Patent Publication Number: US-2023136337-A1

Title: Circuit part and method of manufacturing circuit part

Description:
TECHNICAL FIELD 
     The present invention relates to a circuit part and a method of manufacturing a circuit part. 
     BACKGROUND ART 
     Molded interconnect devices (MIDs) have recently been commercialized in applications such as smartphones, and applications are expected to be expanded to the field of automobiles. An MID is a device composed of a resin molding with a circuit constituted by metal film on its surface, and can contribute to a reduction in the weight of the product, a reduction in thickness and a reduction in the number of parts. 
     MIDs with light-emitting diodes (LEDs) mounted thereon have also been proposed. When electric current flows through LEDs, they emit heat, which needs to be removed from the backside; as such, increasing the heat dissipation of an MID is important. Patent Document 1 proposes a composite part with a heat-dissipating material integrated with the MID. Further, in the MID of Patent Document 1, the circuit wiring is formed from a plating film. 
     PRIOR ART DOCUMENTS 
     Patent Documents 
     
         
         [Patent Document 1] Japanese Patent No. 3443872 
       
    
     SUMMARY OF THE INVENTION 
     Problems to be Solved by the Invention 
     In recent years, electronic devices with increasingly higher performance together with a constant reduction in size have been developed, accompanied by the development of MIDs used therein having higher density and higher functionality, which requires even higher heat dissipation. A heat dissipation material of an MID is constituted by a metal member; in an MID with a resin layer on its metal member, reducing the thickness of this resin layer is effective in improving thermal conduction from the circuit wiring on the resin layer to the metal member. However, the resin layer often contains alumina or silica particles that serve as a filler to provide thermal conduction; thus, there are limits on improving heat dissipation by only reducing the thickness of the resin layer. The present invention solves these problems by providing a circuit part (MID) providing high heat dissipation. 
     Means for Solving the Problems 
     A first aspect of the present invention provides a circuit part including: a metal member; an insulating resin layer located on the metal member; circuit wiring including a plating film located on the insulating resin layer; and a mounted component mounted on the circuit wiring and electrically connected to the circuit wiring, wherein a plurality of non-penetrating holes are provided in a wiring region, the non-penetrating holes being filled with the plating film, the wiring region being a portion of the surface of the insulating resin layer on which the circuit wiring is located, and a ratio of a depth d of the non-penetrating holes to a width D of the non-penetrating holes, d/D, is 0.5 to 5. 
     A surface roughness (Ra) of a portion of the wiring region other than portions of the non-penetrating holes may be not greater than ⅕ of the depth d of the non-penetrating holes. A ratio of a distance P between adjacent ones of the non-penetrating holes to the width D of the non-penetrating holes, P/D, may be 0.3 to 3. A thickness of the circuit wiring may be larger than ½ of the depth d of the non-penetrating holes or larger than ½ of the width D. The width D of the non-penetrating holes may be 10 to 200 μm. A thickness of a portion of the insulating resin layer sandwiched between the circuit wiring and the metal member and which does not include the non-penetrating holes may be 30 to 200 μm. A distance between bottoms of the non-penetrating holes and a face of the insulating resin layer facing the metal member may be 5 to 100 μm. The non-penetrating holes may be disposed in such a sporadic manner that a density of the non-penetrating holes in the wiring region is uniform. 
     The insulating resin layer may include a thermosetting resin. The thermosetting resin may be epoxy resin. The insulating resin layer may include an insulating thermal-conductive filler. The circuit part may further include: an inorganic oxide layer between the metal member and the insulating resin layer. The mounted component may be positioned such that a surface thereof provided with a terminal faces the circuit wiring, and the terminal and the circuit wiring may be electrically connected by solder. 
     A second aspect of the present invention provides a method of manufacturing the circuit part of the first aspect, including; preparing the metal member; forming the insulating resin layer on the metal member; forming the plurality of non-penetrating holes by illuminating the wiring region of the insulating resin layer with a laser beam; forming the circuit wiring in the wiring region by electroplating; and mounting the mounted component on the circuit wiring. 
     Effects of the Invention 
     The circuit part of the present invention provides both high heat dissipation and high adhesion of its circuit wiring. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic top view of a circuit part of an embodiment. 
         FIG.  2 ( a )  is an enlarged view of region IIA shown in  FIG.  1   , and  FIG.  2 ( b )  is a schematic cross-sectional view taken on line IIB-IIB of  FIG.  1   . In  FIG.  2 ( a ) , the mounted component is not shown. 
         FIGS.  3 ( a )-( c )  each show a schematic top view of a wiring region in which non-penetrating holes with an elliptically shaped opening are provided, and  FIGS.  3 ( d ), ( e )  each show a schematic top view of a wiring region in which non-penetrating holes with openings of various shapes are provided. 
         FIG.  4 ( a )  is a schematic top view of a wiring region in which non-penetrating holes are provided at a generally uniform density, and  FIG.  4 ( b )  is a schematic top view of a wiring region in which non-penetrating holes are provided at non-uniform densities. 
         FIG.  5    is a flowchart illustrating a method of manufacturing a circuit part of an embodiment. 
         FIG.  6    shows an exemplary laser drawn pattern in an implementation where non-penetrating holes are formed by laser-beam illumination. 
         FIGS.  7 ( a )-( e )  illustrate how a plating film is formed on a substrate according to an embodiment. 
         FIGS.  8 ( a )-( e )  illustrate how a plating film is formed on a substrate having non-penetrating holes with a low ratio d/D. 
         FIG.  9    is a schematic cross-sectional view of part of a circuit part of a variation. 
         FIG.  10 ( a )  is a schematic top view of a circuit part produced for Inventive Example 13, and  FIG.  10 ( b )  is a schematic cross-sectional view taken on line XB-XB of  FIG.  10 ( a ) . 
         FIG.  11    is a photograph showing a cross section of the circuit part produced for Inventive Example 14. 
     
    
    
     EMBODIMENTS FOR CARRYING OUT THE INVENTION 
     [Circuit Part] 
     The circuit part  100  shown in  FIGS.  1  and  2   ( a ), ( b ) will be described. The circuit part  100  includes: a substrate  70  including a metal member  50  and an insulating resin layer  10 ; circuit wiring  20  including a plating film located on the insulating resin layer  10  of the substrate  70 ; and a mounted component  30  mounted on the insulating resin layer  10  and electrically connected to the circuit wiring  20 . The mounted component  30  is positioned on the circuit wiring  20  and mounted thereon. A wiring region  10 A, which is a portion of the surface  10   a  of the insulating resin layer  10  on which the circuit wiring  20  is located, includes a plurality of non-penetrating holes  11  (i.e., recesses) filled with plating film of the circuit wiring  20 . 
     The metal member  50  releases heat that has been generated by the mounted component  30  mounted on the insulating resin layer  10 . In view of this, the metal member  50  is preferably made of a heat-dissipating metal such as iron, copper, aluminum, titanium, magnesium, or stainless steel (SUS), for example. From the viewpoint of weight reduction, heat dissipation and costs, magnesium and aluminum are particularly preferable. One of these metals may be used alone, or two or more of them may be mixed for use. The thermal conductivity of the metal member  50  may be, for example, 80 to 300 W/m·K. 
     The metal member  50  is not limited to any particular shape and size, and may be designed in any manner suitable for the application of the circuit part  100 . For example, the metal member  50  may be a plate-shaped body (i.e., metal plate), or take the shape of heat-dissipating fins, or may have a complex shape formed by die casting. 
     The insulating resin layer  10  has insulating properties to insulate the circuit wiring  20  and metal member  50  from each other to prevent a short circuit. The degree of insulation of the insulating resin layer  10  depends on the application of the circuit part  100 ; for example, the resistance between the circuit wiring  20  and metal member  50  during application of a voltage of 16 V is not lower than 1 MΩ. If the resistance between the circuit wiring  20  and metal member  50  is below 1 MΩ, fine current may flow from the circuit wiring  20  to the metal member  50  such that the circuit wiring  20  may not be able to function. Further, the insulating resin layer  10  has a certain degree of thermal conductivity to increase the heat dissipation of the circuit part  100 . Thus, the insulating resin layer  10  is an insulating, heat-dissipating resin layer that provides both insulation and a certain degree of thermal conductivity. The thermal conductivity of the insulating resin layer  10  is 1 to 5 W/m·K, for example. 
     The insulating resin layer  10  includes resin. In implementations where the mounted component  30  is mounted on the insulating resin layer  10  by soldering, the resin used for the insulating resin layer  10  is preferably a heat-resistant resin with high melting point having solder-reflow resistance. The melting point of the resin used for the insulating resin layer  10  is preferably not lower than 260° C., and more preferably not lower than 290° C. This does not necessarily apply to implementations where low-temperature solder is used to mount the mounted component  30 . 
     The resin used for the insulating resin layer  10  may be, for example, thermosetting resin, thermoplastic resin, or ultraviolet-curable resin. Particularly preferable is a thermosetting resin that can easily be formed to a thin shape, provides high forming precision, and has high heat resistance and high density after setting. Examples of thermosetting resins that can be used include heat-resistant resins such as epoxy resin, silicone resin, and polyimide resin, where epoxy resin is particularly preferable. Examples of photocuring resins that can be used include polyimide resin, epoxy resin and the like. Examples of thermoplastic resins that can be used include aromatic polyamides such as 6T nylon (GTPA), 9T nylon (9TPA), 10T nylon (10TPA), 12T nylon (12TPA), and MXD6 nylon (MXDPA), and alloy materials thereof, polyphenylene sulfide (PPS), liquid crystal polymer (LCP), polyether ether ketone (PEEK), polyetherimide (PEI), polyphenyl sulfone (PPSU), and the like. One of these thermosetting resins, ultraviolet curable resins and thermoplastic resins may be used alone, or two or more of them may be mixed and used. 
     The insulating resin layer  10  may include an insulating thermal-conductive filler. An insulating thermal-conductive filler can improve thermal conductivity while maintaining the insulating properties of the insulating resin layer  10 . As used herein, insulating thermal-conductive filler means a filler with a thermal conductivity not lower than 1 W/m·K, and excludes electrically conductive heat-dissipating materials such as carbon. Examples of insulating thermal-conductive fillers include ceramic powders such as aluminum oxide, silicon oxide, magnesium oxide, magnesium hydroxide, boron nitride, and aluminum nitride, which are inorganic powders having high thermal conductivity. To increase the ratio of contact between filler particles to increase thermal transfer, a filler with rod-shaped particles, such as wallastonite, and/or a filler with plate-shaped particles, such as talc or boron nitride, may be mixed. One of these insulating thermal-conductive fillers may be used alone, or two or more of them may be mixed and used. 
     The maximum particle diameter of the insulating thermal-conductive filler (i.e., maximum particle size) is preferably 30 μm to 100 μm, for example, in implementations where relatively inexpensive ceramic particles are used. Further, in implementations where the insulating resin layer  10  has a small thickness, the maximum particle diameter of the insulating thermal-conductive filler is preferably 10 μm to 60 μm. 
     The insulating thermal-conductive filler is to be contained in the insulating resin layer  10  in 10 wt. % to 90 wt. %, for example, and preferably in 30 wt. % to 80 wt. %. The circuit part  100  provides sufficient heat dissipation if the amount of the insulating heat-conductive filler is in such a range. 
     The insulating resin layer  10  may further include a filler with rod-shaped or needle-shaped particles, such as glass fiber and/or calcium titanate, to control its strength. Further, the insulating resin layer  10  may include various general-purpose additives that are added to resin moldings, as necessary. A material containing all of the materials constituting the insulating resin layer  10 , such as the resin, the insulating thermal-conductive filler and the like will be hereinafter sometimes referred to as “resin material”. 
     As shown in  FIGS.  2 ( a ), ( b ) , a plurality of non-penetrating holes (i.e., recesses)  11  are provided in a wiring region  10 A, which is a portion of the surface  10   a  of the insulating resin layer  10  on which the circuit wiring  20  is located, where the holes are filled with plating film of the circuit wiring  20 . The ratio of the depth d of the non-penetrating holes  11  to the width D of the non-penetrating holes  11 , d/D, is to be 0.5 to 5. The ratio d/D may preferably be 0.8 to 3.0 μm, or 1.0 to 1.6 μm. If the non-penetrating holes  11  with a ratio d/D within such a range are filled with plating film of the circuit wiring  20 , this improves the adhesion of the circuit wiring  20  to the insulating resin layer  10 . Further, at the non-penetrating holes  11  with a ratio d/D within such a range, the distance between the plating film of the circuit wiring  20  and the metal member  50  is reduced such that heat generated by the circuit wiring  20  and the mounted component  30  positioned thereon can easily be released to the metal member  50 . This improves the heat dissipation of the circuit part  100 . Thus, providing non-penetrating holes (i.e., recesses)  11  with a ratio d/D within such a range as specified above improves the heat dissipation of the circuit part  100  and the adhesion of the circuit wiring  20 . Further, the circuit wiring  20  provided on the wiring region  10 A including non-penetrating holes  11  with a ratio d/D within such a range has a surface  20   a  that provides sufficient flatness (or smoothness). 
     On the other hand, if the ratio d/D is outside such a range, it is impossible to provide both heat dissipation of the circuit part  100  and adhesion of the circuit wiring  20 , as discussed further below. Further, sufficient flatness (or smoothness) of the circuit wiring  20  cannot be obtained. If the ratio d/D is below the lower limit for such a range as specified above, the depth d is small relative to the width D (which means shallow holes), which fails to provide sufficient adhesion of the circuit wiring  20 , potentially decreasing the heat dissipation of the circuit part  100 . Further, since the width D is large relative to the depth d, it is difficult to fill the non-penetrating holes  11  with plating film, potentially decreasing the flatness of the circuit wiring  20  (see  FIGS.  8 ( a )-( e ) , discussed further below). Conversely, if the ratio d/D is to exceed the upper limit for such a range, the depth d must be increased (which means deeper holes). However, if d is not smaller than the thickness of the insulating resin layer  10 , the circuit wiring  20  may contact the metal member  50  such that the circuit wiring  20  and metal member  50  cannot be insulated from each other. If the thickness of the insulating resin layer  10  is increased to enable increasing the depth d (which means deeper holes), this achieves insulation of the circuit wiring  20  and metal member  50  from each other, but impairs heat transfer from the circuit wiring  20  to the metal member  50  and thus reduces heat dissipation. 
     As used herein, width D of the non-penetrating holes  11 , in implementations where the opening  11   a  of a non-penetrating hole  11  in the surface  10   a  (i.e., wiring region  10 A) takes the shape of a perfect circle, means the diameter of this circle. Although not limiting, the shape of the opening  11   a  of a non-penetrating hole  11  is preferably circular to improve the smoothness and adhesion of the plating film constituting the contact wiring  20 . For example, the opening may be elliptical as shown in  FIGS.  3 ( a )-( c ) , or may be shaped as shown in  FIGS.  3 ( d ), ( e ) . If the shape of an opening  11   a  is not perfectly circular, the width D means the diameter of a perfect circle with the same area as that of the opening  11   a . Further, the depth d of a non-penetrating hole  11  is the depth of the deepest portion of the non-penetrating hole  11  (i.e., bottom lib), that is, the distance (i.e., length) between the surface  10   a  and the bottom lib of the non-penetrating hole  11 . 
     The width D of a non-penetrating hole  11  is not limited to any particular value as long as the ratio d/D satisfies such a range as specified above; for example, it may be 10 to 200 μm, 20 to 150 μm, or 30 to 50 μm. If the width D is below the lower limit for such a range, sufficient adhesion of the circuit wiring  20  may not be obtained. If the width D exceeds the upper limit for such a range, it may be difficult to contain the ratio d/D within such an appropriate range as specified above. 
     The depth d of a non-penetrating hole  11  is not limited to any particular value as long as the ratio d/D satisfies such a range as specified above; for example, it may be 20 to 200 μm, 30 to 150 μm, or 50 to 100 μm. If the depth d is below the lower limit for such a range, sufficient adhesion of the circuit wiring  20  may not be obtained. If the depth d exceeds the upper limit for such a range, the circuit wiring  20  and metal member  50  may not be sufficiently insulated from each other, or an increase in the thickness of the insulating resin layer  10  intended to obtain insulation may decrease heat dissipation. 
     The ratio of the distance P between adjacent ones of the non-penetrating holes  11  to the width D of the non-penetrating holes  11 , P/D, is preferably 0.3 to 3, 0.5 to 2.5 or 1.0 to 1.5. As used herein, distance P for the non-penetrating holes  11  means the smallest distance between one non-penetrating hole  11  and another, adjacent non-penetrating hole  11  in the surface  10   a  of the insulating resin layer  10  (i.e., wiring region  10 A), and is the smallest distance from the edge of the opening  11   a  of one non-penetrating hole  11  to the edge of the opening  11   a  of another, adjacent non-penetrating hole  11 . If the ratio P/D is below the lower limit for such a range as specified above, the non-penetrating holes  11 , separated by the distance P, are too close to each other, potentially leading to insufficient flatness of the circuit wiring  20  formed thereon. If the ratio P/D exceeds the upper limit for such a range, the distance P for the non-penetrating holes  11  is too large, reducing the number of non-penetrating holes  11  that can be provided, potentially leading to insufficient heat dissipation of the circuit part  100  and insufficient adhesion of the circuit wiring  20 . 
     The distance P for the non-penetrating holes  11  is not limited to any particular value as long as the ratio P/D satisfies such a range, and may be 20 to 300 μm or 50 to 150 μm, for example. 
     The depth d and width D of a non-penetrating hole  11 , as well as the distance P for the non-penetrating holes  11 , can be calculated by averaging those for the non-penetrating holes  11  present in a predetermined region (i.e., measured region) for example. For example, the calculation may be done by measuring heights in the wiring region  10 A by optical measurement in the following manner: First, the circuit wiring  20  is peeled away from the insulating resin layer  10  to expose the wiring region  10 A. Optical measurement equipment such as a laser microscope is used to measure the surface roughness (Ra) of an entire predetermined sub-region (i.e., measured region) of the wiring region  10 A. A portion of the measured region that has a depth not smaller than twice the surface roughness (Ra) of the entire measured region is determined to be a non-penetrating hole (i.e., recess)  11 ; the width D of each individual non-penetrating hole  11  and the distance P between adjacent ones of the non-penetrating holes  11  are measured; and the average is calculated. In determining the depth d of the non-penetrating holes  11 , to eliminate noise due to optical measurement, it is preferable to take the variations in the depth d into consideration by measuring ten or more non-penetrating holes  11  and calculating the average. 
     Further, the depth d and width D of a non-penetrating hole  11  as well as the distance P for the non-penetrating holes  11  may be calculated by shape analysis using X-ray CT in the following manner: For example, if the metal member  50  is formed from aluminum and the circuit wiring  20  is formed from copper, a portion of the circuit part  100  of a predetermined size that includes part of the circuit wiring  20  is cut out and is measured using X-ray CT. This provides an X-ray CT image of only the circuit wiring  20  which contains copper, which has a lower X-ray permeability than aluminum. Such an X-ray CT image is taken for each of several planes arranged in the depth direction to produce extracted slice data; the depth of the first slice to fail to show the circuit wiring  20  is treated as the depth d of the non-penetrating holes  11 ; and the values of the width D and distance P for the non-penetrating holes  11  are measured based on the shapes in the slice image for the surface  10   a  of the insulating resin layer  10 . The values of the depth d, width D and distance P for individual non-penetrating holes  11  thus obtained are averaged. From the viewpoint of easy sampling and detection sensitivity, the shape analysis by X-ray CT is preferably done by cutting out an area of the wiring part of 3 to 15 mm 2  for measurement. 
     Alternatively, the depth d and width D of the non-penetrating holes  11  may be determined by cross-sectional observation of the circuit wiring  20  of the circuit part  100 . The cross-sectional observation must be done based on a cross section that allows the depth d and width D of the non-penetrating holes  11  to be measured as shown in  FIG.  2 ( b ) , for example, in the following manner: First, the circuit part  100  may be cut and the cut surface of a non-penetrating hole  11  is observed. Thereafter, the cut surface is polished and ground with sand paper, for example, by 2 to 3 μm, and the cut surface is observed once again. This is repeated until a photograph is obtained of a cut surface at a position where the largest depth of the non-penetrating hole  11  is observed, and the depth of the non-penetrating hole  11  determined therefrom is treated as the depth d. If a non-penetrating hole takes the shape of a circular cone as shown in  FIG.  2 ( b ) , the width D can also be calculated from the photograph of the same cut surface that enables calculation of the depth d. It is preferable to take the variations of the depth d and width D into consideration by measuring ten or more non-penetrating holes  11  in the same manner and calculating the average. 
     The non-penetrating holes  11  are not limited to any particular construction, and can take any shape. As shown in  FIGS.  2 ( a ), ( b ) , a non-penetrating hole  11  of an embodiment takes the shape of a circular cone with its bottom located at the surface  10   a  (i.e., wiring region  10 A). As such, the opening  11   a  of a non-penetrating hole  11  takes the shape of a perfect circle. However, the non-penetrating holes  11  are not limited to this shape, and each hole may take the shape of, for example, a polygonal pyramid such as a triangular pyramid or a quadrangular pyramid, or a pyramid with a complex-shaped bottom. Alternatively, each hole may take the shape of a circular column, a rectangular polygonal prism, or a prism with a complex-shaped bottom, or a hemisphere. From the viewpoint of easiness of forming the non-penetrating holes  11  (i.e., ease of work), it is preferable that the interior of each non-penetrating hole  11  does not expand relative to the opening  11   a . That is, the area of a cross section of the interior of a non-penetrating hole  11  that is parallel to the surface  10   a  is preferably not larger than the area of the opening  11   a . In view of this, if a non-penetrating hole  11  takes the shape of a cone or pyramid, column or prism, or hemisphere, it is preferable that the bottom thereof is positioned at the surface  10   a  (i.e., wiring region  10 A). 
     The non-penetrating holes  11  are provided in the wiring region  10 A. Further, it is preferable that the non-penetrating holes  11  are only provided in the wiring region  10 A and no non-penetrating holes are present in the portions of the surface  10   a  excluding the wiring region  10 A. This reduces the time required to form the non-penetrating holes  11  (i.e., processing time), thereby improving the efficiency with which the circuit part  100  is manufactured. Further, it is preferable that the non-penetrating holes  11  are disposed in such a sporadic manner that the density of the holes in the wiring region  10 A is generally uniform. This results in uniformed heat dissipation of the circuit part  100  and uniformed adhesion of the circuit wiring  20 . For example, the density of the non-penetrating holes  11  in the entire wiring region  10 A shown in  FIG.  4 ( a )  is the same as that in  FIG.  4 ( b ) . However, the non-penetrating holes  11  shown in  FIG.  4 ( a )  are disposed in such a sporadic manner that the density in the wiring region  10 A is generally uniform, while the non-penetrating holes  11  shown in  FIG.  4 ( b )  are distributed unevenly in terms of density. In  FIG.  4 ( b ) , the top-left portion has a higher density of non-penetrating holes  11 , while the bottom-right portion has a lower density of non-penetrating holes  11 . Uniform plating film of the circuit wiring  20  grows on the wiring region  10 A shown in FIG.  4 ( a ). On the other hand, plating film does not easily grow on the bottom-right portion of the wiring region  10 A shown in  FIG.  4 ( b ) . Thus, the plating film on the wiring region  10 A shown in  FIG.  4 ( b )  is non-uniform, decreasing the smoothness of the plating film. 
     Further, to form non-penetrating holes  11  in such a sporadic manner that the density in the wiring region  10 A is generally uniform, it is preferable to satisfy the following conditions: It is preferable that, in the wiring region  10 A, the difference between the largest value and the smallest value of the distance P (i.e., smallest distance from the edge of the opening  11   a  of one non-penetrating hole  11  to the edge of the opening  11   a  of another, adjacent non-penetrating hole  11 ) is smaller than 50% of the average distance P in the wiring region  10 A. Further, it is preferable that the difference between the density (number of holes/mm 2 ) in that sub-region of the wiring region  10 A which has the highest density of non-penetrating holes  11  and the density (number of holes/mm 2 ) in that sub-region which has the lowest density is smaller than 50% of the average density (number of holes/mm 2 ) of non-penetrating holes  11  in the wiring region  10 A. 
     The insulating resin layer  10  is not limited to any particular thickness, and may be designed in any manner suitable for the application of the circuit part  100 . The thickness of the insulating resin layer  10  may be generally constant, or may vary depending on location. There is a tendency that the smaller the thickness of the insulating resin layer  10 , the better the heat dissipation of the circuit part  100 ; in view of this, it is preferable to minimize the thickness of portions of the insulating resin layer  10  near the highly heat-generating mounted component  30 . On the other hand, if the thickness of the insulating resin layer  10  is to be too small, there may be high flow resistance of resin during forming of the insulating resin layer  10 , potentially causing forming defects (or filling defects). Further, it makes it difficult to form non-penetrating holes  11  with sufficient depth. In view of all this, the thickness B of portions of the insulating resin layer  11  that are sandwiched between the circuit wiring  20  and metal member  50  and include no non-penetrating holes  11  (i.e., film thickness B of the insulating resin layer  11  below the circuit wiring  20 ) is preferably 30 to 200 μm or 50 to 150 μm. If the thickness B varies depending on location, it is preferable that the smallest value (i.e., thickness of the thinnest portion) is within such a range. 
     Further, it is preferable that the thickness of portions of the insulating resin layer  10  including the non-penetrating holes  11 , i.e., the distance from the bottom lib of a non-penetrating hole  11  to the face  10   b  of the insulating resin layer  10  that faces the metal member  50  (i.e., shortest distance), C, is 5 to 100 μm, 20 to 80 μm, or 30 to 60 μm. If the distance C is smaller than the lower limit for such a range, the circuit wiring  20  and metal member  50  may not be sufficiently insulated from each other. If the distance C is larger than the upper limit for such a range, the heat dissipation of the circuit part  100  may decrease. 
     The surface roughness (Ra) of the portion of the wiring region  10 A other than the portions of the non-penetrating holes  11  is preferably not greater than ⅕, or not higher than 1/10, of the depth d of the non-penetrating holes  11 . In the present embodiments, providing non-penetrating holes  11  improves the adhesion of the circuit wiring  20 , ensuring sufficient adhesion even if the surface roughness (Ra) of the wiring region  10 A is reduced. Further, since the surface roughness (Ra) of the portion of the wiring region  10 A other than the portions of the non-penetrating holes  11  is reduced, this improves the flatness of the circuit wiring  20  formed thereon. On the other hand, to facilitate selectively forming plating film for the circuit wiring  20  such that it is only present in the wiring region  10 A, the surface roughness (Ra) of the wiring region  10 A is preferably greater than the surface roughness (Ra) of the portions of the surface  10   a  other than the wiring region  10 A. Further, the surface roughness (Ra) of the wiring region  10 A may be, for example, 1 to 30 μm, 3 to 20 μm, or 5 to 10 μm. 
     The circuit wiring  20  is formed of plating film on the wiring region  10 A of the surface  10   a  of the insulating resin layer  10 . The circuit wiring  20  is preferably composed of an electroless-plating film  21  formed on the wiring region  10 A and an electroplating film  22  formed on the electroless plating film  21  (see  FIG.  7 ( e ) ). 
     The electroless plating film  21  may be, for example, electroless nickel-phosphorus plating film, electroless copper plating film, or electroless nickel plating film, where electroless nickel-phosphorus plating is preferable. The electroplating film  22  may be nickel-phosphorus electroplating film, copper electroplating film, or nickel electroplating film. To improve solder wettability on the plating film, a plating film of gold, silver, tin or the like may be formed at the outermost surface of the circuit wiring  20 . 
     Since the plating film constituting the circuit wiring  20  fills the non-penetrating holes  11 , the circuit wiring  20  can strongly adhere to the insulating resin layer  20 . The thickness A of the circuit wiring  20  is preferably larger than the smaller one of ½ of the depth d of the non-penetrating holes  11  and ½ of the width D of the holes. That is, the thickness A of the circuit wiring  20  is preferably larger than ½ of the depth d of the non-penetrating holes  11  or larger than ½ of the width D of the holes. If the thickness A of the circuit wiring  20  is within such a range, this further improves the flatness of the plating film constituting the circuit wiring  20 . Nevertheless, if the size of the non-penetrating holes  11  is relatively small, the non-penetrating holes  11  can be filled with plating film even if the thickness A of the circuit wiring  20  is smaller than such a range, thereby ensuring a certain flatness of the circuit wiring  20 . If the size of the non-penetrating holes  11  is relatively small, there is a concern that heat dissipation may decrease; however, reducing the thickness B of the insulating resin layer  10  to position the bottoms lib of the non-penetrating holes  11  and the metal member  50  closer to each other (i.e., reducing the distance C) can ensure that the circuit part  100  provides sufficient heat dissipation. 
     Thickness A of the circuit wiring  20  means the thickness that does not include that of portions thereof that fill the non-penetrating holes  11 . That is, the thickness A of the circuit wiring  20  is the distance from the surface  10   a  of the insulating resin layer  10  up to the face  20   a  of the circuit wiring  20  that faces the mounted component  30 . The thickness A of the circuit wiring  20  may be, for example, 10 to 100 μm, or 20 to 80 μm. 
     As shown in  FIG.  2 ( b ) , the mounted component  30  is positioned such that its face provided with a terminal (i.e., bottom surface)  30   b  faces the circuit wiring  20 , and the terminal and circuit wiring  20  are electrically connected by solder. The soldering is not limited to any particular solder, and a general-purpose solder may be used. When electric current flows through the mounted component  30 , the component generates heat and thus becomes a source of heat. Any mounted component  30  may be used; examples include LEDs (light-emitting diodes), power modules, ICs (integrated circuits), and heat resistors. 
     According to the present embodiments, the surface  20   a  of the circuit wiring  20  on which the mounted component  30  is to be mounted is flat, which increases the adhesive strength of the mounted component  30  with respect to the circuit wiring  20 , thereby improving the thermal conduction from the mounted component  30  to the circuit wiring  20 . This further improves the heat dissipation of the circuit part  100 . 
     [Method of Manufacturing Circuit Part] 
     A method of manufacturing the circuit part  100  will be described with reference to the flow chart shown in  FIG.  5   . First, a metal member  50  is prepared (step S 1  in  FIG.  5   ). The metal member  50  may be, for example, a commercial metal plate (i.e., plate-shaped body) or heat-dissipating fins, or a die casting in any desired shape. 
     The surface of the metal member  50  on which the insulating resin layer  10  is to be formed may be roughened to increase its adhesion to the insulating resin layer  10  that is to be deposited thereon. The roughening of the surface of the metal member  50  may use chemical etching, or a nanomolding technology (NMT) as disclosed in JP 2009-6721 A and Japanese Patent No. 5681076, for example. Alternatively, laser roughening may be performed. 
     Next, an insulating resin layer  10  is formed on the metal member  50  (step S 2  in  FIG.  5   ). For example, the insulating resin layer  10  may be formed by insert molding (i.e., integrated molding). Specifically, the metal member  50  is first placed inside a mold, and resin material is injected to fill in the empty space in the mold. Thus, the metal member  50  and insulating resin layer  10  are molded in an integrated manner. The insert molding used may be injection molding, transfer molding or the like. Thus, the insulating resin layer  10  and metal member  50  may be constituted by an integral molding obtained by integrated molding. As used herein, integral molding means an object produced by a process of joining an insulating resin layer  10  with a metal member  50  during molding of the resin layer (typically, insert molding), rather than separately fabricating a metal member  50  and an insulating resin layer  10  and then bonding or joining them together (i.e., secondary bonding or mechanical joining). 
     Next, a plurality of non-penetrating holes  11  are formed in the wiring region  10 A of the insulating resin layer  10  (step S 3  in  FIG.  5   ). The formation of the non-penetrating holes  11  is not limited to any particular method; for example, the surface  10   a  of the insulating resin layer  10  may be illuminated with a laser beam to cut the surface to form the non-penetrating holes  11  (i.e., laser machining). Laser machining can efficiently form a plurality of non-penetrating holes  11 , and also allows easy adjustment of the size of the non-penetrating holes  11  (width D and depth d). At the same time as the formation of the non-penetrating holes  11 , the entire wiring region  10 A may be illuminated with a laser beam to roughen the wiring region  10 A. Roughening the wiring region  10 A makes it easier to selectively form the circuit wiring  20  (i.e., plating film) such that the wiring is present only in the wiring region  10 A, and also increases the adhesion of the circuit wiring  20 . However, to ensure a certain flatness of the circuit wiring  20  that is to be formed thereon, the surface roughness (Ra) of the portion of the wiring region  10 A other than the portions of the non-penetrating holes  11  is preferably not greater than ⅕, or not greater than 1/10, of the depth d of the non-penetrating holes  11 . The laser machining to form the non-penetrating holes  11  is not limited to any particular type of laser beam or to any particular laser machining equipment, and any appropriate beam/equipment may be chosen for use taking account of the type of the insulating resin layer  10  and/or other factors. 
     In implementations where the non-penetrating holes  11  are formed by laser machining, it is preferable, for example, to perform laser drawing in a pattern composed of discontinuous lines, as shown in  FIG.  6   . The laser drawing shown in  FIG.  6    will be described. First, discontinuous lines L 1  extending in a predetermined direction (Y-direction shown in  FIG.  6   ) are drawn. The discontinuous lines L 1  represent a pattern of line segments (laser-drawn portions), each with a length N 1 , that are arranged with a distance (space) of a length N 2 . Next, discontinuous lines L 2  are laser-drawn where a pattern similar to that of the lines L 1  is translated from the lines L 1  by a distance N 3  in the direction perpendicular to the predetermined direction (i.e., X-direction shown in  FIG.  6   ) and also translated by a distance N 4  in the Y-direction. Here, N 4 =(N 1 +N 2 )/2. Analogous operations are repeated to draw a plurality of sets of discontinuous lines Ln extending in the Y-direction and arranged in the X-direction with an equal distance (i.e., distance N 3 ). This results in a laser-drawn pattern with line segments (laser-drawn portions) each with the length N 1  arranged in the X-direction with a pitch of N 1 +N 2  and arranged in the Y-direction with a pitch of 2×N 3 , as shown in  FIG.  6   . The laser beam is only directed to the line segments with the length N 1 ; however, since the laser beam has a width called spot diameter, it also cuts portions of the insulating resin layer  10  near the drawn pattern lines. If the line length N 1  is small, the width expansion resulting from the spot diameter is generally equal to the cut depth, creating a non-penetrating hole  11  with a cone-shaped laser-machining mark. The distance P is given by: P=√[(N 3 ) 2 +(N 4 ) 2 ]−D, where D is the diameter of the non-penetrating holes  11  formed by cutting with expansion from the laser-illuminated portions with the length N 1 . Patterns of non-penetrating holes  11  of various sizes can be created by changing the values of the lengths N 1  to N 4 . Further, use of such laser drawing allows the non-penetrating holes  11  to be easily formed in the wiring region  10 A in such a sporadic manner that the density is generally uniform. Another method of forming a plurality of non-penetrating holes  11  with a laser beam, other than forming a drawn pattern of discontinuous lines, may be illumination with a laser beam in a pulsing manner. 
     Next, circuit wiring  20  included in the plating film is formed on the wiring region  10 A of the insulating resin layer  10 . The formation of the circuit wiring  20  is not limited to any particular method, and a common method may be used. For example, in one method, a plating film is formed on the entire surface  10   a , the plating film is patterned using a photoresist, and portions of the plating film other than the circuit wiring are removed by etching; in another method, the portions of the surface on which circuit wiring is to be formed are illuminated with a laser beam to roughen the resin layer, and plating film is formed only on the portions illuminated with the laser beam. Especially in implementations where the insulating resin layer  10  used is made of a thermosetting resin such as epoxy resin, roughening the wiring region  10 A with a laser beam promotes adsorption of metal ions that serve as a plating catalyst, making it easier to form electroless plating film only on the wiring region  10 A. 
     Some of the plating film constituting the circuit wiring  20  fills the non-penetrating holes  11 . The formation of the circuit wiring  20  may include, as shown in  FIGS.  7 ( a )-( e ) : forming an electroless plating film  21  on the wiring region  10 A (see  FIG.  7 ( a ) ); and forming an electroplating film  22  on the electroless plating film  21  (see  FIGS.  7 ( b )-( e ) ). 
     The formation of the electroless plating film  21  is not limited to any particular method, and an appropriate common electroless plating method may be selected and used. Forming an electrically conductive electroless plating film  21  on the insulating resin layer  10  enables electroplating on the electroless plating film  21 . Thus, the electroless plating film  21  serves as a foundation on which the electroplating film  22  can be formed. 
     The formation of the electroplating film  22  is not limited to any particular method, and an appropriate common electroplating method may be selected and used, where electroplating methods with high throwing power are preferable. During electroplating, large amounts of electric current flow at the corners and protrusions of the surface on which a plating film is to be formed, while smaller amounts of current flow in central portions and at recesses. The thickness of the electroplating film tends to be proportional to the strength of current; as such, if the surface on which a plating film is to be formed has protrusions and/or recesses, this produces variations in the thickness of the electroplating film. An electroplating method with high throwing power can reduce such variations in the thickness of the electroplating film. As a result, as shown in  FIGS.  7 ( b )-( e ) , the electroplating films  22   a ,  22   b  and  22   c  formed do not have larger thicknesses at the edges of the opening  11   a  (i.e., corners) of a non-penetrating hole  11 , but grow to a generally uniform film thickness from the inner wall of the non-penetrating hole  11  and the surface  10   a . Thus, film can easily fill in the non-penetrating holes  11 , and also increases the flatness of the surface of the electroplating film  23   c  (i.e., surface  20   a  of the circuit wiring  20 ). 
     As discussed above, the ratio d/D of the depth d to the width D of the non-penetrating holes  11  is 0.5 to 5. As the ratio d/D of the non-penetrating holes  11  is within such a range, the electroplating film  22  can easily fill in the non-penetrating holes  11 , and also increases the flatness (or smoothness) of the surface  20   a  of the circuit wiring  20 . On the other hand, if the ratio d/D is outside such a range, it is difficult to fill the non-penetrating holes  11  with plating film, nor can the flatness of the circuit wiring  20  be increased. For example,  FIGS.  8 ( a )-( e )  show how a plating film is formed on a substrate having a non-penetrating hole  111  with a ratio d/D smaller than 0.5, that is, a non-penetrating hole  111  with a width D that is too large relative to the height d. The electroplating films  22   a ,  22   b  and  22   c , which grow from the inner wall of the non-penetrating hole  111 , cannot easily fill in the non-penetrating hole  111  since the width D of the non-penetrating hole  111  is too large relative to the film thickness. It is possible to fill the non-penetrating hole  111  by forming, as shown in  FIG.  8 ( e ) , a plating film with a thickness generally equal to the depth d; however, portions of the plating film located at the edges of the opening  111   a  of the non-penetrating hole  111  are raised, which makes it impossible to provide a flat surface  20   a  of the circuit wiring  20 . To achieve a flat surface  20   a  of the circuit wiring  20 , the thickness of the formed electroplating film  22  must be further increased, which would be inefficient and increase manufacturing costs. 
     After the circuit wiring  20  is formed on the insulating resin layer  10 , a mounted component  30  is mounted on the circuit wiring  20  (step S 5  in  FIG.  5   ). This results in the circuit part  100  of the present embodiments. The mounting of the mounted component  30  is not limited to any particular method, and a common method can be used: for example, the mounted component  30  may be soldered to the insulating resin layer  10  by a solder-reflow method in which solder at room temperature and the mounted component  30  are placed on the circuit wiring  20  and then moved through a high-temperature reflow furnace, or a laser-soldering method (i.e., spot mounting) in which a laser beam is directed to the interface between the insulating resin layer  10  and mounted component  30  to solder them together. 
     In the circuit part  100  of the present embodiments described above, non-penetrating holes  11  with a ratio d/D within a certain range are formed in the wiring region  10 A to provide both high heat dissipation and high adhesion of the circuit wiring  20  to the insulating resin layer  10 . Further, the surface  20   a  of the circuit wiring  20  on which the mounted component  30  is to be mounted is flat, which improves the adhesive strength of the mounted component  30  to the circuit wiring  20  and improves thermal conductivity from the mounted component  30  to the circuit wiring  20 . This further improves the heat dissipation of the circuit part  100 . 
     [Variations] 
     In the circuit part  100  of the embodiments described above, the insulating resin layer  10  is formed directly on top of the metal member  50 ; however, embodiments are not limited to such an arrangement. As shown in  FIG.  9   , a ceramic layer  60  may be provided between the metal member  50  and insulating resin layer  10 . The present variation will be described below with reference to a circuit part  200  including the ceramic layer  60  shown in  FIG.  9   . The construction of the circuit part  200  is the same as that of the above-described circuit part  100  shown in  FIGS.  2 ( a ), ( b )  except for the presence of the ceramic layer  60 . Accordingly, for the present variation, the requirements other than the ceramic layer  60  will not described. 
     The ceramic layer  60  is provided on the metal member  50 . The ceramic layer  60  is more difficult to cut with a laser beam than the insulating resin layer  10 . Thus, if non-penetrating holes  11  are formed with laser-beam illumination, the non-penetrating holes  11  are prevented from reaching the metal member  50 . Further, the ceramic layer  60  provides insulation and works together with the insulating resin layer  10  to insulate the circuit wiring  20  and metal member  50  from each other to prevent a short circuit. The degree of insulation depends on the application of the circuit part  100 ; the resistance is preferably not lower than 5000 MΩ upon application of a voltage of 500 V, for example. 
     Further, the ceramic layer  60  preferably has high thermal conductivity to increase the heat dissipation of the circuit part  100 . Thus, the ceramic layer  60  is preferably an insulating thermal-conductive layer (i.e., insulating heat-dissipating layer) that provides both insulation and high thermal conductivity. The thermal conductivity of the ceramic layer  60  is 5 to 150 W/m·K., for example. Further, to efficiently release heat generated by the mounted component  30  on the insulating resin layer  10  to the metal member  50 , the thermal conductivity of the ceramic layer  60  is preferably lower than the thermal conductivity of the metal member  50  and higher than the thermal conductivity of the insulating resin layer  10 . 
     Examples of the ceramics contained in the ceramic layer include aluminum oxide (alumina), aluminum nitride, boron nitride, silicon nitride, beryllium oxide, silicon carbide, yttria, zirconia, titanium dioxide, silicon dioxide, clay minerals and the like, where yttria and alumina, which can easily form a dense thin film at low cost, are preferable. One of these ceramics may be used alone, or two or more of them may be mixed and used. 
     The film thickness of the ceramic layer  60  may be, for example, 1 μm to 100 μm, 5 μm to 20 μm, or 5 μm to 10 μm. 
     A method of manufacturing the circuit part  200  of the present variation will now be described. First, a metal member  50  is prepared. 
     Next, a ceramic layer  60  is formed on the metal member  50 . The formation of the ceramic layer  60  is not limited to any particular method; examples of methods that can be used include: physical vapor deposition (PVD) methods such as vacuum deposition or ion plating; chemical vapor deposition (CVD) methods such as plasma CVD; aerosol deposition (AD); sputtering; spraying; cold spraying; and warm spraying. In implementations where the metal member  50  is made of aluminum or alloys thereof, the ceramic layer  60  may be an “alumite” layer (i.e., coating of aluminum oxide (alumina)) formed through anodic oxidation. The alumite layer may be formed only on part of the metal member  50 , or may be formed on the entire surface of the metal member  50 . Furthermore, a plurality of ones of the above-described film-forming methods may be used to form a ceramic layer  60  composed of multiple layers to increase film strength. 
     Next, an insulating resin layer  10  is formed on the ceramic layer  60 ; a plurality of non-penetrating holes  11  are formed in the wiring region  10 A of the insulating resin layer  10 ; circuit wiring  20  including plating film is formed on the wiring region  10 A of the insulating resin layer  10 ; and a mounted component  30  is mounted on the circuit wiring  20 , which results in the circuit part  200  of the present variation. The formation of the insulating resin layer  10 , the formation of the plurality of non-penetrating holes  11 , the formation of the circuit wiring  20 , and the mounting of the mounted component  30  can be performed in the same manner as for the above-described method of manufacturing the circuit part  100 . 
     The circuit part  200  of the present variation produces substantially the same effects as the above-described circuit part  100 . Further, the circuit part  200 , including the ceramic layer  60 , can more reliably insulate the circuit wiring  20  and metal member  50  from each other. 
     EXAMPLES 
     Now, the present invention will be specifically described with reference to inventive and comparative examples; however, the present invention is not limited to the inventive and comparative examples described below. 
     Inventive Example 1 
     For the present example, a circuit part  100  as shown in  FIG.  1    was produced. The mounted component  30  was constituted by an LED (light-emitting diode). 
     (1) Preparation of Metal Part 
     To provide a metal member  50 , an aluminum plate (A1050 with 99% or more aluminum, 8 cm by 12 cm) was prepared. 
     (2) Formation of Insulating Resin Layer 
     Next, a general-purpose molding machine was used to perform insert molding (i.e., transfer molding), using an epoxy resin containing 75 wt. % alumina (aluminum oxide) particles with a maximum diameter of 35 μm (thermosetting resin; thermal conductivity; 1 W/m·K), to form an insulating resin layer  10 . This resulted in a substrate  70  composed of an aluminum plate (i.e., metal member)  50  and an insulating resin layer  10 . The size of the insulating resin layer  10  was 40 mm by 40 mm by 200 μm in thickness. The insulating resin layer  10  was formed in central portions of the metal member  50 . 
     (3) Formation of Non-Penetrating Holes 
     The region of the surface  10   a  of the insulating resin layer  10  on which circuit wiring  20  was to be formed (i.e., wiring region  10 A) was illuminated with a laser beam to process the wiring region  10 A. The laser machining (i.e., laser drawing) used a three-dimensional laser marker (MD-9920A YVO 4  laser from Keyence Corporation, with 13 W). 
     First, the region of the surface  10   a  of the insulating resin layer  10  on which the circuit wiring  20  was to be formed (i.e., wiring region  10 A) was illuminated with a laser beam to roughen the region. Specifically, a pattern of parallel lines arranged with a pitch of 40 μm was laser-drawn in the wiring region  10 A (laser-drawing conditions; a linear velocity of 2000 mm/s, a frequency of 40 kHz and a power of 20%). The resulting surface roughness (Ra) of the wiring region  10 A was 13 μm. 
     Next, a plurality of non-penetrating holes (i.e., recesses)  11  were formed in the wiring region  10 A by laser machining. Specifically, a pattern of discontinuous lines as shown in  FIG.  6    was laser drawn in the wiring region  10 A (laser-drawing conditions; a linear velocity of 30 mm/s, a frequency of 50 kHz and a power of 80%), thereby forming a plurality of non-penetrating holes  11 . The number of rounds of laser drawing (i.e., number of rounds of repeated laser drawing) was 1. The dimensions of the laser-drawn patterns were as follows; N 1 =35 μm, N 2 =365 μm, N 3 =200 μm, and N 4 =200 μm. The shape of the resulting non-penetrating holes  11  was that of a circular cone with its bottom positioned at the surface  10   a  (i.e., wiring region  10 A), as shown in  FIGS.  2 ( a ), ( b ) . 
     The width D and depth d of the resulting non-penetrating holes  11 , as well as the distance P between adjacent ones of the non-penetrating holes  11 , were measured using a laser microscope (VK-9700 laser microscope from Keyence Corporation, with an objective magnification of 20×). The depth d was calculated by calculating the depth distribution for one non-penetrating hole  11 , where the largest depth values within the cumulative frequency range of below 1% were determined to be optical noise and ignored, and treating the depth value with a cumulative frequency of 1% as the depth d of this one particular non-penetrating hole. The width D was calculated by calculating the area of the opening  11   a  of one non-penetrating hole  11 , and treating the diameter of the opening  11   a  when treated as being perfectly circular as the width D of this one particular non-penetrating hole  11 . For every one of the non-penetrating holes  11  present in the field of view for measurement, the width D and depth d were determined in the same manner and the averages of the widths D and depths d were calculated. 
     For the distance P for the non-penetrating holes  11 , first, the distance between the centroid of the opening  11   a  of one non-penetrating hole  11  and the centroid of the opening  11   a  of an adjacent non-penetrating hole  11  was measured. For all the non-penetrating holes  11  present in the field of view for measurement, the distance between the centroids of adjacent openings  11   a  was determined in the same manner, and the average of the distances for these centroids was determined. Next, the average of the widths D that had been determined was subtracted from the average of the distances for the centroids to give the distance P for the non-penetrating holes  11 . 
     The width D (average) of the non-penetrating holes  11  thus calculated was 155 μm, the depth d (average) was 178 μm, and the distance P for the non-penetrating holes  11  was 128 μm. Thus, the ratio d/D was 1.15. The calculated values of the width D and depth d of the penetrating holes  11 , the distance P for the non-penetrating holes  11 , and the ratio d/D are shown in Table 4. 
     (4) Formation of Circuit Wiring 
     (a) Application of Electroless Plating Catalyst 
     The substrate  70  with non-penetrating holes  11  formed thereon was immersed, for 5 minutes, in a commercial palladium chloride (PdCl 2 ) aqueous solution (Activator from Okuno Chemical Industries Co., Ltd.) that had been adjusted to be at 30° C. Thereafter, the substrate was removed from the palladium chloride aqueous solution, and was water-washed. 
     (b) Electroless Plating, and Electroplating 
     Next, the substrate was immersed, for 10 minutes, in an electroless nickel-phosphorus plating solution (Top Nicoron LPH-L from Okuno Chemical Industries Co., Ltd., at a pH of 6.5) that had been adjusted to be at 60° C. A nickel-phosphorus film (i.e., electroless nickel-phosphorus plating film) grew about 1 μm on the wiring region  10 A. 
     On the nickel-phosphorus film were further deposited: a 95 μm copper electroplating film; a 4.0 μm electroless nickel-phosphorus plating film; and a 0.1 μm electroless gold film plating in this order, to form circuit wiring  20 . The copper electroplating was performed by an electroplating method with high throwing power. The copper electroplating solution used was a mixture of liquid A: Top Lucina 2000 from Okuno Chemical Industries Co., Ltd.; and liquid B: Copper Gleam HS-200 from Rohm and Haas Electronic Materials LLC. This resulted in circuit wiring  20  composed of an electroless plating film and an electroplating film on the wiring region  10 A illuminated with a laser beam. 
     (5) Mounting of Mounted Component 
     The mounted component  30  used was a surface-mounting-type high luminance LED (NS2W123BT from Nichia Corporation; 3.0 mm by 2.0 mm by 0.7 mm in height). First, as shown in  FIG.  1   , five mounted components  30  were placed on the circuit wiring  20  with solder at room temperature positioned therebetween. The distance between adjacent mounted components  30  was 0.5 mm. Next, the substrate with the LEDs placed thereon was loaded into a reflow furnace (solder reflow). The substrate was heated inside the reflow furnace, where the maximum temperature reached by the substrate was 240° C. to 260° C., with the substrate being heated at the maximum reached temperature for about 1 minute. The solder caused the mounted components  30  to be mounted on the resin  10 , resulting in the circuit part  100  of the present inventive example shown in  FIG.  1   . 
     [Inventive Examples 2 to 12] 
     For each of Inventive Examples 2 to 12, a circuit part  100  was produced by the same method as for Inventive Example 1, except that the thickness of the insulating resin layer  10 , the laser drawing conditions, the various dimensions in the laser-drawn pattern shown in  FIG.  6    (N 1  to N 4 ), and the thickness of the circuit wiring (i.e., thickness of the plating film) were changed to the relevant values shown in Tables 1, 2 and 4. For Inventive Examples 5 to 12, the YVO 4  laser used for Inventive Example 1 was replaced with a UV laser (MD-U1000C three-dimensional laser marker from Keyence Corporation, with an output of 2.5 W). 
     Further, the width D and depth d of the penetrating holes  11  as well as the distance P for the non-penetrating holes  11  were calculated in the same manner as for Inventive Example 1. The calculated values of the width D and depth d of the penetrating holes  11  as well as the distance P for the non-penetrating holes  11  and the ratio d/D are shown in Tables 4 and 5. 
     Inventive Example 13 
     For the present inventive example, a circuit part  300  as shown in  FIGS.  10 ( a ), ( b )  was produced. In the circuit part  300 , the thickness of the resin layer  310  was not constant, as shown in  FIG.  10 ( b ) . Otherwise, the circuit part was substantially the same as the circuit part  100  shown in  FIG.  1   . 
     For the present inventive example, the smallest film thickness of the resin layer  310 , X1, was 75 μm, and the largest film thickness X2 was 450 μm. Since the insulating resin  310  contained filler (i.e., alumina particles) with a maximum particle diameter of 35 μm, it was difficult to mold the entire insulating resin  310  with a thickness of 75 μm; providing a thickness of 75 μm only for some portions made the molding possible. Providing sub-regions with smaller film thicknesses (i.e., regions with the film thickness X1) improves the heat dissipation of the circuit part  300 . Further, it is preferable that the sub-regions with smaller film thicknesses (i.e., regions with the film thickness X1) are located in areas where the mounted components (LED)  30 , which are sources of heat, are mounted. 
     For the present inventive example, a circuit part  300  was produced by the same method as for Inventive Example 1 except that the thickness of the insulating resin layer  310 , the laser drawing conditions, the various dimensions in the laser-drawn pattern shown in  FIG.  6    (N 1  to N 4 ), and the thickness of the circuit wiring (i.e., thickness of the plating film) were changed to the relevant values shown in Tables 2 and 5. For the present inventive example, the UV laser used for Inventive Example 5 was used to form the non-penetrating holes  11 . 
     Further, the width D and depth d of the penetrating holes  11  as well as the distance P for the non-penetrating holes  11  were calculated by the same method as for Inventive Example 1. The calculated values of the width D and depth d of the penetrating holes  11  as well as the distance P for the non-penetrating holes  11  and the ratio d/D are shown in Table 5. 
     Inventive Example 14 
     For the present inventive example, a circuit part was produced having a resin layer  310  with non-constant thickness, as is the case with the circuit part  300  shown in  FIGS.  10 ( a ), ( b ) , and including a ceramic layer  60 , as is the case with the circuit part  200  shown in  FIG.  9   . The circuit part produced for the present inventive example was substantially the same as the circuit part  100  shown in  FIG.  1    except that the thickness of the resin layer was not constant and it included a ceramic layer. For the present inventive example, the smallest film thickness X1 of the resin layer was 65 μm, and the largest film thickness X2 was 450 μm. 
     First, a metal member similar to the one used for Inventive Example 1 was prepared, on which degreasing and chemical etching was performed before hard alumite processing was performed (TAF-TR from Toadenka Co., Ltd.). This resulted in an anodic oxidation coating (i.e., alumite) over the entire metal member. The film thickness of the anodic oxidation coating was 50 μm. 
     Starting with the metal member with the anodic oxidation coating formed thereon the circuit part for the present inventive example was produced by the same method as for Inventive Example 1 except that the thickness of the insulating resin layer, the laser drawing conditions, the various dimensions in the laser-drawn pattern shown in  FIG.  6    (N 1  to N 4 ), and the thickness of the circuit wiring (i.e., thickness of the plating film) were changed to the relevant values shown in Tables 2 and 5. For the present inventive example, the UV laser used for Inventive Example 5 was used to form non-penetrating holes. 
     Further, the width D and depth d of the penetrating holes  11  as well as the distance P for the non-penetrating holes  11  were calculated by the same method as for Inventive Example 1. The calculated values of the width D and depth d of the penetrating holes  11  as well as the distance P for the non-penetrating holes  11  and the ratio d/D are shown in Table 5. 
     Further, a microscope (VH-6000 from Keyence Corporation) was used to perform cross-sectional observation of the circuit part of the present inventive example. As shown in  FIG.  11   , it was observed that the non-penetrating holes were regularly formed in the insulating resin layer. 
     Comparative Example 1 
     For the present comparative example, the non-penetrating holes  11  were replaced with a grid pattern composed of grooves (i.e., recesses) on the entire wiring region  10 A of the substrate  70 . 
     (1) Preparation of Substrate 
     A substrate was produced having an insulating resin layer on a metal member by the same method as for Inventive Example 1 except that the thickness of the insulating resin layer was 150 μm. 
     (2) Formation of Grid Pattern 
     A grid pattern was formed by laser machining in a region of the surface of the insulating resin layer on which circuit wiring was to be formed (i.e., wiring region), under the laser drawing conditions shown in Table 3. The grid pattern was a grid pattern with a pitch of 200 μm. The depth of the grooves forming the grid pattern (i.e., maximum depth of the laser machined portions) was 130 μm. 
     (3) Formation of Circuit Wiring and Mounting of Mounted Component 
     On the substrate provided with the grid pattern, circuit wiring was formed by the same method as for Inventive Example 1, and a mounted component was mounted thereon. This resulted in the circuit part for the present comparative example. The electroplating was performed under the same conditions as for Inventive Example 2 (plating solution composition, current density, and time), which were adjusted such that the average thickness of the circuit wiring was generally equal to that of Inventive Example 2. In Table 5, the value of the average thickness of the circuit wiring is shown in parentheses. 
     Comparative Examples 2 to 4 
     As is the case with Comparative Example 1, for each of Comparative Examples 2 to 4, the non-penetrating holes  11  were replaced with a grid pattern composed of grooves (i.e., recesses) over the entire wiring region of the substrate. For Comparative Examples 2 to 4, a circuit part was produced by the same method as for Comparative Example 1 except that the thickness of the insulating resin layer  10 , the laser drawing conditions and the average thickness of the circuit wiring were changed to the relevant values shown in Tables 3 and 5. For Comparative Examples 3 and 4, the YVO 4  laser used for Comparative Example 1 was replaced by a UV laser (MD-U1000C three-dimensional laser marker from Keyence Corporation, with an output of 2.5 W), and a grid pattern with a pitch of 80 μm was laser drawn. 
     Comparative Example 5 
     As is the case with Comparative Example 1, for the present comparative example, the non-penetrating holes  11  were replaced with a grid pattern composed of grooves (i.e., recesses) over the entire wiring region of the substrate. However, for the present comparative example, a circuit part was produced having a resin layer  310  with non-constant thickness, as is the case with the circuit part  300  shown in  FIGS.  10 ( a ), ( b ) , and including a ceramic layer  60 , as is the case with the circuit part  200  shown in  FIG.  9   . The circuit part produced for the present comparative example was the same as the circuit part produced for Comparative Example 1 except that the thickness of the resin layer was not constant and it included a ceramic layer. For the present comparative example, the smallest film thickness X1 of the resin layer was 65 μm, and the largest film thickness X2 was 450 μm. 
     First, a metal member similar to the one used for Comparative Example 1 was prepared, on which degreasing and chemical etching was performed before hard alumite processing was performed (TAF-TR from Toadenka Co., Ltd.). This resulted in an anodic oxidation coating (i.e., alumite) over the entire metal member. The film thickness of the anodic oxidation coating was 50 μm. 
     Starting with the metal member with the anodic oxidation coating formed thereon, the circuit part for the present comparative example was produced by the same method as for Comparative Example 1 except that the thickness of the insulating resin layer, the laser drawing conditions, and the average thickness of the circuit wiring were changed to the relevant values shown in Tables 3 and 5. For the present comparative example, the YVO 4  laser used for Comparative Example 1 was replaced with the UV laser used for Comparative Example 3. 
     [Comparative Examples 6 and 7] 
     For Comparative Examples 6 and 7, a plurality of through-holes  11  were formed in the region of the surface  10   a  of the insulating resin layer  10  on which the circuit wiring  20  was to be formed (i.e., wiring region  10 A). For Comparative Examples 6 and 7, a circuit part  100  was produced by the same method as for Inventive Example 1 except that the thickness of the insulating resin layer  10 , the laser drawing conditions, the various dimensions in the laser-drawn pattern shown in  FIG.  6    (N 1  to N 4 ), and the thickness of the circuit wiring (i.e., thickness of the plating film) were changed to the relevant values shown in Tables 3 and 5. For Comparative Examples 6 and 7, the YVO 4  laser used for Inventive Example 1 was replaced with the UV laser used for Comparative Example 3. 
     Further, the width D and depth d of the penetrating holes  11  as well as the distance P for the non-penetrating holes  11  were calculated by the same method as for Inventive Example 1. The calculated values of the width D and depth d of the penetrating holes  11 , the distance P for the non-penetrating holes  11  and the ratio d/D are shown in Table 5. It is to be noted that the depth d of the non-penetrating holes  11  of Comparative Example 7 was determined by cross-sectional observation. 
     
       
         
           
               
               
             
               
                   
                 TABLE 1 
               
             
            
               
                   
                   
               
               
                   
                 Inventive Examples 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                   
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
                 7 
                 8 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Ceramic Layer 
                 — 
                 — 
                 — 
                 — 
                 — 
                 — 
                 — 
                 — 
               
               
                 Thickness 
                 200 
                 150 
                 150 
                 150 
                 200 
                 100 
                 100 
                 100 
               
               
                 of Resin Layer (μm) 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
            
               
                 Laser 
                 Laser type 
                 YVO 4   
                 YVO 4   
                 YVO 4   
                 YVO 4   
                 UV 
                 UV 
                 UV 
                 UV 
               
               
                 Drawing 
                 Power (%) 
                 80 
                 80 
                 80 
                 80 
                 80 
                 80 
                 80 
                 80 
               
               
                 Conditions 
                 Linear 
                 30 
                 100 
                 400 
                 800 
                 20 
                 200 
                 200 
                 100 
               
               
                   
                 velocity 
               
               
                   
                 (mm/s) 
               
               
                   
                 Frequency 
                 50 
                 50 
                 50 
                 50 
                 50 
                 100 
                 100 
                 100 
               
               
                   
                 (kHz) 
               
               
                   
                 No. of 
                 1 
                 1 
                 1 
                 1 
                 3 
                 1 
                 1 
                 1 
               
               
                   
                 rounds 
               
               
                   
                 of drawing 
               
               
                 Laser 
                 N1 (μm) 
                 35 
                 35 
                 35 
                 35 
                 10 
                 10 
                 10 
                 10 
               
               
                 Drawing 
                 N2 (μm) 
                 365 
                 215 
                 215 
                 215 
                 90 
                 90 
                 90 
                 90 
               
               
                 Pattern 
                 N3 (μm) 
                 200 
                 160 
                 200 
                 200 
                 80 
                 80 
                 80 
                 80 
               
               
                 Size 
                 N4 (μm) 
                 200 
                 125 
                 125 
                 125 
                 50 
                 50 
                 50 
                 50 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
             
               
                   
                 TABLE 2 
               
             
            
               
                   
                   
               
               
                   
                 Inventive Examples 
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 9 
                 10 
                 11 
                 12 
                 13 
                 14 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 Ceramic Layer 
                 — 
                 — 
                 — 
                 — 
                 — 
                 alumite 
               
               
                 Thickness 
                 150 
                 100 
                 100 
                 100 
                 75-450 
                 65-450 
               
               
                 of Resin Layer (μm) 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 Laser 
                 Laser type 
                 UV 
                 UV 
                 UV 
                 UV 
                 UV 
                 UV 
               
               
                 Drawing 
                 Power (%) 
                 80 
                 80 
                 80 
                 80 
                 80 
                 80 
               
               
                 Conditions 
                 Linear 
                 20 
                 20 
                 20 
                 20 
                 20 
                 20 
               
               
                   
                 velocity 
               
               
                   
                 (mm/s) 
               
               
                   
                 Frequency 
                 100 
                 100 
                 100 
                 100 
                 100 
                 100 
               
               
                   
                 (kHz) 
               
               
                   
                 No. of 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
               
               
                   
                 rounds 
               
               
                   
                 of drawing 
               
               
                 Laser 
                 N1 (μm) 
                 10 
                 10 
                 10 
                 10 
                 10 
                 10 
               
               
                 Drawing 
                 N2 (μm) 
                 90 
                 70 
                 110 
                 190 
                 90 
                 90 
               
               
                 Pattern 
                 N3 (μm) 
                 80 
                 60 
                 100 
                 120 
                 80 
                 80 
               
               
                 Size 
                 N4 (μm) 
                 50 
                 40 
                 60 
                 100 
                 50 
                 50 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
             
               
                   
                 TABLE 3 
               
             
            
               
                   
                   
               
               
                   
                 Comparative Examples 
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                   
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
                 7 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
               
               
            
               
                 Ceramic Layer 
                 — 
                 — 
                 — 
                 — 
                 alumite 
                 — 
                 — 
               
               
                 Thickness 
                 150 
                 150 
                 100 
                 100 
                 65-450 
                 100 
                 420  
               
               
                 of Resin Layer (μm) 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Laser 
                 Laser type 
                 YVO 4   
                 YVO 4   
                 UV 
                 UV 
                 UV 
                 UV 
                 UV 
               
               
                 Drawing 
                 Power (%) 
                 80 
                 80 
                 80 
                 80 
                 80 
                 80 
                 80 
               
               
                 Conditions 
                 Linear 
                 800 
                 1600 
                 200 
                 600 
                 600 
                 200 
                 20 
               
               
                   
                 velocity 
               
               
                   
                 (mm/s) 
               
               
                   
                 Frequency 
                 50 
                 50 
                 100 
                 100 
                 100 
                 100 
                 50 
               
               
                   
                 (kHz) 
               
               
                   
                 No. of 
                 1 
                 1 
                 1 
                 1 
                 1 
                 1 
                 10 
               
               
                   
                 rounds 
               
               
                   
                 of drawing 
               
               
                 Laser 
                 N1 (μm) 
                 — 
                 — 
                 — 
                 — 
                 — 
                 10 
                 10 
               
               
                 Drawing 
                 N2 (μm) 
                 — 
                 — 
                 — 
                 — 
                 — 
                 90 
                 90 
               
               
                 Pattern 
                 N3 (μm) 
                 — 
                 — 
                 — 
                 — 
                 — 
                 80 
                 80 
               
               
                 Size 
                 N4 (μm) 
                 — 
                 — 
                 — 
                 — 
                 — 
                 50 
                 50 
               
               
                   
               
            
           
         
       
     
     [Evaluation of Circuit Part] 
     The above-described circuit parts fabricated for Inventive Examples 1 to 14 and Comparative Examples 1 to 7 were evaluated as described further below. The evaluation results are shown in Tables 4 and 5. Further, together with the evaluation results, the following values relating to the circuit parts for Inventive Examples 1 to 14 and Comparative Examples 1 to 7 are shown in Tables 4 and 5: the width D and depth d of the non-penetrating holes  11 ; the ratio d/D; the distance P for the non-penetrating holes  11 ; the ratio P/D; the surface roughness of the wiring region  10 A (Ra); the ratio d/5; the thickness B of the resin layer below the circuit wiring; the distance C; the thickness A of the circuit wiring; and the smaller one of the values of D/2 and d/2. Further, for Comparative Examples 1 to 5, the depth d of the non-penetrating holes  11  and the thickness A of the circuit wiring are replaced with the depth of the grooves forming the grid pattern and the average thickness of the circuit wiring, shown in parentheses in Table 5. 
     (1) Adhesion Testing of Circuit Wiring (Plating Film) 
     Separately from the above-described circuit parts fabricated for Inventive Examples 1 to 14 and Comparative Examples 1 to 7, specimens for adhesion testing for the inventive and comparative examples were prepared by the following method: First, substrates were prepared composed of metal members and insulating resin layers of the same respective materials that were used for Inventive Examples 1 to 14 and Comparative Example 1 to 7. Laser drawing was performed on the insulating resin layers of the substrates in the same respective manner as for the inventive and comparative examples. On each substrate after laser drawing was formed a 1 μm electroless nickel-phosphorus plating film, on top of which a 40 μm copper electroplating was formed to produce a specimen for adhesion testing. The plating film of each specimen had a size of 2 mm in width and 40 mm in length. The adhesive strength of the plating film of the measurement specimen was measured by perpendicular tensile testing, and the adhesion of the circuit wiring (i.e., plating film) was evaluated in accordance with the following evaluation criteria. 
     &lt;Evaluation Criteria for Adhesion&gt; 
     A: The adhesive strength of the plating film of a measurement specimen was not lower than 15 N/cm. 
     B: The adhesive strength of the plating film of a measurement specimen was not lower than 10 N/cm and lower than 15 N/cm. 
     C: The adhesive strength of the plating film of a measurement specimen was not lower than 1 N/cm and lower than 3 N/cm. 
     E: The adhesive strength of the plating film of a measurement specimen was lower than 1 N/cm. 
     (2) Insulation Testing of Insulating Resin Layer 
     In each of the circuit parts fabricated for Inventive Examples 1 to 14 and Comparative Examples 1 to 7, a voltage of 500 V was applied between the circuit wiring  20  and metal member  50 ; the resistance value between the circuit wiring  20  and metal member  50  was measured using a tester; and the insulation of the insulating resin layer was evaluated based on the following evaluation criteria for insulation. It is to be noted that for Inventive Example 14 and Comparative Example 5, portions of the alumite layer on which no insulating resin layer was formed were ground with a metal file to expose the metal member, and the resistance between the circuit wiring  20  and metal member  50  was measured. 
     &lt;Evaluation Criteria for Insulation&gt; 
     A: The resistance value between the circuit wiring  20  and metal member  50  was not lower than 5000 MΩ. 
     B: The resistance value between the circuit wiring  20  and metal member  50  was not lower than 100 MΩ and lower than 5000 MΩ. 
     C: The resistance value between the circuit wiring  20  and metal member  50  was not higher than 1 MΩ. 
     E: A short circuit was found between the circuit wiring  20  and metal member  50 . 
     (3) Heat Dissipation Testing of Circuit Part 
     In each of the circuit parts fabricated for Inventive Examples 1 to 14 and Comparative Examples 1 to 7, a thermocouple was bonded to an end of the mounted component (i.e., LED)  30 ; a constant current (0.8 A) was caused to flow therethrough to turn on the LED  30 ; and, 30 minutes after the LED  30  had been turned on, the temperature thereof was measured. The average temperature of all the LEDs  30  on the circuit part was calculated and the heat dissipation of the circuit part was evaluated in accordance with the evaluation criteria provided below. However, for the circuit part in which a short circuit between the circuit wiring  20  and metal member  50  was found during the above-described “(2) Insulation Testing” of the insulating resin layer (evaluation result: E), the present testing was not conducted since current would have flowed through the metal member, making it impossible to measure a correct value. 
     &lt;Evaluation Criteria for Heat Dissipation of Circuit Part&gt; 
     A: The LED surface temperature 30 minutes after it had been turned on was not higher than 90° C. 
     B: The LED surface temperature 30 minutes after it had been turned on was higher than 90° C. and not higher than 100° C. 
     C: The LED surface temperature 30 minutes after it had been turned on was higher than 100° C. and not higher than 120° C. 
     E: The LED surface temperatures 30 minutes after it had been turned on was higher than 120° C. 
     (4) Evaluation of Flatness of Circuit Wiring (Plating Film) 
     For each of the circuit parts fabricated for Inventive Examples 1 to 14 and Comparative Examples 1 to 7, the plating surface of the circuit wiring  20  was observed using a microscope, and the difference between the heights of the highest and deepest points of the plating surface was measured in a sectional profile (i.e., height profile) along the width direction of the circuit wiring. Such a measurement was performed for three fields of view and the average was treated as the surface roughness of the circuit wiring, and the flatness was evaluated based on the following evaluation criteria for flatness. 
     &lt;Evaluation Criteria for Flatness&gt; 
     A: The surface roughness of the circuit wiring was not greater than 5 μm. 
     B: The surface roughness of the circuit wiring was greater than 5 μm and not greater than 10 μm. 
     C: The surface roughness of the circuit wiring was greater than 10 μm and not greater than 20 μm. 
     E: The surface roughness of the circuit wiring was greater than 20 μm. 
     
       
         
           
               
               
             
               
                   
                 TABLE 4 
               
             
            
               
                   
                   
               
               
                   
                 Inventive Examples 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
               
               
            
               
                   
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
                 7 
                 8 
                 9 
                 10 
                 11 
                 12 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
               
               
               
            
               
                 Insulating 
                 Width D 
                 155 
                 152 
                 110 
                 102 
                 54 
                 39 
                 40 
                 38 
                 41 
                 42 
                 40 
                 41 
               
               
                 Resin 
                 of non-penetrating holes (μm) 
               
               
                 Layer 
                 Depth d 
                 178 
                 132 
                 98 
                 75 
                 115 
                 61 
                 41 
                 24 
                 61 
                 60 
                 61 
                 63 
               
               
                   
                 of non-penetrating holes (μm) 
               
               
                   
                 Ratio d/D 
                 1.15 
                 0.87 
                 0.89 
                 0.74 
                 2.13 
                 1.56 
                 1.03 
                 0.63 
                 1.49 
                 1.43 
                 1.53 
                 1.54 
               
               
                   
                 Distance P 
                 128 
                 51 
                 126 
                 134 
                 40 
                 55 
                 54 
                 56 
                 53 
                 30 
                 77 
                 115 
               
               
                   
                 for non-penetrating holes 
               
               
                   
                 (μm) 
               
               
                   
                 Ratio P/D 
                 0.82 
                 0.34 
                 1.14 
                 1.31 
                 0.75 
                 1.42 
                 1.36 
                 1.48 
                 1.30 
                 0.72 
                 1.92 
                 2.81 
               
               
                   
                 Surface roughness (Ra) 
                 13 
                 12 
                 14 
                 12 
                 4 
                 4 
                 5 
                 4 
                 4 
                 4 
                 4 
                 4 
               
               
                   
                 of wiring region 10A 
               
               
                   
                 (d/5) 
                 35.6 
                 26.4 
                 19.6 
                 15 
                 23 
                 12 
                 8 
                 5 
                 12 
                 12 
                 12 
                 13 
               
               
                   
                 Thickness B of resin layer 
                 194 
                 145 
                 143 
                 144 
                 197 
                 96 
                 97 
                 98 
                 146 
                 98 
                 97 
                 98 
               
               
                   
                 below circuit wiring (μm) 
               
               
                   
                 Distance C (μm) 
                 16 
                 13 
                 45 
                 69 
                 82 
                 35 
                 56 
                 74 
                 85 
                 38 
                 36 
                 35 
               
               
                 Circuit 
                 Thickness A 
                 100 
                 80 
                 80 
                 80 
                 50 
                 50 
                 50 
                 50 
                 50 
                 50 
                 50 
                 50 
               
               
                 Wiring 
                 of circuit wiring (μm) 
               
               
                   
                 Smaller one 
                 77.5 
                 66 
                 49 
                 38 
                 27 
                 19.5 
                 20 
                 12 
                 20.5 
                 21 
                 20 
                 20.5 
               
               
                   
                 of D/2 and d/2 (μm) 
               
               
                 Evaluation 
                 (1) Adhesion 
                 A 
                 A 
                 A 
                 B 
                 A 
                 A 
                 A 
                 B 
                 A 
                 A 
                 A 
                 A 
               
               
                 Results 
                 (2) Insulation 
                 B 
                 B 
                 A 
                 A 
                 A 
                 A 
                 A 
                 A 
                 A 
                 A 
                 A 
                 A 
               
               
                   
                 (3) Heat dissipation 
                 B 
                 B 
                 B 
                 B 
                 B 
                 A 
                 B 
                 B 
                 B 
                 A 
                 A 
                 A 
               
               
                   
                 (4) Flatness 
                 C 
                 C 
                 B 
                 C 
                 B 
                 A 
                 A 
                 B 
                 A 
                 B 
                 B 
                 B 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
               
             
               
                   
                 TABLE 5 
               
             
            
               
                   
                   
               
               
                   
                 Inventive Ex. 
                 Comparative Examples 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
            
               
                   
                 13 
                 14 
                 1 
                 2 
                 3 
                 4 
                 5 
                 6 
                 7 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
            
               
                 Insulating 
                 Width D 
                 40 
                 40 
                 — 
                 — 
                 — 
                 — 
                 — 
                 40 
                 68 
               
               
                 Resin 
                 of non-penetrating holes (μm) 
               
               
                 Layer 
                 Depth d 
                 62 
                 58 
                 (130)  
                 (90) 
                 (80) 
                 (52) 
                 (51) 
                 15 
                 (352)  
               
               
                   
                 of non-penetrating holes (μm) 
               
               
                   
                 Ratio d/D 
                 1.55 
                 1.45 
                 — 
                 — 
                 — 
                 — 
                 — 
                 0.38 
                    5.18 
               
               
                   
                 Distance P 
                 54 
                 54 
                 — 
                 — 
                 — 
                 — 
                 — 
                 54 
                 26 
               
               
                   
                 for non-penetrating holes 
               
               
                   
                 (μm) 
               
               
                   
                 Ratio P/D 
                 1.36 
                 1.36 
                 — 
                 — 
                 — 
                 — 
                 — 
                 1.36 
                    0.39 
               
               
                   
                 Surface roughness(Ra) 
                 5 
                 4 
                 — 
                 — 
                 — 
                 — 
                 — 
                 3 
                  5 
               
               
                   
                 of wiring region 10A 
               
               
                   
                 (d/5) 
                 12 
                 12 
                 — 
                 — 
                 — 
                 — 
                 — 
                 3 
                 70 
               
               
                   
                 Thickness B of resin layer 
                 73 
                 62 
                 — 
                 — 
                 — 
                 — 
                 — 
                 97 
                 445  
               
               
                   
                 below circuit wiring (μm) 
               
               
                   
                 Distance C (μm) 
                 11 
                 4 
                 20 
                 60 
                 20 
                 48 
                 14 
                 82 
                 93 
               
               
                 Circuit 
                 Thickness A 
                 50 
                 50 
                 (80) 
                 (80) 
                 (80) 
                 (50) 
                 (50) 
                 50 
                 50 
               
               
                 Wiring 
                 of circuit wiring (μm) 
               
               
                   
                 Smaller one 
                 20 
                 20 
                 — 
                 — 
                 — 
                 — 
                 — 
                 8 
                 34 
               
               
                   
                 of D/2 and d/2 (μm) 
               
               
                 Evaluation 
                 (1) Adhesion 
                 A 
                 A 
                 B 
                 C 
                 B 
                 C 
                 C 
                 E 
                 B 
               
               
                 Results 
                 (2) Insulation 
                 B 
                 A 
                 E 
                 C 
                 E 
                 C 
                 E 
                 A 
                 E 
               
               
                   
                 (3) Heat dissipation 
                 A 
                 A 
                 — 
                 E 
                 — 
                 E 
                 — 
                 E 
                 — 
               
               
                   
                 (4) Flatness 
                 A 
                 B 
                 E 
                 E 
                 E 
                 E 
                 E 
                 A 
                 C 
               
               
                   
               
            
           
         
       
     
     As shown in Tables 4 and 5, it was found that, for each of the circuit parts fabricated for Inventive Examples 1 to 14, all the evaluation results were good: both high heat dissipation and high adhesion of circuit wiring were achieved, the circuit wiring and metal member were reliably insulated, and the surface of the circuit wiring was flat. Also, for each of the circuit parts of Inventive Examples 1 to 14, the surface roughness (Ra) of the wiring region  10 A was not greater than ⅕ of the depth d of the non-penetrating holes  11 , the ratio P/D was in the range of 0.3 to 3, the thickness A of the circuit wiring (i.e., plating film)  20  was either larger than ½ of the depth d of the non-penetrating holes  11  or larger than ½ of the width D, the width D of the non-penetrating holes was in the range of 10 to 200 μm, the thickness B of the resin layer was in the range of 30 to 200 μm, and the distance C was in the range of 5 to 100 μm. 
     On the other hand, for each of Comparative Examples 1 to 5 which replaced the non-penetrating holes  11  with a grid pattern composed of grooves (i.e., recesses) over the entire wiring region  10 A, the result of the evaluation of flatness was poor (evaluation result: E). This is presumably because the recesses and protrusions of the grid pattern formed over the entire wiring region  10 A deteriorated the flatness of the plating film formed thereupon. 
     Further, for each of Comparative Examples 1, 3 and 5, in addition to the result of the evaluation of flatness, the result of the evaluation of insulation was poor (evaluation result: E); accordingly, no heat dissipation test was conducted. The reason for these results is presumed to be the following: If grooves are formed in a grid by laser drawing, the intersections are illuminated twice with a laser beam, which increases variations in groove depth. The microscopic observations allowed only grooves with depths smaller than the thickness of the insulating resin layer to be observed. However, in the real grid pattern, there were portions with grooves of depths larger than the thickness of the insulating resin layer, which is presumed to have decreased insulation. 
     Further, for each of Comparative Examples 2 and 4, in addition to the result of the evaluation of flatness, the result of the evaluation of heat dissipation was poor (evaluation result: E). The reason for this result is presumed to be the following: A first presumed factor is that the decreased smoothness of the plating film increased the film thickness of solder between the plating film and mounted component. A second factor is that Comparative Examples 2 and 4, compared with Comparative Examples 1 and 3, respectively, had improved insulation due to the smaller groove depths, but had decreased adhesion between the plating film and insulating resin layer (evaluation result: C). This is presumed to have increased the heat resistance from the plating film to the insulating resin layer. A presumed third factor is that the smaller groove depths increased the thicknesses of portions of the insulating resin layer between the plating film and metal member (i.e., distance C), leading to decreased heat transfer to the metal member. 
     Further, for Comparative Example 6 where the ratio d/D of the non-penetrating holes  11  was lower than 0.5, the results of the evaluations of adhesion and heat dissipation were poor (evaluation result: E). For Comparative Example 6, the same factors as the above-discussed second and third factors for the decreased heat dissipation for Comparative Examples 2 and 4 are presumed to have decreased the adhesion between the plating film and insulating resin layer and increased the thickness of portions of the insulating resin layer between the plating film and metal member (i.e., distance C), decreasing heat dissipation. 
     For Comparative Example 7 where the ratio d/D of the non-penetrating holes  11  was not lower than 5, the result of the evaluation of insulation was poor (evaluation result: E); accordingly, no heat dissipation test was conducted. The reason for this result is presumed to be the following: For Comparative Example 7, the number of rounds of laser drawing was increased (number of rounds of laser drawing:  10 ) to increase the depth of the non-penetrating holes  11 . A cross-sectional observation showed that the thickness of portions of the insulating resin layer between the bottoms of the non-penetrating holes  11  and metal member (i.e., distance C) was 93 μm; however, the larger number of rounds of laser drawing is presumed to have rendered portions of the insulating resin layer between the non-penetrating holes  11  and metal member brittle. It is presumed that the brittle insulating resin layer was penetrated by plating solution such that plating film grew, which caused a short circuit between the circuit wiring (i.e., plating film) and metal member. 
     INDUSTRIAL APPLICABILITY 
     The circuit part of the present invention has high heat dissipation. Thus, the circuit part of the present invention is suitably used as a part with a mounted component such as an LED mounted thereon, and is applicable as a part in a smartphone or an automobile. 
     REFERENCE SIGNS LIST 
     
         
         
           
               10 : insulating resin layer 
               11 : non-penetrating holes (recesses) 
               20 : circuit wiring 
               30 : mounted component (LED) 
               50 : metal member 
               70 : substrate 
               100 : circuit part