JP6046063B2 - substrate - Google Patents

Description

  The present invention relates to a method for manufacturing a substrate used in an automobile or the like.

  A DC-DC converter used in an automobile includes a plurality of components such as a voltage conversion transformer and a smoothing choke coil. Of these components, components that are loaded with high voltage and large current need to be manufactured separately and then connected to the outside of the substrate. However, such a configuration causes an increase in the size of the apparatus and a poor assemblability, so that a more compact DC-DC converter is required.

  On the other hand, there is a resin-molded substrate in which a lead frame bent in advance with resin by injection molding is covered and a part of the lead frame is exposed at an attachment part of an electronic component (for example, Patent Document 1).

JP 2000-133897 A

  However, as in Patent Document 1, if a part of the injection resin is recessed to expose the internal circuit conductor, it becomes difficult to join the electronic component and the circuit conductor. For example, usually, a method is used in which solder is placed on a substrate by screen printing, electronic components are placed, and then the electronic components are connected together in a reflow furnace. However, if an uneven surface exists on the substrate as in Patent Document 1, screen printing cannot be performed. Therefore, it is difficult to apply solder.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide a substrate that can be screen-printed without unevenness on the surface of the substrate.

In order to achieve the above-mentioned object, the present invention provides an injection-molded substrate formed by injecting an injection resin onto the surface of a circuit conductor, wherein a step portion provided by bending a part of the circuit conductor, and the step A circuit conductor exposed portion in which a part of the circuit conductor is exposed on the surface of the injection resin by a portion, and the surface of the circuit conductor other than the circuit conductor exposed portion is covered with the injection resin, The surface of the exposed portion and the surface of the injection resin are formed in substantially the same plane, and a notch or a recess is provided between the adjacent circuit conductor exposed portions, and the notch or the recess has the injection the circuit conductor exposed portion in the surface of the substrate by a resin is placed is divided injection holes from at least one surface of the molded substrate is formed, a part of the surface of the stepped portion that you exposed in the hole It is the board | substrate characterized.
An injection-molded substrate formed by injecting an injection resin onto the surface of a circuit conductor, wherein a step part provided by bending a part of the circuit conductor, and a part of the circuit conductor formed by the step part A circuit conductor exposed portion exposed on the surface of the injection resin, and the surface of the circuit conductor other than the circuit conductor exposed portion is covered with the injection resin, the surface of the circuit conductor exposed portion, and the injection resin Are formed on substantially the same plane, and a notch or a recess is provided between adjacent circuit conductor exposed portions, and the injection resin is disposed in the notch or the recess so that the substrate is disposed. The circuit conductor exposed portion is sectioned on the surface, and a through hole is formed in the stepped portion.

  It is desirable that the pair of circuit conductors be arranged so that a gap is provided between the circuit conductor exposed portions, and the notched portion or the concave portion is formed along the facing direction of the circuit conductor. .

  The circuit conductors other than the exposed part of the circuit conductor and the parts other than the stepped part may be arranged at the approximate center of the thickness of the injection resin.

  A hole may be formed in a part of the injection resin on the back side of the circuit conductor exposed portion.

  A thin-walled portion may be formed on a part of the surface on the stepped portion side of the circuit conductor exposed portion, and the thin-walled portion may be covered with the injection resin.

  The width of the stepped portion side of the circuit conductor exposed portion may be narrower than other portions of the circuit conductor exposed portion.

  A heat radiating member may be further provided, and the surface of the heat radiating member and the surface of the injection resin may be formed on substantially the same plane.

  According to the first invention, a part of the circuit conductor is bent to form a stepped portion, and a part of the circuit conductor is exposed to the surface of the injection resin, whereby irregularities are formed on the surface of the substrate. Can be prevented. For this reason, solder screen printing on the surface of the circuit conductor is possible. Moreover, since solder can be screen-printed, an electronic component can be mounted at a predetermined position of the circuit conductor.

  At this time, the range of the circuit conductor exposed from the injection resin can be regulated by forming a notch or a recess in the vicinity of the exposed portion of the circuit conductor. For this reason, it can suppress that a solder flows out of a predetermined range.

  In particular, a plurality of circuit conductors are arranged with a gap therebetween, and a notch or a recess is formed along the opposing direction of the circuit conductor, so that an electronic component arranged so as to straddle the circuit conductor is provided. Thus, it is possible to reliably regulate the region where the solder flows in the joint portion with each circuit conductor exposed portion.

  In addition, the circuit conductors other than the exposed portions of the circuit conductors and the stepped portions are arranged at substantially the center of the thickness of the injection resin, so that the resin amounts on both surfaces of the injection molded substrate are substantially the same, and the influence of deformation due to heat is reduced. can do.

  Further, heat can be radiated by forming a hole in a part of the injection resin on the back side of the exposed portion of the circuit conductor.

  Further, by forming a thin portion on a part of the step conductor side surface of the circuit conductor exposed portion and coating the thin portion with an injection resin, a more accurate circuit conductor exposure range can be formed.

  Moreover, the hole is formed from at least one surface of the injection-molded substrate, and a part of the surface of the step portion is exposed to the hole, so that the restriction on the direction parallel to the substrate surface of the step portion can be relaxed.

  Moreover, the rigidity of a circuit conductor exposure part and a step part can be made small by making the width | variety of the step part side of a circuit conductor exposure part narrower than the width | variety of the other site | part of a circuit conductor exposure part. For this reason, the position of the notch can be preferentially deformed, and the stress applied to the electronic component to be mounted can be relaxed.

  Moreover, the rigidity of a step part can be made small by providing a through-hole in a step part. For this reason, a step part can be deformed preferentially and the stress given to the electronic component mounted can be relieved.

  Further, the heat dissipation member is further provided, and the surface of the heat dissipation member and the surface of the injection resin are formed on substantially the same surface, so that the heat dissipation property of the substrate can be improved without hindering the screen printability. .

  ADVANTAGE OF THE INVENTION According to this invention, the board | substrate etc. which can eliminate the unevenness | corrugation of the surface of a board | substrate and can perform screen printing can be provided.

The top view which shows the injection molding board | substrate 3. FIG. It is sectional drawing of the injection molding board | substrate 3, and is the sectional view on the AA line of FIG. (A) is sectional drawing of the injection molding board | substrate 3, BB sectional drawing of FIG. 1, (b) is a figure which shows the other form of (a). The top view which shows the board | substrate 1. FIG. It is sectional drawing of the board | substrate 1, and CC sectional view taken on the line of FIG. The perspective view of the circuit conductor 5. FIG. The figure which shows the state which has arrange | positioned the circuit conductor 5 in the metal mold | die 21. FIG. (A) is the figure which shows the state which formed the step part in the circuit conductor 5, (b) is the figure which shows the state which formed the thin part 25 further, (c) shows the state which inject | emitted injection resin in this state Figure. Sectional drawing of the injection molding board | substrate 3a. The perspective view of the circuit conductor 5a. Sectional drawing of the injection molding board | substrate 3b. Sectional drawing of the injection molding board | substrate 3c. Sectional drawing of the injection molding board | substrate 3d. Sectional drawing of the injection molding board | substrate 3e.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 is a plan view showing an injection-molded substrate 3, FIG. 2 is a cross-sectional view taken along line AA in FIG. 1, and FIG. 3A is a cross-sectional view taken along line BB in FIG. The injection-molded substrate 3 is a substrate used as, for example, a DC-DC converter for automobiles.

  In the injection molded substrate 3, a part of the circuit conductor 5 is covered with the injection resin 9. A part of the circuit conductor 5 is exposed from the injection resin 9. The portion exposed from the injection resin 9 becomes the circuit conductor exposed portion 7.

  The injection resin 9 is not particularly limited, and for example, PPS (polyphenylene sulfide) can be used.

  As shown in FIG. 2, the circuit conductor 5 is bent inside the injection resin 9 to form a stepped portion 11. Part of the circuit conductor 5 is exposed on the surface of the injection resin 9 by the step portion 11.

  Sites other than the stepped portion 11 and the circuit conductor exposed portion 7 of the circuit conductor 5 are arranged at substantially the center in the thickness direction of the injection resin 9. On the other hand, the surface of the circuit conductor exposed portion 7 and the surface of the injection resin 9 are formed on substantially the same plane. Therefore, no irregularities are formed on the surface of the injection-molded substrate 3.

  It should be noted that a portion such as a transformer coil where the plurality of circuit conductors 5 are laminated at intervals in the thickness direction of the injection-molded substrate 3 is completely injected resin 9 so as not to be exposed on the surface of the injection-molded substrate 3. Covered with.

  A hole 12 penetrating to the back surface of the injection molded substrate 3 is formed on the back surface side of the circuit conductor exposed portion 7. The hole 12 functions as a heat radiating part of the circuit conductor exposed part 7. The holes 12 may be omitted if not necessary. In addition, the formation method of the hole 12 is mentioned later. The function of the hole 12 as a heat radiating part is obtained by exposing the back side of the circuit conductor exposed part 7 through the hole 12, and thermally couples the back side of the circuit conductor exposed part 7 with a housing (not shown). Can also be obtained. For example, when there is no need to electrically insulate the circuit conductor exposed portion 7 from the housing or the like, it can be thermally coupled to the housing or the like via a metal paste or the like filled in the holes 12. When it is necessary to electrically insulate the circuit conductor exposed portion 7 from the housing or the like, an insulating heat dissipation sheet can be disposed in the hole 12 and thermally coupled to the housing or the like.

  As shown in FIG. 3A, the circuit conductor exposed portion 7 of the circuit conductor 5 is provided with a plurality of notches 13. An injection resin 9 is provided in the notch 13. The notch 13 is formed up to the step 11.

  As shown in FIG. 1, at least a pair of circuit conductors 5 are arranged such that circuit conductor exposed portions 7 face each other with a gap therebetween. At this time, the notch 13 is formed along the facing direction of the circuit conductor 5 (the left-right direction in the figure). For this reason, the plurality of circuit conductor exposed portions 7 are divided by the notch portions 13 in plan view. That is, a plurality of circuit conductor exposed portions 7 extend substantially parallel to each other through the notch portions 13 at the end portions of the circuit conductors 5.

  Note that the notched portion 13 may not be provided if the circuit conductor exposed portion 7 can be divided into a plurality of portions by the injection resin 9 in plan view. For example, as illustrated in FIG. 3B, a recess 15 may be formed in a groove shape between the plurality of exposed circuit conductors 7. Even in this case, since the injection resin 9 wraps around the upper surface of the concave portion 15, the circuit conductor exposed portion 7 can be divided into a plurality of portions.

  Next, the board | substrate 1 which joined the electronic component 17 to the injection molding board | substrate 3 is demonstrated. 4 is a plan view of the substrate 1, and FIG. 5 is a cross-sectional view taken along the line CC of FIG. A plurality of electronic components 17 are mounted on the substrate 1. The substrate 1 according to the present invention is not limited to the arrangement and shape as shown in the drawings, and it goes without saying that other components and the like can be appropriately mounted, and the arrangement and shape can be appropriately changed. Yes.

  As shown in FIG. 5, the electronic component 17 is connected to the circuit conductor exposed portion 7 by solder 19. In addition, the connection method of the electronic component 17 is as follows. First, the solder 19 is applied to the circuit conductor exposed portion 7 of the injection molded substrate 3 by screen printing. As described above, since the surfaces of the injection resin 9 and the exposed circuit conductor 7 are smooth on the upper surface of the injection-molded substrate 3, screen printing is easy. Next, the electronic component 17 and the printed circuit board are arranged at predetermined positions, and a plurality of electronic components 17 and the like can be collectively mounted on the injection-molded substrate 3 by passing through a reflow furnace.

  Here, the periphery of the circuit conductor exposed portion 7 is surrounded by the injection resin 9. Therefore, the solder 19 is suppressed from flowing outside the area of the circuit conductor exposed portion 7 due to the difference in wettability. That is, the position of the solder 19 is restricted by the area of the circuit conductor exposed portion 7.

  For example, when the electronic component 17 is a DC converter, a plurality of electronic components 17 may be arranged in parallel as shown in FIG. Even in this case, since the notch 13 or the recess 15 is provided, the circuit conductor exposed portions 7 are separated by the injection resin 9. For this reason, the solder 19 does not flow to other adjacent circuit conductor exposed portions 7.

  Next, a method for manufacturing the injection molded substrate 3 will be described. First, as shown in FIG. 6, the circuit conductor 5 is molded. The circuit conductor 5 is processed from a metal plate by a press or the like. The metal plate used is made of, for example, copper or a copper alloy. The thickness of the metal plate is, for example, about 0.4 mm to 3 mm.

  A metal plate is punched into a predetermined shape to form a stepped portion 11 to form a circuit conductor exposed portion 7. The circuit conductor exposed portion 7 and the portions of the other circuit conductors 5 excluding the step portion 11 are formed in parallel. The notch 13 is formed with a length that reaches at least the step 11. By doing in this way, the circuit conductor exposed part 7 can be reliably divided on the surface of the injection-molded substrate 3.

  In this way, the circuit conductor 5 is formed, and the circuit conductors 5 are joined together as necessary. The joining between the circuit conductors 5 is performed by welding, for example. Note that the circuit conductor 5 may be formed not only in a plane but also in multiple layers.

  FIG. 7 is a view showing a state in which the plurality of circuit conductors 5 formed in this way are set in the mold 21. The circuit conductor 5 is held by pins or the like in the mold 21. In this state, the injection resin 9 is injected into the mold 21, whereby the surface or interlayer of the circuit conductor 5 is covered with the injection resin 9, and the injection-molded substrate 3 is formed.

  Here, a pin 23 is disposed on the back side of the circuit conductor exposed portion 7. The pin 23 is a portion that presses the circuit conductor exposed portion 7 against the inner surface of the mold 21. Since the circuit conductor exposed portion 7 is pressed against the inner surface of the mold 21 in this way, the injection resin 9 is prevented from flowing around the surface of the circuit conductor exposed portion 7 (the gap between the circuit conductor exposed portion 7 and the inner surface of the mold 21). can do.

  When the injection resin 9 is injected in this way, a hole corresponding to the pin 23 is formed. That is, the above-described hole 12 is formed on the back side of the circuit conductor exposed portion 7. The hole 12 can function as a heat radiating part of the circuit conductor exposed part 7.

  As described above, the circuit conductor 5 may be formed by bending after punching with a press. However, when the pressing is performed, an uneven shape is provided on the surface of the press die, and the circuit conductor 5 is formed. You may form fine uneven | corrugated shape on the surface (for example, back surface). By increasing the surface roughness, the adhesion with the resin can be improved by the anchor effect. In addition to the formation of irregularities by a press die, the surface of the circuit material may be roughened by surface treatment by blast treatment, copper plating roughening, nickel plating roughening, or the like.

  As described above, according to the injection-molded substrate 3 of the present embodiment, the circuit conductor exposed portion 7 and the injection-molded substrate 3 are formed on the same surface, so that irregularities are formed on the injection-molded substrate 3. There is nothing. Therefore, screen printing of the solder 19 is easy.

  Moreover, since the notch part 13 or the recessed part 15 which divides the circuit conductor exposed part 7 is formed, the several circuit conductor exposed part 7 can be provided side by side mutually independently. For this reason, it is suppressed that the solder 19 flows into the connection with an adjacent electronic component or the like.

  In addition, since the circuit conductor 5 other than the circuit conductor exposed portion 7 and the stepped portion 11 is disposed at substantially the center in the thickness direction of the injection-molded substrate 3, the amount of the injection resin 9 on the front and back surfaces of the circuit conductor 5 becomes substantially equal. The influence of deformation due to heat can be reduced.

  In addition, since the circuit conductor exposed portion 7 is pressed against the inner surface of the mold 21 from the back surface by the pin 23 at the time of manufacturing, the injection resin 9 can be prevented from flowing around the surface of the circuit conductor exposed portion 7. Further, the hole 12 formed at this time can function as a heat radiating portion of the circuit conductor exposed portion 7.

(Other embodiment 1)
Further, a thin portion may be formed in the circuit conductor 5. FIG. 8 is a diagram illustrating an example of a process for forming a thin portion. First, as shown in FIG. 8A, the circuit conductor 5 is formed by the method described above. Next, as shown in FIG. 8B, a thin portion 25 is formed by cutting a part of the circuit conductor exposed portion 7 (near the end portion on the step portion 11 side).

  When the injection resin 9 is injected to the circuit conductor 5 in which the thin portion 25 is formed in this manner, the injection resin 9 also wraps around the surface of the thin portion 25. That is, the range of the circuit conductor exposed portion 7 is regulated by the thin portion 25.

  Normally, when the circuit conductor 5 is bent, a slight angle R is formed at the bent portion. For this reason, there is a possibility that the injection resin may circulate from the corner R portion to the surface of the circuit conductor exposed portion 7 to form burrs. Further, since the shape of the bent portion is not necessarily constant, the exposure range of the circuit conductor exposed portion 7 may vary.

  On the other hand, by forming the thin portion 25, the influence of the angle R of the bent portion can be eliminated, and the wraparound of the injection resin 9 can be suppressed. Moreover, since the range of the circuit conductor exposed portion 7 can be easily controlled by the formation range of the thin portion 25, the size of the circuit conductor exposed portion 7 exposed on the surface of the injection molded substrate 3 can be controlled more accurately. .

  In addition, you may form the thin part 25 by methods other than cutting. For example, the thin portion may be formed by crushing the target portion when punching with a press.

  As described above, by forming the thin portion 25 on a part of the surface of the circuit conductor exposed portion 7 on the stepped portion 11 side, it is possible to suppress the injection resin 9 from entering the surface of the circuit conductor exposed portion 7. The exposed range of the circuit conductor exposed portion 7 can be accurately regulated.

(Other embodiment 2)
FIG. 9 is a cross-sectional view of the injection-molded substrate 3a at a position corresponding to the line CC in FIG. In addition to the holes 12 formed by pins for pressing the circuit conductor exposed portion 7 from the back surface, other holes 12a and 12b may be provided as in the injection-molded substrate 3a shown in FIG. The hole 12a is formed along the step portion 11 from the surface side where the circuit conductor exposed portion 7 is exposed. That is, one surface perpendicular to the substrate surface of the stepped portion 11 is exposed in the hole 12a. The hole 12b is the same as the hole 12a, but is formed along the step portion 11 from the side opposite to the surface where the circuit conductor exposed portion 7 is exposed.

  Thus, by forming the holes 12a and 12b, the restriction on the direction in which the step portion 11 is parallel to the substrate surface is relaxed. Therefore, the stress generated in the circuit conductor 5 can be relaxed. Moreover, since the exposed area of the circuit conductor 5 increases, heat dissipation can be improved.

(Other embodiment 3)
Like the circuit conductor 5 a shown in FIG. 10, a notch 13 a may be formed in the circuit conductor exposed portion 7. That is, the width on the base side (step portion 11 side) of the circuit conductor exposed portion 7 may be narrowed. Furthermore, the width of the step portion 11 may be narrowed by extending the notch portion 13a. By doing in this way, the rigidity of the circuit conductor exposure part 7 and the step part 11 can be made small. For this reason, the position of the notch 13a can be preferentially deformed, and the stress applied to the electronic component to be mounted can be relaxed.

(Other embodiment 4)
11 is a cross-sectional view of the injection-molded substrate 3b at a position corresponding to the line CC in FIG. A hole 27 that is a through hole may be formed in the step portion 11 of the circuit conductor 5 as in the injection-molded substrate 3b shown in FIG. By providing the hole 27 in the step portion 11, the rigidity of the step portion 11 can be reduced. For this reason, the step part 11 can be preferentially deformed and the stress applied to the electronic component to be mounted can be relaxed.

(Other embodiment 5)
12 is a cross-sectional view of the injection-molded substrate 3c at a position corresponding to the line CC in FIG. As in the injection molded substrate 3c shown in FIG. 12, a heat radiating member 29 may be provided in the facing portion between the circuit conductors 5. That is, the heat radiating member 29 may be disposed between the circuit conductor exposed portions 7 and at a portion where the electronic component is mounted. The heat radiating member 29 is, for example, a heat radiating sheet made of metal or a resin material.

  When the heat radiating member 29 is conductive, the heat radiating member 29 is not electrically connected to the circuit conductor 5. That is, the injection resin 9 or an electrically insulating heat dissipation sheet is provided between the circuit conductor 5 and the heat dissipation member 29. The heat dissipation member 29 is exposed on the surface opposite to the mounting surface of the electronic component. The heat dissipation member 29 is exposed on the same surface as the surface on the back side of the substrate. For this reason, at the time of the above-described injection molding, it is pressed against the inner surface of the mold by a pin or the like. Therefore, a hole 12 c is formed on the upper surface side (electronic component mounting surface side) of the heat radiating member 29.

  Thus, by providing the heat radiating member 29, the heat dissipation of a board | substrate can be improved. Further, by reducing the thickness of the injection resin 9 below the electronic component, internal stress generated in the injection resin 9 can be reduced.

  In addition, arrangement | positioning of the thermal radiation member 29 is not restricted to the example shown in FIG. For example, you may arrange | position so that the circuit conductor 5 may be contacted like the injection molding board | substrate 3d shown in FIG. Even in this case, the heat radiating member 29 does not protrude from the upper surface or the back surface of the substrate, and is formed on the same surface as the injection resin 9.

(Other embodiment 6)
FIG. 14 is a cross-sectional view of the circuit conductor exposed portion 7 and the transformer coil portion of the injection molded substrate 3e in which the transformer coil portion is formed in the vicinity of the circuit conductor exposed portion 7. Like the injection-molded substrate 3e shown in FIG. 14, the present invention can also be applied to a transformer coil section. In this case, the ferrite core 31 is integrally molded. Further, around the ferrite core 31, a circuit conductor 5b as a primary coil and a circuit conductor 5c as a secondary coil are arranged. The circuit conductor 5c has the same configuration as the circuit conductor 5 and the like. In the example shown in the figure, a step portion 11 is formed on a part of the circuit conductor 5c, and a circuit conductor exposed portion 7 is formed.

  Thus, even if the circuit conductor is a coil, the circuit conductor exposed portion 7 does not protrude from the substrate surface and is formed on the same surface as the injection resin 9.

  As mentioned above, although embodiment of this invention was described referring an accompanying drawing, the technical scope of this invention is not influenced by embodiment mentioned above. It is obvious for those skilled in the art that various modifications or modifications can be conceived within the scope of the technical idea described in the claims, and these are naturally within the technical scope of the present invention. It is understood that it belongs.

  For example, it goes without saying that the above-described configurations can be combined with each other.

1 ... Substrate 3, 3a, 3b, 3c, 3d, 3e ......... Injection molded substrate 5, 5a, 5b, 5c ......... Circuit conductor 7 ...... Circuit conductor exposed part 9 ... Injection resin 11 ... ...... Steps 12, 12a, 12b, 12c ......... Hole 13, 13a ......... Notch 15 ......... Recess 17 ......... Electronic component 19 ......... Solder 21 ......... Mold 23 ......... Pin 25 ......... Thin portion 27 ......... Hole 29 ......... Heat dissipation member 31 ......... Ferrite core

Claims (8)

An injection molded substrate formed by injecting injection resin onto the surface of a circuit conductor,
A step provided by bending a part of the circuit conductor;
A circuit conductor exposed portion in which a part of the circuit conductor is exposed on the surface of the injection resin by the stepped portion;
Comprising
The surface of the circuit conductor other than the circuit conductor exposed portion is covered with the injection resin, and the surface of the circuit conductor exposed portion and the surface of the injection resin are formed on substantially the same plane,
Between the adjacent circuit conductor exposed parts, a notch or a recess is provided, and the circuit conductor exposed part is divided on the substrate surface by placing the injection resin in the notch or the recess ,
Injection hole from at least one surface of the molded substrate is formed, the substrate portion of the surface of the step portion is characterized that you exposed in the hole. An injection molded substrate formed by injecting injection resin onto the surface of a circuit conductor,
A step provided by bending a part of the circuit conductor;
A circuit conductor exposed portion in which a part of the circuit conductor is exposed on the surface of the injection resin by the stepped portion;
Comprising
The surface of the circuit conductor other than the circuit conductor exposed portion is covered with the injection resin, and the surface of the circuit conductor exposed portion and the surface of the injection resin are formed on substantially the same plane,
Between the adjacent circuit conductor exposed parts, a notch or a recess is provided, and the circuit conductor exposed part is divided on the substrate surface by placing the injection resin in the notch or the recess ,
Substrate, wherein Rukoto through hole is formed in the stepped portion. A pair of the circuit conductors are arranged with a gap therebetween so that the exposed portions of the circuit conductors are opposed to each other, and the cutout portion or the concave portion is formed along the facing direction of the circuit conductors. The substrate according to claim 1 or 2 . 4. The substrate according to claim 1 , wherein the circuit conductors other than the exposed portion of the circuit conductor and the portions other than the stepped portion are arranged at a substantially center of the thickness of the injection resin. 5. . The circuit on the back side of the conductor exposed portion, the substrate according to any one of claims 1 to 4, characterized in that holes are formed in a part of the injected resin. The thin portion is formed in a part of the stepped portion of the surface of the circuit conductor exposed portion, the thin portion, to one of the claims 1 to 5, characterized in that it is coated with the injected resin The substrate described.   The substrate according to any one of claims 1 to 6, wherein a width of the circuit conductor exposed portion on the stepped portion side is narrower than other portions of the circuit conductor exposed portion. The substrate according to any one of claims 1 to 7 , further comprising a heat dissipating member, wherein the surface of the heat dissipating member and the surface of the injection resin are formed on substantially the same plane.

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