Electronic unit

Abstract

To provide an electronic unit capable of suppressing temperature rise in a wiring board at low cost.SOLUTION: An electronic unit 1 includes a wiring board 3, a heat dissipation sheet 8 having elasticity, a heat sink 7, and a case 6 housing these. The heat sink 7 includes a plate part 71 in contact with the heat dissipation sheet 8 and an erected part 72 erected from the plate part 71 on a side opposite the heat dissipation sheet 8. The case 6 includes an opposing plate part 51, a pressing part 55 projecting form the opposing plate part 51 to the wiring board side 3 and pressing the plate part 71 of the heat sink 7 to compress the heat dissipation sheet 8, and a through hole 53 passing through the erected part 72 of the heat sink 7. The plate part 71 is pressed by the pressing part 55, so that the heat sink 7 is restricted to move in a thickness direction of the plate part 71, and the erected part 72 is passed through the through hole 53, so that the heat sink 7 is restricted to move in a surface direction of the plate part 71.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an electronic unit with a heat sink. [Background technology]

[0002] Conventionally, a heat sink has been mounted on a wiring board as a measure against heat generation in an electronic unit (see, for example, Patent Document 1). A common method for fixing the heat sink is to use double-sided tape. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-143449 Summary of the Invention [Problem to be solved by the invention]

[0004] In the conventional heat sink fixing method described above, there is a concern that the adhesive strength of the double-sided tape will deteriorate over time. In addition to the double-sided tape method, there is also a fixing method using push pins, but this method has the problem of being costly.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an electronic unit that can suppress temperature rise in the wiring board at low cost. [Means for solving the problem]

[0006] The present invention is an electronic unit comprising a wiring board, an elastic heat dissipation sheet superimposed on the wiring board, a heat sink superimposed on the heat dissipation sheet, and a case housing the wiring board, the heat dissipation sheet, and the heat sink, wherein the heat sink has a plate portion in contact with the heat dissipation sheet and a standing portion standing from the plate portion on the opposite side of the heat dissipation sheet, and the case has an opposing plate portion facing the wiring board, a pressing portion protruding from the opposing plate portion toward the wiring board and compressing the heat dissipation sheet by pressing against the plate portion of the heat sink, and a through hole formed through the opposing plate portion and passing through the standing portion of the heat sink, wherein the heat sink has its plate portion pressed against the pressing portion, thereby restricting movement of the plate portion in the thickness direction, and its standing portion passing through the through hole, thereby restricting movement of the plate portion in the planar direction. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an electronic unit capable of suppressing a temperature rise in a wiring board at low cost. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 2 is a diagram showing an electronic unit according to an embodiment of the present invention. [Figure 2] 2 is a see-through view of the inside of the case of the electronic unit in FIG. 1. [Figure 3] FIG. 2 is a cross-sectional view taken along line AA in FIG. [Figure 4] FIG. 2 is a cross-sectional view taken along line AA in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] An "electronic unit" according to one embodiment of the present invention will be described with reference to FIGS.

[0010] The electronic unit 1 shown in Figures 1 to 4 comprises a wiring board 3, a bus bar 2 superimposed on one surface of the wiring board 3, a heat dissipation sheet 8 superimposed on the surface opposite to the one surface of the wiring board 3, a heat sink 7 superimposed on the heat dissipation sheet 8, and a case 6 that houses these.

[0011] Wiring board 3 is a printed circuit board and is soldered to bus bar 2. A plurality of electronic components 11 and 12 are mounted on wiring board 3.

[0012] The bus bar 2 is made of a metal plate and formed in a strip shape. A high voltage current flows through the bus bar 2.

[0013] The heat dissipation sheet 8 is made of a resin material with high thermal conductivity and has elasticity.

[0014] The heat sink 7 has a plate portion 71 in contact with the heat dissipation sheet 8 and a plurality of standing portions 72 standing from the plate portion 71 on the side opposite the heat dissipation sheet 8. The standing portions 72 are generally called "fins." The plate portion 71 is formed in a rectangular plate shape. The plurality of standing portions 72 stand from a portion of the plate portion 71 excluding the ends (near the four sides). The ends of the plate portion 71 are pressed by the pressing portion 55 described below, so no standing portions 72 are provided. In this example, the plurality of standing portions 72 are rib-shaped and extend in the longitudinal direction of the wiring board 3. The plurality of standing portions 72 are aligned in the width direction of the wiring board 3.

[0015] The case 6 is formed by assembling a first case 4 arranged on the one surface side (busbar 2 side) of the wiring board 3 and a second case 5 arranged on the opposite surface side of the wiring board 3. The first case 4 and the second case 5 are made of insulating synthetic resin.

[0016] The first case 4 has an opposing plate portion 41 facing the one surface of the wiring board 3, a side plate portion 42 standing upright from the outer edge of the opposing plate portion 41, and a locking portion 44.

[0017] Two notches 43 are formed in the side plate portion 42 for leading both ends of the bus bar 2 out of the case 6. When the first case 4 and the second case 5 are assembled, the notches 43 form lead-out openings for the bus bar 2 between the first case 4 and the second case 5.

[0018] The locking portions 44 are formed as protrusions that protrude outward from the outer surface of the side plate portion 42. The locking portions 44 are provided at a plurality of locations on the side plate portion 42.

[0019] The second case 5 has an opposing plate portion 51 facing the opposite surface of the wiring board 3, a side plate portion 52 standing upright from the outer edge of the opposing plate portion 51, a locking receiving portion 54 that locks with the locking portion 44, and a pressing portion 55.

[0020] The locking receiving portion 54 is formed in a frame shape connected to the side plate portion 52. The locking receiving portion 54 is provided at multiple locations on the side plate portion 52. The locking portion 44 and the locking receiving portion 54 are locked by being brought close to each other in the thickness direction of the wiring board 3. The engagement of multiple pairs of the locking portion 44 and the locking receiving portion 54 maintains the assembled state of the first case 4 and the second case 5. The inner dimension of the frame of the locking receiving portion 54 is formed larger than the outer shape of the locking portion 44 to allow for dimensional tolerances.

[0021] A rectangular through-hole 53 is formed in the opposing plate portion 51. All of the standing portions 72 of the heat sink 7 are passed through the through-holes 53, and their tip portions are positioned outside the case 6.

[0022] The pressing portion 55 protrudes from the opposing plate portion 51 toward the wiring board 3, and is formed in a frame shape around the through hole 53. The pressing portion 55 presses the plate portion 71 of the heat sink 7, thereby compressing the heat dissipation sheet 8.

[0023] The end of plate portion 71 of heat sink 7 is pressed by pressing portion 55, restricting movement of plate portion 71 in the thickness direction, and the upright portion 72 is passed through through hole 53, restricting movement of plate portion 71 in the planar direction. Therefore, heat sink 7 is fixed to wiring board 3 and case 6 without using fasteners such as push pins or double-sided tape. In addition, because heat dissipation sheet 8 is compressed, there is zero clearance between locking portion 44 and lock-receiving portion 54 in the thickness direction of wiring board 3.

[0024] In this way, the electronic unit 1 can fix the heat sink 7 to the wiring board 3 and the case 6 without using fasteners such as push pins or double-sided tape, thereby achieving reliable fixation that is inexpensive and does not deteriorate over time. Furthermore, rattle between the first case 4 and the second case 5 can be suppressed while allowing for dimensional tolerances between them. Furthermore, in the electronic unit 1, a portion of the heat sink 7 protrudes from the case 6 through the through-hole 53, thereby further enhancing the heat dissipation effect. Furthermore, because a portion of the heat sink 7 protrudes from the case 6 through the through-hole 53, the thickness of the case 6 can be reduced, thereby reducing the thickness of the entire unit.

[0025] The above-described embodiment merely shows a typical form of the present invention, and the present invention is not limited to this embodiment. In other words, the present invention can be implemented with various modifications within the scope of the gist of the present invention. As long as such modifications still include the configuration of the present invention, they are of course included in the scope of the present invention. [Explanation of symbols]

[0026] 1 Electronic Unit 2 Busbar 3 Wiring board 6 cases 7 Heatsink 8 Heat dissipation sheet 53 Through hole 55 Pressing section 71 Board part 72 Standing section

Claims

1. a wiring board; a heat dissipation sheet having elasticity and placed on the wiring board; a heat sink placed on the heat dissipation sheet; and a case that houses the wiring board, the heat dissipation sheet, and the heat sink; the heat sink has a plate portion in contact with the heat dissipation sheet and an upright portion that stands upright from the plate portion on the opposite side to the heat dissipation sheet, the case has an opposing plate portion facing the wiring board, a pressing portion protruding from the opposing plate portion toward the wiring board and pressing the plate portion of the heat sink to compress the heat dissipation sheet, and a through hole formed through the opposing plate portion and passing through the erected portion of the heat sink; The plate portion of the heat sink is pressed against the pressing portion, thereby restricting movement of the plate portion in a thickness direction, and the upright portion is passed through the through hole, thereby restricting movement of the plate portion in a planar direction. An electronic unit characterized by:

2. The through hole has a rectangular shape, The pressing portion is formed in a frame shape around the through hole.

2. The electronic unit according to claim 1.

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