JP2798656B2 - Circuit board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a circuit board.

[0002]

2. Description of the Related Art A conventional circuit board will be described with reference to the drawings.

FIG. 4 is a sectional view showing an example of a conventional circuit board.

FIG. 4 shows a circuit board 11 of this conventional example.
Reference numeral 1 denotes the content disclosed in JP-A-3-255690, which is a type having circuit patterns 112 and 126 on both surfaces of a substrate 118, and an insulating sheet 113 having a circuit pattern 112 on the surface, an adhesive layer 114, and an insulating sheet 113. Heating metal plate 115, adhesive layer 121, insulating plate 122, adhesive layer 123, heat equalizing metal plate 124, and adhesive layer 125
And an insulating sheet 127 having a circuit pattern 126 on the front surface (lower surface side) are laminated and integrated, and in an insulating substrate 116 configured by an insulating plate 122 and adhesive layers 121 and 123,
The heat absorbing portion 117a of the heat pipe 117 formed flat so as to have a plane parallel to the surface of the substrate 118 is embedded therein.

The heat absorbing portion 117a of the heat pipe 117 is buried immediately below the heat-generating component mounting portion 112a as in the prior art.
The radiator (not shown) is exposed to the outside. Further, a heat-generating component mounting portion may be provided also on the circuit pattern 126 on the lower surface side.

[0006] Paraffin (hydrocarbon mixture) is provided between the case and the mounting surface of a component requiring cooling of the printed circuit board.
An electronic device characterized by the following is disclosed in Japanese Utility Model Laid-Open No. 59-140492.

[0007]

In this conventional circuit board, since the heat absorbing portion of the heat pipe is buried in a flat molded state, the heat conductivity from the heat-generating component mounting portion to the heat pipe heat absorbing portion is reduced. It has the advantage that the temperature rise of the circuit board and the heat-generating components can be suppressed efficiently, but since there is no heat storage function, when the external environment condition becomes low temperature for a short time, the electric components mounted on the circuit board also have a short time. There is a problem that the time becomes low.

Further, in an electronic device in which a paraffin is filled between a circuit board and a case, it is necessary to seal the component or coat the outer surface of the component so that the component is immersed in paraffin. However, there is a problem that it is not easy and the heat transfer characteristics are not good.

[0009]

A circuit board according to the present invention includes an insulating plate having a circuit pattern formed on an upper surface thereof, and a substrate adhered to a lower surface of the insulating plate. And a heat storage member is sealed in the cavity, and the insulating plate is made of Al ₂ O 3.
_The substrate is made of an aluminum member,
The heat storage member is made of a paraffin member.

[0010]

Next, the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of the present invention.
(A) is a top view thereof, and (b) is a sectional view taken along line AA of (a).

In FIG. 1, a circuit board 6 according to the present embodiment is shown.
Includes an insulating plate 5 made of an Al ₂ O ₃ member having a circuit pattern formed on an upper surface thereof, and a substrate 2 made of an aluminum member adhered to the lower surface of the insulating plate 5.
A uniform cavity 2a hermetically sealed over the entire surface of the substrate 2.
And a paraffin member is sealed as the heat storage member 4 in the hollow portion 2a.

FIG. 2 is a diagram showing the flow of heat in the case of heat storage in the present embodiment, and FIG. 3 is a diagram showing the flow of heat in the case of heat dissipation in the present embodiment.

Next, how the ambient temperature changes in the present embodiment will be described with reference to FIGS. 1, 2 and 3. FIG.

In FIG. 1 and FIG. 2, in the case where the ambient temperature becomes high and the electronic component 3 is prevented from becoming high with self-heating, the heat generated in the electronic component 3 is transferred to an insulating plate made of an Al ₂ O ₃ member. 5 → substrate 2 of aluminum member → heat storage member 4 of paraffin member, and heat storage member 4 melts and stores heat.

In FIG. 1 and FIG. 3, when the ambient temperature is low to prevent the electronic component 3 from lowering, when the electronic component 3 starts radiating heat by self-heating, it is stored in the heat storage member 4. The heat flows from the aluminum member to the substrate 2 → the insulating material 5 made of Al ₂ O ₃ member → the electronic component 3, and the heat storage member 4 solidifies by absorbing heat and releases heat.

As described above, the heat storage member 4 in which the paraffin member is encapsulated stores and radiates heat in response to a change in the ambient temperature, and suppresses the temperature of the electronic component 3 from becoming high or low.

Accordingly, such a circuit board 6 can be mounted on an artificial satellite or the like in which the external environment changes greatly.

[0019]

As described above, the present invention comprises an insulating plate having a circuit pattern formed on the upper surface thereof, and a substrate adhered to the lower surface of the insulating plate. The first effect is that the deterioration of the electronic component due to a temperature change is reduced by having a uniform and closed cavity and a heat storage member sealed in the cavity.

The reason for this is that a sudden change in temperature of the electronic component is eliminated, so that metal fatigue due to expansion and contraction of the electronic component and the metal part related to the electronic component is reduced.

A second effect is that the temperature dependence of the electrical performance of the electronic component can be reduced.

The reason is that the heat generated by energizing the electronic components is stored and dissipated when no current is applied. Therefore,
The temperature of the electronic component is substantially constant, and the temperature dependence of the electrical performance is eliminated.

From the above two effects, there is an effect that the reliability of the electronic component can be improved and the electronic component can be mounted on an artificial satellite or the like in which the external environment is severely changed.

[Brief description of the drawings]

FIGS. 1A and 1B show an embodiment of the present invention, wherein FIG. 1A is a top view thereof, and FIG. 1B is a sectional view taken along line AA of FIG.

FIG. 2 is a diagram showing a flow of heat in the case of heat storage in the present embodiment.

FIG. 3 is a diagram showing a flow of heat in the case of heat radiation in the present embodiment.

FIG. 4 is a cross-sectional view illustrating an example of a conventional circuit board.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 pattern 2 aluminum substrate 2 a cavity 3 electronic component (example: IC) 4 heat storage member (example: paraffin) 5 insulating plate made of Al ₂ O ₃ member 6 circuit board

Claims (3)

(57) [Claims] An insulating plate having a circuit pattern formed on an upper surface thereof; and a substrate closely attached to a lower surface of the insulating plate.
A circuit board, characterized in that the board has a uniform cavity closed over the entire surface of the board, and a heat storage member is sealed in the cavity. 2. The circuit board according to claim 1, wherein said insulating plate is made of an Al ₂ O ₃ member, and said substrate is made of an aluminum member. 3. The circuit board according to claim 1, wherein said heat storage member is made of a paraffin member.