JPH09116239A - Metallic-base multilayered circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable metallic-base multilayered circuit board which has a structure in which a circuit board is joined to a metallic plate through an insulating adhesive layer containing a metal oxide and/or metal nitride, an excellent heat radiating property, and a high dielectric breakdown voltage value. SOLUTION: In a metallic-base multilayered circuit board, an insulating circuit board 6 having a first circuit conductor 5 on at least one surface and a second circuit conductor 3 are formed on at least one main surface of a metallic plate with an insulating adhesive layer 2 in between. The shortest distance between the end face of the second circuit conductor 3 to the end section of the circuit board 6 is adjusted to >=0.5mm and the preferable thickness of the layer 2 is 50-200μm. The thickness of at least the part of the first circuit conductor 5 which is in contact with the adhesive layer 2 is adjusted to 35-500μm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a metal-based multi-layer circuit board, and more particularly to a metal-based multi-layer circuit board having excellent heat dissipation characteristics, high dielectric breakdown voltage value and high reliability.

[0002]

2. Description of the Related Art Conventionally, a metal base circuit board has been used in the field of high power because it has excellent heat dissipation characteristics and can mount electronic parts that generate a large amount of heat. The metal base circuit board is a circuit in which a metal plate is coated with an insulating agent such as an epoxy resin filled with an inorganic filler to have a thickness of about several tens of μm, a conductive foil is attached to the insulating agent, and the conductive foil is further processed. Is formed.

However, demands for higher density of electronic component mounting boards in recent years are strict, and the metal base circuit board may not be satisfied, so that a circuit board is further laminated on the metal base circuit board. A metal-based multilayer circuit board in which a control circuit and an output circuit are integrated has come to be used (Japanese Patent Laid-Open No. 4-119696).

[0004]

However, in the metal-based multilayer circuit board disclosed in the above publication, the circuit board is laminated on the metal-based circuit board via the insulating adhesive layer, and the insulating adhesive layer is formed. It is generally manufactured by curing the resin, but in the process of lamination and curing, variations in pressure during lamination, residual stress due to differences in curing shrinkage between the circuit board and the insulating adhesive layer to be laminated, etc. As a result, there is a problem that the dielectric breakdown voltage value may be low.

Therefore, when a high heat-generating component that operates at a high voltage is mounted on a metal-based multilayer circuit board, the thickness of the insulating adhesive layer is reduced by sacrificing the high thermal conductivity of the metal-based circuit board. Since it is necessary to increase the thickness and ensure the insulating property, it is not satisfactory from the viewpoint of increasing the density of the circuit board.

An object of the present invention is to improve a metal-based multi-layer circuit board, and to provide a metal-based multi-layer circuit board having excellent heat dissipation, high dielectric breakdown voltage value and high reliability. .

[0007]

According to the present invention, an insulating circuit board having a first circuit conductor on at least one surface and a second circuit conductor on at least one main surface of a metal plate with an insulating adhesive layer interposed therebetween. A metal-based multilayer circuit board, wherein the distance from the end face of the second circuit conductor to the end of the insulated circuit board is 0.5 mm or more. .

Further, the present invention is the above-mentioned metal-based multilayer circuit board, wherein the thickness of the insulating adhesive layer is 50 μm or more and 200 μm or less, and further, the insulating adhesion of the first circuit conductor is provided. The thickness of the part in contact with the agent layer is 35
The metal-based multilayer circuit board is characterized in that it is not less than μm and not more than 500 μm.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to the drawings.

FIG. 1 shows an example of the structure of the metal-based multilayer circuit board of the present invention. The insulating circuit board 6 having the first circuit conductors 5 on both surfaces of the insulating substrate 4 and the second circuit conductor 3 are laminated and integrated on the metal plate 1 with the insulating adhesive layer 2 interposed therebetween.

In the present invention, the shortest distance between the second circuit conductor 3 formed on the metal plate 1 and the insulating circuit board 6 is 0.5 m.
m or more. Here, the shortest distance is, as illustrated by symbol A in FIG. 1, a portion where a side surface (hereinafter referred to as an end surface) of the second circuit conductor 3 contacts the insulating adhesive layer 2 and a side surface of the insulating substrate 4 (hereinafter referred to as an end surface). Represents the shortest distance between the insulating adhesive layer 2 and the portion in contact with the insulating adhesive layer 2. If the shortest distance is less than 0.5 mm, the dielectric breakdown voltage value of the metal base circuit board decreases due to residual stress such as pressure during stacking and curing shrinkage of the upper layer board. Therefore, in order to secure the insulation reliability of the metal base circuit board, it is desirable that the distance between the second circuit conductor 3 and the insulating board 4 is 0.5 mm or more, preferably 1.0 mm or more. On the other hand, when the distance between the second circuit conductor 3 and the insulating substrate 4 exceeds 20.0 mm, the insulation reliability is improved, but the mounting density is reduced, which poses a problem in practical use as a circuit substrate.

As the insulating adhesive layer 2, a resin filled with an inorganic filler is mainly used. Adhesiveness as resin,
Epoxy resin, phenolic resin, butyral, etc. are used from the viewpoint of electrical insulation, and epoxy resin is particularly preferably used because it has excellent adhesiveness to metal and electrical insulation. As the inorganic filler, aluminum oxide, silicon oxide, magnesium oxide, aluminum nitride, silicon nitride,
Boron nitride or the like is used. Above all, aluminum oxide, silicon oxide, and boron nitride, which have excellent electric insulation and thermal conductivity, are preferably used. Further, in addition to the inorganic filler, glass fiber, glass cloth, inorganic fiber and the like may be mixed.

The thickness of the insulating adhesive layer 2 is 50 μm or more and 200 μm or less. Insulating adhesive layer thickness is 50 μm
If it is less than 20%, insulation reliability may decrease, and
If the thickness exceeds 0 μm, the insulation reliability is secured, but the thermal conductivity decreases, and it may not be possible to mount an element having a high heat generation amount. Particularly, in the case of 70 μm or more and 150 μm or less, it is suitable for mounting an element having a high heat generation amount, which is excellent in both thermal conductivity and insulation reliability.

The thickness of at least the portion of the first circuit conductor which is in contact with the insulating adhesive layer 2 is 35 μm or more and 500 μm or more.
It is as follows. If the thickness is less than 35 μm, the conductor circuit may generate heat and melt and become unusable when a current required to operate an element having a large heat generation is applied. If the thickness exceeds 500 μm, The dielectric breakdown voltage value of the metal-based multilayer circuit board may decrease due to the difference in coefficient of thermal expansion between the conductor circuit and the metal plate or between the conductor circuit and the insulating substrate, which adversely affects the reliability. Especially 35 μm or more 12
A preferable range is 0 μm or less.

In the present invention, a resin substrate represented by a glass cloth-impregnated epoxy resin substrate is mainly used as the insulating circuit substrate 6, but the present invention is not limited to this. A double-sided resin substrate in which a resin filled with an inorganic filler is used as an insulating substrate and two metal foils are bonded to both surfaces thereof, or a flexible resin circuit board in which a resin not containing an inorganic filler in the double-sided resin substrate is used as an insulating substrate It is also possible to use a metal base circuit board having an electrically insulating metal plate as an insulating substrate, or a ceramic substrate.
Furthermore, in order to increase the mounting density, the insulating circuit board may be a multi-layer circuit board having a multi-layer circuit.

Insulating board 4 constituting the insulating circuit board 6
Has a thickness of 100 μm or more and 1000 μm or less. If the thickness of the insulating substrate 4 is less than 100 μm, the electrical insulating property of the insulating circuit substrate 6 cannot be ensured. This is because the reliability, that is, the electrical insulation between the second conductor circuit and the metal plate, is adversely affected. The thickness of the insulating substrate 4 is 100 μm or more 100
When the thickness is 0 μm or less, both the electric insulation of the insulating circuit board and the electric insulation of the metal base circuit board can be secured, but the case of 150 μm or more and 400 μm or less is particularly preferable.

The step of joining the insulated circuit board to the metal plate having the second conductor circuit via the insulating adhesive layer is as follows.
It is general to employ a method of press-bonding while heating with a press (bonding by pressing), but the method is not limited to this, and other methods such as a laminator method may be used.

The metal plate 1 used in the present invention is not particularly limited, but aluminum, copper, iron, etc. may be used.
And its alloys are used. The thickness is not particularly limited, but a thickness of 0.5 mm or more and 20.0 mm or less is used. Further, it is also possible to use a metal plate whose surface is insulated by anodic oxidation or the like, or which has been blackened in order to enhance heat radiation.

The present invention will be described in detail below with reference to examples.

[0020]

【Example】

[Example 1] A metal base circuit board (manufactured by Denki Kagaku Kogyo Co., Ltd., trade name: Denka HITT plate, thickness of insulating adhesive layer: 1;
A glass epoxy resin circuit board (Mitsubishi Gas Chemical Co., Ltd.) that is hollowed out so that it does not overlap with the circuit conductor of the metal base circuit board in the exposed portion of the insulating adhesive layer of 00 μm, the thickness of the circuit conductor: 300 μm). ), Product name: CCL
-E170, the thickness of the insulating substrate was 300 μm) was laminated on the metal base circuit board to prepare a metal base multilayer circuit board. At this time, the shortest distance from the circuit conductor end surface of the metal base circuit board to the glass epoxy resin end surface of the insulating substrate was set to 0.6 mm. The dielectric breakdown voltage between the conductor circuit (second conductor circuit) on the metal base circuit board and the metal board of this metal base multilayer circuit board is determined according to JIS C21.
The thermal resistance was measured by the method shown below by the stepwise boosting method of 10. The results are shown in Table 1.

<Method of Measuring Thermal Resistance> The circuit conductor on the metal base circuit board of the metal base multilayer circuit board is etched to form a pad portion of 10 × 15 mm, and a transistor (TO-220, Ltd.) is formed on the pad portion. Sold by Toshiba).
Next, a radiation fin is attached to the back surface of the metal plate of the metal-based multi-layer circuit board through a radiation grease (Sun Hayato Co., Ltd., SCH-20), and the transistor is energized while air-cooling the radiation fin, and the transistor upper surface and the metal plate surface. Was measured. The thermal resistance was calculated from the electric power supplied to the transistor and the temperature difference between the transistor and the metal plate (in the method described in the catalog of Denka HITT plate manufactured by Denki Kagaku Kogyo Co., Ltd., the metal base circuit board was made into metal). Replaced with the base multilayer circuit board and measured.).

[0022]

[Table 1]

[Examples 2 to 9] The shortest distance from the second circuit conductor on the metal base circuit board to the glass epoxy resin end face of the insulating board, the thickness of the glass epoxy resin board, and the second circuit of the metal base circuit board. Various metal-based multilayer circuit boards obtained through the same operation as in Example 1 except that the thickness of the conductor and the thickness of the insulating adhesive layer were changed under the conditions shown in Table 1 were the same as those in Example 1. Example 2 with the same evaluation
It was set to ~ 9. The results are shown in Table 1.

Comparative Example 1 As a comparative example, the same operation as in Example 1 except that the shortest distance from the second conductor circuit end surface of the metal base circuit board to the end surface of the glass epoxy resin board was 0.3 mm. Then, a metal-based multilayer circuit board was produced and evaluated. The results are shown in Table 1.

[0025]

The metal-based multi-layer circuit board of the present invention is excellent in heat dissipation, has a high breakdown voltage, and is highly reliable. Therefore, it is possible to mount high heat-generating components operating at high voltage in high density. This is useful in industry.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a metal-based multilayer circuit board of the present invention.

[Explanation of symbols]

 1 Metal Plate 2 Insulating Adhesive Layer 3 Second Circuit Conductor 4 Insulating Board 5 First Circuit Conductor 6 Insulating Circuit Board

Claims (3)

[Claims] 1. A metal-based multilayer circuit board in which an insulating circuit board having a first circuit conductor on at least one surface thereof and a second circuit conductor are laminated on at least one main surface of a metal plate via an insulating adhesive layer. The metal-based multilayer circuit board, wherein the shortest distance from the end face of the second circuit conductor to the end portion of the insulated circuit board is 0.5 mm or more. 2. The metal-based multilayer circuit board according to claim 1, wherein the insulating adhesive layer has a thickness of 50 μm or more and 200 μm or less. 3. The metal-based multilayer circuit board according to claim 1, wherein a thickness of a portion of the first circuit conductor which is in contact with the insulating adhesive layer is 35 μm or more and 500 μm or less.