JP2007067067A - Resin injection type power circuit unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin injection type power circuit unit, capable of favorable heat dissipation from electronic components without enlarging the case size. <P>SOLUTION: A circuit substrate 2, mounting two or more electronic components 3 to 6 with irregular height, is accommodated in a case 1 with an opening at one end, and the circuit substrate 2, and the electronic components 3 to 6 are embedded in a resin mold 8, formed by injecting the insulating resin into the case 1. A heat sink 7, having heat dissipation fins 7c, is thermally combined with electronic components 4 and 5 with a small height measured from the plate surface of the circuit substrate 2 among the electronic components 3 to 6 mounted in the circuit substrate 2. The heat sink 7 has a part of it embedded in the insulating resin, in a state where the heat dissipation fins 7c are made to expose to the outside. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a resin cast type power circuit unit constituting a circuit having a function of controlling power supplied from a power source to a load, such as an inverter, a rectifier circuit, or a rectifier circuit with a voltage regulator.

  For example, as disclosed in Patent Document 1, a resin-casting type power circuit unit houses a circuit board on which a plurality of electronic components are mounted in a case having one end opened, and an insulating resin is contained in the case. It is composed by casting. The electronic component and the circuit board are embedded in a resin mold portion formed of a casting resin. In this case, in order to increase the current capacity of the circuit unit, it is necessary to improve heat dissipation from the electronic components that generate heat.

  If the height of the electronic components mounted on the circuit board (height measured from the board surface of the circuit board) is uneven, the resin mold part is so that all the electronic parts can be covered with the resin mold part. It is formed according to the height of the electronic component having the highest height.

  In this case, since the thickness of the resin covering the electronic component having a high height can be reduced, heat dissipation can be performed without any problem, but the electronic component having a low height is covered with a considerably thick insulating resin. Therefore, it is inevitable that the heat resistance of the heat radiation path is increased and the heat radiation is deteriorated.

In the unit described in Patent Document 1, a metal case is used as a case for housing an electronic component, and heat radiation fins are formed on the outer surface of the unit to enhance the heat radiation performance from the electronic component. However, in this case, it is necessary to increase the heat dissipation area of the case in order to perform heat dissipation from the low-height electronic components that are deeply embedded in the insulating resin without any trouble. It is necessary to use it.
JP 2004-363208 A

  As described above, in the conventional resin-casting power circuit unit, when the heights of the electronic components mounted on the circuit board are uneven, it is possible to perform heat dissipation from the electronic components having a low height without any trouble. Since there was a need to use a large case, there was a problem that the unit became large.

  An object of the present invention is to provide a resin-casting type power circuit unit capable of improving the heat dissipation performance without increasing the size of the case.

  The present invention accommodates a circuit board on which a plurality of electronic components having irregular heights are mounted in a case opened at one end, and a circuit board and a circuit board are formed in a resin mold portion formed by casting an insulating resin in the case. The present invention relates to a resin cast type power circuit unit in which electronic parts are embedded.

  In the circuit unit targeted by the present invention, the plurality of electronic components includes a high electronic component and a low electronic component measured from the board surface of the circuit board, and the resin mold portion is mounted on the circuit board. Among the electronic components, the electronic component is provided so as to cover all electronic components including the electronic component having the highest height measured from the surface of the circuit board.

  And in this invention, it is an electronic component which produces heat | fever among several electronic components mounted in the circuit board, Comprising: The heat sink which has a radiation fin in the electronic component whose height is lower than the highest electronic component Are thermally coupled, and the heat sink is embedded in the insulating resin in a state in which at least a part of the radiating fin is exposed to the outside.

  In a preferred aspect of the present invention, the heat sink includes a bottom wall portion, a peripheral wall portion rising from the outer peripheral portion of the bottom wall portion, and a plurality of radiating fins rising from the bottom wall portion inside the peripheral wall portion. The heat sink is disposed in a state where the bottom wall portion and at least a part of the peripheral wall portion are embedded in the insulating resin.

  As described above, a heat sink is attached to an electronic component that is low in height and is deeply embedded in the insulating resin, and at least a part of the heat radiating fin of the heat sink is exposed to the outside. And heat dissipation from the electronic components that are deeply embedded in the resin, so that the electronic components can be efficiently cooled without using a large case as a power circuit. The unit can be prevented from becoming large.

  When there are a plurality of electronic components having a low height that are thermally coupled to the heat sink, the plurality of electronic components having a low height can be collectively coupled to a common heat sink. Therefore, it is preferable to arrange a plurality of electronic components having a low height so as to be adjacent to each other in a specific region on the circuit board.

  As described above, when there are a plurality of electronic components that generate heat and have a low height, the plurality of electronic components with a low height are arranged together in a specific region of the circuit board. Then, since the heat sink can be used in common for a plurality of electronic components, the number of components can be reduced and the structure can be simplified.

  As described above, according to the present invention, among a plurality of electronic components mounted on a circuit board and having uneven heights, the heat sink is an electronic component that generates heat, and the low-height electronic component has a heat dissipation fin. The heat sink is placed embedded in the resin with at least a part of the heat radiating fin exposed to the outside, so that cooling of electronic components is good without using a large case Thus, a power circuit unit having a large current capacity can be obtained without increasing the size of the unit.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a top view showing an embodiment of a power circuit unit according to the present invention, and FIG. 2 is a sectional view taken along line II-II in FIG.
1 and 2, reference numeral 1 denotes a rectangular parallelepiped case having an open end, and has a bottom wall portion 1a and side wall portions 1b to 1e. This case may be made of a metal or an insulating resin.

  Reference numeral 2 denotes a rectangular circuit board on which printed wiring is formed in a predetermined pattern, and on this circuit board, electronic components 3 to 6 constituting a circuit for controlling power such as an inverter and a rectifier circuit are mounted. Yes. Electronic components mounted on a circuit board are semiconductor elements such as diodes, MOSFETs, thyristors, and the like, capacitors, and the like.

  In general, electronic components mounted on a circuit board are uneven in height measured from the plate surface of the circuit board 2, and include an electronic component with a high height and a low electronic component. In the illustrated example, each of the electronic components 3 to 6 is a semiconductor element that generates heat when energized, 3 and 6 are electronic components having a high height, and 4 and 5 are electronic components having a low height. . The illustrated electronic components 4 and 5 are the same kind of electronic components, and the upper ends of the respective exteriors are formed flat, and the heights of both the electronic components 4 and 5 from the plate surface are attached to the circuit board 2. Are equal. Other electronic components such as a capacitor and a resistor are also mounted on the circuit board 2, but these are not shown.

  In the present embodiment, electronic components 4 and 5 that are elements that generate heat and have a low height are arranged together near the center of the circuit board 2, and the heat sink 7 is brought into contact with these electronic components 4 and 5. It has been. The electronic components 3 and 6 having a high height are arranged near one end and the other end in the longitudinal direction of the circuit board 2.

  The illustrated heat sink 7 is made of a molded product of metal having good thermal conductivity such as aluminum, and includes a bottom wall portion 7a, a peripheral wall portion (side wall portion) 7b rising from the outer peripheral portion of the bottom wall portion, and a peripheral wall. A plurality of radiating fins 7c rising from the bottom wall 7a inside the portion 7b are integrally provided. In the illustrated example, since the heights of the electronic components 4 and 5 are equal, the outer surface 7a1 of the bottom wall portion 7a of the heat sink 7 is formed flat, and this flat outer surface 7a1 is electronically bonded by an adhesive having good thermal conductivity. It is joined to the flat upper surface of the exterior of the parts 4 and 5.

  The circuit board 2 on which the electronic components 3 to 6 are mounted is inserted into the case 1 together with the heat sink 7 attached to the electronic components 4 and 5. The illustrated heat sink 7 is formed in such a size that the upper end of the heat sink 7 is arranged at the same height as the opening end of the case 1 while being attached to the electronic components 4 and 5 and inserted into the case. Yes. When the resin is cast into the case 2, the circuit board 2 is arranged in a state of being floated from the bottom surface of the case 1 so that the resin also rotates on the back side of the circuit board 2. 1 is positioned. In addition, the dimensions of the case 1 are set so that a gap for flowing resin is formed between the peripheral portion of the circuit board 2 and the inner surface of the case 1. When a metal case is used as the case 1, the circuit board 2 is positioned with respect to the case while being insulated from the case 1 by an appropriate means.

  An insulating resin such as an epoxy resin is cast in the case 1 to form a resin mold portion 8. The resin mold portion 8 covers all the electronic components including the electronic components 3 and 6 having the highest height measured from the surface of the circuit board among the electronic components 3 to 6 mounted on the circuit board 2. Is provided. In this embodiment, since the electronic components 3 and 6 are components that generate heat, the distance between the upper ends of these electronic components 3 and 6 and the upper surface of the resin mold portion 8 (the upper surfaces of the electronic components 3 and 6 are covered). The thickness of the insulating layer is set sufficiently thin so as not to hinder heat dissipation from the electronic components 3 and 6.

  The heat sink 7 is arranged in a state in which most of the peripheral wall portion 7 b and the bottom wall portion 7 a are embedded in the resin mold portion 8. The heat sink 7 has a peripheral wall portion 7b that rises from the outer peripheral portion of the bottom wall portion 7a. Since the heat radiating fins 7c are disposed inside the peripheral wall portion, the heat radiating fins 7c are embedded in the resin. It is exposed outside.

  In order to connect the circuit in the case to the outside, the lead wire connected to the circuit board 2 is led out through the grommet, or is attached to the end of the lead wire connected to the external circuit on the side surface of the case 1 A connector for connecting the side connector is attached, but these are not shown.

  As described above, among the plurality of electronic components 3 to 6 with uneven heights mounted on the circuit board 2, the heat generating fins 7 c are provided on the electronic components 4 and 5 that generate heat and have a low height. If the heat sink 7 is embedded in the resin in a state where the heat sink 7 is brought into contact with the heat radiating fins 7c exposed to the outside, heat is radiated from a short electronic component deeply embedded in the resin mold portion. Because it can be performed well, it is possible to improve the cooling of electronic parts without using a large case with a large heat dissipation area, and for power with a large current capacity without causing an increase in size of the unit A circuit unit can be obtained.

  In the above embodiment, when a metal case 1 is used, a heat radiating fin can be provided on the outer surface of the case 1. In this way, if heat radiating fins are also provided on the outer surface of the case 1, heat can be radiated from the electronic components more efficiently.

  In the above embodiment, the heat sink 7 is formed so that the cross section of the peripheral wall portion 7b of the heat sink 7 has a rectangular shape. However, the heat sink 7 has a heat sink fin and a peripheral wall portion that prevents the resin from flowing to the heat sink fin side. The cross-sectional shape of the peripheral wall portion of the heat sink 7 is not limited to a rectangular shape. For example, the shape of the cross section of the peripheral wall portion 7b of the heat sink 7 may be circular.

  In the above embodiment, the plurality of heat radiation fins 7c are formed of flat fins arranged in parallel to each other, but have a closed cross-sectional shape (rectangular shape in the illustrated example) as shown in FIG. You may make it arrange | position the radiation fin 7c concentrically.

  When a plurality of radiating fins are concentrically arranged, all the radiating fins may be closed, but as shown in FIG. 3, the radiating fins 7c arranged in the center are formed in a flat plate shape. Also good.

  In the above embodiment, the position of the upper end of the radiating fin is substantially the same position as the opening end of the case, but the position of the upper end of the radiating fin is not limited to the illustrated example.

  In the above embodiment, the outer surface of the resin mold portion 8 is positioned slightly below the opening end (upper end) of the case. However, the position of the outer surface of the resin mold portion 8 is that of the electronic component having the highest height. Determined by height. The positional relationship between the outer surface of the resin mold portion 8 and the open end of the case is arbitrary.

  In the above embodiment, since the heights of the electronic parts 4 and 5 that require low heat dissipation are equal, the outer surface of the bottom wall portion 7a of the heat sink 7 is formed flat, but is thermally coupled to the heat sink 7. When there is a difference in the height of the electronic components 4 and 5 to be performed, the heat sink 7 is arranged so that the exteriors of both the electronic components 4 and 5 having different heights can be brought into surface contact with the outer surface of the bottom wall portion of the heat sink 7. A step is formed on the outer surface of the bottom wall 7a, or a space made of a material having good thermal conductivity between the outer surface of the bottom wall 7a of the heat sink 7 and the electronic component having a lower height. The electronic component is thermally coupled to the heat sink with a spacer interposed.

  In the above embodiment, the heat sink 7 is not directly connected to the case 1. However, for example, as shown in FIG. 4, at least a part of the heat sink 7 is connected to the case 7 or a part of the heat sink is connected to the case. You may make it contact. In the example shown in FIG. 4, the outer surface of the opposite side of the peripheral wall portion 7 b of the heat sink 7 is brought into contact with the inner surface of the case 1.

  In the above description, the opening end of the case 1 is the upper end of the case, and the end of the electronic component to which the heat sink is attached is the upper end of the electronic component. However, the orientation of the case when using the unit is arbitrary.

  As described above, when the heat sink 7 having the peripheral wall portion 7b is used and the heat dissipating fins 7c are arranged inside the peripheral wall portion 7b, the upper end of the heat sink 7 is positioned near the opening end of the case. Since the heat radiating fins 7c can be exposed to the outside, it is possible to prevent the heat sink from protruding outward from the case and to increase the size of the unit, but it is possible to allow the heat sink to protrude from the case to some extent. In such a case, as shown in FIG. 5, a part of the radiating fin 7c is exposed to the outside by using a heat sink 7 having a shape in which the radiating fin 7c protrudes from the bottom wall 7a without providing a peripheral wall. A part of the heat sink 7 may be embedded in the resin mold portion 8.

It is a top view which shows one Embodiment of the circuit unit for electric power concerning this invention. It is the II-II sectional view taken on the line of FIG. It is the top view which showed the structure of other embodiment of this invention. It is the top view which showed the structure of further another embodiment of this invention. It is sectional drawing which showed the structure of other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Case 2 Circuit board 3 thru | or 6 Electronic component which produces heat 7 Heat sink 7a Bottom wall part 7b Perimeter wall part 7c Radiation fin

Claims (3)

A circuit board on which a plurality of electronic components having uneven heights are mounted is housed in a case having one end opened, and the circuit board and the electronic component are formed in a resin mold portion formed by casting an insulating resin in the case. In the resin-casting power circuit unit,
The plurality of electronic components include an electronic component having a high height and a low electronic component measured from a plate surface of the circuit board,
The resin mold part is provided so as to cover all electronic parts including the electronic parts having the highest height measured from the plate surface of the circuit board among the electronic parts mounted on the circuit board,
Among the plurality of electronic components mounted on the circuit board, an electronic component that generates heat, and a heat sink having heat radiation fins is thermally coupled to an electronic component that is lower than the electronic component having the highest height. And
The heat sink is a resin-casting power circuit unit embedded in the insulating resin in a state where at least a part of the radiating fin is exposed to the outside. A circuit board on which a plurality of electronic components having uneven heights are mounted is housed in a case having one end opened, and the circuit board and the electronic component are formed in a resin mold portion formed by casting an insulating resin in the case. In the resin-casting power circuit unit,
The plurality of electronic components include an electronic component having a high height and a low electronic component measured from a plate surface of the circuit board,
The resin mold part is provided so as to cover all electronic parts including the electronic parts having the highest height measured from the plate surface of the circuit board among the electronic parts mounted on the circuit board,
Of the plurality of electronic components mounted on the circuit board, an electronic component that generates heat, the electronic component having a lower height than the electronic component having the highest height, and a bottom wall portion and The bottom wall portion of the heat sink having a peripheral wall portion rising from the outer peripheral portion and a plurality of heat radiation fins rising from the bottom wall portion inside the peripheral wall portion is thermally coupled,
The heat sink is a resin cast type power circuit unit in which the bottom wall portion and at least a part of the peripheral wall portion are arranged in the insulating resin. A plurality of low-height electronic components thermally coupled to the heat sink are provided, and the plurality of low-height electronic components are arranged adjacent to each other in a specific region of the circuit board. The resin cast type power circuit unit according to claim 1 or 2.

Images