JP2019197848A - Circuit structure and electric connection box - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the heat dissipation of a circuit structure 11. SOLUTION: In a circuit structure 11 according to the present embodiment, a FET 26 is connected to a conductive pattern 22 of a first surface 21 on which a conductive pattern 22 is formed, and the FET 26 is formed on the side opposite to the first surface 21. An insulative second resist layer 31 is formed on the exposed second surface 28, and a heat transfer pattern thermally conductively connected to the conductive pattern 22 from a heat dissipation window portion 32 opened in the second resist layer 31. The circuit board 14 having the exposed 33 and the second heat transfer layer 31 have a higher thermal conductivity than the second resist layer 31 and are thermally connected to the heat transfer pattern 33 exposed from the heat dissipation window 32. 34, a second heat transfer section 35 having a higher thermal conductivity than that of the second resist layer 31 and being heat transfer connected to the first heat transfer section 34, and a second heat transfer section 35 and a heat transfer And a heat sink 13 connected to. [Selection diagram] Figure 1

Description

  The technology disclosed in this specification relates to a circuit structure and an electrical junction box.

  Conventionally, as a circuit structure in which a heat generating component is mounted on a circuit board, one described in Japanese Patent Application Laid-Open No. 2014-170868 is known. This circuit component is housed inside a metal housing. A grease-like heat dissipating material is disposed between the circuit board and the metal casing. This heat dissipation material is in contact with both the circuit board and the metal casing. As a result, it was expected that the heat generated in the heat-generating component when energized was transmitted from the circuit board to the metal casing through the heat dissipation material and dissipated from the metal casing to the outside.

JP 2014-170868 A

  An insulating resist layer is formed on the front and back surfaces of the circuit board. This resist layer has a relatively large thermal resistance. For this reason, in the prior art, a resist layer having a relatively large thermal resistance is interposed between the conductive pattern formed on the circuit board and the grease-like heat dissipation material. Was not enough.

  The technology disclosed in the present specification has been completed based on the above circumstances, and an object thereof is to provide a circuit structure body and an electrical junction box with improved heat dissipation.

  The technology disclosed in the present specification is a circuit structure, wherein the heat generating component is connected to the conductive pattern on the first surface on which the conductive pattern is formed, and is opposite to the first surface. An insulating resist layer is formed on the second surface formed on the side, and a heat transfer pattern thermally connected to the conductive pattern is exposed from a heat dissipation window portion opened in the resist layer. A circuit board having a thermal conductivity higher than that of the resist layer and thermally connected to the heat transfer pattern exposed from the heat radiating window, and heat higher than that of the resist layer. A second heat transfer portion having high conductivity and thermally connected to the first heat transfer portion, and a heat sink thermally connected to the second heat transfer portion are provided.

  The technology disclosed in the present specification is an electrical junction box, and includes the above-described circuit structure and a cover that is attached to the circuit structure and covers the circuit board.

  The heat generated in the heat-generating component during energization is transferred to the conductive pattern to which the heat-generating component is connected, and then transferred to the heat transfer pattern that is thermally connected to the conductive pattern, and reaches the first heat transfer section. Then, it is reliably transmitted to the second heat transfer section that is connected in heat transfer with the first heat transfer section. The heat that has reached the second heat transfer section is transferred from the second heat transfer section to the heat sink and is dissipated from the heat sink to the outside.

  Since the first heat transfer section has a higher thermal conductivity than the resist layer, heat is transferred from the heat transfer pattern to the second heat transfer section as compared with the case where heat is transferred to the second heat transfer section through the resist layer. It can be transmitted efficiently. Thereby, heat can be efficiently dissipated from the heat generating component to the outside through the heat sink, so that the heat dissipation of the circuit structure can be improved.

  The following aspects are preferred as embodiments of the technology disclosed in this specification.

  The protruding height dimension of the first heat transfer portion from the heat transfer pattern is set to be equal to or larger than the thickness dimension of the resist layer.

  According to said structure, the protrusion edge part of a 1st heat-transfer part protrudes on the heat sink side rather than a resist layer. Thereby, since a 1st heat-transfer part can contact with a 2nd heat-transfer part reliably, the heat dissipation of a circuit structure body can be improved reliably.

  Spacers are interposed between the heat sink and the circuit board.

  According to said structure, the space | interval of a heat sink and a circuit board can be set correctly with a spacer. Thereby, it can suppress that a space | gap arises between a 2nd heat-transfer part and a 1st heat-transfer part. As a result, the heat dissipation of the circuit structure can be further improved.

  The first heat transfer part is made of solder.

  According to said structure, a heat-transfer pattern and a 1st heat-transfer part can be reliably connected by the simple method of soldering. Thereby, since the heat-transfer efficiency between a heat-transfer pattern and a 1st heat-transfer part can be improved, the heat dissipation of a circuit structure body can be improved more.

  The second heat transfer part has a grease shape or a gel shape.

  According to said structure, since the 2nd heat-transfer part has comprised the shape of grease or gel, it can deform | transform easily following the shape of a 1st heat-transfer part and a heat sink. As a result, the adhesion between the first heat transfer section and the second heat transfer section is improved, and the adhesion between the second heat transfer section and the heat sink is also improved, so that the heat dissipation of the circuit structure can be further improved. it can.

  The second heat transfer part has a sheet shape.

  According to said structure, since the 2nd heat-transfer part has comprised the sheet form, handling is easy. Thereby, the manufacturing efficiency of a circuit structure can be improved.

  A plurality of the first heat transfer portions are formed at intervals, and the second heat transfer that has entered between the plurality of first heat transfer portions is connected to the heat transfer pattern in a heat transfer manner. ing.

  According to said structure, since the path | route through which heat is transmitted from a heat-transfer pattern to a 2nd heat-transfer part is formed, the heat dissipation of a circuit structure body can be improved more.

  A thermal via hole connecting the conductive pattern and the heat transfer pattern;

  According to said structure, since the efficiency of the heat conduction from a conductive pattern to a heat-transfer pattern can be improved, the heat dissipation of a circuit structure body can be improved more.

  According to the technique disclosed in this specification, the heat dissipation of the circuit structure and the electrical junction box can be improved.

Sectional drawing which shows the electrical-connection box which concerns on Embodiment 1. Partially enlarged plan view showing FET mounted on first surface of circuit board The partially expanded bottom view of a circuit board which shows the heat-transfer pattern formed in the 2nd surface of a circuit board, and a 1st heat-transfer part. The partially expanded bottom view of a circuit board which shows the heat-transfer pattern formed in the 2nd surface of the circuit board which concerns on Embodiment 2, and a 1st heat-transfer part. The partially expanded bottom view of a circuit board which shows the heat-transfer pattern formed in the 2nd surface of the circuit board which concerns on Embodiment 3, and a 1st heat-transfer part. Sectional view showing electrical junction box according to virtual technology

<Embodiment 1>
Embodiment 1 of the technique disclosed in this specification will be described with reference to FIGS. 1 to 3. The electrical junction box 10 according to the present embodiment includes a circuit configuration body 11. The electrical junction box 10 is mounted on a vehicle (not shown) and is disposed between a power source (not shown) and a device (not shown). In the following description, about some same members, a code | symbol may be attached | subjected only to some members, and a code | symbol may be abbreviate | omitted about another member.

  As shown in FIG. 1, the electrical junction box 10 is formed by assembling a cover 12 to a circuit component 11. The circuit structure 11 includes a heat sink 13 and a circuit board 14 fixed to the heat sink 13.

  In the present embodiment, the heat sink 13 is made of metal, and includes a bottom wall 15 and a boss 16 (an example of a spacer) protruding upward from the upper surface of the bottom wall 15. The boss 16 has a cylindrical shape. A screw hole 17 extending downward is formed on the upper surface of the boss 16. As a metal which comprises the heat sink 13, arbitrary metals, such as aluminum, aluminum alloy, iron, stainless steel, copper, a copper alloy, can be selected suitably as needed. The heat sink 13 may be made of a synthetic resin having heat dissipation properties.

  The cover 12 includes an upper wall 18 and a side wall 19 that extends downward from a side edge of the upper wall 18. The side wall 19 is fitted on the bottom wall 15 of the heat sink 13. The cover 12 and the heat sink 13 include a lock protrusion (not shown) protruding from the side edge of the bottom wall 15 of the heat sink 13 and an elastically deformable lock receiving portion (not shown) formed on the side wall 19 of the cover 12. Are integrally assembled by elastically engaging with each other. Further, the cover 12 and the heat sink 13 may be assembled together by screwing. As described above, the cover 12 and the heat sink 13 are integrally assembled by a known method.

  In a state where the heat sink 13 and the cover 12 are assembled together, an area above the bottom wall 15 of the heat sink 13 and below the upper wall 18 of the cover 12 is an accommodation space 20 in which the circuit board 14 is accommodated. Is done.

  The circuit board 14 is formed by forming a metal pattern on an insulating plate made of an insulating synthetic resin by a printed wiring technique. A conductive pattern 22 is formed on the first surface 21 located on the upper side of the circuit board 14. Although not shown in detail, the conductive pattern 22 forms a circuit.

  The circuit board 14 has a through hole 24 through which the bolt 23 is passed. With the circuit board 14 placed on the upper surface of the boss 16 of the heat sink 13, the bolt 23 inserted through the through hole 24 of the circuit board 14 is screwed into the screw hole 17 formed in the boss 16. A circuit board 14 is fixed to the heat sink 13.

  As shown in FIG. 2, a plurality of lands 25 (an example of a conductive pattern 22) are formed on the first surface 21 of the circuit board 14. A lead 27 of a field effect transistor (FET) 26 is electrically connected to the land 25 by a known method such as soldering. The FET 26 is an example of a heat generating component. Examples of the heat generating component include a component that generates heat when energized, such as a relay, a capacitor, a coil, and a microcomputer.

  The lands 25 formed on the circuit board 14 are connected to electronic components (not shown) such as resistors and diodes in addition to the heat generating components. The land 25 has a substantially rectangular shape when viewed from above. A first resist layer 60 made of an insulating material is formed on the first surface 21 of the circuit board 14. The first resist layer 60 is generally formed in a region different from the land 25, but may be formed so as to overlap a part of the land 25.

  Two leads 27 protrude outward from the side edge of the FET 26. One of the two leads 27 is a gate terminal, and the other is a drain terminal. A source terminal is formed on the lower surface of the FET 26. The gate terminal, drain terminal, and source terminal of the FET 26 are soldered to lands 25 formed on the upper surface of the circuit board 14.

  The circuit board 14 according to the present embodiment includes a plurality of conductive patterns 22 stacked in an electrically insulated state. The second surface 28 located on the lower side of the circuit board 14 is connected to a land 25 formed on the first surface 21 and a plurality of (three in this embodiment) thermal via holes 29 in a heat transfer manner. A thermal pattern 33 is formed. The thermal via hole 29 is filled with a heat transfer portion 30 having thermal conductivity in a through hole 24 that penetrates the first surface 21 and the second surface 28 of the circuit board 14. The heat transfer section 30 can be formed by a known technique such as chemical plating or a cured synthetic resin material containing metal powder. The heat conductivity of the heat transfer section 30 is higher than that of the insulating synthetic resin that constitutes the circuit board 14.

  As shown in FIG. 2, an insulating second resist layer 31 (an example of a resist layer) is formed on the second surface 28 of the circuit board 14. The second resist layer 31 has a heat radiating window 32 that opens downward. The heat transfer pattern 33 is exposed from the heat radiation window 32. The heat radiation window 32 has a substantially rectangular shape when viewed from below.

  A first heat transfer section 34 is connected to the heat transfer pattern 33 in a heat transfer manner. For the first heat transfer section 34, any material such as metal, synthetic resin, ceramic, or the like can be appropriately selected as necessary. The thermal conductivity of the first heat transfer section 34 is set higher than that of the second resist layer 31. The first heat transfer unit 34 according to the present embodiment is made of solder. The first heat transfer section 34 can be formed by, for example, applying cream solder to the heat transfer pattern 33, melting the cream solder by heating, and then solidifying the cream solder.

  The first heat transfer section 34 has a rectangular shape with rounded corners when viewed from below. The outer shape of the first heat transfer section 34 is formed slightly smaller than the outer shape of the heat transfer pattern 33.

  A second heat transfer unit 35 is disposed below the first heat transfer unit 34. The thermal conductivity of the second heat transfer part 35 is set higher than that of the second resist layer 31. The second heat transfer unit 35 may be a conductor or may have an insulating property. The second heat transfer section 35 may have a sheet shape or a film shape, or may have a grease shape or a gel shape. The second heat transfer section 35 is in the form of a grease or a gel at least in the process of fixing the circuit board 14 to the heat sink 13 and solidifies after the circuit board 14 and the heat sink 13 are fixed. Also good. Further, it may be in the form of grease or gel throughout the process of fixing the circuit board 14 to the heat sink 13. The second heat transfer unit 35 may include a filler having a high thermal conductivity.

  The second heat transfer section 35 according to the present embodiment is an insulating synthetic resin, and in the step of fixing the circuit board 14 to the heat sink 13, has a grease shape or a gel shape. After being fixed to, it solidifies.

  The downward protruding height dimension H of the first heat transfer section 34 from the lower surface of the heat transfer pattern 33 is set to be equal to or larger than the thickness dimension T of the second resist layer 31. In the present embodiment, the protruding height dimension H of the first heat transfer section 34 from the heat transfer pattern 33 is set to be larger than the thickness dimension T of the second resist layer 31.

Manufacturing Process Subsequently, an example of a manufacturing process of the electrical junction box 10 according to the present embodiment will be described. The manufacturing process of the electrical junction box 10 is not limited to the following description.

  Cream solder is applied to the heat transfer pattern 33 formed on the second surface 28 of the circuit board 14 by known screen printing. Thereafter, the first heat transfer portion 34 is formed in the heat transfer pattern 33 by heating the circuit board 14 in a reflow furnace.

  Cream solder is applied to the lands 25 formed on the first surface 21 of the circuit board 14 by known screen printing. An electronic component including the FET 26 is placed. By heating the circuit board 14 in a reflow furnace, the land 25 and an electronic component including the FET 26 are connected.

  A grease-like or gel-like second heat transfer portion 35 is applied to a portion of the heat sink 13 corresponding to the first heat transfer portion 34 formed on the second surface 28 of the circuit board 14. The circuit board 14 is placed on the upper surface of the boss 16 of the heat sink 13. The bolt 23 is screwed into the screw hole 17 formed in the boss 16 while the bolt 23 is inserted into the through hole 24 of the circuit board 14. When the circuit board 14 approaches the heat sink 13 by screwing the bolts 23, the first heat transfer part 34 disposed on the second surface 28 of the circuit board 14 contacts the second heat transfer part 35 from above. Further, the circuit board 14 is fixed to the heat sink 13 by screwing the bolts 23. Thereby, the circuit structure 11 is completed.

  Subsequently, the cover 12 is assembled to the heat sink 13 from above. Thereby, the electrical junction box 10 is completed.

Operational Effects of the Present Embodiment Next, operational effects of the present embodiment will be described. In the circuit structure 11 according to this embodiment, the FET 26 is connected to the FET 26 and the conductive pattern 22 on the first surface 21 on which the conductive pattern 22 is formed, and the second structure formed on the opposite side of the first surface 21. An insulating second resist layer 31 is formed on the surface 28, and the heat transfer pattern 33 that is thermally connected to the conductive pattern 22 is exposed from the heat radiation window 32 opened in the second resist layer 31. The first heat transfer section 34 having a higher thermal conductivity than the second resist layer 31 and thermally connected to the heat transfer pattern 33 exposed from the heat dissipation window section 32; A second heat transfer portion 35 having a higher thermal conductivity than the resist layer 31 and thermally connected to the first heat transfer portion 34; and a heat sink thermally connected to the second heat transfer portion 35. 13.

  First, in order to explain the effect of this embodiment, an electrical junction box 110 according to a virtual technique is shown in FIG. The electrical junction box 110 has a circuit structure 111. A first resist layer 160 is formed on the upper surface of the circuit board 114 included in the circuit structure 111, and a second resist layer 131 is formed on the lower surface of the circuit board 114. The heat transfer pattern 133 formed on the circuit board 114 is exposed by removing a part of the second resist layer 131. A grease-like second heat transfer section 135 is disposed at a position corresponding to the heat transfer pattern 133. In addition, about the code | symbol, what added 100 to the code | symbol attached | subjected to the member which concerns on Embodiment 1 was used unless it mentions especially.

  According to the above technique, the second heat transfer portion 135 does not reach the heat transfer pattern 133 due to the thickness of the second resist layer 131, but rather between the heat transfer pattern 133 and the second heat transfer portion 135. An air layer is formed. For this reason, the heat dissipation of the circuit structure 111 cannot be sufficiently improved by the above-described virtual technique.

  On the other hand, in the present embodiment, the heat generated in the FET 26 when energized is transferred to the land 25 (conductive pattern 22) to which the FET 26 is connected, and then is transferred to the land 25 in a heat transfer manner. Conducted to the pattern 33, transmitted to the first heat transfer unit 34, and further reliably transmitted to the second heat transfer unit 35 connected in heat transfer with the first heat transfer unit 34. The heat that has reached the second heat transfer unit 35 is transmitted from the second heat transfer unit 35 to the heat sink 13 and is dissipated from the heat sink 13 to the outside.

  Since the first heat transfer section 34 has higher thermal conductivity than the second resist layer 31, the heat transfer pattern 33 is compared to the case where heat is transferred to the second heat transfer section 35 via the second resist layer 31. The heat can be efficiently transferred from the heat to the second heat transfer section 35. Thereby, heat can be efficiently dissipated from the FET 26 to the outside through the heat sink 13, so that the heat dissipation of the circuit structure 11 can be improved.

  According to the present embodiment, the protruding height dimension H of the first heat transfer section 34 from the heat transfer pattern 33 is set to be equal to or larger than the thickness dimension T of the second resist layer 31.

  According to said structure, the protrusion edge part of the 1st heat-transfer part 34 protrudes in the heat sink 13 side rather than the 2nd resist layer 31. FIG. Thereby, since the 1st heat-transfer part 34 can contact the 2nd heat-transfer part 35 reliably, the heat dissipation of the circuit structure 11 can be improved reliably.

  According to the present embodiment, the boss 16 protruding from the heat sink 13 toward the circuit board 14 is interposed between the heat sink 13 and the circuit board 14.

  According to the above configuration, the distance between the heat sink 13 and the circuit board 14 can be accurately set by the height dimension of the boss 16. Thereby, since the filling amount of the 2nd heat-transfer part 35 which makes the shape of a grease or a gel can be estimated correctly, that a space | gap arises between the 2nd heat-transfer part 35 and the 1st heat-transfer part 34. Can be suppressed. As a result, the heat dissipation of the circuit structure 11 can be further improved.

  According to this embodiment, the 1st heat-transfer part 34 consists of solder.

  According to said structure, the heat-transfer pattern 33 and the 1st heat-transfer part 34 can be connected reliably. Thereby, since the heat transfer efficiency between the heat transfer pattern 33 and the 1st heat transfer part 34 can be improved, the heat dissipation of the circuit structure 11 can be improved more.

  According to this embodiment, the 2nd heat-transfer part 35 has comprised the grease form or the gel form.

  According to said structure, since the 2nd heat-transfer part 35 has comprised the shape of a grease or a gel, it can deform | transform easily following the shape of the 1st heat-transfer part 34 and the heat sink 13. FIG. As a result, the adhesion between the first heat transfer section 34 and the second heat transfer section 35 is improved, and the adhesion between the second heat transfer section 35 and the heat sink 13 is also improved. It can be improved further.

  According to the present embodiment, the conductive pattern 22 and the heat transfer pattern 33 are connected by the thermal via hole 29.

  According to said structure, since the efficiency of the heat conduction from the conductive pattern 22 to the heat transfer pattern 33 can be improved, the heat dissipation of the circuit structure 11 can be improved more.

<Embodiment 2>
Next, in the circuit board 40 according to this embodiment, which is described with reference to FIG. 4, Embodiment 2 of the technology disclosed in the present specification, a plurality of first transmission lines are provided on the lower surface of the heat transfer pattern 33. The heat part 41 is formed in a discrete state with an interval. Each first heat transfer section 41 has a substantially rectangular shape when viewed from below. In the present embodiment, the first heat transfer section row 42 in which a plurality (six in this embodiment) of the first heat transfer sections 41 are arranged at intervals in the vertical direction in FIG. 4 is spaced in the left-right direction in FIG. A plurality (three rows in this embodiment) are formed side by side.

  The second heat transfer part 35 in the form of grease or gel can enter the gap 43 formed between the plurality of first heat transfer parts 41. The second heat transfer section 35 that has entered the gap 43 is in direct contact with the heat transfer pattern 33.

  Since the configuration other than the above is substantially the same as that of the first embodiment, the same members are denoted by the same reference numerals, and redundant description is omitted.

  According to the present embodiment, the second heat transfer unit 35 is moved into the gap 43 by being pressed by the first heat transfer unit 41. Thereby, even when air bubbles are present at a position corresponding to the first heat transfer unit 41 in the second heat transfer unit 35, the air bubbles are pressed by the first heat transfer unit 41, It moves into the gap 43 together with the second heat transfer part 35 present around the bubbles. As a result, air is excluded from the position corresponding to the first heat transfer section 41 in the second heat transfer section 35, and the first heat transfer section 41 and the second heat transfer section 35 can be reliably brought into contact with each other. . Thereby, the heat dissipation of the circuit structure 11 can be improved.

  Further, for the second heat transfer section 35 that has moved into the gap 43, the heat transfer pattern 33 that directly contacts the heat transfer pattern 33 is a path through which heat is directly transferred from the heat transfer pattern 33 to the second heat transfer section 35. Therefore, the heat dissipation of the circuit structure 11 can be further improved.

<Embodiment 3>
Next, a third embodiment of the technique disclosed in this specification will be described with reference to FIG. In the circuit board 50 according to the present embodiment, a plurality (six in the present embodiment) of first heat transfer portions 51 are arranged on the lower surface of the heat transfer pattern 33 at intervals in the vertical direction in FIG. Is formed. Each first heat transfer section 51 has a substantially rectangular shape when viewed from below.

  The second heat transfer portion 35 in the form of grease or gel can enter the gap 52 formed between the plurality of first heat transfer portions 51. The second heat transfer section 35 that has entered the gap 52 is in direct contact with the heat transfer pattern 33.

  Since the configuration other than the above is substantially the same as that of the first embodiment, the same members are denoted by the same reference numerals, and redundant description is omitted.

  According to the present embodiment, the second heat transfer unit 35 moves into the gap 52 by being pressed by the first heat transfer unit 51. Thereby, even when air bubbles are present at a position corresponding to the first heat transfer unit 51 in the second heat transfer unit 35, the air bubbles are pressed by the first heat transfer unit 51, It moves into the gap 52 together with the second heat transfer section 35 present around the bubbles. As a result, air is excluded from the position corresponding to the first heat transfer part 51 in the second heat transfer part 35, and the first heat transfer part 51 and the second heat transfer part 35 can be reliably brought into contact with each other. . Thereby, the heat dissipation of the circuit structure 11 can be improved.

  Further, of the second heat transfer section 35 that has moved into the gap 52, a path through which heat is transferred from the heat transfer pattern 33 to the second heat transfer section 35 is formed for the one that directly contacts the heat transfer pattern 33. Therefore, the heat dissipation of the circuit structure 11 can be further improved.

<Other embodiments>
The technology disclosed in the present specification is not limited to the embodiments described with reference to the above description and drawings, and for example, the following embodiments are also included in the technical scope of the technology disclosed in the present specification.

(1) In the first embodiment, the boss 16 formed integrally with the heat sink 13 functions as a spacer interposed between the heat sink 13 and the circuit board 14. However, the present invention is not limited to this. May be separate. As the spacer separate from the heat sink 13, for example, an arbitrary material such as a metal plate material, a synthetic resin plate material, or a ceramic plate material can be selected as appropriate.

(2) In the first embodiment, the second heat transfer unit 35 is arranged at a position corresponding to the heat transfer pattern 33. However, the second heat transfer unit 35 is not limited to this, and the circuit board 14 is not limited thereto. It is good also as a structure arrange | positioned so that all the 2nd surfaces 28 may be covered.

(3) The shape of the heat transfer pattern 33 may be a polygonal shape such as a triangular shape or a pentagonal shape, or may be a circular shape or an oval shape, and can be any shape as necessary.

(4) In the first embodiment, the conductive pattern 22 and the heat transfer pattern 33 are connected by the three thermal via holes 29. However, the present invention is not limited to this. One to two, or four or more It is good also as a structure connected with the thermal via hole 29. FIG.

(5) On the lower surface of the heat sink 13, a plurality of fins may protrude downward.

(6) In the present embodiment, the protruding height dimension H of the first heat transfer section 34 from the heat transfer pattern 33 is set to be equal to or larger than the thickness dimension T of the second resist layer 31. However, the present invention is not limited to this, and the protruding height dimension H of the first heat transfer section 34 from the heat transfer pattern 33 may be set smaller than the thickness dimension T of the second resist layer 31. Even in this case, the heat dissipation of the circuit component 11 can be improved by the second heat transfer section 35 that is thermally connected to the first heat transfer section 34.

(7) The second heat transfer section may be in the form of a sheet. Thereby, since handling of the 2nd heat transfer part becomes easy, the manufacture efficiency of circuit composition object 11 can be raised. For example, the second heat transfer section can be easily cut into a shape that follows the shape of the first heat transfer section. Thereby, the yield of the second heat transfer section can also be improved. In addition, the 2nd heat-transfer part which makes a sheet form may be a product made from a synthetic resin, and may be made from metal. An adhesive or a pressure-sensitive adhesive may be applied in advance to the sheet-like second heat transfer section. Moreover, you may affix the 2nd heat-transfer part which makes a sheet form on the heat sink 13 with which the adhesive agent or the adhesive was apply | coated.

10: Electrical junction box 11: Circuit structure 13: Heat sink 14, 40, 50: Circuit board 16: Boss (an example of a spacer)
21: First surface 22: Conductive pattern 26: FET
28: Second surface 29: Thermal via hole 31: Second resist layer (an example of a resist layer)
32: Heat dissipation window 33: Heat transfer pattern 34, 41, 51: First heat transfer 35: Second heat transfer

Claims (9)

Heat-generating parts,
The heat generating component is connected to the conductive pattern on the first surface on which the conductive pattern is formed, and an insulating resist layer is formed on the second surface formed on the side opposite to the first surface, A circuit board in which a heat transfer pattern thermally connected to the conductive pattern is exposed from a heat radiating window portion opened in the resist layer;
A first heat transfer portion having a higher thermal conductivity than the resist layer and thermally connected to the heat transfer pattern exposed from the heat radiating window portion;
A thermal conductivity higher than that of the resist layer, and a second heat transfer section connected in heat transfer with the first heat transfer section;
A circuit structure comprising: a heat sink thermally connected to the second heat transfer unit.   The circuit structure according to claim 1, wherein a protruding height dimension of the first heat transfer portion from the heat transfer pattern is set to be equal to or larger than a thickness dimension of the resist layer.   The circuit structure according to claim 1, wherein a spacer is interposed between the heat sink and the circuit board.   The circuit configuration body according to any one of claims 1 to 3, wherein the first heat transfer section is made of solder.   The circuit structure according to any one of claims 1 to 4, wherein the second heat transfer section is in a grease shape or a gel shape.   The circuit configuration body according to any one of claims 1 to 4, wherein the second heat transfer section has a sheet shape.   A plurality of the first heat transfer portions are formed at intervals, and the second heat transfer that has entered between the plurality of first heat transfer portions is connected to the heat transfer pattern in a heat transfer manner. The circuit structure according to claim 5 or 6.   The circuit structure according to any one of claims 1 to 7, further comprising a thermal via hole that connects the conductive pattern and the heat transfer pattern. A circuit structure according to any one of claims 1 to 8,
An electrical junction box, comprising: a cover attached to the circuit structure and covering the circuit board.

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