RELATED APPLICATION

[0001] This application claims the benefit of priority to Japanese Application No. 2020- 038214, filed on March 05, 2020 and is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

[0002] The present invention relates to a molded circuit board and a manufacturing method thereof.

BACKGROUND ART

[0003] Conventionally, a molded circuit board having a molded body formed from an insulating material such as plastic resin or the hke in which a metal terminal plate is integrated is used. The molded circuit board is provided with a circuit pattern formed by means of a plating layer on the board surface thereof. Patent Document 1 discloses a board on which LEDs are mounted as an example of a molded circuit board. Such molded circuit boards may be referred to as molded interconnect devices (MID).

[0004] Patent Document 1 Japanese Unexamined Patent Application Publication No. 2018- 532251

SUMMARY

[0005] When the circuit pattern on a molded circuit board is formed using an electroplating method, first, the surface of the resin is roughened by laser irradiation, and an electrically conductive ink is applied continuously on the surface of the roughened resin and the surface of the terminal plate, and then electroplating is performed using the terminal plate as a negative electrode. In this way, a continuous plating layer (circuit pattern) is formed from the terminal plate to the surface of the resin. By roughening the surface of the resin, the adhesiveness between the surface of the resin and the plating layer can be enhanced, and the plating layer can be stably formed on the surface of the resin. However, when using the molded circuit board, not only the plating layer, but also the terminal plate functions as a part of the circuit. The terminal plate may also be used as an electrode in the electroplating step. Therefore, stable forming of the plating layer on the terminal plate, and ensuring high conductivity from the terminal plate to the plating layer formed on the surface of the resin is preferable.

[0006] A molded circuit board proposed in the present disclosure includes a terminal plate formed of metal, a molded body having a first insulated part covering one surface of the terminal plate, and a plating layer formed on a surface of the first insulated part and constitutes a circuit pattern. The terminal plate has an exposed part that is exposed from the first insulated part, the plating layer has a connecting part formed on the exposed part, and the exposed part is formed with an intersecting surface that intersects a direction along the surface of the first insulated part. With regards to this molded circuit board, the adhesiveness of the terminal plate to the plating layer can be improved, and the plating layer can be stably formed on the terminal plate. Therefore, high conductivity can be ensured from the terminal plate to the plating layer formed on the surface of the first insulated part.

[0007] A manufacturing method of the molded circuit board proposed in the present disclosure includes a forming step of forming a metal plate into a prescribed shape, a molding step of forming a molded body with a first resin part covering one surface of a terminal plate that is one part of the metal plate and that is integrated with the terminal plate while ensuring exposing of a part exposed from the first resin part to the terminal plate, a coating step of coating the surface of the first resin part and the exposed part with conductive ink, and a plating step of forming a plating layer positioned on the conductive ink and the exposed part using the terminal plate as an electrode. In the coating step, it is ensured that there are regions of the surface of the exposed part that are coated with conductive ink and regions of the surface of the exposed part that are not coated. According to this manufacturing method, the adhesiveness of the terminal plate to the plating layer can be improved, and the plating layer can be stably formed on the terminal plate. Therefore, high conductivity can be ensured from the terminal plate to the plating layer formed on the surface of the first insulated part. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG. 1 is a plan view illustrating an example of a molded circuit board proposed in the present disclosure.

[0009] FIG. 2 is a cross-sectional view taken along the II-II line illustrated in FIG. 1. [0010] FIG. 3 A is a diagram explaining a manufacturing step of the molded circuit board. [0011] FIG. 3B is a cross-sectional view taken along the Illa-IIIa line illustrated in FIG. 3 A.

[0012] FIG. 4 A is a cross-sectional view explaining a manufacturing step of the molded circuit board.

[0013] FIG. 4B is a cross-sectional view explaining a manufacturing step of the molded circuit board.

[0014] FIG. 4C is a cross-sectional view explaining a manufacturing step of the molded circuit board.

[0015] FIG. 5 is a cross-sectional view illustrating another example of a molded circuit board proposed in the present disclosure.

[0016] FIG. 6 is a cross-sectional view illustrating another example of a molded circuit board proposed in the present disclosure.

[0017] FIG. 7A is a plan view illustrating another example of a molded circuit board proposed in the present disclosure.

[0018] FIG. 7B is a cross-sectional view along the Vllb-VIIb line illustrated in FIG. 7A. [0019] FIG. 8 A is a plan view illustrating another example of a molded circuit board proposed in the present disclosure.

[0020] FIG. 8B is a cross-sectional view along the Vlllb-VIIIb line illustrated in FIG. 8A.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] An example of a molded circuit board proposed in the present disclosure will be described below. Hereinafter, the XI and X2 directions illustrated in FIG. 1 are referred to as rightward and leftward respectively, and the Z1 and Z2 directions illustrated in FIG. 2 are referred to as upward and downward, respectively. These directions are used to describe the relative positional relationships of various portions of the molded circuit board, and do not limit the posture of the molded circuit boards being mounted on other devices. [0022] As illustrated in FIG. 2, a molded circuit board 1 includes a resin molded body 11 and a terminal plate 20 formed of metal. (Hereinafter, the molded circuit board 1 is simply referred to as a board). Note that the molded body 11 is formed from a plastic resin in the present embodiment, but may also be formed from an insulating material such as ceramic. The material of the molded body 11 is not particularly limited as long as a formable insulating material is used. The resin molded body 11 and the terminal plate 20 are integrated, for example, using insert molding. In other words, when molding the resin molded body 11, the cavity portion of the mold in which the terminal plate 20 is arranged is filled with the molten resin, which is the material of the resin molded body 11, to form a resin molded body 11 that is integrated with the terminal plate 20. The resin molded body 11 includes an upper resin 11 A (insulating portion) covering the top surface of the terminal plate 20, and a lower resin 11B (insulating portion) covering the bottom surface of the terminal plate 20. An end part 20c of the terminal plate 20 is exposed on a side surface 1 lc of the resin molded body 11. In the present specification, the upper resin HArefers to the entire portion positioned above the top surface of the terminal plate 20, and the lower resin 11 B refers to the entire portion positioned below the bottom surface of the terminal plate 20.

[0023] In the examples illustrated in the diagrams, there is one terminal plate 20 retained by the resin molded body 11, however, this also can be two terminal plates, or three terminal plates. Furthermore, the bottom surface of the terminal plate 20 need not necessarily be covered by the resin molded body 11. The terminal plate 20 is formed by performing a pressing process on a metal plate having conductivity such as brass or phosphor bronze. The resin molded body 11 is formed from a plastic resin, for example a phenol resin or polybutylene terephthalate.

[0024] The board 1 includes a plating layer 30. The plating layer 30 is formed on the surface (top surface 1 la) of the upper resin 11 A, and constitutes a circuit pattern. The material of the plating layer 30, for example, is copper, nickel, tin, gold, or the like. When the board 1 is mounted on another device and used, an electronic component (not illustrated) such as a light emitting diode (LED) or a transistor is mounted on the top surface 11a of the upper resin 11 A, and is connected to a circuit pattern. [0025] As illustrated in FIG. 2, the terminal plate 20 includes an exposed part 21 that is exposed from the upper resin 11 A. An opening Ha is formed in the upper resin 11 A The exposed part 21 is exposed from the upper resin 11A inside the resin opening Ha. (The opening Ha is referred to as a resin opening.) The resin opening Ha is circular in a plan view of the board 1 (see FIG. 1), however, the shape thereof is not limited to a circle, and may be a polygonal shape such as a triangular or square, for example. The plating layer 30 includes a connecting part 31 that is formed on the exposed part 21 and is electrically connected to the exposed part 21.

[0026] The board 1 may have a conductive ink layer 41 between the plating layer 30 and upper resin 11 A. The conductive ink layer 41 is a layer formed of conductive ink applied to the upper resin 11 A. The material of the conductive ink layer 41 is, for example, copper ink or silver ink. The conductive ink layer 41 is formed in a region of a circuit pattern (electric wire). A portion 41a of the conductive ink layer 41 is formed continuously on the exposed part 21 from the surface of the upper resin 11 A and electrically connects with other portions of the conductive ink layer 41 (portions formed on the upper resin 11 A).

[0027] The plating layer 30 is formed, for example, by electroplating as follows. First, a conductive ink is apphed in a circuit pattern position. The conductive ink is applied, for example, using an ink-jet method. Conductive ink is formed on the upper resin 11A to form the conductive ink layer 41. Here, the surface of the upper resin 11 A may be roughened by laser irradiation to strengthen the adhesion between the plating layer and the upper resin 11 A.

[0028] The portion 41a of the conductive ink layer 41 is formed on the exposed part 21 and electrically connected to the exposed part 21. After forming the conductive ink layer 41, an electroplating step is performed while using the terminal plate 20 as a cathode. In this manner, by forming the conductive ink layer 41 prior to the electroplating step, the terminal plate 20 can be used as the cathode in the electroplating step. The terminal plate 20 is only used in the electroplating step, and may not be used when the molded circuit board 1 is mounted on another device. (In other words, the terminal plate 20 may not be used for signal transmission and supplying power to electronic components.) The method of manufacturing the board 1 is described in detail below with reference to FIG. 3 A through FIG. 4C.

[0029] Note that in the manufacturing steps of the board 1 , after the electroplating step, the conductive ink applied to the upper resin 11 A and the exposed part 21 do not have to be present as the conductive ink layer 41. If the material of the conductive ink and the material of the plating layer 30 are the same, for example, if the conductive ink is a copper ink and plating layer 30 is a copper plating layer, the ink can permeate the plating layer 30 and there is no need to form the conductive ink layer 41.

[0030] As illustrated in FIG. 2, the exposed part 21 includes an intersecting surface 21a that intersects in a direction along the top surface 11a of the upper resin 11A (the X1-X2 direction in FIG. 2). In other words, the intersecting surface 21a intersects in a horizontal plane orthogonal to the thickness direction (Z 1 -Z2 direction) of the board 1. The intersecting surface 21a is, for example, essentially perpendicular to the direction along the top surface 11a (horizontal direction). The intersecting surface 21a may be substantially parallel to the discharge direction of the inkjet from which the conductive ink is applied. The exposed part 21 may have a portion that conceals the intersecting surface 21a from the discharge opening of the inkjet. The top surface 11a of the upper resin llA need not necessarily be flat, for example, an inclined surface, a concave surface, or the like may be formed. A portion of the plating layer 30 is formed along the intersecting surface 21a. In the example of the board 1, a hole Hn passing through the exposed part 21 is formed. The inner surface of the through hole Hn functions as the intersecting surface 21a. The through hole Hn is, for example, a circular hole, and the intersecting surface 21a is annular, for example, in a plan view of the board 1.

[0031] The size of the through hole Hn is smaller than the size of the resin opening Ha formed in the upper resin 11 A. In the example of the board 1, the through hole Hn and the resin opening Ha are both circular, and as illustrated in FIG. 2, the diameter of the through hole Hn is smaller than the diameter R2 of the resin opening Ha. The exposed part 21 has a horizontal surface 21c around the through hole Hn along a plane that is parallel with the top surface 11a of the resin molded body 11. The horizontal surface 21c has formed a continuous conductive ink layer 41 from the surface of the upper resin llAto the exposed part 21 of the terminal plate 20.

[0032] The intersecting surface 21a can improve the adhesion between the exposed part 21 and the connecting part 31 of the plating layer 30. For example, in the step of applying the conductive ink to the upper resin 11 A, the amount of conductive ink that adheres to the intersecting surface 21a can be reduced or eliminated in order for the intersecting surface 21a to intersect with the direction along the top surface 11a of the upper resin 11A, in other words, because the intersecting surface 21a is in an upright posture with respect to the horizontal plane.

[0033] In the example of the board 1, as illustrated in FIG. 2, a conductive ink layer 41 is formed on the upper resin 11A. Aportion 41a of the conductive ink layer 41 is also formed on the exposed part 21. The amount of conductive ink present per unit area on the intersecting surface 21a of the exposed part 21 is less than the amount of conductive ink present per unit area on the horizontal surface 21c. In the examples illustrated in the figures, the conductive ink layer 41 is formed on the horizontal surface 21c of the exposed part 21, but is not formed on the intersecting surface 21a. Therefore, the connecting part 31 of the plating layer 30 is formed directly on the intersecting surface 21a. As a result, the adhesion between the terminal plate 20 and the plating layer 30 can be improved on the intersecting surface 21a beyond that of the surface of the upper resin 11A and horizontal surface 21c on which the conductive ink layer 41 is formed between the terminal plate 20 and the plating layer 30.

[0034] As illustrated in FIG. 2, the inner surface of the resin opening Ha formed on the upper resin 11 A is an inclined surface 11 g such that the size of an upper edge 1 le of the resin opening Ha is larger than the lower edge Ilf. In other words, as the distance from the terminal plate 20 in the thickness direction (the Z1-Z2 direction) of the board 1 increases, the size of the resin opening Ha increases. In the example illustrated in the figure, the resin opening Ha is circular and the diameter R2 of the resin opening Ha increases as the distance from the terminal plate 20 increases. The inclined surface 11 g is formed along the entire circumference of the inner surface of the resin opening Ha. With this inclined surface 11 g, the resin molded body 11 has an obtuse angle 01 at the upper edge lie of the resin opening Ha. As a result, the conductive ink can easily be applied to the inclined surface llg, and the conductive ink layer 41 can be formed continuously from the top surface 11a to the inclined surface llg.

[0035] As described above, the exposed part 21 includes an intersecting surface 21a. The angle of the intersecting surface 21a with respect to the thickness direction (the Z1-Z2 direction) of the board 1 is smaller than the angle Q2 of the inclined surface llg of the resin opening Ha with respect to the thickness direction of the board 1. Thus, when the conductive ink is applied to the inclined surface llg using an ink-jet method, an angle between the discharge direction of the conductive ink (for example, the Z1-Z2 direction) and the inclined surface llg is ensured; while the conductive ink is appropriately applied to the inclined surface llg, the angle between the discharge direction of the conductive ink and the intersecting surface 21a is reduced, so applying the conductive ink to the intersecting surface 21a can be avoided.

[0036] Regarding the board 1, the intersecting surface 21a is substantially parallel with the thickness direction of the board 1. In other words, the intersecting surface 21a is perpendicular relative to the top surface 11a of the upper resin 11 A. The angle of the intersecting surface 21a is not limited to the example of the board 1. The intersecting surface 21a may be inclined with respect to the thickness direction of the board 1.

[0037] The exposed part 21 is also exposed from the lower resin 11B. With the board 1, a resin opening Hb is formed on the lower resin 11B. The bottom surface 21 d of the exposed part 21 is exposed toward the lower side inside the resin opening Hb. The connecting part 31 of the plating layer 30 is formed along the intersecting surface 21a and the bottom surface 2 Id of the exposed part 21. The resin opening Hb is formed so that a through hole Hn of the exposed part 21 is positioned inside the resin opening Hb. The size of the resin opening Ha formed in the upper resin 11 A and the size of the resin opening Hb formed in the lower resin 11B may be mutually different.

[0038] As described above, the exposed part 21 includes not only the intersecting surface 2 Id but also the surface that is not visible from the upper side of the resin molded body 11 (in this example, the bottom surface 21d). According to this structure, in the step of discharging the conductive ink onto the upper resin 11 Aand the exposed part 21 from above, the conductive ink does not adhere to the intersecting surface 21a and also does not adhere to the bottom surface 2 Id of the exposed part 21. Therefore, the plating layer 30 directly contacts the terminal plate 20 at the intersecting surface 21a and the bottom surface 21d.

[0039] There is a difference in the coefficient of thermal expansion between the resin molded body 11, the terminal plate 20, and the plating layer 30. Therefore, when changes in environmental temperature occur, thermal stress is generated therebetween. On the board 1, the plating layer 30 extends to the bottom surface 21d of the exposed part 21, thereby increasing tolerance to such thermal stress.

[0040] In addition, since the resin openings Ha, Hb are formed in the upper resin 11 A and the lower resin 11B, and the through hole Hn is formed in the exposed part 21, a solution containing metal ions flows smoothly over the exposed part 21 in the plating step. Therefore, the plating layer 30 can be formed smoothly and with sufficient thickness. In other words, the plating layer 30 formed directly on the surface of the terminal plate 20, the plating layer 30 formed on the surface of the terminal plate 20 with the conductive ink layer 41 interposed, and the plating layer 30 formed on the surface of the upper resin 11 A with the conductive ink layer 41 interposed is formed continuously and with sufficient thickness. The plating layer 30 having such sufficient thickness has high adhesion with respect to the terminal plate 20 based on the aforementioned presence of the intersecting surface 21a. Therefore, the electrical conductivity of the circuit pattern formed by the terminal plate 20 and the plating layer 30 can be further improved.

[0041] An example of a manufacturing method for a molded circuit board 1 will be described. First, a metal plate 20 A (see FIG. 3a) is prepared. A portion of the metal plate 20A is the terminal plate 20 described above, and a portion remaining thereof is a bridge portion 20m and a carrier part 20n that protrude from the side surface lie of the resin molded body 11. The metal plate 20 A has a plurality of portions, each serving as a terminal plate 20. A through hole Hn described above is formed in each part (terminal plate 20). The carrier portion 20n connects the bridge portion 20m extending from the plurality of portions (terminal plates). The metal plate 20A is formed into a desired shape by press forming a plate, for example, of phosphor bronze or brass.

[0042] Next, as illustrated in FIG. 3 A and FIG. 3B, the resin molded body 11 integrated with the metal plate 20A is formed. This can be done using insert molding. Resin openings Ha, Hb that expose the exposed part 21 are formed in the resin molded body 11.

[0043] Next, the region where the circuit pattern is formed on the top surface 1 la of the upper resin 11 A is roughened. As illustrated in FIG. 4A, texturization can be performed by irradiating, for example, the region for the circuit pattern (ablation step) with laser beam E. In this manner, the adhesion between the plating layer 30 formed in the plating step described below and the upper resin 11A can be improved. The laser beam E may be irradiated just in the region of the circuit pattern or may be irradiated in a wider range than the circuit pattern.

[0044] The laser beam E is irradiated in a direction perpendicular to the top surface 11a of the upper resin 11 A (the thickness direction of the board 1), for example. Since the inner surface of the resin opening Ha is the inclined surface 11 g, the angle between the direction in which the laser beam E is irradiated and the intersecting surface 2 la of the exposed part 21 is smaller than the angle between the irradiation direction of the laser beam E and the inclined surface llg. Therefore, although the laser beam E is irradiated on the inclined surface llg and the horizontal surface 21c of the exposed part 21, the intersecting surface 21a and the bottom surface 21d of the exposed part 21 are less likely to be irradiated. Therefore, the problem of the surface of the exposed part 21 becoming oxidized by the laser beam E and increasing electrical resistance can be suppressed.

[0045] Next, as illustrated in FIG. 4B, a conductive ink F is applied to the region of the circuit pattern and the exposed part 21 on the top surface 1 la of the upper resin 11A to form the conductive ink layer 41. As described above, the material of the conductive ink F is, for example, copper ink or silver ink. The conductive ink F is liquid, and an ink-jet method may be used for application. [0046] The conductive ink F is discharged, for example, in a direction perpendicular to the top surface 11a of the upper resin 11 A (the thickness direction of the board 1). Since the inner surface of the resin opening Ha is the inclined surface llg, the angle between the discharge direction of the conductive ink F and the intersecting surface 21a is smaller than the angle between the discharge direction of the conductive ink F and the inclined surface llg. Regarding the board 1, the intersecting surface 21a is essentially parallel with the discharge direction (thickness direction of the board 1) of the ink F, and the conductive ink F is applied to the inclined surface llg and the horizontal surface 21c of the exposed part 21, but is not applied to the intersecting surface 21a or the bottom surface 21d of the exposed part 21. In other words, a region where the conductive ink F is applied (horizontal surface 21c) and a region where the conductive ink F is not applied (intersecting surface 21a, bottom surface 21d) are ensured on the surface of the exposed part 21. The conductive ink layer 41 may be formed over the entire circumference of the inner surface (inclined surface llg) of the resin opening Ha.

[0047] Next, as illustrated in FIG. 4C, the plating layer 30 is formed by electroplating. Here, a wire is connected to the carrier portion 20m, and the metal plate 20A is used as the negative electrode. As a result, the plating layer 30 is formed on the conductive ink layer 41. As described above, the material of the plating layer 30 is copper, nickel, tin, gold, or the like. Finally, the molded circuit board 1 is obtained by separating the bridge portion 20m from the terminal plate 20.

[0048] Note that the method of manufacturing the board 1 is not limited to that described with reference to FIG. 3A to FIG. 4C. For example, instead of using the inkjet method as a forming method for the conductive ink layer 41, for example, a vapor deposition method can be used. In this case, the conductive ink layer 41 formed in a region different from the circuit pattern may be removed by various methods such as a laser.

[0049] FIG. 5 is a cross-sectional view illustrating a molded circuit board 101 as another example of a molded circuit board proposed in the present disclosure. The following is a description of the difference between the molded circuit board 1 and the molded circuit board 101 as described above. For matters not described for the molded circuit board 101, the matters described for the molded circuit board 1 may be applied.

[0050] The molded circuit board 101 (hereinafter simply referred to as the board) has a terminal plate 120, a resin molded body 111, and a plating layer 30, similar to the board 1.

[0051] Aresin opening Ha is formed in an upper resin 111A of the resin molded body 111. The terminal plate 120 has an exposed part 121 exposed from the resin opening Ha. The exposed part 121 has a top surface exposed from the upper resin 111 A. The exposed part 121 has a convex part 121e that causes the top surface to bulge upward. The convex part 121e is, for example, circular in plan view of the board 101. A side surface (outer circumferential surface) of the convex part 121e is an intersecting surface 121a of the exposed part 121. The intersecting surface 121a intersects with the direction along the top surface 11a of the upper resin 111A (the X1-X2 direction in FIG. 5). For example, the intersecting surface 121a is essentially perpendicular to the direction along the top surface 11a. The exposed part 121 has a horizontal surface 121c around the convex part 121e along a plane that is parallel with the top surface 11a of the upper resin 111 A.

[0052] With the board 101, the conductive ink layer 41 is formed on the horizontal surface 121c of the exposed part 121 and a top surface 12 If of the convex part 121e, but is not formed on the intersecting surface 121a (side surface of the convex part 121e) of the exposed part 121. The amount of conductive ink present per unit area on the intersecting surface 121a is less than the amount of conductive ink present per unit area on the horizontal surface 121c. With this intersecting surface 121a, similar to the intersecting surface 21a illustrated in FIG. 2, the connecting part 31 of the plating layer 30 directly contacts the intersecting surface 121a, and the adhesion between the exposed part 121 and the plating layer 30 can be improved.

[0053] In addition, because the intersecting surface 121a intersects with the direction along the top surface 11a of the upper resin 111A, in other words, because the intersecting surface 121a is upright on the horizontal surface 121c, the intersecting surface 121a is less likely to be irradiated in the laser beam irradiation step (ablation step). As a result, the problem of the top surface of the exposed part 121 becoming oxidized by the laser beam and increasing electrical resistance can be suppressed.

[0054] As illustrated in FIG. 5, the inner surface of the resin opening Ha formed in the upper resin 111A is an inclined surface llg, and the size of an upper edge lie of the resin opening Ha is inclined so as to be larger than the lower edge 1 If. The angle of the intersecting surface 121a with respect to the thickness direction (the Z1-Z2 direction) of the board 101 is smaller than the angle Q2 (see FIG. 2) of the inclined surface llg of the resin opening Ha with respect to the thickness direction of the board 101.

[0055] As a result, the inclined surface llg can be sufficiently irradiated with a laser beam, while the intersecting surface 121a is prevented from being irradiated with the laser beam. In addition, the conductive ink is applied to the inclined surface llg and the horizontal surface 121c, while the conductive ink is prevented from being applied to the intersecting surface 121a. Regarding the board 101, the intersecting surface 121a is substantially parallel with the thickness direction of the board 101. In other words, the intersecting surface 121a is perpendicular to the top surface 11a of the upper resin 111 A.

[0056] In the example of the board 101, the conductive ink layer 41 is formed on the top surface 121f of the convex part 121e included in the exposed part 121. Unlike this, the conductive ink layer 41 need not be formed on the top surface 121f of the convex part 121e. FIG. 6 is a cross-sectional view illustrating a molded circuit board 101 A as an example of such a molded circuit board. The following describes the difference between the molded circuit board 101 and the molded circuit board 101 described above. For matters not described for the molded circuit board 101 A, the matters described for the molded circuit board 101 may be applied.

[0057] In the board 101 A illustrated in FIG. 6, a conductive ink layer 41 is formed on the horizontal surface 121c of the exposed part 121. When a liquid conductive ink is applied to the exposed part 121 using an ink-jet method, the conductive ink spreads out to areas other than where applied. However, regarding the board 101A, because the convex part 121e is formed on the exposed part 121, when the conductive ink is applied to the exposed part 121 avoiding the position of the convex part 12 le, the side surface (intersecting surface 121a) of the convex part 121e suppresses the conductive ink from spreading. As a result, the conductive ink layer 41 is not formed on the top surface 12 If of the convex part 121e. According to this structure, the top surface 12 If of the convex part 121e, as well as the intersecting surface 121a, also contributes to improving the adhesion between the exposed part 121 of the terminal plate 120 and the connecting part 31 of the plating layer 30.

[0058] FIG. 7Aand FIG. 7B illustrate a molded circuit board 201 as yet another example of a molded circuit board proposed in the present disclosure. FIG. 7A is a plan view, and FIG. 7B is a cross-sectional view taken along line Vllb-VIIb illustrated in FIG. 7A. The following describes the difference between the molded circuit board 201 and the molded circuit board 1 described above. For matters not described for the molded circuit board 201, the matters described for the molded circuit board 1 may be applied.

[0059] Similar to the board 1, the molded circuit board 201 includes a terminal plate 220, a resin molded body 211, and a plating layer 30. The resin molded body 211 includes an upper resin 211 A that covers the top surface of the terminal plate 220 and a lower resin 21 IB that covers the bottom surface of the terminal plate 220. A resin opening Ha is formed in the upper resin 211 A. The resin opening Ha is located at the edge of the upper resin 211 A, and opens upward and laterally (direction to the left in FIG. 7B). The terminal plate 220 includes an exposed part 221 that is exposed from the upper resin 211A. The resin opening Ha is rectangular in plan view of the board 201. The shape of the resin opening Ha may be circular. The plating layer 30 includes a connecting part 31 formed on the exposed part 221.

[0060] A hole Hn is formed in the top surface of the exposed part 221. The hole Hn does not pass through the exposed part 221 and has a bottom part 221c. The hole Hn has an intersecting surface 221a as an inner surface thereof. The intersecting surface 221a is annular in plan view of the board 201. The exposed part 221 has a horizontal surface 221d surrounding the hole Hn. The conductive ink layer 41 is formed on the top surface 211a of the upper resin 211A and a portion of the horizontal surface 221d, but is not formed on the intersecting surface 221a. The plating layer 30 directly contacts the exposed part 221 at the intersecting surface 221a. In the example illustrated in FIG. 7B, the conductive ink layer 41 is not formed on the bottom part 221c of the hole Hn and the left side (opposite side to the circuit pattern) of the hole Hn in the exposed part 221. Thus, the plating layer 30 directly contacts the exposed part 221 at the bottom part 221c of the hole Hn and the left side of the hole Hn.

[0061] In the manufacturing process of the board 201, the conductive ink is applied to the top surface of the upper resin 211 A and a portion of the horizontal surface 22 Id (right side of the hole Hn in the diagram), and is not applied to the inside of the hole Hn and to the left side of the hole Hn. If the conductive ink applied to a portion of the horizontal surface 22 Id is spread on the surface of the exposed part 221, the conductive ink can flow to the bottom part 221c of the hole Hn. Even when such a flow occurs, the conductive ink reaching the intersecting surface 221a of the hole Hn can be suppressed.

[0062] As illustrated in FIG. 7B, the upper resin 211Ahas an inclined surface 21 lg as an inner surface of the resin opening Ha. The inclined surface 21 lg gradually decreases in height from the top surface 211a of the upper resin 211 A to the height of the horizontal surface 221d of the exposed part 221. With the inclined surface 211g, the angle 01 of the upper resin 211 A at a top edge 2 lie of the resin opening Ha is obtuse. The angle of the intersecting surface 221a with respect to the thickness direction of the board 201 is smaller than the angle of the inclined surface 211 g with respect to the thickness direction of the board 201.

[0063] Note that with the board 201 illustrated in FIG. 7A and FIG. 7B, the top surface of the exposed part 221 may be changed to the hole Hn and may have a convex part similar to the exposed part 121 as illustrated in FIG. 5. In this case, the side surface of the convex part may function as the intersecting surface.

[0064] As yet another example , the hole Hn and the convex part are not necessarily circular. For example, the hole Hn may be a groove extending between two edges 221s, 22 It (see FIG. 7A) positioned on opposite side of the exposed part 221. In other words, the hole Hn may be a groove extending from one edge 221s and connected to the other edge 22 It. This ensures that the conductive ink layer 41 reaches the left side (opposite the circuit pattern) of the hole Hn (groove).

[0065] FIG. 8 is a cross-sectional view illustrating a molded circuit board 301 as yet another example of a molded circuit board proposed in the present disclosure. The following describes the difference between the molded circuit board 301 and the molded circuit board 1 described above. For matters not described for the molded circuit board 201, the matters described for the molded circuit board 1 may be applied.

[0066] Similar to the board 1, the molded circuit board 301 includes a terminal plate 320, a resin molded body 311, and a plating layer 30. The terminal plate 320 includes an exposed part 321 and a non-exposed part 322. The top surface of the non-exposed part 322 is covered by the upper resin 311 A of the resin molded body 311, and the bottom surface of the non- exposed part 322 is covered by the lower resin 311B of the resin molded body 311. An end part 322a of the non-exposed part 322 is exposed from a side surface 311c of the resin molded body 311. The exposed part 321 is exposed from the upper resin 321A.

[0067] The terminal plate 320 is bent in the thickness direction (more specifically, upward) of the board 301 between the non-exposed part 322 and the exposed part 321, and the exposed part 321 is positioned on the top surface 311a of the resin molded body 311. The terminal plate 320 includes an inclined part 323 extending diagonally upward from the non- exposed part 322 toward the exposed part 321. Unlike the example illustrated in FIG. 2 and the like, a hole exposing the exposed part 321 is not formed in the upper resin 311A. The exposed part 321 is positioned inside the outer circumferential edge of the resin molded body 311 in a plan view of the board 301, and the entire periphery of the exposed part 321 is surrounded by the resin molded body 311.

[0068] A convex part 321e is formed on the top surface of the exposed part 321. The exposed part 321 has a side surface (outer circumferential surface) of the convex part 321e as an intersecting surface 321a. The intersecting surface 321a intersects with the direction along the top surface 311a of the upper resin 311A (X1-X2 direction in FIG. 8). More specifically, the intersecting surface 321a is a surface orthogonal to the direction along the top surface 311a of the upper resin 311 A. In the example illustrated in the diagrams, the convex part 321e is circular in plan view of the board 301, and the intersecting surface 321a is annular in plan view. The exposed part 321 has a horizontal surface 321c surrounding the convex part 321e along a plane that is parallel with the top surface 311a of the upper resin 311A.

[0069] The conductive ink layer 41 is formed on the top surface 311a of the upper resin 311 A and a portion of the horizontal surface 321c of the exposed part 321 (the portion on the circuit pattern side), but is not formed on the intersecting surface 321a and a top surface 321f of the convex part 321e. In addition, the conductive ink layer 41 is not formed on the horizontal surface 321c of the exposed part 321 on the side (left side in the diagram) opposite to the circuit pattern across from the convex part 321e.

[0070] When a liquid conductive ink is applied to the exposed part 321 using an ink-jet method, the conductive ink spreads out to areas other than where applied. However, regarding the example illustrated in FIG. 8, because the convex part 321e is formed on the exposed part 321, when the conductive ink is applied to the exposed part 321 except the position of the convex part 321e, the side surface (intersecting surface 121a) of the convex part 121e restricts the conductive ink from spreading. Therefore, the conductive ink layer 41 is not formed on the top surface 121f of the convex part 121e, the intersecting surface 121a, or the left side of the horizontal surface 321c. Therefore, with the structure of the board 301, the exposed part 321 and the plating layer 30 directly come into contact with each other on not only the intersecting surface 121a, but also on the top surface 121f of the convex part 321 e and the left side portion of the horizontal surface 321c.

[0071] In the example illustrated in FIG. 8Aand FIG. 8B, the conductive ink layer 41 is formed only in the region on the circuit pattern side (the region on the right side in FIG. 8) on the convex part 32 le, and the conductive ink layer 41 is not formed in the region on the opposite side of the circuit pattern (the region on the left side in FIG. 8) across from the convex part 321 e. [0072] A recessed part may be formed in the exposed part 321 instead of the convex part 321e. In addition, the shape of the convex part 321e may be rectangular instead of circular. The exposed part 321 may be connected to two opposing edges.

[0073] As yet another example, the convex part 321e is not necessarily circular. For example, the convex part 321e may be a wall extending between two edges 321s, 32 It (see FIG. 8A) positioned on opposite sides of the exposed part 321. In other words, the convex part 32 le may be a wall extending from one edge 321s connecting to the other edge 32 It. This ensures that the conductive ink layer 41 reaches the left side (side opposite the circuit pattern) of the convex part 32 le (wall).

[0074] The molded circuit board 1, 101, 201, 301 as described above has a terminal plate 20, 120, 220, 320 formed of metal, a resin molded body 11, 111, 211, 311 having an upper resin 11A, 111A, 211A, 311A covering the top surface of the terminal plate, and a plating layer 30 formed on the top surface of the upper resin and constitutes a circuit pattern. The terminal plate has an exposed part 21, 121, 221, 321 that is exposed from the upper resin. The plating layer has a connecting part 31 formed on the exposed part. The exposed part is formed with an intersecting surface 21a, 121a, 221a, 321a that intersects along the direction of the top surface of the upper resin. According to this molded circuit board, the adhesiveness between the plating layer forming the circuit pattern and the terminal plate can be improved, and the plating layer 30 can be stably formed on the terminal plate 20, 120, 220, 320. Therefore, high conductivity can be ensured from the terminal plate 20 to the plating layer 30 formed on the surface of the upper molded body 11.

[0075] The manufacturing method of the molded circuit board includes a forming step of forming a metal plate 20A into a prescribed shape, a molding step of forming a molded resin molded body 11, 111, 211, 311 with an upper resin 11A, 111A, 211A, 311A, covering the top surface of the metal plate 20Aand that is integrated with the terminal plate while securing the exposed part 21, 121, 221, 321 exposed from the upper resin to the terminal plate, a coating step of coating the top surface of the upper resin and the exposed part with a conductive ink F, and a plating step of forming a plating layer 30 positioned on the conductive ink and the exposed part using the terminal plate as an electrode. In the coating step, there is a way to ensure that there are regions of the top surface of the exposed part that are coated, and regions of the top surface of the exposed part that are not coated with conductive ink. With this manufacturing method, the adhesiveness between the plating layer 30 and the terminal plate 20, 120, 220, 320 can be improved, and the plating layer 30 can be stably formed on the terminal plate 20, 120, 220, 320. Therefore, high conductivity can be ensured from the terminal plate 20 to the plating layer 30 formed on the surface of the upper molded body 11.

[0076] Note that the method of manufacturing the molded circuit board is not limited to that described with reference to FIG. 3Ato FIG. 4C. For example, the method of forming the conductive ink layer 41 may be vapor deposited, for example, rather than an ink-jet method. In this case, the conductive ink layer 41 formed in a region different from the circuit pattern may be removed by various methods such as a laser.

[0077] 1, 101, 101 A, 201, 301: molded circuit board; 11, 111, 211, 311: resin molded body; 11A, 111A, 211A, 311A: upper resin; 11B, 111B, 211B, 311B: lower resin; 11a: top surface; lie: side surface; lie: top line; Ilf: bottom line; 20, 120, 220, 320: terminal plate; 20A: metal plate; 20c: end part; 20n: carrier portion; 20m: bridge portion; 21, 121, 221, 321: exposed part; 21a: intersecting surface; 21c: horizontal surface; 2 Id: bottom surface; 30: plating layer; 31: connecting part; 41: conductive ink layer; Ha: resin opening; Hb: resin opening; Hn: hole.