Abstract:
A printed board unit includes: a base material; an electrode formed on the base material; a resist film formed on the base material, the resist film has an opening to expose the electrode; a recess part formed on an inner wall of the resist film; an electronic component including a lead terminal electrically coupled to the electrode; and a bonding material which bonds the lead terminal to the electrode in the opening, a portion of the bonding material being mounted on the lead terminal at an inner side of the opening opposite to the recess part.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2014-110245, filed on May 28, 2014, the entire contents of which are incorporated herein by reference. 
       FIELD 
       [0002]    The embodiments discussed herein are related to a printed board unit, a printed board, and an information processing apparatus. 
       BACKGROUND 
       [0003]    There is a technology in which a dam material having an annular dam shape and made of a material repelling a conductive connection material is formed on a land in advance, the conductive connection material is supplied onto the land in an opening part of the dam material, and the thickness of the conductive connection material is controlled by changing an area of the opening part. 
         [0004]    Moreover, there is a technology in which an electrode of a substrate and an electrode of a component are connected to each other with a conductive adhesive, and a Sn-based metal in a surface plated layer of the electrode of the component is reformed by thermal treatment. 
         [0005]    In the structure where a connection terminal of a component is electrically bonded to an electrode on a base material by soldering and thereafter with a bonding material, for example, thereby allowing the connection terminal to be firmly bonded to the electrode. 
         [0006]    However, further executing the bonding process with the bonding material or the like after executing the bonding process by solder increases the number of processes. 
         [0007]    The following are reference documents. 
         [0008]    [Document 1] Japanese Laid-open Patent Publications No. 2013-179351 and 
         [0009]    [Document 2] Japanese Laid-open Patent Publications No. 2006-324629. 
       SUMMARY 
       [0010]    According to an aspect of the invention, a printed board unit includes: a base material; an electrode formed on the base material; a resist film formed on the base material, the resist film has an opening to expose the electrode; a recess part formed on an inner wall of the resist film; an electronic component including a lead terminal electrically coupled to the electrode; and a bonding material which bonds the lead terminal to the electrode in the opening, a portion of the bonding material being mounted on the lead terminal at an inner side of the opening opposite to the recess part. 
         [0011]    The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims. 
         [0012]    It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, as claimed. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0013]      FIG. 1  is a plan view partially illustrating a printed board unit according to a first embodiment; 
           [0014]      FIG. 2  is a vertical cross-sectional view partially illustrating the printed board unit in the first embodiment; 
           [0015]      FIG. 3  is a perspective view illustrating a mobile telephone as an example of an information processing apparatus; 
           [0016]      FIG. 4  is a perspective view illustrating a smartphone as an example of the information processing apparatus; 
           [0017]      FIG. 5  is a flowchart illustrating a part of a process of manufacturing the printed board unit; 
           [0018]      FIG. 6  is another flowchart illustrating a part of the process of manufacturing the printed board unit; 
           [0019]      FIG. 7  is a plan view illustrating the printed board unit; 
           [0020]      FIG. 8  is a plan view illustrating the printed board unit; 
           [0021]      FIG. 9  is a plan view illustrating a part of the process of manufacturing the printed board unit; 
           [0022]      FIG. 10  is a vertical cross-sectional view illustrating a part of the process of manufacturing the printed board unit; 
           [0023]      FIG. 11  is a plan view illustrating a part of the process of manufacturing the printed board unit; 
           [0024]      FIG. 12  is a vertical cross-sectional view illustrating a part of the process of manufacturing the printed board unit; 
           [0025]      FIG. 13  is a plan view partially illustrating a printed board unit according to a second embodiment; 
           [0026]      FIG. 14  is a vertical cross-sectional view partially illustrating the printed board unit in the second embodiment; 
           [0027]      FIG. 15  is a plan view partially illustrating a printed board unit according to a third embodiment; 
           [0028]      FIG. 16  is a cross-sectional view partially illustrating the printed board unit; 
           [0029]      FIG. 17  is a cross-sectional view partially illustrating the printed board unit; 
           [0030]      FIG. 18  is an explanation view illustrating a method of determining a shape of a recess part; and 
           [0031]      FIG. 19  is an explanation view illustrating a method of determining a shape of the recess part. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0032]    A first embodiment will be described in details based on the drawings. 
         [0033]    A printed board unit  12  according to the first embodiment includes, as illustrated in  FIG. 1  and  FIG. 2 , a printed board  14 , and an electronic component  16  which is bonded and mounted onto the printed board  14  with a conductive adhesive  18 . As illustrated in  FIG. 2 , the electronic component  16  is surface-mounted with respect to the printed board  14 . 
         [0034]    The printed board unit  12  is formed, for example, in the interior of a mobile telephone  20  illustrated in  FIG. 3 . The mobile telephone  20  is formed with input keys  22  and a display  24 . Information inputted with the input keys  22  is sent to the printed board unit  12 . Moreover, information from the printed board unit  12  is displayed on the display  24 . The input keys  22  are an example of an input unit, and the display  24  is an example of an output unit. 
         [0035]    The mobile telephone  20  is an example of an information processing apparatus. Another example of the information processing apparatus may include, for example, a smartphone  26  illustrated in  FIG. 4 , or a tablet-type, notebook-type, or desktop-type computer. The smartphone  26  has such a structure that the display  24  functions as both of the input unit and the output unit in many cases. Some smartphones have such a structure that input keys (input unit) are formed in addition to the display  24 . 
         [0036]    As illustrated in detail in  FIG. 2 , the printed board  14  includes a base material  28 , a foot pattern  30 , and a solder resist  32 . 
         [0037]    The base material  28  is formed in a plate shape of a material having a flexural rigidity and an insulation property, for example, a glass epoxy. Hereinafter, a plan view indicates that the base material  28  is seen in a normal direction (direction of an arrow A 1 ). 
         [0038]    The foot pattern  30  is formed on the base material  28 . The foot pattern  30  is formed in a predetermined pattern shape of a material having conductivity. A lead terminal  34  of the electronic component  16  is electrically connected to a part of the foot pattern  30 . The foot pattern  30  is an example of an electrode. 
         [0039]    The solder resist  32  is formed on the base material  28 . An opening part  36  is formed in the solder resist  32 . The opening part  36  is formed a rectangular shape larger than the foot pattern  30  in the plan view. 
         [0040]    As illustrated in  FIG. 2 , a depth D 1  of the opening part  36  is deeper than a height T 1  from the base material  28  to an upper surface  30 T of the foot pattern  30 . This generates a level difference G 1  between an upper surface  32 T of the solder resist  32  and the upper surface  30 T of the foot pattern  30 . 
         [0041]    The solder resist  32  excluding the opening part  36  covers the base material  28  and the foot pattern  30 . This protects the base material  28  and the solder resist  32  from an outside environment, and restricts deterioration or corrosion of the base material  28  and the solder resist  32 . 
         [0042]    In the opening part  36 , a lead bonding part  38  at the tip of the lead terminal  34  and the foot pattern  30  are bonded and electrically connected to each other with the conductive adhesive  18 . In the example illustrated in  FIG. 2 , the lead bonding part  38  is bonded to the foot pattern  30  in a parallel state. As is understood from  FIG. 1 , when the base material  28  is viewed in plan, the lead bonding part  38  has a rectangular shape smaller in size than the foot pattern  30 . 
         [0043]    As illustrated in  FIG. 1 , recess parts  42  are formed on long sides  36 L of the opening part  36 . The recess part  42  is formed in such a manner that the opening part  36  is partially recessed in a direction apart from the foot pattern  30  in the plan view. In the example illustrated in  FIG. 1 , positions at which the recess parts  42  are formed and the number of the recess parts  42  are different to one another in three opening parts  36 . In other words, in an opening part  36 A, a pair of the opposed recess parts  42  is formed at positions close to an end portion in the longitudinal direction of the foot pattern  30 . In an opening part  36 B, a pair of the opposed recess parts  42  is formed at the center portion in the longitudinal direction of the foot pattern  30 . In an opening part  36 C, two pairs of the recess parts  42  are formed close to the center portion in the longitudinal direction of the foot pattern  30 . In this manner, out of the multiple recess parts  42 , a pair (two) or more pairs of the recess parts  42  which are formed at opposed positions interposed the foot pattern  30  and the lead bonding part  38  therebetween in the plan view are present. Hereinafter, a direction along a side on which the recess part  42  is formed (the long side  36 L) is referred to as a width direction of the recess part  42 . 
         [0044]    A back surface  42 B of the recess part  42  has a curved shape in which a center of the back surface  42 B in the width direction is farther from the foot pattern  30  than both sides of the back surface  42 B in the width direction. In particular, the shape of the back surface  42 B is designed to allow a mounted part  44  to be effectively formed, as described later. 
         [0045]    Although the conductive adhesive  18  is housed inside the opening part  36 , a part of the conductive adhesive  18  is mounted on the lead bonding part  38  in a given area TA (see  FIG. 11 ) at an opposite side of the recess part  42  (side of the opening part  36 ) to form the mounted part  44 . Here, the given area TA at the opposite side of the recess part  42  is a given area which is positioned on the lead bonding part  38  and at the opening part  36  side with respect to the recess part  42 , in the plan view. 
         [0046]    In the embodiment, specially, the two opposed recess parts  42  are formed to form a continuous part  46  in which the two mounted parts  44  are continuous while traversing the lead bonding part  38 . 
         [0047]    Next, a method of mounting the electronic component  16  on the printed board  14 , and an effect by the embodiment will be described. 
         [0048]    The printed board  14  is manufactured in accordance with an example of a procedure illustrated in a manufacturing flow  FIG. 5 . Firstly, a board  50  manufactured beforehand is prepared. The board  50  is a non-conductive plate material (for example, glass epoxy or the like) serving as the base material  28  in the printed board  14 . 
         [0049]    As illustrated in  FIG. 7  and  FIG. 8 , the board  50  has a size to allow multiple sheets of the printed boards  14  as products to be arranged. A cut part  52  is formed in advance in the form the board  50 . In the course of a manufacturing process of the printed board  14  thereafter, cutting the board  50  along the cut part  52  makes it possible to obtain the base material  28  having a predetermined size which matches the size of the printed board  14 . 
         [0050]    Note that, the board  50  before being cut may preferably be, for example, as illustrated in  FIG. 7 , the board  50  of a type in which areas corresponding to a printed board  14 L of a large size and a printed board  14 S of a small size are isolated. Alternatively, as illustrated in  FIG. 8 , areas corresponding to the printed board  14 L of a large size and areas corresponding to the printed board  14 S of a small size may preferably be disposed on the same the board  50 . 
         [0051]    Firstly, drilling is performed on the base material  28  at Step S 102 . Subsequently, at Step S 104  to Step S 108 , plating treatment, circuit pattern formation, and roughening treatment are sequentially performed. 
         [0052]    In addition, at Step S 110 , the solder resist  32  is formed on the base material  28 . In this process, the opening part  36  is formed in the solder resist  32 , and the recess parts  42  are further formed. 
         [0053]    Subsequently, at Step S 112 , predetermined information display is formed (printed) on the solder resist  32  using a coating material. At Step S 114 , the foot pattern  30  is subjected to rustproofing treatment. In this manner, the printed board  14  is manufactured. 
         [0054]    The printed board  14  includes the base material  28 , and a circuit pattern (the foot pattern  30 ) and the solder resist  32  which are on the base material  28 . At this stage, as mentioned above, the opening part  36  surrounding the foot pattern  30  in the plan view is formed in the solder resist  32 , and the recess parts  42  are further formed. 
         [0055]    Next, the printed board unit  12  is manufactured in accordance with an example of a procedure illustrated in  FIG. 6 . Firstly, at Step S 122 , a bonding material (the conductive adhesive  18  in the embodiment) is supplied into the opening part  36 . A coating amount of the conductive adhesive  18  is an amount which allows a part of the conductive adhesive  18  to cover the lead bonding part  38  bonded to the foot pattern  30 , as is described later. 
         [0056]    Subsequently, at Step S 124 , components are mounted on the base material  28 . The “components” include the electronic component  16 . In other words, as illustrated in  FIG. 9  and  FIG. 10 , the lead bonding part  38  of the lead terminal  34  is immersed into the conductive adhesive  18  inside the opening part  36 . 
         [0057]    In this process, when the electronic component  16  is pushed to the printed board  14  side, a force from the lead bonding part  38  acts on the conductive adhesive  18 . This force causes the conductive adhesive  18  to flow, as illustrated in  FIG. 9  as arrows M 1 , so as to be pushed out to an outer circumference side of the opening part  36 . In other words, the pushing pressure of the lead bonding part  38  to the conductive adhesive  18  positively generates waves in the conductive adhesive  18  toward an inner wall  40 . 
         [0058]    The conductive adhesive  18  which flows to the outer circumference side in this manner are reflected by the solder resist  32 , and tends to return to the foot pattern  30  side as illustrated in  FIG. 11  as arrows M 2 . In this process, the embodiment exhibits an effect that a part of the returned conductive adhesive  18  is aggregated in the given areas TA of the lead bonding part  38  because the recess parts  42  are formed in the opening part  36 . In other words, as illustrated in  FIG. 12 , a part of the lead bonding part  38  is covered with the conductive adhesive  18 . The conductive adhesive  18  is cured in this state to maintain such a state that the part of the conductive adhesive  18  is positioned on the lead bonding part  38  in the given areas TA. 
         [0059]    In addition, at Step S 126 , the conductive adhesive  18  is heated to lower the viscosity. A heating method of the conductive adhesive  18  is not specially limited, however, for example, it may be implemented by a reflow of the printed board  14 . 
         [0060]    In this manner, in the embodiment, a part of the conductive adhesive  18  is positioned on the lead bonding part  38  to achieve a lager bonded area with the conductive adhesive  18  than a structure in which no part of the conductive adhesive  18  is position on the lead bonding part  38 . In addition, the part of the cured conductive adhesive  18  covers the lead bonding part  38 . This increases a contact area of the conductive adhesive  18  with respect to the lead bonding part  38 , in other words, a bonded area of the conductive adhesive  18  in the embodiment to achieve a higher bonding strength of the lead bonding part  38  with respect to the foot pattern  30 . 
         [0061]    Note that, from the viewpoint of enhancing the bonding strength by the conductive adhesive  18 , it is considered that a large amount of the conductive adhesive  18  is supplied to the opening part  36 , for example, in the structure in which no recess part  42  is formed in the solder resist  32 . However, simply increasing the amount of the conductive adhesive  18  may not contribute increase in the bonded area in some cases because a phenomenon (wicking phenomenon) in which a part of the conductive adhesive  18  is raised along the lead terminal  34  occurs at a certain surface tension of the conductive adhesive  18 . 
         [0062]    Another method of enhancing the bonding strength may include, for example, a method of connecting a portion expected to have a higher bonding strength after the lead bonding part  38  is bonded to the foot pattern  30  using solder, with a bonding material other than the solder. However, this results in the increased processes because two types of materials of the solder and the bonding material other than the solder are supplied. For example, in the flow illustrated in  FIG. 6 , after supplying the solder at Step S 122 , mounting an electronic component at Step S 124 , and heating at Step S 126 , a process of further applying a bonding material, and curing the bonding material is added. Further, such an addition of the process may result in an increased manufacturing cost. 
         [0063]    Still another method of enhancing the bonding strength may include a method in which a solder resist having a lager thickness is formed to increase the height of an opening part, so that a bonding material of a larger amount is supplied into the opening part to cause a lead bonding part to be embedded into the bonding material. However, forming a solder resist having a lager thickness may lower a mounting performance of component with respect to components other than a component which is expected to have a high bonding strength (the components may be difficult to be mounted). 
         [0064]    In the embodiment, it is neither desired to increase the amount of the conductive adhesive  18  nor to use several types of bonding materials (solder and a bonding material other than the solder). Further, it is possible to enhance the bonding strength between the lead bonding part  38  and the foot pattern  30  by reducing dependence of the conductive adhesive  18  on the physical properties (wettability) and the strength characteristics and without adding new processes. For example, as illustrated in  FIG. 2 , the use of the conductive adhesive  18  allows the electronic component  16  to be surface-mounted with a high bonding strength. Further, no manufacturing process is newly added in the embodiment. This may restrict a manufacturing cost from increasing. In addition, in the embodiment, no solder resist having a lager thickness is formed. This further may restrict the mounting performances of other components from lowering. 
         [0065]    The structure in which the bonding strength of the lead bonding part  38  with respect to the foot pattern  30  is high may be implemented also in an electronic apparatus formed with the printed board unit  12 . 
         [0066]    Next, a second embodiment will be described. In the second embodiment, the same reference numerals are given to the same elements, members, and the like as those in the first embodiment in the drawings, and the detailed explanation thereof may be omitted. 
         [0067]    In a printed board unit  62  in the second embodiment, as illustrated in  FIG. 13  and  FIG. 14 , a wall part  66  is formed on the solder resist  32  of a printed board  64 . The wall part  66  rises from the surroundings of the opening part  36  and the recess part  42  upward (opposite side of the base material  28 ). Forming the wall part  66  increases the level difference G 1  between the upper surface  32 T of the solder resist  32  and the upper surface  30 T of the foot pattern  30 , compared with a structure in which no wall part is formed. 
         [0068]    Accordingly, in the second embodiment, the conductive adhesive  18  of a larger amount may be supplied into the opening part  36 . For example, even when the lead bonding part  38  has a thickness larger than that in the case illustrated in the first embodiment ( FIG. 2  see), it is possible to reliably form the mounted part  44 . Moreover, even if the conductive adhesive  18  flows when the lead terminal  34  is pushed in, it is possible to restrict the conductive adhesive  18  from overflowing. 
         [0069]    Note that, a method of forming the wall part  66  is not specially limited. For example, the wall part  66  may be formed simultaneously with the printing when an information display, a name of the component or an arrangement of the components, is printed on the solder resist  32 , using a printing material (which is referred to as silk in some cases) such as a coating material or ink. In this manner, forming the wall part  66  when the predetermined information is printed on the solder resist  32  reduces an additional process of forming the wall part  66 . 
         [0070]    The height of the wall part  66  is not specially limited. For example, the height T 1  from the upper surface  32 T of the solder resist  32  may be set within the range of 10 to 30 μm. The height of the solder resist  32  may be set to 50 μm, so that the level difference G 1  becomes 60 to 80 μm. 
         [0071]    Next, a third embodiment will be described. Also in the third embodiment, the same reference numerals are given to the same elements, members, and the like as those in the first embodiment in the drawings, and the detailed explanation thereof may be omitted. 
         [0072]    In a printed board unit  72  in the third embodiment, as illustrated in  FIG. 15 , protrusion parts  76  are formed at the inner wall  40  in the opening part  36  of the solder resist  32 , on a printed board  74 . The protrusion parts  76  protrude toward the foot pattern  30  from both sides in the width direction of the recess part  42  in the plan view, 
         [0073]    Accordingly, in the third embodiment, the protrusion parts  76  guide the conductive adhesive  18  reflected by the recess parts  42  into the given areas TA. In other words, the conductive adhesive  18  may be guided into the given area TA, so that the mounted part  44  may be efficiently formed. 
         [0074]    In the respective embodiments mentioned above, the mounted part  44  does not have to cover the whole area of the upper surface of the lead bonding part  38 . For example, as illustrated in  FIG. 16 , the two opposed mounted parts  44  may preferably be structured so as to be non-continuous with each other on the lead bonding part  38 . Alternatively, as illustrated in  FIG. 17 , the mounted part  44  may preferably be formed on an end portion in the longitudinal direction of the lead bonding part  38 , as an example. Even in the examples illustrated in  FIG. 16  and  FIG. 17 , the mounted part  44  covers the lead bonding part  38  so as to be sandwiched therebetween with the foot pattern  30 . Accordingly, the bonding strength between the lead bonding part  38  and the foot pattern  30  is high, compared with a structure in which no mounted part  44  is formed. 
         [0075]    In the examples illustrated in  FIG. 1 ,  FIG. 13  and  FIG. 15 , the conductive adhesives  18  reflected by the two recess parts  42  are brought into contacted with each other on the lead bonding part  38  to form the continuous part  46  in which the mounted parts  44  are continuous. This allows the lead bonding part  38  to be firmly bonded to the foot pattern  30 , compared with a structure of the two mounted parts  44  being separated on the lead bonding part  38 . 
         [0076]    The number of the recess parts  42  is not limited. When multiple recess parts  42  are formed, multiple mounted parts  44  corresponding to the recess parts  42  are also formed. 
         [0077]    In a structure in which multiple recess parts  42  are formed, the presence of a pair of the recess parts  42  which are opposed to each other makes easy to form the mounted parts  44  continuous with each other on the lead bonding part  38 , as mentioned above. 
         [0078]    The recess part  42  may preferably be formed at a short side  36 S of the opening part  36 . However, forming the recess part  42  at the long side  36 L makes it easy to form the mounted part  44  on the lead bonding part  38  because of a short distance from the recess part  42  to the lead bonding part  38 . 
         [0079]    The shape of the recess part  42  is not limited as long as the conductive adhesive  18  may be reflected to cause the conductive adhesive  18  to be concentrated into the given area TA. In the embodiments mentioned above, the back surface  42 B of the recess part  42  has a shape in which the center of the back surface  42 B in the width direction is farther from the foot pattern  30  than both sides thereof in the width direction. This allows the conductive adhesive  18  to be effectively concentrated into the given area TA, compared with a structure of the flat back surface  42 B of the recess part  42 . 
         [0080]    The shape of the back surface  42 B viewed in the plan view may preferably be a shape in which the back surface  42 B is linearly slanted from the both sides in the width direction toward the center in the width direction so that the center in the width direction is farther from the foot pattern  30  at the center, for example. Moreover, the shape of the back surface  42 B may preferably be a parabolic shape of which focal point is a target position P (point in the given area TA) on which the conductive adhesive  18  is intended to be concentrated. This allows the conductive adhesive  18  which contacts the wall part  66  from the front surface to be effectively concentrated on the given area TA. 
         [0081]    The following method may be employed to determine a specific shape of the back surface  42 B. 
         [0082]    Firstly, a depth L 1  is determined in a portion at an end portion in the width direction of the recess part  42 , in other words, a portion where the recess part  42  has a shortest depth. 
         [0083]    Next, within a range W 1  in the width direction of the recess part  42 , multiple flows (in the example illustrated in  FIG. 18 , nine flows of a to i) of the conductive adhesive  18  in a normal direction of the inner wall  40  are sequentially considered. 
         [0084]    A tangent line La is firstly drawn such that the flow a of the conductive adhesive  18  reflects from the back surface  42 B, the conductive adhesive  18  after being reflected passes the target position P. Subsequently, a tangent line Lb is determined such that at an intersection point between the adjacent flow b and the tangent line La, the flow b reflects from a reflection position Ra of the back surface  42 B and the conductive adhesive  18  after being reflected passes the target position P. 
         [0085]    In addition, a tangent line Lc is determined such that at an intersection point between the adjacent flow c and the tangent line Lb, the flow c reflects from the back surface  42 B and the conductive adhesive  18  after being reflected passes the target position P. The similar operation is repeated thereafter sequentially up to the flow i to determine the shape of the back surface  42 B. In the example illustrated in  FIG. 18 , the nine flows of a to i are illustrated. The more the number of these flows is employed (the shorter the interval of the flows becomes), the closer to a smoothly curved curve the shape of the back surface  42 B becomes. 
         [0086]    As illustrated in  FIG. 19 , a point Q having a distance A in the width direction from the target position P is considered, and a distance from the point Q to a reflection position R of the conductive adhesive  18  is set as B. Further, an angle formed by a side RP with a side RQ is set as θ. A slope angle of a tangent line L of the back surface  42 B at the reflection position R is set as x, and an angle formed by the tangent line L with the side RQ is set as y. 
         [0087]    In this case, tan θ=A/B 
         [0088]    in other words, θ=tan −1 (A/B) is obtained. 
         [0089]    Moreover, y=(180−θ)/2 is obtained. 
         [0090]    Accordingly, x=90−y=θ/2=tan −1 (A/B)/2 is obtained. 
         [0091]    In this manner, the slope angle x of the tangent line in the back surface  42 B may be obtained. 
         [0092]    The number of the recess parts  42  is not limited. For example, one recess part  42  may preferably be formed per one opening part  36 . Further, when multiple recess parts  42  are formed for one opening part  36 , multiple mounted parts  44  of the conductive adhesive  18  reflected from the recess part  42  are formed. In particular, the presence of the two recess parts  42 , out of the multiple recess parts  42 , which are opposed to each other with the foot pattern  30  interposed therebetween allows the continuous part  46  in which the mounted parts  44  are continuous with each other on the lead bonding part  38  to be formed. Further, the continuous part  46  may enhance the bonding strength between the lead bonding part  38  and the foot pattern  30 . 
         [0093]    The recess part  42  may preferably be formed on the inner wall  40  at short side  36 S of the opening part  36 . However, forming the recess part  42  on the inner wall at the long side  36 L makes it easy to mount the conductive adhesive  18  on the lead bonding part  38  because of a short distance with the lead bonding part  38 , in the plan view. 
         [0094]    The opening part  36  is formed to have the depth D 1  higher than the height T 1  of the foot pattern  30  from the upper surface of the base material  28 , as mentioned above, to allow a larger amount of the conductive adhesive  18  to be stored inside the opening part  36 . This may contribute to a reliable formation of the mounted part  44 . 
         [0095]    The use of the conductive adhesive  18  mentioned above as a bonding material allows the foot pattern  30  and the lead bonding part  38  to be bonded, and the foot pattern  30  and the lead bonding part  38  to be conducted with the conductive adhesive  18 . 
         [0096]    Moreover, compared with the solder, a material having a desired viscosity may be used in the conductive adhesive  18  so as to be mounted on the lead bonding part  38  by waves generated due to the pushing pressure of the lead bonding part  38 . 
         [0097]    In the respective embodiments mentioned above, the electronic component  16  may include various kinds of semiconductor chips to be mounted on the base material  28 . In addition, the electronic component  16  may be a connection component formed with an insertion-removal part  23 . The insertion-removal part  23  is, for example, a terminal, a connector, or a slot for a card such as a memory card, or the like, for electrically connecting to an external member. Insertion or removal of an external apparatus into and from the insertion-removal part  23  in such a connection component may apply a stress between the lead bonding part  38  and the foot pattern  30  in some cases. In the embodiments mentioned above, the high bonding strength between the lead bonding part  38  and the foot pattern  30  may inhibit the electronic component  16  from being detached when such a stress is applied thereto. 
         [0098]    All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although the embodiments of the present invention have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.