JPH10173100A - Mold circuit - Google Patents

Abstract

(57) [Problem] To provide a compact molded circuit body with high reliability against heat generation and insulation. A heat-generating component that generates a large amount of heat, a weak heat-resistant component that is weak to heat, a printed wiring board on which the heat-generating component and the weak heat-resistant component are respectively mounted, A heat interrupter 4 that conducts heat well.
Is a molded circuit body 7 which is disposed in a direction in which the heat generated by the heat-generating component 1 is shielded from the weak heat-resistant component 2 and sealed with the insulating resin 6, and is small in size and has high reliability for heat generation and insulation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molded circuit body, and more particularly to a heat insulation structure.

[0002]

2. Description of the Related Art Circuits such as power modules used in motor control devices have been designed to be small and thin, and various measures for heat radiation and insulation have been taken to reduce the size by high integration. .

For example, a component that generates a large amount of heat, such as a power transistor, is provided with an aluminum radiator that radiates the generated heat to the surroundings. Also,
A metal substrate such as aluminum is used for a printed wiring board for connecting a transistor that generates heat, and the printed wiring board also has a heat dissipation function. Furthermore, the peripheral circuit components of the power transistor such as the resistor, the capacitor and the IC are mounted on the same printed wiring board,
In some cases, heat dissipation and insulation measures are taken by molding with insulating resin having high thermal conductivity.

As described above, the heat radiating structure and the insulating structure of the circuit body having the heat-generating component include mounting a heat radiating component such as aluminum, and mounting a circuit body using a metal-based printed wiring board on MgO, SiC having good thermal conductivity. It is common to seal with a thermoplastic or thermosetting highly heat conductive insulating resin containing a filler such as.

[0005]

However, the conventional high-integration and miniaturized circuit body mainly dissipates heat from heat-generating components, and secures the reliability of weak heat-resistant components around the heat-generating components against heat. Insufficient, there was a need to actively protect weak heat resistant components from heat.

Aluminum used as a heat dissipating component has good thermal conductivity and the degree of heat dissipating is determined by its thickness and size (surface area), which is indispensable for miniaturization. The heat-resistant component has a problem that the life is shortened because the heat-resistant component continues to receive heat due to natural convection from the heat radiation component. In addition, in the case of a molded circuit body which is incorporated in a peripheral circuit device and is sealed with an insulating resin in order to secure an insulation distance from a peripheral component, heat is more likely to accumulate and the heat generation is restricted. was there.

Particularly, weak heat-resistant components such as aluminum electrolytic capacitors and photocouplers whose life is significantly shortened by heat need to be protected by shutting off heat.

The present invention solves such a conventional problem. The heat of a heat-generating component is shielded from the heat-resistant component to actively protect the weak heat-resistant component from heat. It is an object of the present invention to provide a highly reliable molded circuit body.

[0009]

SUMMARY OF THE INVENTION In order to solve this problem, the present invention provides a heat shield having high orientation, such as graphite, which blocks heat generated by a heat-generating component from a weak heat-resistant component. And sealed with an insulating resin.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to solve this problem, the present invention relates to a heat-generating component such as a power transistor which generates a large amount of heat, and a heat-resistant component such as an aluminum electrolytic capacitor and a photocoupler which are heat-sensitive in peripheral circuit components. And a printed wiring board on which the heat-generating component and the weak heat-resistant component are respectively mounted, and a heat barrier having high orientation such as graphite and transmitting heat well in the orientation direction. A molded circuit body disposed in a direction in which heat generated by the heat-generating component is blocked from the weak heat-resistant component and sealed with an insulating resin.

As described above, the heat shield that conducts heat in the direction of orientation is used. The heat can be efficiently conducted in one specific direction. What is necessary is just to arrange | position a heat interrupter near a heat-producing component so that it may block or avoid, and the heat of a heat-producing component can be heat-insulated with respect to a weak heat-resistant component.

As a result, the restriction on the arrangement of the low heat resistant components in the circuit body is reduced, and high integration is possible, and the miniaturization of the circuit body and the reliability of the low heat resistant parts against heat are improved.

Further, since the circuit body is sealed with the insulating resin, insulation can be secured for peripheral components, and the heat radiation efficiency is improved by the heat interrupter, and the device using the molded circuit body can be downsized. Will be possible.

[0014]

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a heat-generating component, a power transistor as a switching element, 2 denotes an aluminum electrolytic capacitor, which is a weak heat-resistant component of peripheral circuit components, 3 denotes a printed wiring board, and two printed wiring boards 3 The ends are connected by connectors. Reference numeral 4 denotes a heat shield, which is disposed between the two printed wiring boards 3. Reference numeral 5 denotes a peripheral circuit component such as a resistor, and reference numeral 6 denotes an insulating resin, which seals a circuit body except for a connection portion between a mounting hole and a terminal, such as a terminal. Reference numeral 7 denotes a molded circuit body configured as described above.

As shown in FIG. 2, the heat shield 4 is formed from a sheet-like graphite base material having a high orientation in the direction of the arrow into a required shape in consideration of the orientation direction. The graphite sheet having high orientation is better than the thermal conductivity of aluminum, and the heat conducting through the thermal barrier 4 is particularly easy to conduct in the direction of the arrow, that is, in the direction of orientation, and is difficult to conduct in the thickness direction. It is sufficient that the heat-resistant component is attached so as to block the weak heat-resistant component, and if the heat-resistant component is further avoided, the heat shielding is more effective.

When the molded circuit 7 operates and the power transistor 1 generates heat, this heat is generated by the power transistor 1.
A thermal barrier 4 disposed between another printed wiring board 3 on which the electrolytic capacitor 2 is mounted;
Although the heat is conducted to the insulating resin 6 which encapsulates the circuit body, the heat interrupter 4 efficiently conducts heat in the direction of orientation, so that the aluminum electrolytic capacitor 2 is as if the heat was interrupted by the heat interrupter 4. Therefore, the heat received by the aluminum electrolytic capacitor 2 is minimized, and is radiated to the outside air via the insulating resin 6. Further, if an insulating resin having high thermal conductivity is used as the insulating resin 6, more efficient heat radiation can be achieved.

FIG. 3 shows one printed circuit board on which circuit components are mounted. A power transistor 1, an aluminum electrolytic capacitor 2, a resistor 5, and the like are mounted on a printed circuit board 3a and connected by soldering. The thermal breaker 4 is arranged so as to block the power transistor 1 and the aluminum electrolytic capacitor 2. The surface on which the components are mounted is covered and sealed with an insulating resin 6 except for a connection portion between the mounting hole and the outside such as a terminal. As described above, the heat conducted in the orientation direction by the heat shield 4 is radiated to the outside air via the insulating resin 6. Further, if an insulating resin having high thermal conductivity is used as the insulating resin 6, more efficient heat radiation can be achieved.

The method of arranging the heat shield is as follows.
Bonding, screwing, bundling, and a mold may be combined.

FIG. 4 is a circuit diagram of an embodiment of the molded circuit body 7, which is used for a part of an inverter of a motor control device.

[0021]

As is apparent from the above embodiment, according to the present invention, a heat shield which conducts heat in the direction of orientation is disposed between a heat-generating component and a weak heat-resistant component and molded with an insulating resin. The heat generated by the heat-generating components can be blocked by the heat shield against the weak heat-resistant components, and the weak heat-resistant components can be protected from the heat. Can be obtained, and the size of the apparatus using the molded circuit can be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view of a molded circuit body according to one embodiment of the present invention.

FIG. 2 is an explanatory view of an orientation direction and a heat conduction direction of a thermal barrier.

FIG. 3 is a perspective view of a molded circuit body according to another embodiment of the present invention.

FIG. 4 is a circuit diagram of one embodiment of a molded circuit body;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Heat-generating component 2 Low heat-resistant component 3, 3a Printed wiring board 4 Heat blocker 5 Peripheral circuit component 6 Insulating resin 7 Mold circuit

Claims (1)

[Claims] 1. A heat-generating component such as a power transistor which generates a large amount of heat; a heat-resistant component such as an aluminum electrolytic capacitor and a photocoupler which are heat-sensitive in peripheral circuit components; and the heat-generating component and a weak heat-resistant component. Printed wiring board, having a high orientation such as graphite, comprising a heat blocking body that transmits heat well in the orientation direction, the heat blocking body with respect to the heat generated by the heat generating component to the weak heat resistant component Molded circuit body that is placed in the direction that blocks heat and sealed with insulating resin.