 2 B shown in  FIG.  2 A . 
     A light emitting device  400  of the present embodiment includes a substrate  100  for light emitting elements and at least one light emitting element  70 . The substrate  100  for light emitting elements includes a first lower electrically-conductive layer  21 , a second lower electrically-conductive layer  22 , and a first upper electrically-conductive layer  41  and a second upper electrically-conductive layer  42  provided on the first surface  10   a  side of the resin layer  10 , such that the upper electrically-conductive layers  41  and  42  are spaced away from each other. Herein, the first electrically-conductive layer  21  shown in  FIG.  1 B  and  FIG.  1 C  is the first lower electrically-conductive layer  21 , and the second electrically-conductive layer  22  shown in  FIG.  1 B  and  FIG.  1 C  is the second lower electrically-conductive layer  22 . The first upper electrically-conductive layer  41  is electrically connected to the first lower electrically-conductive layer  21 . The second upper electrically-conductive layer  42  is electrically connected to the second lower electrically-conductive layer  22 . The light emitting device  400  of the present embodiment includes the substrate  100  for light emitting elements and at least one light emitting element  70  provided on the first surface  10   a  side of the resin layer  10 . The at least one light emitting element  70  includes a first light emitting element  71 . The first light emitting element  71  includes a first electrode  81  electrically connected to the first upper electrically-conductive layer  41  and a second electrode  82  electrically connected to the second upper electrically-conductive layer  42 . 
     Hereinafter, respective components will be described in detail. 
     [Resin Layer  10 ] 
     The resin layer  10  at least includes a plurality of fiber bundles  11  and a resin  12  as will be described later. In the configuration illustrated in  FIG.  1 A ,  FIG.  1 B  and  FIG.  1 C , the resin layer  10  is in the form of a sheet. The resin layer  10  has the first surface  10   a  and the second surface  10   b , which are parallel to the xy plane, and lateral surfaces  10   c  extending between the first surface  10   a  and the second surface  10   b . The lateral surfaces  10   c  may be perpendicular to the xy plane. The thickness d 1  of the resin layer  10  is, for example, equal to or greater than 200 μm and equal to or smaller than 900 μm. Herein, the thickness d 1  of the resin layer  10  is, for example, 300 μm. The “thickness of the resin layer” refers to the distance in the z direction between the first surface  10   a  and a part of the second surface  10   b  of the resin layer  10  in which the groove portion  30  is not provided. 
     The planar shape of the resin layer  10 , i.e., the shape of the first surface  10   a  and the second surface  10   b , is for example tetragonal. Each side of the tetragonal shape is parallel to the x axis or the y axis. In the example shown in  FIG.  1 B , the second surface  10   b  has a rectangular shape that has four corners c 1 , c 2 , c 3  and c 4  and four sides s 1 , s 2 , s 3  and s 4 . The sides s 1  and s 3  are parallel to the x axis, and the side s 3  is located on the +y side of the side s 1 . The sides s 2  and s 4  are parallel to the y axis, and the side s 4  is located on the −x side of the side s 2 . The corner formed by the side s 1  and the side s 2  is the corner c 1 . The corner c 2  is formed by the side s 2  and the side s 3 . The corner c 3  is formed by the side s 3  and the side s 4 . The corner c 4  is formed by the side s 4  and the side s 1 . The first surface  10   a  shown in  FIG.  1 A  also has a rectangular shape that is substantially equal to the second surface  10   b . The size of the first surface  10   a  and the second surface  10   b  is, for example, 6 mm×6 mm. The planar shape of the resin layer  10  may be a polygonal shape other than tetragonal shapes, for example, a triangular, pentagonal, or hexagonal shape. Note that, in this specification, the polygonal shape may involve a polygon with reshaped corners subjected to processing, such as cutting angles, chamfering, beveling, rounding, or the like, will be referred to as a polygon. Moreover, the location of such processing is not limit to a corner (an end of a side). Rather, a shape subjected to processing in the intermediate portion of a side will similarly be referred to as a polygon. In other words, any polygon-based shape subjected to processing should be understood to be included in the interpretation of a “polygon” in the description and the accompanying claims. Alternatively, the planar shape of the resin layer  10  may be a shape that includes a curve of a circular or elliptical shape. 
     As shown in  FIG.  1 B , the second surface  10   b  of the resin layer  10  has at least one groove portion  30  and a plurality of planned electrically-conductive layer regions. The planned electrically-conductive layer regions mean regions on which electrically-conductive layers  20  are to be provided. The groove portion  30  is located between two adjacent planned electrically-conductive layer regions. In the present embodiment, the plurality of planned electrically-conductive layer regions include a first region R 1  and a second region R 2 . The groove portion  30  includes a first groove portion  31  located between the first region R 1  and the second region R 2 . 
     In the example shown in  FIG.  1 B , the second surface  10   b  includes the first groove portion  31 , the first region R 1  located on the −x side of the first groove portion  31 , and the second region R 2  located on the +x side of the first groove portion  31 . The first groove portion  31  is a groove portion extending linearly in the y axis direction between the first region R 1  and the second region R 2 . The first region R 1  refers to a region surrounded by the first groove portion  31  and the periphery of the second surface  10   b  (herein, the sides s 3 , s 4  and s 1 ), and the second region R 2  refers to a region surrounded by the first groove portion  31  and the periphery of the second surface  10   b  (herein, the sides s 1 , s 2  and s 3 ). In this example, the opposite ends of the first groove portion  31  are in contact with the sides s 1  and s 3 , respectively, of the second surface  10   b  although there may be a gap between the first groove portion  31  and the side s 1  or between the first groove portion  31  and the side s 3 . Note that the first groove portion  31  may be provided according to the planar shape and the positional relationship of the first region R 1  and the second region R 2  such that, for example, the first groove portion  31  extends parallel to the x axis or extends in a direction intersecting with the x axis or the y axis (e.g., a direction inclined by ±450 with respect to the x axis). When the resin layer  10  has a polygonal planar shape, such as tetragonal planar shape, the first groove portion  31  may be provided between two vertices of the polygon so as to extend along the diagonal joining these two vertices. 
     The first groove portion  31  is preferably provided so as to intersect with a line segment of shortest distance L 1  between the first electrically-conductive layer  21  and the second electrically-conductive layer  22  in a plan view. With this arrangement, occurrence of a short circuit due to ion migration between the first electrically-conductive layer  21  and the second electrically-conductive layer  22  can be more effectively suppressed. 
     The second surface  10   b  of the resin layer  10  may be divided (separated) by at least one groove portion  30  into a plurality of regions that include the first region R 1  and the second region R 2 . The phrase “divided by a groove portion” or “separated by a groove portion” means that the groove portion  30  is provided such that the second surface  10   b  is divided into a plurality of regions and the groove portion  30  defines at least part of the periphery of each of the regions. The groove portion  30  may not be provided such that the planned electrically-conductive layer regions are thoroughly spaced away from each other. For example, the space between two planned electrically-conductive layer regions may include a portion in which the groove portion  30  is not provided. 
     The number of groove portions  30  and the number of planned electrically-conductive layer regions are not particularly limited. The second surface  10   b  of the resin layer  10  may have a plurality of groove portions  30  and three or more planned electrically-conductive layer regions. For example, the second surface  10   b  may be divided by a plurality of groove portions  30  into three or more planned electrically-conductive layer regions. The plurality of planned electrically-conductive layer regions divided by the groove portions  30  are each provided with a single electrically-conductive layer  20 , so that occurrence of a short circuit due to ion migration between two adjacent electrically-conductive layers  20  can be suppressed. In this case, in a plan view, at least one of the groove portions  30  may be provided between the two adjacent electrically-conductive layers  20 . 
     &lt;Groove Portion  30 &gt; 
     The groove portion  30  in the second surface  10   b  of the resin layer  10  can include a linear part that extends linearly in a plan view and/or a curvilinear part that extends curvilinearly in a plan view. The curvilinear part may be in the shape of a circle or ellipse or in the shape of an arc that is a part of a circle or ellipse. 
     The groove portion  30  has edges at the boundaries between the groove portion  30  and the planned electrically-conductive layer regions (herein, the first region R 1  and the second region R 2 ). In the example shown in  FIG.  1 B  and  FIG.  1 C , the first groove portion  31  has the first edge e 1  located on the first region R 1  side and the second edge e 2  located on the second region R 2  side. The first edge e 1  and the second edge e 2  face each other. The first edge e 1  and the second edge e 2  may be substantially parallel to each other. The first edge e 1  and the second edge e 2  are parallel to the y axis. The width w of the first groove portion  31 , i.e., the distance between the first edge e 1  and the second edge e 2 , is preferably equal to or greater than 50 μm and equal to or smaller than 1000 μm, more preferably equal to or greater than 100 μm and equal to or smaller than 500 μm. 
     As shown in  FIG.  1 C  and  FIG.  1 D , the groove portion  30  has the bottom P that includes a bottom surface f 3  in a cross-sectional view. In this specification, the “bottom of a groove portion” refers to a part of the groove portion  30  that is closest to the +z side in a cross-sectional view taken along the width direction of the groove portion  30 . The depth d 2  of the groove portion  30  (maximum depth) is preferably equal to or greater than ⅓ and equal to or smaller than ⅔ of the thickness d 1  of the resin layer  10 . For example, the depth d 2  is about ½ of the thickness d 1 . When the depth d 2  of the groove portion  30  is within the above-described range, the creepage distance of insulation between the electrically-conductive layers  20  located at the both sides of the groove portion  30  can be large, so that ion migration can be effectively suppressed. In contrast, when the depth d 2  of the groove portion  30  is equal to or smaller than ⅔ of the thickness d 1  of the resin layer  10 , the decrease in strength of the substrate  100 , which is attributed to the partially-reduced thickness of the resin layer  10  because of the groove portion  30 , can be suppressed. The depth d 2  of the groove portion  30  may be, for example, equal to or greater than 130 μm and equal to or smaller than 600 μm. 
     The cross-sectional shape of the groove portion  30  is not particularly limited although, in the example shown in  FIG.  1 D , the cross-sectional shape of the first groove portion  31  includes a part of a rectangle. The first groove portion  31  has the bottom surface f 3 , a lateral surface f 1  located between the bottom surface f 3  and the first edge e 1 , and a lateral surface f 2  located between the bottom surface f 3  and the second edge e 2 . The bottom surface f 3  may be substantially parallel to a portion of the second surface  10   b  exclusive of the groove portion  30  (substantially parallel to the xy plane). The lateral surfaces f 1  and f 2  may each be substantially perpendicular to the bottom surface f 3  (perpendicular to the xy plane). 
     The groove portion  30  may include another groove portion in addition to the first groove portion  31 . The width w, depth d 2 , and cross-sectional shape of the another groove portion may be the same as, or may be different from, those of the first groove portion  31 . 
     &lt;Configuration and Material of Resin Layer  10 &gt; 
       FIG.  3 A  is an enlarged cross-sectional view showing a part of the resin layer  10 .  FIG.  3 A  shows a cross section including the first groove portion  31 , the first electrically-conductive layer  21  and the second electrically-conductive layer  22 .  FIG.  3 B  is an enlarged top view showing an example of a fiber layer  13  included in the resin layer  10 .  FIG.  3 C  is an enlarged bottom view showing a part of the substrate  100 . 
     The resin layer  10  at least includes a plurality of fiber bundles  11  and a resin  12 . The resin layer  10  is realized by reinforcing the resin  12  with the fiber bundles  11 . Each of the fiber bundles  11  is a bundle including a plurality of fibers. The thickness of a single fiber is, for example, equal to or greater than 4 μm and equal to or smaller than 10 μm. In this example, the fiber bundles  11  include a plurality of longitudinal fiber bundles  112  that are substantially parallel to the y-axis direction and a plurality of transverse fiber bundles  113  that are substantially parallel to the x-axis direction. The longitudinal fiber bundles  112  and the transverse fiber bundles  113  are provided so as to intersect with each other in a plan view. In the illustrated example, the longitudinal fiber bundles  112  are provided along the y axis and the transverse fiber bundles  113  are provided along the x axis, although they are not limited to these arrangements. 
     The resin layer  10  may include at least one fiber layer  13  configured of a plurality of fiber bundles  11 . Each fiber layer  13  may be fiber cloth formed by weaving together the longitudinal fiber bundles  112  and the transverse fiber bundles  113  as illustrated in  FIG.  3 B . The resin layer  10  preferably includes a plurality of fiber layers  13 . As shown in  FIG.  3 A , the plurality of fiber layers  13  may be stacked up in the thickness direction of the resin layer  10  (z direction) with predetermined intervals therebetween. 
     The plurality of fiber bundles  11  include at least one continuous first fiber bundle  11 Y located at a position shallower than the bottom P of the first groove portion  31 . In a part of the resin layer  10  (herein, a part of the resin layer  10  in which the groove portion  30  is not provided), the first fiber bundle  11 Y is located at a smaller depth along the +z direction from the second surface  10   b  of the resin layer  10  than the depth of the bottom P. The resin layer  10  preferably includes a plurality of first fiber bundles  11 Y. 
     As shown in  FIG.  3 A  and  FIG.  3 C , the first fiber bundles  11 Y are provided so as to extend across the first region R 1 , the first groove portion  31  and the second region R 2  inside the resin layer, in a cross-sectional view and in a plan view. That is, in a cross-sectional view and in a plan view, a part of a first fiber bundle  11 Y overlapping the first region R 1 , another part of the first fiber bundle  11 Y overlapping the first groove portion  31 , and still another part of the first fiber bundle  11 Y overlapping the second region R 2  are connected together (continuous). In the illustrated example, the first fiber bundles  11 Y meet the first edge e 1  and the second edge e 2  of the first groove portion  31 . 
     In the present specification, in a plan view, parts p 1  of the resin layer  10  overlapping the electrically-conductive layers  20  are referred to as “first portions,” and a part p 2  of the resin layer  10  overlapping the groove portion  30  is referred to as “second portion.” In this example, parts of the resin layer  10  overlapping the first electrically-conductive layer  21  and the second electrically-conductive layer  22  are the first portions p 1 , and a part of the resin layer  10  overlapping the first groove portion  31  is the second portion p 2 . The thickness of the second portion p 2  is smaller than that of the first portions p 1  by, for example, the depth d 2  of the first groove portion  31 . 
     The first fiber bundles  11 Y may extend across the first portions p 1  and the second portion p 2  in a plan view. As seen from  FIG.  3 A , the first fiber bundles  11 Y in the first portions p 1  of the resin layer  10  are located at a position shallower than the bottom P of the first groove portion  31 , while the first fiber bundles  11 Y in the second portion p 2  are located between the bottom P of the first groove portion  31  and the first surface  10   a  of the resin layer  10 . Accordingly, the surface of at least one groove portion  30  is defined by only the resin portion  12  of the resin layer  10 . In a cross-sectional view, the first fiber bundles  11 Y are bent in the depth direction of the first groove portion  31  (+z direction) along the first groove portion  31 . As shown in the drawings, in a cross-sectional view including the first electrically-conductive layer  21 , the first groove portion  31  and the second electrically-conductive layer  22 , the first fiber bundles  11 Y are bent in the +z direction along the lateral surfaces f 1  and f 2  of the first groove portion  31  and, thus, the first fiber bundles  11 Y have a recessed portion  11 Yd that is recessed in the +z direction. 
     The plurality of fiber layers  13  may include at least one first fiber layer  13 Y located at a position shallower than the bottom P of the first groove portion  31 . The first fiber layer  13 Y may be continuously provided across the first region R 1 , the first groove portion  31  and the second region R 2  in a plan view. For example, three or more fiber layers  13  may be stacked up in the resin layer  10 . In this case, the strength of the resin layer  10  can be more effectively improved. One or some of the plurality of fiber layers  13  located at a position deeper than the bottom P of the first groove portion  31  may include fiber bundles  11  bent in the +z direction along the lateral surfaces f 1  and f 2  of the first groove portion  31 . 
     The second surface  10   b  of the resin layer  10  can have a plurality of groove portions  30  that includes the first groove portion  31 . The foregoing description has been provided based on an example of the configuration of fiber bundles  11  that overlap the first groove portion  31 , the first region R 1  and the second region R 2  in a plan view, although fiber bundles  11  that overlap each of the plurality of groove portions  30  and planned electrically-conductive layer regions located on the opposite sides of the groove portion  30  in a plan view can also have the same configuration as that described above. That is, the plurality of fiber bundles  11  include at least one continuous first fiber bundle located at a position shallower than the bottom P of each groove portion  30 , and the first fiber bundle may be provided so as to extend across the groove portion  30  and two planned electrically-conductive layer regions located on the both sides of the groove portion  30  in a plan view. The first fiber bundle may be bent in the depth direction (+z direction) along the groove portion  30  in a cross-sectional view. 
     The resin layer  10  includes the first portions p 1  overlapping the first electrically-conductive layer  21  or the second electrically-conductive layer  22  in a plan view and the second portion p 2  overlapping at least one groove portion  30  in a plan view. The second portion p 2  of the resin layer  10  has a smaller thickness than the first portions p 1  but can include an approximately equal number of fiber bundles  11  or an approximately equal number of fiber layers  13  to those included in the first portions p 1 . Therefore, the density of the fiber bundles  11  in the second portion p 2  of the resin layer  10  can be greater than the density of the fiber bundles  11  in the first portions p 1 . Thus, the strength of the second portion p 2  of the resin layer  10  can be secured. 
     At least one fiber bundle  11  may include two or more fiber bundles  11  that are stacked up in the thickness direction of the resin layer  10  between the first surface  10   a  and the second surface  10   b  of the resin layer  10 . When the resin layer  10  includes the first portions p 1  overlapping the first electrically-conductive layer  21  or the second electrically-conductive layer  22  in a plan view and the second portion p 2  overlapping at least one groove portion  30  in a plan view, the stacking interval of the fiber bundles  11  in the second portion p 2  of the resin layer  10  is preferably smaller than the stacking interval of the fiber bundles  11  in the first portions p 1 . It is preferred that, for example, two or more fiber layers  13  each including the fiber bundles  11  are stacked up in the thickness direction of the resin layer  10 , and the stacking interval of the fiber layers  13  in the second portion p 2  is smaller than the stacking interval of the fiber layers  13  in the first portions p 1 . 
     In the resin layer  10  of the present embodiment, the first fiber bundles  11 Y located at a position shallower than the bottom P of the groove portion  30  are continuously provided so as to extend across the groove portion  30  in a plan view. That is, a part of the first fiber bundles  11 Y is located between the groove portion  30  and the first surface  10   a  of the resin layer  10 . The surface of the groove portion  30  is defined by only the resin  12  such that the fiber bundles  11  cannot be exposed, as is the second surface  10   b  of the resin layer  10  exclusive of the groove portion  30 . Therefore, the entire second surface  10   b  of the resin layer  10  is smooth. The method of forming the resin layer  10  having such a configuration will be described later. 
     The resin layer  10  is a layer formed by curing a pre-preg as will be described later. In this specification, the pre-preg is a material provided by impregnating fiber bundles with a thermosetting resin. The thermosetting resin in the pre-preg is in a state called B stage, in which the resin is not yet fully cured. B stage means that the thermosetting resin is semi-cured. The semi-cured resin can be once melted by increasing the temperature and, thereafter, application of heat can cause a curing reaction of the resin so that the resin can be fully cured. 
     The type of the resin  12  in the resin layer  10  is not particularly limited. The resin  12  can be an epoxy resin, polyimide resin, phenol resin or melamine resin, or a combination thereof. 
     The material of the fiber bundles  11  is not particularly limited. The material of the fiber bundles  11  can be glass fiber, ceramic fiber, carbon fiber or aramid fiber, or a combination thereof. The resin layer  10  of the present embodiment is preferably a glass epoxy resin layer formed by impregnating glass fiber cloth with an epoxy resin and performing a heat curing treatment on the resultant cloth. 
     The resin layer  10  may further include an inorganic filler of high thermal conductivity such that the resin layer  10  can have a heat radiation function. The inorganic filler can be silica, alumina, aluminum nitride, boron nitride, silicon carbide, magnesium oxide, zinc oxide, aluminum hydroxide, or the like. 
     [Electrically-Conductive Layers  20 ] 
     The electrically-conductive layers  20  include at least a pair of positive and negative electrically-conductive layers, through which power is supplied to a light source section (described later) placed on the first surface  10   a  of the resin layer  10 . The electrically-conductive layers  20  are electrically connected to, for example, an external circuit or power supply. 
     In the example illustrated in  FIG.  1 B  and  FIG.  1 C , the planar shape of each electrically-conductive layer  20  is substantially rectangular. The size of the rectangle in a plan view is, for example, 6 mm×6 mm. Note that the size of the electrically-conductive layers  20  may be smaller than the planned electrically-conductive layer regions on which the electrically-conductive layers  20  are to be provided (herein, the first region R 1  and the second region R 2 ). The planar shape of the electrically-conductive layers  20  is not limited to rectangular shapes. As shown in the drawings, some of the electrically-conductive layers  20  may have a cutaway portion at a corner such that the polarity of the electrically-conductive layers  20  can be identified. Each of the electrically-conductive layers  20  can have a planar shape substantially similar or conformable to a corresponding planned electrically-conductive layer region R 1 , R 2 . Further, the planar shape or size of the plurality of electrically-conductive layers  20  may be the same or may be different. 
     As shown in  FIG.  1 B , the plurality of electrically-conductive layers  20  are provided on the second surface  10   b  of the resin layer  10  so as to be spaced away from each other. In this example, the first electrically-conductive layer  21  and the second electrically-conductive layer  22  are provided as the electrically-conductive layers  20 . Note that three or more electrically-conductive layers  20  may be provided on the second surface  10   b . Each of the electrically-conductive layers  20  is provided on either of a plurality of planned electrically-conductive layer regions in the second surface  10   b . Preferably, a single electrically-conductive layer  20  is provided on a single planned electrically-conductive layer region. Preferably, each of the electrically-conductive layers  20  is located away from the edges of the groove portion  30  in a plan view. 
     Preferably, the shortest distance L 1  between two adjacent electrically-conductive layers  20  in a plan view is, for example, equal to or greater than 50 μm. In this case, occurrence of a short circuit due to ion migration between these electrically-conductive layers  20  can be more effectively suppressed. The upper limit of the shortest distance L 1  between the electrically-conductive layers  20  is not particularly limited but may be, for example, equal to or smaller than 1000 μm from the viewpoint of reducing the size of the light emitting device. 
     [Upper Electrically-Conductive Layers  40 ] 
     As shown in  FIG.  1 A  and  FIG.  1 C , the substrate  100  may further include a plurality of upper electrically-conductive layers  40  on the first surface  10   a  of the resin layer  10 . 
     The plurality of upper electrically-conductive layers  40  include at least a pair of positive and negative electrically-conductive layers and can be electrically connected to the electrodes of a light source section placed on the upper surface  100   a  side of the substrate  100 , which will be described later. Each of the upper electrically-conductive layers  40  is electrically connected to, for example, a corresponding one of the electrically-conductive layers  20  via an electrical conductor  50  provided in a through-hole of the resin layer  10 . In a plan view, each of the upper electrically-conductive layers  40  may be provided so as to overlap at least a part of a corresponding one of the electrically-conductive layers  20 . 
     In the example illustrated in  FIG.  1 A , the planar shape of each of the upper electrically-conductive layers  40  is substantially rectangular. The size of the rectangle is, for example, 3 mm×1 mm. Note that the planar shape, size, and arrangement of the upper electrically-conductive layers  40  can be selected according to the shape, size, and arrangement of the positive and negative electrodes of the light emitting element. The planar shape and size of the plurality of upper electrically-conductive layers  40  may be the same or may be different. 
     In the present embodiment, the plurality of upper electrically-conductive layers  40  include the first upper electrically-conductive layer  41  and the second upper electrically-conductive layer  42 . The first upper electrically-conductive layer  41  and the second upper electrically-conductive layer  42  are provided on the first surface  10   a  of the resin layer  10  so as to be spaced away from each other. The first upper electrically-conductive layer  41  is electrically connected to the first electrically-conductive layer  21  provided on the second surface  10   b  of the resin layer  10 . Likewise, the second upper electrically-conductive layer  42  is electrically connected to the second electrically-conductive layer  22 . The material of the lower electrically-conductive layers  20  and the upper electrically-conductive layers  40  can be a metal selected from the group consisting of Cu, Ag, Au, Ni, Fe and Al, or at least one type of alloys containing these metals as a major constituent. In the present embodiment, the lower electrically-conductive layers  20  are, for example, Cu layers plated with Au. The thickness of the electrically-conductive layers  20  is, for example, equal to or greater than 10 μm and equal to or smaller than 110 μm. The upper electrically-conductive layers  40  are, for example, Cu layers covered by an Au film. The thickness of the upper electrically-conductive layers  40  is, for example, equal to or greater than 10 μm and equal to or smaller than 110 μm. 
     [Electrical Conductor  50 ] 
     As shown in  FIG.  1 A ,  FIG.  1 B  and  FIG.  1 C , the substrate  100  may further include a plurality of electrical conductors  50 . Each of the electrical conductors  50  is provided in a through-hole penetrating through the resin layer  10  in the thickness direction. Each of the electrical conductors  50  is in contact with a corresponding one of the electrically-conductive layers  20  and a corresponding one of the upper electrically-conductive layers  40  such that these electrically-conductive layers  20  and the upper electrically-conductive layers  40  are electrically connected together. The electrical conductors  50  are, for example, Cu layers. The electrical conductors  50  preferably fill the through-holes of the resin layer  10  but may be provided only on the lateral surface of the through-holes. 
     In the illustrated example, the electrical conductors  50  include the first electrical conductor  51  and the second electrical conductor  52 . The first electrical conductor  51  electrically connects the first electrically-conductive layer  21  and the first upper electrically-conductive layer  41 . The second electrical conductor  52  electrically connects the second electrically-conductive layer  22  and the second upper electrically-conductive layer  42 . 
     (First Substrate  1000 ) 
     The substrate of the present embodiment may be a substrate having a plurality of unit regions (hereinafter, referred to as “first substrate”). The first substrate  1000  can be divided or singulated into individual pieces corresponding to the unit regions, whereby a plurality of substrates  100  are obtained. Note that, in this specification, the term “substrate for light emitting elements” involves not only the substrates obtained after the singulation but also the first substrate before the singulation. 
       FIG.  4 A  is a schematic bottom view showing an example of the first substrate  1000 .  FIG.  4 B  is an enlarged bottom view showing a part of the first substrate  1000 .  FIG.  4 C  is an enlarged cross-sectional view of the first substrate  1000  taken along line  4 C- 4 C shown in  FIG.  4 B . 
     The first substrate  1000  includes a plurality of unit regions U that are two-dimensionally arrayed. In the illustrated example, the plurality of unit regions U are aligned in the x direction and the y direction. 
     The first substrate  1000  includes a resin layer  10  that has a first surface  10   a  and a second surface  10   b . The resin layer  10  is continuous across the plurality of unit regions U. In each of the unit regions U, a plurality of upper electrically-conductive layers  40  are provided on the first surface  10   a  of the resin layer  10 , and a first electrically-conductive layer  21  and a second electrically-conductive layer  22  are provided on the second surface  10   b . In each of the unit regions U, the second surface  10   b  of the resin layer  10  has a first groove portion  31 . In the illustrated example, in each of the unit regions U, the shape and arrangement of the electrically-conductive layers  20 , the upper electrically-conductive layers  40  and the groove portion  30  are, for example, the same as or similar to those in the substrate  100  illustrated in  FIG.  1 A ,  FIG.  1 B  and  FIG.  1 C . 
     The groove portion  30  in each of the unit regions U may be in communication with the groove portions  30  in the neighboring unit regions U. In this example, the first groove portions  31  of two-unit regions U that neighbor each other in the y direction are in communication with each other. As shown in the drawings, the first groove portions  31  may be provided continuously in the y direction across the first substrate  1000 . Alternatively, as illustrated in  FIG.  5   , the first groove portions  31  of the unit regions U may be provided so as to be spaced away from one another. Note that, in the first substrate  1000  shown in  FIG.  4 A ,  FIG.  4 B ,  FIG.  4 C  and  FIG.  5   , the through-holes penetrating through the resin layer  10  in the thickness direction and the electrical conductors  50  are not shown. 
     (Light Emitting Device  400 ) 
     Next, an example of a light emitting device  400 , which includes the substrate  100  of the present embodiment, is described with reference again to  FIG.  2 A  and  FIG.  2 B . 
     The light emitting device  400  includes a substrate  100  and a light source section  200 . 
     [Light Source Section  200 ] 
     The light source section  200  is provided on the upper surface  100   a  side of the substrate  100 . The light source section  200  has a light emission surface  200   a  located opposite to the substrate  100 . 
     In the present embodiment, the light source section  200  includes at least one light emitting element  70 , which includes the first light emitting element  71 . The light emitting element  70  is located on the upper surface  100   a  side of the substrate  100 , i.e., the first surface  10   a  side of the resin layer  10 . In the illustrated example, only the first light emitting element  71  is provided on the upper surface  100   a  of the substrate  100 , although two or more light emitting elements  70  may be two-dimensionally arrayed on the upper surface  100   a.    
     &lt;Light Emitting Element  70 &gt; 
     As shown in  FIG.  2 B , the light emitting element  70  has a light exit surface  70   a  from which large part of light exits, an electrode-formation surface  70   b  located opposite to the light exit surface  70   a , and lateral surfaces  70   c  connected to the light exit surface  70   a  and the electrode-formation surface  70   b . The light emitting element  70  includes at least a pair of positive and negative electrodes  81  and  82  located on the electrode-formation surface  70   b . In the illustrated example, the light exit surface  70   a  of the light emitting element  70  is identical with the light emission surface  200   a  of the light source section  200 . The electrodes  81  and  82  are each electrically connected to a corresponding one of the upper electrically-conductive layers  40  via a bonding material, such as solder, electrically-conductive paste, or the like. In this example, the electrode  81  is electrically connected to the first upper electrically-conductive layer  41  while the electrode  82  is electrically connected to the second upper electrically-conductive layer  42 . 
     The shape of the light emitting element  70  in a plan view is, for example, rectangular. The size of the light emitting element  70  is not particularly limited. The longitudinal and transverse dimensions of the light emitting element  70  are, for example, equal to or smaller than 5 mm, preferably equal to or smaller than 4 mm. More preferably, the longitudinal and transverse dimensions of the light emitting element  70  are equal to or smaller than 3 mm. In the present embodiment, in a plan view, the light emitting element  70  has a square shape of 3 mm on each side. 
     The light emitting element  70  can be selected from various types of light emitting elements, including semiconductor lasers, light-emitting diodes, etc. In the present embodiment, the light emitting element  70  is, for example, a light-emitting diode that includes a light-transmitting substrate, such as sapphire substrate, and a semiconductor multilayer body stacked on the light-transmitting substrate. The wavelength of light to be emitted from the light emitting element  70  is discretionary selectable. For example, light emitting elements including a nitride semiconductor (In x Al y Ga 1-x-y N, 0≤X, 0≤Y, X+Y≤1), or a semiconductor such as ZnSe and GaP, can be used as blue and green light emitting elements. Light emitting elements including a semiconductor such as GaAlAs, AlInGaP, or the like, can be used as red light emitting elements. 
     Semiconductor light emitting elements including other materials than those mentioned above can also be used. The composition of the materials in the light emitting elements used, the color of light to be emitted from the light emitting elements, and the size and number of the light emitting elements may be appropriately selected according to what the light emitting elements are applied to. As will be described later, when the light source section  200  includes a wavelength conversion layer, the emission layer of the light emitting element  70  preferably emits light at such a short wavelength that the light can efficiently excite a wavelength converting substance contained in the wavelength conversion layer. 
     The electrodes  81 ,  82  are made of a known metal material that can be electrically connected to the semiconductor multilayer body. The material of the electrodes  81 ,  82  can be, for example, at least one type of metal selected from Ni, Pt, Cu, Au, Ag, AuSn, and the like. The shape of the electrodes  81 ,  82  in a plan view is not particularly limited but may be appropriately selected from rectangular, polygonal, circular, and elliptical shapes. 
     [Other Examples of Light Source Section] 
     The configuration of the light source section is not limited to the example shown in  FIG.  2 A  and  FIG.  2 B .  FIG.  6    is a cross-sectional view for illustrating the substrate  100  and another light source section  201  according to the present embodiment. 
     The light source section  201  includes a light emitting element  70  (herein, first light emitting element  71 ), a wavelength conversion layer  90 , a diffusing layer  92 , and a reflector  94 . The light source section  201  has a light emission surface  201   a  located on or above (+x direction) the light exit surface  70   a  of the light emitting element  70 . In this example, the light source section  201  includes only a single light emitting element  70 , although the light source section  201  may include a plurality of light emitting elements  70  that are two-dimensionally arrayed. 
     &lt;Wavelength Conversion Layer  90 &gt; 
     The wavelength conversion layer  90  is located on or above (+z direction) the light exit surface  70   a  of the light emitting element  70 . The wavelength conversion layer  90  absorbs at least part of light emitted from the light emitting element  70  such that light exiting from the wavelength conversion layer  90  has a different wavelength from that of the light emitted from the light emitting element  70 . 
     The wavelength conversion layer  90  may have a substantially rectangular shape in a plan view. Preferably, in a plan view, the wavelength conversion layer  90  is larger than the light exit surface  70   a  of the light emitting element  70  and covers the entire light exit surface  70   a . In this case, the light emitted from the light emitting element  70  can efficiently enter the wavelength conversion layer  90 , and the light exiting from the wavelength conversion layer  90  can have a converted wavelength. 
     In the present embodiment, the wavelength conversion layer  90  is in the shape of, for example, a square of 3.2 mm on each side in a plan view. The thickness in the z-axis direction of the wavelength conversion layer  90  is, for example, 40 μm. 
     The wavelength conversion layer  90  contains, for example, a resin as the basic material, and a wavelength converting substance dispersed in the resin. The basic material can be, for example, a light-transmitting material, such as epoxy resin, silicone resin, or a mixture thereof, or glass. From the viewpoint of light resistance and easy moldability, the basic material of the wavelength conversion layer  90  is preferably a silicone resin. Particularly preferably, the basic material contains a phenyl silicone resin as a major constituent. The wavelength conversion layer  90  may be made of a ceramic or glass material (major material) in which a wavelength converting substance is contained. 
     The wavelength converting substance is excited by light emitted from the light emitting element  70  to emit light having a different wavelength from that of the light emitted from the light emitting element  70 . Examples of the wavelength converting substance include yttrium aluminum garnet (YAG)-based phosphors activated with cerium (e.g., Y 3 (Al,Ga) 5 O 12 :Ce), lutetium aluminum garnet (LAG)-based phosphors activated with cerium (e.g., Lu 3 (Al,Ga)O 12 :Ce), terbium aluminum garnet-based phosphors (e.g., Tb 3  (Al, Ga) 5 O 12 : Ce), nitrogen-containing calcium aluminosilicate (CaO—Al 2 O 3 —SiO 2 )-based phosphors activated with europium and/or chromium, silicate ((Sr,Ba) 2 SiO 4 )-based phosphors activated with europium, β sialon-based phosphors (e.g., (Si,Al) 3 (O,N) 4 :Eu), α sialon-based phosphors (e.g., M z (Si,Al) 12 (O,N) 16  (where 0&lt;z≤2 and M is Li, Mg, Ca, Y, or a lanthanide element other than La and Ce)), nitride-based phosphors such as CASN-based phosphors (e.g., CaAlSiN 3 :Eu) or SCASN-based phosphors (e.g., (Sr,Ca)AlSiN 3 :Eu), fluoride-based phosphors such as KSF-based phosphors (e.g., K 2 SiF 6 :Mn 4+ ) or MGF-based phosphors (e.g., 3.5MgO.0.5MgF 2 . GeO 2 :Mn), sulfide-based phosphors, perovskite, chalcopyrite, and quantum dots. The other types of phosphors than those mentioned above can also be used so long as they have similar properties, functions, and effects. The wavelength conversion layer  90  may contain only one type of the aforementioned wavelength converting substances but preferably contains a plurality of types of wavelength converting substances. For example, the wavelength conversion layer  90  preferably contains a LAG-based phosphor capable of emission of greenish light and a CASN-based phosphor capable of emission of reddish light. In this case, the light source section  201  capable of emission of white light can be realized. Because a plurality of types of wavelength converting substances are contained, the wavelength band can be enlarged, and occurrence of a wavelength range of low emission intensity can be suppressed. The amount of the wavelength converting substances contained in the wavelength conversion layer  90  is, for example, 10 to 80 weight %. Note that, in this specification, the term “weight %” means the proportion of the weight of a substance (herein, wavelength converting substance) contained in a basic material with respect to the total weight of the basic material and the contained substance. 
     The wavelength conversion layer  90  may contain a material other than the wavelength converting substance. For example, a material whose refractive index is different from that of the basic material may be dispersed in the wavelength conversion layer  90 . For example, particles capable of diffusing light, such as titanium oxide or silicon oxide particles, may be dispersed in the basic material of the wavelength conversion layer  90 . 
     &lt;Diffusing Layer  92 &gt; 
     The diffusing layer  92  may be located on or above (+z direction) the wavelength conversion layer  90 . The diffusing layer  92  diffuses light emitted from the light emitting element  70 . 
     The diffusing layer  92  may have a substantially rectangular shape in a plan view. Preferably, in a plan view, the diffusing layer  92  is larger than the light exit surface  70   a  of the light emitting element  70  and covers the entire light exit surface  70   a . The size of the diffusing layer  92  may be substantially equal to the size of the wavelength conversion layer  90 . In the present embodiment, the diffusing layer  92  is in the shape of, for example, a square of 3.2 mm on each side in a plan view. The thickness in the z-axis direction of the diffusing layer  92  is, for example, 30 μm. 
     The diffusing layer  92  includes a resin as the basic material and a diffusing material dispersed in the resin. The basic material can be a light-transmitting material, such as epoxy resin, silicone resin, or a mixture thereof, or glass. From the viewpoint of light resistance and easy moldability, the basic material of the diffusing layer  92  is preferably a silicone resin. Particularly preferably, the basic material contains a phenyl silicone resin as a major constituent. When the basic material of the diffusing layer  92  is the same resin as that of the wavelength conversion layer  90 , the adhesion between the wavelength conversion layer  90  and the diffusing layer  92  can be improved. The diffusing layer  92  may be formed of a ceramic or glass material (major material) in which the diffusing material is contained. 
     The diffusing material may be, for example, a high-reflectance material, such as white filler of titanium oxide, silicon oxide, alumina, zinc oxide, or the like. The concentration of the diffusing material is preferably equal to or higher than 0.1 weight % and equal to or lower than 3.0 weight %. The diffusing layer  92  may further contain a glass filler, or the like, in order to suppress expansion and shrinkage of the basic material resin due to heat. The concentration of the glass filler is preferably equal to or higher than 50 weight % and equal to or lower than 80 weight %. Note that the concentrations of the diffusing material and the glass filler are not limited to these examples. The diffusing layer  92  preferably contains titanium oxide and a glass filler. 
     &lt;Reflector  94 &gt; 
     The reflector  94  covers at least the lateral surfaces  70   c  of the light emitting element  70 , the electrode-formation surface  70   b , the lateral surfaces of the electrodes  81 ,  82 , the lateral surfaces of the wavelength conversion layer  90 , and the lateral surfaces of the diffusing layer  92 . 
     The reflector  94  reflects light emitted from the lateral surfaces  70   c  of the light emitting element  70  such that the reflected light travels toward a side above the light emitting element  70  (in the +z direction). The reflector  94  also reflects light traveling from the electrode-formation surface  70   b  of the light emitting element  70  toward the substrate  100  side such that the reflected light travels toward a side above the light emitting element  70  (in the +z direction). Thus, the utilization efficiency of the light emitted from the light emitting element  70  can be improved. 
     The reflector  94  includes a resin as the basic material and a reflective substance dispersed in the resin. The basic material can be a light-transmitting material, such as epoxy resin, silicone resin, or a mixture thereof. From the viewpoint of light resistance and easy moldability, the basic material of the reflector  94  is preferably a silicone resin. When the basic material of the reflector  94  is the same resin as those of the wavelength conversion layer  90  and the diffusing layer  92 , the adhesion to the wavelength conversion layer  90  and the diffusing layer  92  can be improved. 
     Examples of the reflective substance include titanium oxide, silicon oxide, zirconium oxide, yttrium oxide, yttria-stabilized zirconia, potassium titanate, alumina, aluminum nitride, boron nitride, and mullite. The concentration of the reflective substance in the reflector  94  is preferably equal to or higher than 10 weight % and equal to or lower than 70 weight %. The reflector  94  may further contain a glass filler, or the like, in order to suppress expansion and shrinkage of the basic material resin due to heat. The concentration of the glass filler is preferably higher than 0 weight % and lower than 30 weight %, more preferably equal to or higher than 5 weight % and equal to or lower than 20 weight %. Note that the concentrations of the reflective substance and the glass filler are not limited to these examples. The reflector  94  preferably contains titanium oxide and a glass filler. 
     [Lens Unit  300 ] 
     The light emitting device of the present embodiment may be a light emitting device  500  that further includes a lens  300 . An example of the light emitting device  500  is now described that includes the substrate  100  of the present embodiment.  FIG.  7 A  is a schematic top view of the light emitting device  500 .  FIG.  7 B  is a schematic bottom view of the light emitting device  500 .  FIG.  7 C  is a schematic cross-sectional view of the light emitting device  500  taken along line  7 C- 7 C shown in  FIG.  7 A  and  FIG.  7 B .  FIG.  7 D  is a schematic lateral side view of the light emitting device  500  as viewed in the +y axis direction. 
     The lens  300  includes a lens section  310  and a lens holder  320  located outside the lens section  310  so as to surround the periphery of the lens section  310 . The lens holder  320  is continuously (integrally) formed with the lens section  310 . 
     As shown in  FIG.  7 A ,  FIG.  7 B  and  FIG.  7 C , the lens  300  is provided so as to cover the light source section  200 . As shown in the drawings, the lens  300  may cover the upper surface  100   a  and the lateral surfaces of the substrate  100  while the lower surface  100   b  of the substrate  100  is exposed. 
     The lens  300  may be formed of a light-transmitting resin. The light-transmitting resin can be a thermoplastic resin, such as polycarbonate, acrylic resins, cyclic polyolefin, polyethylene terephthalate, and polyester, or a thermosetting resin, such as phenolic resins, urea resins, melamine resins, epoxy resins, silicone resins, and polyurethane. Among these examples, polycarbonate is preferred. 
     &lt;Lens Portion  310 &gt; 
     The lens section  310  is located on or above (+z direction) the light emission surface  200   a  of the light source section  200  (herein, the light exit surface  70   a  of the light emitting element  70 ). The lens section  310  is an optical function section capable of refracting light emitted from the light source section  200  and transmitted through the lens section  310  such that the light exiting from the lens section  310  travels in the +z direction. The lens section  310  preferably covers the entire light emission surface  200   a  in a plan view. The lens section  310  may be a convex lens, such as biconvex lens, plano-convex lens, and convex meniscus lens, a concave lens, such as biconcave lens, plano-concave lens, and concave meniscus lens, or a Fresnel lens. 
     In the present embodiment, the contour of the lens section  310  in a plan view is substantially circular. The diameter of the lens section  310  is preferably equal to or greater than 6 mm and equal to or smaller than 8 mm, and may be about 6.8 mm, for example. The thickness of the lens section  310  is preferably equal to or greater than 1 mm and equal to or smaller than 2 mm, and may be about 1.5 mm, for example. Note that the contour of the lens section  310  in a plan view is not particularly limited but may have a polygonal shape, such as tetragon, hexagon or octagon. 
     The lens section  310  has a light entry surface  310   b  located on the light emission surface  200   a  side of the light source section  200  and a light exit surface  310   a  located on the side (+z side) opposite to the light entry surface  310   b . In the present embodiment, the light entry surface  310   b  of the lens section  310  has a Fresnel shape. The center of the lens section  310  is coincident with the center of the light emission surface  200   a  (herein, the light exit surface  70   a  of the first light emitting element  71 ). Meanwhile, the light exit surface  310   a  of the lens section  310  is substantially flat. In this example, the term “the light exit surface of the lens section” refers to a part of the lens  300  overlapping the light entry surface  310   b  in a plan view. When the lens section  310  has a Fresnel shape, the thickness of the lens  300  can be reduced. Accordingly, the thickness of the light emitting device  500  can be reduced. 
     &lt;Lens Holder  320 &gt; 
     The lens holder  320  is a member for holding the lens section  310 . The lens holder  320  is continuous at the periphery of the lens section  310  and is elongated downward (in the −z direction). In this example, the lens holder  320  has a cylindrical shape in a plan view. The thickness in the x-axis direction or the y-axis direction of the lens holder  320  is, for example, equal to or greater than 0.3 mm and equal to or smaller than 1.0 mm. The height in the z direction of the lens holder  320 , i.e., the distance from the upper end of the lens holder  320  (in other words, the light exit surface  310   a ) to the lower end of the lens holder  320 , is for example equal to or greater than 1.0 mm and equal to or smaller than 5.0 mm, and can be adjusted such that an air layer can be formed between the light entry surface  310   b  of the lens section  310  and the light emission surface  200   a  of the light source section  200 . 
     The lower surface  320   b  of the lens holder  320  is preferably coplanar with the lower surface  100   b  of the substrate  100  or located at a position lower than the lower surface  100   b . In a cross-sectional view, the lens holder  320  may be spaced away from the substrate  100 . 
     In this example, in a plan view, the periphery of the lens holder  320  has a tetragonal shape, and the size of the tetragon is, for example, 8 mm×8 mm. The shape of the periphery of the lens holder  320  in a plan view is not particularly limited but may be circular, elliptical, or polygonal. The lens holder  320  may have a cutaway portion in at least one corner such that the orientation of the light emitting device  500  can be identified. 
     When the light source section  200  includes a plurality of light emitting elements  70  that are two-dimensionally arrayed, the center of the lens section  310  may be aligned with the center of the substrate. When the lens section  310  includes a plurality of Fresnel lenses and the plurality of light emitting elements  70  are provided so as to form one-to-one pairs with the Fresnel lenses, the center of each of the Fresnel lenses may be aligned with the center of a corresponding one of the light emitting elements  70 . 
     (Method of Producing Substrate for Light Emitting Elements) 
     Hereinafter, a method of producing a substrate according to the present embodiment is described with reference to the drawings, based on an example of the method of producing the first substrate  1000  shown in  FIG.  4 A ,  FIG.  4 B  and  FIG.  4 C .  FIG.  8 A  and  FIG.  8 B  are, respectively, a top view and a cross-sectional view showing a part of a metal plate for use in production of the first substrate.  FIG.  8 C  is a cross-sectional view showing a part of a pre-preg for use in production of the first substrate.  FIG.  9 A ,  FIG.  9 B ,  FIG.  9 C ,  FIG.  9 D ,  FIG.  9 E ,  FIG.  9 F  and  FIG.  9 G  are each a cross-sectional view showing a step of the production method of the first substrate. For the sake of simplicity,  FIG.  9 A ,  FIG.  9 B ,  FIG.  9 C ,  FIG.  9 D ,  FIG.  9 E ,  FIG.  9 F  and  FIG.  9 G  show only a part of the first substrate corresponding to two-unit regions U. 
     A method of producing a substrate for light emitting elements according to the present embodiment includes: (I) providing a sheet-like metal plate  120  and a pre-preg, the metal plate  120  having a first surface  120   a  and at least one raised portion (or ridge)  121  at the first surface  120   a , the pre-preg including a plurality of fiber bundles and a resin; (II) binding together the first surface of the metal plate and the pre-preg; (III) forming a resin layer  10 , which includes curing the pre-preg; (IV) forming a resist on the metal plate; (V) etching away the at least one raised portion of the metal plate; and (VI) removing the resist. 
     According to the present embodiment, after a first substrate  1000  that has a plurality of unit regions U has been produced by the above-described method, the first substrate  1000  may be divided or singulated into individual pieces corresponding to the unit regions U. This procedure can improve the productivity. 
     &lt;Step (I)&gt; 
     Providing a Metal Plate 
     A metal plate  120  shown in  FIG.  8 A  and  FIG.  8 B  is provided. Herein, a Cu plate having the thickness of, for example, 0.1 mm and the size of, for example, 1.2 m×1.0 m is provided, and etching (e.g., wet etching) is performed on a surface of the Cu plate, whereby a sheet-like metal plate  120  having at least one raised portion  121  is formed. The metal plate  120  has a first surface  120   a  and a second surface  120   b  located opposite to the first surface  120   a . The first surface  120   a  preferably has a plurality of raised portions  121 . The height of the raised portions  121  is, for example, 0.05 mm while the thickness of the metal plate  120  exclusive of the raised portions  121  is, for example, equal to or greater than 0.035 mm and equal to or smaller than 0.5 mm. 
     In this example, in a plan view, the plurality of raised portions  121 , which are parallel to the y axis, are provided with intervals in the x direction across the first surface  120   a . Each of the raised portions  121  may continuously extend from one end to the other end of the first surface  120   a  of the metal plate  120 . The height of the raised portions  121  can be determined according to, for example, the depth of the groove portions  30  to be formed in the first substrate  1000  shown in  FIG.  4 B . The number, the arrangement, and the width in the x-axis direction in a plan view of the raised portions  121  can be determined according to the number, the arrangement, and the width in the x-axis direction in a plan view of the groove portions  30  to be formed in the first substrate  1000 . The corner of the raised portion  121  may have a rounded shape (R shape). That is, modifying the shape of the raised portions  121  can improve the design flexibility of the groove portions  30 . 
     Providing Pre-Preg 
     As shown in  FIG.  8 C , a pre-preg  110  is provided that includes a plurality of fiber bundles and a thermosetting resin in a semi-cured state (B-stage). The pre-preg  110  has a first surface  110   a  and a second surface  110   b  located opposite to the first surface  110   a . Further, metal foil  140  is provided on the first surface  110   a  side of the pre-preg  110 . The metal foil  140  is, for example, Cu foil (thickness: for example, equal to or greater than 0.1 mm and equal to or smaller than 0.2 mm). The metal foil  140  is used for formation of the upper electrically-conductive layers. 
     &lt;Step (II)&gt; 
     Next, the first surface  120   a  of the metal plate  120  and the pre-preg  110  are bound together. First, as shown in  FIG.  9 A , the second surfaces  120   b  of two metal plates  120  are set so as to face each other with a sheet-like supporter  130  interposed therebetween. In Step (II), two or more metal plates  120  are used so that the productivity of the first substrate  1000  can be improved. The supporter  130  can be a metal plate of stainless steel or the like, or a sheet of paper. 
     Then, as shown in  FIG.  9 B , the two metal plates  120  are stacked up with the supporter  130  interposed therebetween. Then, the second surface  110   b  of the pre-preg  110  is set so as to face the first surface  120   a  of the metal plate  120 . In this example, the second surfaces  110   b  of the two pre-pregs  110  are set so as to face the first surfaces  120   a  of the two metal plates  120 . 
     Then, as shown in  FIG.  9 C , the first surface  120   a  of the metal plate  120  and the second surface  110   b  of the pre-preg  110  are brought together. In this step, the metal foil  140  provided on the first surface  110   a  side of the pre-preg  110  is also compressed together, resulting in a multilayer body  150 . In  FIG.  9 C , two multilayer bodies  150  are stacked up with the supporter  130  interposed therebetween. Note that, to further improve the productivity, three or more multilayer bodies  150  may be stacked up with supporters  130  interposed therebetween. 
     &lt;Step (III)&gt; 
     Thereafter, a resin layer  10  is formed by, for example, curing the pre-preg  110 . 
     When a plurality of multilayer bodies  150  are stacked up, a plurality of pre-pregs  110  may be concurrently cured. The method of curing the pre-pregs  110  is not particularly limited. Herein, the multilayer bodies  150  are compressed in the stacking direction (z-axis direction) by, for example, pressing, while the multilayer bodies  150  are heated. The heating temperature can be set to, for example, a temperature equal to or higher than 130° C. and equal to or lower than 200° C., and the pressing pressure can be set to, for example, a pressure equal to or higher than 20 kg/cm 2  and equal to or lower than 60 kg/cm 2 . Under such conditions, in the multilayer body  150 , the semi-cured resin in the pre-preg  110  is once re-melted and then fully cured. In this way, the resin layer  10  is formed from the pre-preg  110 . Because the pre-preg  110  deforms according to the shape of the first surface  120   a  of the metal plate  120 , recesses  30 E, which are to be the groove portions  30 , are formed on the second surface  10   b  of the resin layer  10  in parts of the pre-preg  110  that are in contact with the raised portions  121  of the first surface  120   a  of the metal plate  120 . 
     In this step, the fiber bundles in the pre-preg  110  can also deform according to the shape of the raised portions  121  of the first surface  120   a  of the metal plate  120 . In the present embodiment, the resin layer  10  is formed such that a portion of at least one of the plurality of fiber bundles in the pre-preg  110  overlapping at least one groove portion  30  in a plan view is bent in the depth direction along the at least one groove portion  30 . (See  FIG.  3 A .) 
     Thereafter, in the resin layer  10  resulting from the curing of the pre-preg  110 , a plurality of through-holes are formed by, for example, laser or drilling. In this step, preferably, through-holes are also concurrently formed in either of the metal plate  120  or the metal foil  140 . Thereafter, an electrical conductor  50  is provided in each of the through-holes. Note that the lateral surface of the through-holes may be plated with Cu as the electrical conductor  50 . After the resin layer  10  has been formed, the multilayer body  150  including the resin layer  10  is separated off from the supporter  130  as shown in  FIG.  9 D . 
     &lt;Step (IV)&gt; 
     Subsequently, an etching resist (hereinafter, sometimes abbreviated to “resist”) is formed on the metal plate  120 . As shown in  FIG.  9 E , in the multilayer body  150 , a first resist  161  and a second resist  162  are formed on the first surface  120   a  of the metal plate  120  and the surface  140   a  of the metal foil  140 , respectively. Herein, the etching resist is applied onto the first surface  120   a  of the metal plate  120  and the surface  140   a  of the metal foil  140  and subjected to exposure and development, whereby the first resist  161  and the second resist  162  are formed. The first resist  161  is provided in parts of the first surface  120   a  of the metal plate  120  that are not overlapping the groove portions  30  in a plan view. The first resist  161  has a pattern corresponding to the electrically-conductive layers  20  ( FIG.  9 F ), and the second resist  162  has a pattern corresponding to the upper electrically-conductive layers  40  ( FIG.  9 F ). 
     &lt;Step (V)&gt; 
     Next, at least one raised portion  121  of the metal plate  120  is etched away. As shown in  FIG.  9 F , etching is performed on the metal plate  120  using the first resist  161  as an etching mask, whereby parts of the metal plate  120  including the raised portions  121  are etched away. As a result, at least one groove portion  30  corresponding to the at least one raised portion  121  of the metal plate  120  is formed in the resin layer  10 . Because the raised portions  121  of the metal plate  120  are removed and the groove portions  30  are formed after the pre-preg  110  has been cured, the shape of the groove portions  30  as designed can be precisely and easily realized. Further, by removing the raised portions  121 , the metal plate  120  can be divided by the groove portions  30  into two or more parts, whereby the electrically-conductive layers  20  are formed. 
     Likewise, etching is performed on the metal foil  140  using the second resist  162  as an etching mask, whereby the metal foil  140  can be divided into the upper electrically-conductive layers  40 . 
     &lt;Step (VI)&gt; 
     Thereafter, as shown in  FIG.  9 G , the first resist  161  and the second resist  162  are removed. In this way, the first substrate  1000  is produced. 
     Thereafter, the first substrate  1000  produced by the above-described method is divided or singulated into individual pieces corresponding to the unit regions U. By this singulation, the substrate  100  shown in  FIG.  1 A ,  FIG.  1 B ,  FIG.  1 C  and  FIG.  1 D  can be produced from each of the unit regions U. The first substrate  1000  may be divided into individual pieces after one or a plurality of light source sections  200  ( FIG.  2 B ) or one or a plurality of light source sections  201  ( FIG.  6   ) have been formed in each of the unit regions U on the first surface  10   a  of the first substrate  1000 . 
     The method of singulation is not particularly limited. For example, the first substrate  1000  may be cut along the boundary between neighboring unit regions U by, for example, blade dicing or laser dicing. Although the unit regions U are rectangular in the example illustrated in  FIG.  4 A  and  FIG.  4 B , the shape of the unit regions U is not limited to this example. The planar shape of the substrate  100  after the singulation may be circular, elliptical, or any other shape. 
     According to the above-described method, the first substrate  1000  and the substrate  100  can be produced, which have the groove portions  30  that can suppress a short circuit due to ion migration between electrically-conductive layers. 
     For example, when a groove portion is formed in a resin layer by a method of a reference example with the use of a dicer or laser, a fiber bundle  911 Y located at a position shallower than the bottom of the groove portion  930  is cut off as shown in  FIG.  21   , and the cut sections of the fiber bundle  911 Y are exposed at the surface of the groove portion  930  (in other words, at the surface  910   b  of the resin layer  910 ). Thus, there is a probability that the strength of the substrate will decrease. In contrast, in the present embodiment, the groove portion  30  is formed by deforming a semi-cured resin using the metal plate  120  that has the raised portions  121  ( FIG.  8 A  and  FIG.  8 B ). By this method, as shown in  FIG.  3 A , in the resin layer  10  of the present embodiment, the first fiber bundle  11 Y located at a position shallower than the bottom P of the groove portion  30  is continuously provided so as to extend across the groove portion  30  inside the resin layer in a plan view. That is, the first fiber bundle  11 Y is not cut off in forming the groove portion  30 , and a part of the first fiber bundle  11 Y is present between the groove portion  30  and the first surface  10   a  of the resin layer  10 . Thus, the decrease in strength of the substrate  100  due to formation of the groove portion  30  can be suppressed. 
     Hereinafter, variant examples of the substrate and the light emitting device of the present embodiment are described. In the following description of the variant examples, the same features as those of the previously-described embodiments may not be described. 
     Variant Example 1 of Substrate 
       FIG.  10 A  and  FIG.  10 B  are, respectively, a top view and a bottom view of a substrate  101  of Variant Example 1.  FIG.  10 C  is a schematic cross-sectional view of the substrate  101  taken along line  10 C- 10 C shown in  FIG.  10 A  and  FIG.  10 B . 
     The substrate  101  includes a plurality of electrically-conductive layers  20  and a plurality of upper electrically-conductive layers  40 . The plurality of electrically-conductive layers  20  include the first through eighth electrically-conductive layers  21 ,  22 ,  23 ,  24 ,  25 ,  26 ,  27  and  28 . The plurality of upper electrically-conductive layers  40  include the first through eighth upper electrically-conductive layers  41 ,  42 ,  43 ,  44 ,  45 ,  46 ,  47  and  48 . 
     As shown in  FIG.  10 B , the second surface  10   b  of the resin layer  10  is divided into eight planned electrically-conductive layer regions by groove portions  30 , which include the first through fourth groove portions  31 ,  32 ,  33  and  34 . The eight planned electrically-conductive layer regions are the first through eighth regions R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7  and R 8 . 
     The first through fourth groove portions  31 ,  32 ,  33  and  34  linearly extend in a plan view and intersect at point Qb, which is the center of the second surface  10   b . In this example, the second surface  10   b  of the resin layer  10  has a rectangular shape having four corners c 1 , c 2 , c 3  and c 4  and four sides s 1 , s 2 , s 3  and s 4 , which is the same as the example shown in  FIG.  1 B . The first groove portion  31  extends from the corner c 1  to the corner c 3  of the second surface  10   b . The third groove portion  33  extends from the corner c 2  to the corner c 4  of the second surface  10   b . That is, the first groove portion  31  and the third groove portion  33  are located on the diagonals of the second surface  10   b . The second groove portion  32  is substantially parallel to the x axis and divides the second surface  10   b  into the upper and lower parts (i.e., into two parts with respect to the y direction). The opposite ends of the second groove portion  32  may be in contact with the sides s 2  and s 4 , respectively, of the second surface  10   b . The fourth groove portion  34  is substantially parallel to the y axis and divides the second surface  10   b  into the left and right parts (i.e., into two parts with respect to the x direction). The opposite ends of the fourth groove portion  34  may be in contact with the sides s 1  and s 3 , respectively, of the second surface  10   b . In a plan view, the first through eighth regions R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7  and R 8  are right triangular regions surrounded by the groove portions  30  and the four sides of the second surface  10   b  of the substrate  101 . 
     The first through eighth electrically-conductive layers  21 ,  22 ,  23 ,  24 ,  25 ,  26 ,  27  and  28  are located in the first through eighth regions R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7  and R 8 , respectively. The first through eighth electrically-conductive layers  21 ,  22 ,  23 ,  24 ,  25 ,  26 ,  27  and  28  can have planar shapes that are substantially similar to the first through eighth regions R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , R 7  and R 8 , respectively. In this example, the planar shape of each of the first through eighth electrically-conductive layers  21 ,  22 ,  23 ,  24 ,  25 ,  26 ,  27  and  28  is a right triangle whose two sides are parallel to the x axis and the y axis. 
     As shown in  FIG.  10 A , the first surface  10   a  of the resin layer  10  includes a plurality of planned light source section regions and a peripheral region Vb that surrounds the planned light source section regions. The planned light source section regions mean regions on which light source sections including light emitting elements are to be placed. In this example, the plurality of planned light source section regions include four rectangular regions V 1 , V 2 , V 3  and V 4 . Each side of the rectangular regions V 1 , V 2 , V 3  and V 4  is parallel to the x axis or the y axis. The regions V 1 , V 2 , V 3  and V 4  arrayed in two rows (x direction) and two columns (y direction). Herein, the regions V 1 , V 2 , V 3  and V 4  are the lower right region, the upper right region, the upper left region, and the lower left region with respect to point Qa. Point Qa is, for example, the center of the first surface  10   a . Point Qa is the center of all the regions V 1 , V 2 , V 3  and V 4  and is preferably coincident with point Qb, which is the center of the second surface  10   b , in a plan view. 
     The first through eighth upper electrically-conductive layers  41 ,  42 ,  43 ,  44 ,  45 ,  46 ,  47  and  48  are provided on the first surface  10   a  of the resin layer  10  so as to be spaced away from one another. The first through eighth upper electrically-conductive layers  41 ,  42 ,  43 ,  44 ,  45 ,  46 ,  47  and  48  are electrically connected to the first through eighth electrically-conductive layers  21 ,  22 ,  23 ,  24 ,  25 ,  26 ,  27  and  28 , respectively, via the electrical conductors  50  in the through-holes formed in the resin layer  10 . In this example, the shape of the first through eighth upper electrically-conductive layers  41 ,  42 ,  43 ,  44 ,  45 ,  46 ,  47  and  48  in a plan view is a right triangle whose two sides are parallel to the x axis and the y axis. In the region V 1 , the first upper electrically-conductive layer  41  and the second upper electrically-conductive layer  42  are provided. In the region V 2 , the third upper electrically-conductive layer  43  and the fourth upper electrically-conductive layer  44  are provided. In the region V 3 , the fifth upper electrically-conductive layer  45  and the sixth upper electrically-conductive layer  46  are provided. In the region V 4 , the seventh upper electrically-conductive layer  47  and the eighth upper electrically-conductive layer  48  are provided. In a plan view, the hypotenuses of the right triangles of two upper electrically-conductive layers  40  provided in each of the regions V 1 , V 2 , V 3  and V 4  face each other. 
     The substrate  101  can also be produced by the same method as that previously described with reference to  FIG.  8 A ,  FIG.  8 B  and  FIG.  8 C  and  FIG.  9 A ,  FIG.  9 B ,  FIG.  9 C ,  FIG.  9 D ,  FIG.  9 E ,  FIG.  9 F  and  FIG.  9 G . In Step (I) illustrated in  FIG.  8 A  and  FIG.  8 B , the metal plate  120  is used that has the plurality of raised portions  121  that linearly extend in a plan view, so that the groove portions  30  including the first through fourth groove portions  31 ,  32 ,  33  and  34  can be formed. 
       FIG.  11    is an enlarged bottom view showing a part of a first substrate  1001  according to the present embodiment. One of the unit regions U of the first substrate  1001  is the substrate  101 . In the first substrate  1001 , the first through fourth groove portions  31 ,  32 ,  33  and  34  in one of the unit regions U may be in communication with the groove portions  30  of a unit region U that is neighboring in the x direction, the y direction, or a diagonal direction. 
     Variant Example 1 of Light Emitting Device 
     An example of a light emitting device that includes the substrate  101  of Variant Example 1 is described. 
       FIG.  12 A  is a schematic top view of a light emitting device  401 .  FIG.  12 B  is a bottom view of the light emitting device  401 .  FIG.  12 C  is a cross-sectional view of the light emitting device  401  taken along line  12 C- 12 C shown in  FIG.  12 A . 
     The light emitting device  401  includes a substrate  101 , a light source section  202 , and a lens  300 . The lens  300  has the configuration the same as or similar to that of the lens previously described with reference to  FIG.  7 A ,  FIG.  7 B ,  FIG.  7 C  and  FIG.  7 D . The light source section  202  of the light emitting device  401  includes a plurality of light emitting elements  70 . Hereinafter, the configuration of the light source section  202  is described in detail. 
     [Light Source Section  202 ] 
       FIG.  13    is a diagram for illustrating the substrate  101  and the light source section  202 . Specifically,  FIG.  13    is a cross-sectional view of a structure equivalent to the light emitting device  401  shown in  FIG.  12 C  from which the lens  300  has been removed. 
     The light source section  202  is provided on the upper surface  101   a  side of the substrate  101 . The light source section  202  has a light emission surface  202   a  located opposite to the substrate  101 . The light source section  202  includes a plurality of light emitting elements  70  that are two-dimensionally arrayed. The light source section  202  further includes a plurality of wavelength conversion layers  90 , a plurality of diffusing layers  92 , and a reflector  94 . 
     As shown in  FIG.  12 A , each of the plurality of light emitting elements  70  is provided in a corresponding one of the planned light source section regions on the first surface  10   a  of the resin layer  10  of the substrate  101 . In a plan view, each of the light emitting elements  70  is rectangular and is provided such that each side of the rectangle is parallel to the x axis or the y axis. Each of the light emitting elements  70  is provided so as to extend across the hypotenuses of neighboring two of the first through eighth upper electrically-conductive layers  41 ,  42 ,  43 ,  44 ,  45 ,  46 ,  47  and  48  in a plan view. The positive and negative electrodes of each of the light emitting elements  70  are present above the two neighboring upper electrically-conductive layers. The positive and negative electrodes of the light emitting elements  70  have a triangular (herein, right triangular) planar shape. 
     In this example, the plurality of light emitting elements  70  are the first through fourth light emitting elements  71 ,  72 ,  73  and  74 . The first through fourth light emitting elements  71 ,  72 ,  73  and  74  are provided in the regions V 1 , V 2 , V 3  and V 4 , respectively, on the first surface  10   a  of the resin layer  10 . The electrodes  81 ,  82  of the first light emitting element  71  are electrically connected to the first upper electrically-conductive layer  41  and the second upper electrically-conductive layer  42  via, for example, a bonding material such as solder. Likewise, the electrodes  83 ,  84 ,  85 ,  86 ,  87  and  88  of the second through fourth light emitting elements  72 ,  73  and  74  are electrically connected to the third through eighth upper electrically-conductive layers  43 ,  44 ,  45 ,  46 ,  47  and  48 , respectively. 
     As shown in  FIG.  13   , the plurality of wavelength conversion layers  90  are provided on the light exit surfaces  70   a  of corresponding ones of the light emitting elements  70  and are separated from one another. In this example, each of the light emitting elements  70  includes a wavelength conversion layer  90 , although a common wavelength conversion layer may be provided for the plurality of light emitting elements  70 . 
     Each of the plurality of diffusing layers  92  is provided on the upper surface of a corresponding one of the wavelength conversion layers  90 . The plurality of diffusing layers  92  are separated from one another. In this example, each of the light emitting elements  70  includes a diffusing layer  92 , although a common diffusing layer  92  may be provided for the plurality of light emitting elements  70 . 
     The reflector  94  encapsulates, and integrally holds, the first through fourth light emitting elements  71 ,  72 ,  73  and  74 . The reflector  94  may be provided for each of the light emitting elements  70 . In this case, the reflectors  94  may be separated from one another. When a reflector  94  is provided between two neighboring light emitting elements  70 , transmission of light between the light emitting elements  70  can be suppressed, so that unevenness in emission color can be reduced. Further, in the lighting operation where the plurality of light emitting elements  70  are controlled independently of one another, the contrast between lit light emitting elements and unlit light emitting elements can be improved. 
     Variant Example 2 of Substrate 
       FIG.  14 A  and  FIG.  14 B  are, respectively, a top view and a bottom view of a substrate  102  of Variant Example 2.  FIG.  14 C  is a cross-sectional view of the substrate  102  taken along line  14 C- 14 C shown in  FIG.  14 A  and  FIG.  14 B . 
     The substrate  102  includes a plurality of electrically-conductive layers  20 , which include the first through fifth electrically-conductive layers  21 ,  22 ,  23 ,  24  and  25 , and a plurality of upper electrically-conductive layers  40 , which include the first through eighth upper electrically-conductive layers  41 ,  42 ,  43 ,  44 ,  45 ,  46 ,  47  and  48 . 
     As shown in  FIG.  14 B , the second surface  10   b  of the resin layer  10  has groove portions  30  and a plurality of planned electrically-conductive layer regions. The groove portions  30  include an annular groove portion or a groove portion having an arc portion in a plan view. In this example, the groove portions  30  include the first through fifth groove portions  31 ,  32 ,  33 ,  34  and  35 , which are annular or have an arc portion in a plan view. The plurality of planned electrically-conductive layer regions are the first through fifth regions R 1 , R 2 , R 3 , R 4  and R 5 . In a plan view, the first groove portion  31  is annular, the first region R 1  is a region surrounded by the first groove portion  31 , and the second through fifth regions R 2 , R 3 , R 4  and R 5  are located on the side opposite to the first region R 1  with respect to the first groove portion  31  interposed therebetween. 
     In a plan view, the first groove portion  31  is annular. The first groove portion  31  has, in a plan view, the first annular edge e 1  and the second annular edge e 2  that is on the outer side of the first edge e 1  and that is opposite to the first edge e 1 . In this example, the first groove portion  31  is in the shape of a substantially circular annulus in a plan view. In the present specification, the term “annular” refers to a ring in the shape of a circle, an ellipse, or a polygon with rounded corners in a plan view. An annular groove portion may include an arc portion that is a part of a circle or ellipse, or may include a linear portion, so long as the annular groove portion has a ring-like shape in a plan view. 
     The second through fifth groove portions  32 ,  33 ,  34  and  35  include, in a plan view, a portion overlapping the first annular groove portion  31  and are located on the second edge e 2  side of the first groove portion  31 . In other words, each of the second through fifth groove portions  32 ,  33 ,  34  and  35  and the first annular groove portion  31  share a part of the groove portions  30 . In this example, the second surface  10   b  has a rectangular shape, which has four corners c 1 , c 2 , c 3  and c 4  and four sides s 1 , s 2 , s 3  and s 4 . The second groove portion  32  has an arc portion concaved toward the corner c 1  in a plan view. Likewise, the third through fifth groove portions  33 ,  34  and  35  have arc portions concaved toward the corners c 2 , c 3  and c 4 , respectively, in a plan view. 
     The second surface  10   b  is divided by the above-described first through fifth groove portions  31 ,  32 ,  33 ,  34  and  35  into the first through fifth regions R 1 , R 2 , R 3 , R 4  and R 5  and the outer region Rb. 
     The first region R 1  refers to a region surrounded by the first groove portion  31 . The second through fifth regions R 2 , R 3 , R 4  and R 5  are located on the outer side of the first groove portion  31 . In the illustrated example, each of the second through fifth regions R 2 , R 3 , R 4  and R 5  is located between the first region R 1  and a corresponding one of the four corners c 1 , c 2 , c 3  and c 4 . The second region R 2  refers to a region surrounded by the second groove portion  32  in the shape of an arc and two sides s 1 , s 2  that form the corner c 1  of the resin layer  10 . Likewise, the third through fifth regions R 3 , R 4  and R 5  refer to regions surrounded by the third through fifth groove portions  33 ,  34  and  35  and two sides that form corresponding ones of the corners c 2 , c 3  and c 4 . 
     The outer region Rb is located on the outer side of the planned electrically-conductive layer regions and refers to a region on which the electrically-conductive layers  20  are not to be provided. The outer region Rb may be a single continuous region or may include a plurality of separate regions. The outer region Rb is separated from the planned electrically-conductive layer regions by the groove portions  30 . In this example, the outer region Rb is located outside the first region R 1 , at a position between two neighboring planned electrically-conductive layer regions. Between the two-neighboring planned electrically-conductive layer regions and the outer region Rb located therebetween, the groove portions  30  are provided. In this example, in a plan view, in a part of the second surface  10   b  of the resin layer  10  that is on the side opposite to the first region R 1  with respect to the first groove portion  31  interposed therebetween, the second groove portion  32  is located between the second region R 2  and the outer region Rb positioned outward of the second region R 2 . Further, the second groove portion  32  includes a portion elongated in the shape of an arc or annulus. Likewise, the third groove portion  33  is located between the third region R 3  and the outer region Rb. The fourth groove portion  34  is located between the fourth region R 4  and the outer region Rb. The fifth groove portion  35  is located between the fifth region R 5  and the outer region Rb. 
     The first through fifth electrically-conductive layers  21 ,  22 ,  23 ,  24  and  25  are provided in the first through fifth regions R 1 , R 2 , R 3 , R 4  and R 5 , respectively. The first electrically-conductive layer  21  is located on the inner side of the first edge e 1  of the first groove portion  31  so as to be spaced away from the first edge e 1 . The second through fifth electrically-conductive layers  22 ,  23 ,  24  and  25  are located on the inner side of the edges of the second through fifth groove portions  32 ,  33 ,  34  and  35 , respectively, that are in the shape of an arc so as to be spaced away from the edges. In this example, the first through fifth electrically-conductive layers  21 ,  22 ,  23 ,  24  and  25  have a substantially circular planar shape. In a plan view, the second through fifth electrically-conductive layers  22 ,  23 ,  24  and  25  may have a smaller area than the first electrically-conductive layer  21 . 
     That is, the second surface  10   b  of the resin layer  10  has a rectangular shape, which has four corners c 1 , c 2 , c 3  and c 4 . In a plan view, the second surface  10   b  of the resin layer  10  further includes the second region R 2 , the third region R 3 , the fourth region R 4  and the fifth region R 5 , and the outer region Rb exclusive of the second region R 2 , the third region R 3 , the fourth region R 4  and the fifth region R 5 . The second region R 2 , the third region R 3 , the fourth region R 4  and the fifth region R 5  are located between the first groove portion  31  and the four corners c 1 , c 2 , c 3  and c 4 , respectively. The substrate  100  for light emitting elements further includes the third electrically-conductive layer  23 , the fourth electrically-conductive layer  24  and the fifth electrically-conductive layer  25  provided in the third region R 3 , the fourth region R 4  and the fifth region R 5 , respectively. In a plan view, at least one groove portion  30  further includes the second groove portion  32  located between the second region R 2  and the outer region Rb, the third groove portion  33  located between the third region R 3  and the outer region Rb, the fourth groove portion  34  located between the fourth region R 4  and the outer region Rb, and the fifth groove portion  35  located between the fifth region R 5  and the outer region Rb. In a plan view, each of the second groove portion  32 , the third groove portion  33 , the fourth groove portion  34  and the fifth groove portion  35  has an arc portion that is in contact with the first groove portion  31 . 
     As shown in  FIG.  14 A , the first surface  10   a  of the resin layer  10  includes a plurality of planned light source section regions and a peripheral region Vb that surrounds the planned light source section regions. In this example, the plurality of planned light source section regions are four rectangular regions V 1 , V 2 , V 3  and V 4 . Each side of the rectangular regions V 1 , V 2 , V 3  and V 4  is parallel to the x axis or the y axis. Herein, the regions V 1 , V 2 , V 3  and V 4  are the lower right region, the upper right region, the upper left region, and the lower left region with respect to point Qa. Point Qa is the center of all the regions V 1 , V 2 , V 3  and V 4  and is, for example, the center of the first surface  10   a.    
     The first through eighth upper electrically-conductive layers  41 ,  42 ,  43 ,  44 ,  45 ,  46 ,  47  and  48  are provided across the first surface  10   a  of the resin layer  10  so as to be spaced away from one another. In this example, each of the first through eighth upper electrically-conductive layers  41 ,  42 ,  43 ,  44 ,  45 ,  46 ,  47  and  48  has a right triangular shape whose two sides are parallel to the x axis and the y axis. In the region V 1 , the first upper electrically-conductive layer  41  and the second upper electrically-conductive layer  42  are provided. In the region V 2 , the third upper electrically-conductive layer  43  and the fourth upper electrically-conductive layer  44  are provided. In the region V 3 , the fifth upper electrically-conductive layer  45  and the sixth upper electrically-conductive layer  46  are provided. In the region V 4 , the seventh upper electrically-conductive layer  47  and the eighth upper electrically-conductive layer  48  are provided. In a plan view, two upper electrically-conductive layers  40  provided in each region V are provided such that the hypotenuses of the right triangles face each other. In a plan view, in each of the regions V 1 , V 2 , V 3  and V 4 , the right angle vertex of the right triangle of one of the upper electrically-conductive layers  40  (herein, the second upper electrically-conductive layer  42 , the fourth upper electrically-conductive layer  44 , the sixth upper electrically-conductive layer  46 , or the eighth upper electrically-conductive layer  48 ) is located near point Qa of the first surface  10   a , while the right angle vertex of the right triangle of the other upper electrically-conductive layer  40  (herein, the first upper electrically-conductive layer  41 , the third upper electrically-conductive layer  43 , the fifth upper electrically-conductive layer  45 , or the seventh upper electrically-conductive layer  47 ) is located near a corresponding one of the four corners of the first surface  10   a.    
     The second upper electrically-conductive layer  42 , the fourth upper electrically-conductive layer  44 , the sixth upper electrically-conductive layer  46  and the eighth upper electrically-conductive layer  48  are each electrically connected to the first electrically-conductive layer  21  via the electrical conductor  50  in the through-hole formed in the resin layer  10 . Meanwhile, the first upper electrically-conductive layer  41 , the third upper electrically-conductive layer  43 , the fifth upper electrically-conductive layer  45  and the seventh upper electrically-conductive layer  47 , which are located near the four corners of the first surface  10   a , are electrically connected to the second through fifth electrically-conductive layers  22 ,  23 ,  24  and  25 , respectively, via the electrical conductors  50  in the through-holes formed in the resin layer  10 . 
     The substrate  102  can also be produced by the same method as that previously described with reference to  FIG.  8 A ,  FIG.  8 B  and  FIG.  8 C  and  FIG.  9 A ,  FIG.  9 B ,  FIG.  9 C ,  FIG.  9 D ,  FIG.  9 E ,  FIG.  9 F  and  FIG.  9 G . In Step (I) illustrated in  FIG.  8 A  and  FIG.  8 B , the metal plate  120  is used that has a raised portion elongated in the shape of an arc or annulus in a plan view, so that the groove portions  30  including an annular or arc portion can be formed. A collective first substrate may be produced by the above-described method and thereafter divided into individual pieces corresponding to the unit regions. 
       FIG.  15    is an enlarged bottom view showing a part of a collective first substrate  1002  according to the present embodiment. In the first substrate  1002 , the second through fifth arc-shaped groove portions  32 ,  33 ,  34  and  35  of one of the unit regions U may be in communication with the arc-shaped groove portions of a neighboring unit region that is adjacent in the x direction or the y direction. The second through fifth groove portions  32 ,  33 ,  34  and  35  of neighboring unit regions U may be in communication with one another such that annular groove portions can be formed. 
       FIG.  16    is a bottom view showing an alternative substrate  103  according to Variant Example 2. In the example illustrated in  FIG.  16   , the second surface  10   b  of the resin layer  10  has a first annular groove portion  31 , and second through fifth groove portions  32 ,  33 ,  34  and  35  that are located on the outer side of the first groove portion  31  in a plan view. In a plan view, the second through fifth groove portions  32 ,  33 ,  34  and  35  are each an annular groove portion and are located in the −y direction, the +x direction, the +y direction and the −x direction, respectively, relative to the first groove portion  31 . Each of the second through fifth groove portions  32 ,  33 ,  34  and  35  may be in contact with the first groove portion  31 . 
     The second surface  10   b  of the resin layer  10  includes the first through fifth regions R 1 , R 2 , R 3 , R 4  and R 5 , which are the planned electrically-conductive layer regions, and an outer region Rb positioned outward of the planned electrically-conductive layer regions. The first through fifth regions R 1 , R 2 , R 3 , R 4  and R 5  refer to regions surrounded by the first through fifth groove portions  31 ,  32 ,  33 ,  34  and  35 , respectively. The areas of the first through fifth regions R 1 , R 2 , R 3 , R 4  and R 5  may be substantially equal or may be different from one another. The outer region Rb refers to a region located outside the first through fifth regions R 1 , R 2 , R 3 , R 4  and R 5 . In this example, the outer region Rb is a single continuous region. 
     The first through fifth electrically-conductive layers  21 ,  22 ,  23 ,  24  and  25  are provided in the first through fifth regions R 1 , R 2 , R 3 , R 4  and R 5 , respectively. The planar shapes of the first through fifth electrically-conductive layers  21 ,  22 ,  23 ,  24  and  25  may be similar to, or different from, the planar shapes of the first through fifth regions R 1 , R 2 , R 3 , R 4  and R 5 , respectively. 
     In this variant example, the number, shape, and arrangement of the groove portions  30 , the planned electrically-conductive layer regions and the electrically-conductive layers  20  are not limited to the examples illustrated in the drawings. The substrates  102  and  103  shown in  FIG.  14 A ,  FIG.  14 B  and  FIG.  14 C  and  FIG.  16    have five planned electrically-conductive layer regions and five electrically-conductive layers  20 , although the number of planned electrically-conductive layer regions and the number of electrically-conductive layers  20  may be two or more. 
     Variant Example 3 of Substrate 
     Hereinafter, as Variant Example 3, another arrangement example of the groove portions and the planned electrically-conductive layer regions in the second surface of the resin layer is described. 
       FIG.  17 A  is a bottom view illustrating a substrate  104  of Variant Example 3. 
     In the substrate  104 , the planar shape of the second surface  10   b  of the resin layer  10  is a rectangular shape having four corners c 1 , c 2 , c 3  and c 4  and four sides s 1 , s 2 , s 3  and s 4 , which is the same as the example shown in  FIG.  1 B . The second surface  10   b  has groove portions  30  that include portions extending linearly in different directions in a plan view. The second surface  10   b  is divided by the groove portions  30  into a plurality of planned electrically-conductive layer regions. 
     In the example illustrated in the drawing, the groove portions  30  include the first groove portion  31  that extends so as to divide the second surface  10   b  into left and right parts (x direction), the second groove portion  32  that extends so as to divide the region on the right side (+x side) of the first groove portion  31  into upper and lower parts (y direction), and the third groove portion  33  that extends so as to divide the region on the left side (−x side) of the first groove portion  31  into upper and lower parts (y direction). The second groove portion  32  and the third groove portion  33  are linear groove portions extending in directions intersecting each other. The second groove portion  32  is in communication with the first groove portion  31 , and the end on the +x direction side of the second groove portion  32  is in contact with the periphery (side s 2 ) of the second surface  10   b . Likewise, the third groove portion  33  is in communication with the first groove portion  31 , and the end on the −x direction side of the third groove portion  33  is in contact with the periphery (side s 4 ) of the second surface  10   b . In a plan view, the first groove portion  31 , the second groove portion  32  and the third groove portion  33  meet at a single point Qc. 
     The second surface  10   b  is divided by the above-described groove portions  30  into the first through fourth regions R 1 , R 2 , R 3  and R 4 . In the first through fourth regions R 1 , R 2 , R 3  and R 4 , the first through fourth electrically-conductive layers  21 ,  22 ,  23  and  24  are respectively provided. 
     In this variant example, at least one groove portion  30  may include a groove portion that has, in a plan view, the first position at the periphery of the second surface  10   b  of the resin layer  10 , the second position that is present within the second surface  10   b , and a linear portion extending linearly from the first position to the second position. The “first position” and the “second position” of the groove portion may be the ends of the groove portion. In the example illustrated in the drawing, the second groove portion  32  and the third groove portion  33  each include the first position at the periphery of the second surface  10   b , the second position including point Qc that is positioned inner side of the second surface  10   b , and a linear portion extending linearly from the first position to the second position. 
     According to the method previously described with reference to  FIG.  8 A ,  FIG.  8 B  and  FIG.  8 C  and  FIG.  9 A ,  FIG.  9 B ,  FIG.  9 C ,  FIG.  9 D ,  FIG.  9 E ,  FIG.  9 F  and  FIG.  9 G , by modifying the shape of the raised portions  121  of the metal plate  120 , groove portions can be more easily formed so as to meet within the second surface  10   b  (herein, intersect at point Qb), for example, as do the second groove portion  32  and the third groove portion  33  shown in  FIG.  17 A . 
       FIG.  17 B  is a bottom view illustrating an alternative substrate  105   a  of Variant Example 3. 
     In the substrate  105   a , the groove portions  30  include a linear groove portion extending parallel to the y axis and linear groove portions extending parallel to the x axis. In this example, in a plan view, the groove portions  30  include the first groove portion  31  that extends along the y axis so as to divide the second surface  10   b  in the x direction, the second groove portion  32  and the third groove portion  33  that divide the region on the right side (+x side) of the first groove portion  31  in the y direction into three parts, and the fourth groove portion  34  that divides the region on the left side (−x side) of the first groove portion  31  in the y direction. The second through fourth groove portions  32 ,  33  and  34  may be linear groove portions extending parallel to the x axis in a plan view. Each of the second groove portion  32  and the third groove portion  33  may be in communication with the first groove portion  31  at one end on the −x direction side, while the other end on the +x direction side may be in contact with the periphery (side s 2 ) of the second surface  10   b . The fourth groove portion  34  may be in communication with the first groove portion  31  at one end on the +x direction side, while the other end on the −x direction side may be in contact with the periphery (side s 4 ) of the second surface  10   b . The second through fourth groove portions  32 ,  33  and  34  each have the first position at the periphery of the second surface  10   b , the second position that is positioned inner side of the second surface  10   b  (herein, the position at which the groove portion connects with the first groove portion  31 ), and a linear portion extending linearly from the first position to the second position. 
     The second surface  10   b  is divided by the above-described groove portions  30  into the first through fifth regions R 1 , R 2 , R 3 , R 4  and R 5 . In the first through fifth regions R 1 , R 2 , R 3 , R 4  and R 5 , the first through fifth electrically-conductive layers  21 ,  22 ,  23 ,  24  and  25  are respectively provided. 
     Also in this variant example, the number, planar shape, and arrangement of the groove portions and the planned electrically-conductive layer regions are not limited to the examples illustrated in the drawings. For example, as shown in  FIG.  18   , in the substrate  105   b , the second surface  10   b  of the resin layer  10  has the first through fifth groove portions  31 ,  32 ,  33 ,  34  and  35  radially extending from point Qd, which is positioned inner side of the second surface  10   b , toward the periphery of the second surface  10   b  in a plan view. 
     Variant Example 4 of Substrate 
     Other examples of the cross-sectional shape of the groove portions are described. By appropriately changing the cross-sectional shape of the raised portions  121  of the metal plate  120  (see  FIG.  8 A  and  FIG.  8 B ), the groove portions  30  formed in the resin layer  10  can have various shapes. Therefore, the cross-sectional shape of the groove portions  30  can be set with high flexibility. For example, the width of the groove portions  30  may be varied in the depth direction (z direction). For example, the width w of the opening of the groove portions  30  may be greater than the width of the bottom P of the groove portions  30 . The depth of a groove portion may be varied in the width direction (±x direction) of the groove portion. A single continuous groove portion may include a plurality of portions that have different cross-sectional shapes, or that have different opening widths w. 
     Hereinafter, variant examples of the shape of the groove portions  30  provided in the resin layer  10  are described. Note that the shapes of the groove portions in this variant example are applicable to some or all of the groove portions in the substrates of the present embodiment (for example, the previously-described substrates  101 ,  102 ,  103 ,  104 ,  105   a  and  105   b ). 
       FIG.  19 A ,  FIG.  19 B  and  FIG.  19 C  are cross-sectional views of the substrates  106 ,  107  and  108 , respectively, of Variant Example 4, which show the groove portions  30 A,  30 B and  30 C and the first electrically-conductive layer  21  and the second electrically-conductive layer  22  provided on the opposite sides of the groove portion. 
     In the substrate  106  shown in  FIG.  19 A , the cross-sectional shape of the groove portion  30 A includes an arc that is a part of a circle or ellipse. In this example, in a cross-sectional view, the bottom of the groove portion  30 A is in the shape of a concaved arc. The groove portion  30 A includes the bottom P that is the deepest point in a cross-sectional view. 
     In the substrate  107  shown in  FIG.  19 B , the cross-sectional shape of the groove portion  30 B is a V shape. In this example, in a cross-sectional view, the groove portion  30 B has a bottom P that is the deepest point, a lateral surface f 1  located between the bottom P and the first edge e 1 , and a lateral surface f 2  located between the bottom P and the second edge e 2 . In a cross-sectional view, the angle between the lateral surface f 1  and the lateral surface f 2  may be, for example, about 90°. That is, the groove portion  30 B may be a part of a rectangle. 
     In the substrate  108  shown in  FIG.  19 C , the cross-sectional shape of the groove portion  30 C has a bottom surface f 3  whose width is smaller than the width of the opening. In a cross-sectional view, the groove portion  30 C includes the bottom surface f 3  that is the bottom P of the groove portion  30 C, lateral surfaces f 1 , ff 1  located between the bottom surface f 3  and the first edge e 1 , and lateral surfaces f 2 , ff 2  located between the bottom surface f 3  and the second edge e 2 , and hence has steps. The width wa of the bottom surface f 3  is smaller than the width w of the opening of the groove portion  30 C. The lateral surfaces f 1 , ff 1 , f 2 , ff 2  each may be a flat surface inclined with respect to the second surface  10   b . Because the groove portion  30 C has the steps, the creepage distance of insulation between the first electrically-conductive layer  21  and the second electrically-conductive layer  22  can be further increased. 
       FIG.  20    is a bottom view of an alternative substrate  109  of Variant Example 4. In the substrate  109 , in a plan view, the groove portion  30 D includes a plurality of portions of different opening widths. Specifically, the groove portion  30 D includes portions g 1  that have a width w 1  and a portion g 2  that has a width w 2 . The width w 2  is greater than the width w 1 . These portions g 1 , g 2  may be in communication with one another. In this case, in a plan view, between the first electrically-conductive layer  21  and the second electrically-conductive layer  22 , the distance D 1  measured across the portion g 1  of the first groove portion  31  may be smaller than the distance D 2  measured across the portion g 2  of the first groove portion  31 . 
     A substrate for light emitting elements and a light emitting device according to the present disclosure are suitably applicable to various uses including lighting devices, camera flashlights, vehicle headlights, etc. The substrate and the light emitting device are particularly suitably applicable to light sources for flashlights of small-size cameras included in smartphones and the like. 
     It is to be understood that although certain embodiments of the present invention have been described, various other embodiments and variants may occur to those skilled in the art that are within the scope and spirit of the invention, and such other embodiments and variants are intended to be covered by the following claims.