JPH0690071A - Metal substrate for circuit - Google Patents

Abstract

PURPOSE:To obtain a metal substrate for an electronic equipment circuit with improved cooling property and withstand voltage property by providing an insulator which is provided between a metal base and a conductive layer on the same plane as a plurality of insulation layers where a thermal conductivity and a composition differ. CONSTITUTION:An insulator 12 which is provided between a metal base 11 and a conductive layer 13 is formed in a multilayer structure. Namely, an inorganic filler mixed resin where aluminum oxide 50-70 pts.wt. silicon dioxide 1-10 pts.wt. magnesium silicate 1-10 pts.wt. and thermosetting resin 20-50 pts.wt. are blended is applied to a glass fiber non-woven cloth in a first insulation layer 14. Also, an inorganic filler mixed resin where aluminum hydroxide 10-20 pts.wt. magnesium silicate 10-20 pts.wt. silicon dioxide 1-5 pts.wt. and thermosetting resin 60-80 pts.wt are blended is applied to the glass non-woven cloth in a second insulation layer 15 (a, b). Further, the thermosetting resin is applied to aromatic series polyamide fiber non-woven cloth in a third insulation layer 16 (a, b).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal substrate for a circuit,
In particular, the present invention relates to a circuit metal substrate useful for electronic device circuits that require heat dissipation, voltage resistance, and heat resistance.

[0002]

2. Description of the Related Art Paper phenolic copper-clad laminates, glass-copper-clad laminates and the like have been known as circuit metal substrates used in electronic equipment circuits. The paper phenol copper-clad laminate is used as a single-sided copper-clad laminate, and the glass copper-clad laminate is used as a double-sided copper-clad laminate or a multi-layered copper-clad laminate depending on the application.

Recently, as a result of miniaturization of components, weight reduction, improvement of reliability, and progress of surface mounting technology, it is necessary to radiate heat generated from components, especially power modules such as inverters, for reliability and miniaturization. Has become an indispensable element. As a metal substrate that meets this requirement, a method in which an insulating layer interposed between a metal base and a conductive layer is uniformly coated with an epoxy resin containing an inorganic filler within a range of 0.05 mm to 0.15 mm is the mainstream. .

[0004]

However, according to the conventional metal substrate, since the insulating layer is thin, it is difficult to eliminate defects such as pinholes, and the curing distortion of the resin layer caused by heat curing is eliminated. As a result, the conductive layer is warped. This effect is greatly affected by the component mounting after circuit formation and its reliability. In particular, radiating local heat generated from a power module or the like on the same substrate causes a partial difference in thermal expansion, and this acceleration of the distortion leads to dielectric breakdown. Therefore, there has been a demand for a metal substrate having both heat dissipation and withstand voltage functions.

The present invention has been made in view of the above circumstances, and by forming the insulating layer between the metal base and the conductive layers from a plurality of insulators having different thermal conductivities on the same plane, the heat dissipation and the withstand voltage can be improved. It is an object of the present invention to provide an excellent metal substrate for a circuit.

[0006]

Insulation considering the withstand voltage is either to thicken the insulating layer or to remove voids (air bubbles) in the insulating layer. For insulation considering heat dissipation, there is a method in which the insulating layer is thinned or a resin component in the insulating layer is mixed with an inorganic filler having excellent thermal conductivity.

When considering a circuit board in which an insulating layer on a metal base and a copper foil are sequentially formed, for example, AI (aluminum) is used as the material of the metal base and the thickness thereof is 1.0 mm. When the thickness is 0.035 mm,
The thickness (mm) of the insulating layer is 0.25mm, 0.41mm, 0.44
mm, 0.59 mm, the thermal conductivity (kcal / m · h · ° C) of the metal substrate is 2.57, 1.96,
It changes to 1.76 and 1.44.

On the other hand, when the thickness of the insulating layer is 0.45 mm and the thickness of the copper foil is 0.035 mm, (type of metal base, thickness (mm)) is (copper, 1.2), (copper, 1.5), ( AI, 1.0),
When changed to (AI, 1.5) and (AI, 2.0), the thermal conductivity (kcal / m · h · ° C) of the metal substrate is 6.24 and 6.9, respectively.
It changes to 5, 1.70, 3.37, 4.34. From such data, the present inventors have determined that the insulating thickness of the metal base is effective for improving the characteristics in order to improve heat dissipation.

That is, the first invention of the present application provides a circuit metal substrate comprising a heat-dissipating metal base and a conductive layer provided on at least one surface of the metal base via an insulator, wherein the insulator is A first insulating layer, a second insulating layer formed adjacent to the first insulating layer and having a height lower than that of the first insulating layer, and on the second insulating layer on the same surface as the first insulating layer And a third insulating layer formed so that
Insulating layer is glass fiber non-woven fabric with aluminum oxide 50 to 7
An inorganic filler mixed resin consisting of 0 parts by weight, 1 to 10 parts by weight of silicon dioxide, 1 to 10 parts by weight of magnesium silicate, and 20 to 50 parts by weight of a thermosetting resin is applied, and the second insulating layer is glass. Nonwoven fabric with aluminum hydroxide 10-2
0 parts by weight, 10 to 20 parts by weight of magnesium silicate, 1 to 5 parts by weight of silicon dioxide, and 60 to 80 parts by weight of a thermosetting resin are applied as an inorganic filler mixed resin, and the third insulating layer is A metal substrate for a circuit, characterized in that an aromatic polyamide fiber nonwoven fabric is coated with a thermosetting resin.

A second aspect of the present invention is a metal base for heat dissipation,
In a metal substrate for a circuit, comprising a conductive layer provided on at least one surface of the metal base via an insulator, the insulator is formed on the same surface as the first insulating layer. And a third insulating layer formed on the same surface of the first and second insulating layers, the first insulating layer being a glass fiber non-woven fabric and aluminum oxide 50-
70 parts by weight, 1 to 10 parts by weight of silicon dioxide, 1 to 10 parts by weight of magnesium silicate, and 20 to 50 parts by weight of a thermosetting resin are applied as an inorganic filler mixed resin, and the second insulating layer is glass. Aluminum hydroxide 10 to non-woven fabric
20 parts by weight, 10 to 20 parts by weight of magnesium silicate, 1 to 5 parts by weight of silicon dioxide, and 60 to 80 parts by weight of a thermosetting resin are applied as an inorganic filler mixed resin, and the third insulating layer is A metal substrate for a circuit, comprising a non-woven aromatic polyamide fiber coated with a thermosetting resin.

In the present invention, the mixing ratio of the thermosetting resin is set to 60 to 80 parts by weight because the withstanding voltage cannot be obtained sufficiently when the resin ratio is less than 60 parts by weight and exceeds 80 parts by weight. This is because sufficient heat dissipation cannot be obtained. Therefore, when sufficient withstand voltage is required, the ratio of the resin in the withstand voltage insulator is 60 to 80 parts by weight. Of course,
When the resin ratio is high, the withstand voltage property is further improved, but the withstand voltage insulating layer formed on the same plane in contact with the high thermal conductive insulator required in the present invention is filled with the thermosetting resin in the insulator. The ratio of agents is kept at 60-80 parts by weight. The reason is an indispensable condition for maintaining sufficient heat dissipation and withstand voltage.

On the other hand, in an area requiring heat dissipation, the withstanding voltage is sacrificed to some extent, and the proportion of the filler in the proportion of the resin as the main component of the insulator and the filler is kept at 60 parts by weight or more. The reason is that if the proportion of the filler is less than 60 parts by weight, sufficient heat dissipation cannot be obtained. Therefore, when a sufficient heat dissipation property is desired, the proportion of the filler in the high thermal conductive insulator is 60 parts by weight or more.

In the present invention, each filler in the inorganic filler mixed resin, that is, aluminum oxide, silicon dioxide, magnesium silicate, and the thermosetting resin are limited as described above for the following reason.

(1) of the first insulating layer forming a part of the insulator
Tensile elastic modulus is 1100-1800Kgf / mm² , The source of high thermal conductivity
With sufficient rigidity, low expansion coefficient and high glass transition point (T
g) is needed. Here, the expansion coefficient, Tg is
Using a 1.5 mm aluminum plate as the metal base,
Use 0.035mm thick copper foil as an electric layer, and insulate between them.
On a metal substrate with first to third insulating layers that form the body interposed
As a result of measurement, Tg of the first insulating layer is 140.
C, expansion coefficient (temperature below Tg) is 1.61 to 5.9 × 10^-Five/
And the tensile modulus of elasticity of the second and third insulating layers is 600-
900 Kgf / mm² And Tg is 100 ° C compared to the first insulation layer, wire
Expansion coefficient is 1.5 to 3.8 × 10^-FiveFlexible configuration at / ° C
Has been done.

(2) When the first to third insulating layers are formed on the same plane, when the first insulating layer is abnormally overheated, high Tg (140 ° C.) and low linear expansion coefficient 1.61 to 5.
9 × 10 ^-5 / ℃ absorbs the warp and twist of the substrate, the glass transition point of the second and third insulating layers is 100 ℃, the linear expansion coefficient is 3.8 × 10
The linear expansion coefficient of the first insulating layer in contact with it at ^-5 / ° C is 2.7.
It is 7 * 10 < ^-5 > / ^degreeC . Metal based aluminum
The reason for selecting the inorganic filler of the present invention is that the materials are well balanced at 2.4 × 10 ⁻⁵ / ° C.

(3) The aluminum oxide contained in the first insulating layer has sufficient thermal conductivity when it is set to 50 to 70 parts by weight as described above. However, the hardness of aluminum oxide is higher than that of resin, and the tensile elastic modulus is high, and it is difficult to increase the filling rate by itself as an insulator of a metal substrate. Therefore, in addition to aluminum oxide, 1 to 10 parts by weight of each of the above-mentioned silicon dioxide and magnesium silicate is blended so as to have both flexibility and rigidity. In addition, it is effective to maximize the characteristics of each inorganic filler that the upper limit of the ratio of these inorganic fillers to the thermosetting resin is 80:20.

(4) The same applies to the case of the second and third insulating layers as in the case of the first insulating layer. However, in the second insulating layer,
Aluminum hydroxide is required to maintain flame resistance, magnesium silicate is required to maintain flexibility, and silicon dioxide is required to maintain electrical properties and rigidity. The characteristics can be fully utilized. It should be noted that it is effective to keep the ratio of these inorganic fillers to the thermosetting resin to 80:20 at the maximum in order to maintain the electrical characteristics and the thermal conductivity.

[0018]

In the present invention, the heat dissipation metal base and the conductive interlayer insulator are formed by appropriately combining a plurality of insulating layers having different thermal conductivities, specifically, a high thermal conductive insulating layer and a withstand voltage insulating layer. Therefore, an excellent circuit metal substrate having both characteristics can be obtained.

[0019]

EXAMPLES Examples of the present invention will be described below. (Embodiment 1) Reference will be made to FIGS. here,
1A is a cross-sectional view of the circuit metal substrate, and FIG. 1B is a plan view of the insulating layer of FIG. 1A.

Reference numeral 11 in the figure denotes a heat-dissipating metal base made of copper and having a thickness of 1.5 mm. A thickness of 0.
A copper foil pattern (conductive layer) 13 having a thickness of 0.035 mm is provided via a 25 mm insulator 12. Here, the insulator 12 is provided on both sides of the first insulating layer (high thermal conductive insulating layer) 14 having a thickness of 0.25 mm in the central portion, and the first insulating layer 14 Second insulating layers (voltage resistant insulating layers) 15a and 15b having a low height, and the first and second insulating layers 15a and 15a,
Third insulating layer 16 having a thickness of 0.05 mm formed on each of 15b
It consists of a and 16b.

The first insulating layer 14 is made of glass fiber non-woven fabric (50 g / m ² In addition, 100 parts by weight of the following epoxy resin A (thermosetting resin) is mixed with each filler, that is, 200 parts by weight of aluminum oxide, 15 parts by weight of silicon dioxide and 15 parts by weight of magnesium silicate, and an inorganic filler mixed resin. (Mixture) is applied. The second insulating layer 15
a and 15b are non-woven glass (50 g / m ² ), A mixture prepared by kneading 100 parts by weight of the following epoxy resin B (thermosetting resin) with each filler, 20 parts by weight of aluminum hydroxide, 10 parts by weight of magnesium silicate and 10 parts by weight of silicon dioxide is applied. It is a thing. The third insulating layers 16a, 16
In b, an aromatic polyamide fiber nonwoven fabric is coated with an epoxy resin. Instead of this epoxy resin, the filled epoxy resin B used for forming the first insulating layer 14 may be used. Here, the adhering amount of the mixture varies depending on the thickness of the insulating layer, but in order to secure a thickness of 0.25 mm, for example, 350 to 450 g / m ² Need to be applied.

The epoxy resin A focuses on heat resistance and thermal conductivity. That is, the bismaleimide triazine resin that constitutes a part of the epoxy resin A is preferably in the range of 20 to 60% with respect to the bisphenol type epoxy resin because it contributes to the increase of the glass transition point and the improvement of heat resistance.
Also, by adding each filler such as aluminum hydroxide,
It lowers the coefficient of thermal expansion and improves heat dissipation. On the other hand, epoxy resin B has flame retardancy and electrical characteristics (dielectric constant, insulation resistance,
This is a characteristic required for excellent withstand voltage) and sufficiently fulfilling the functions of the different insulating layers on the same plane of the present invention. (Epoxy resin A) Bisphenol type epoxy resin: 100 parts by weight Bismaleimide triazine resin: 30 parts by weight Dicyandiamide (curing agent): 6 parts by weight Imidazole (accelerator): 0.2 parts by weight Acetone (solvent): 90 parts by weight Methyl ethyl ketone (Solvent) ... 100 parts by weight (Epoxy resin B) Brominated epoxy resin ... 100 parts by weight Dicyandiamide ... 6 parts by weight Imidazole ... 0.2 parts by weight Acetone ... 90 parts by weight Methyl ethyl ketone ... 10 parts by weight

In fact, in the metal substrate of FIG. 1, the region of the first insulating layer 14, the second insulating layers 15a and 15b and the third insulating layer 16 are formed.
The thermal conductivity (Kcal / m · h · ° C) and the dielectric breakdown voltage (KV) in the regions a and 16b were as shown in Table 1 below. Table 1 Thermal conductivity Dielectric breakdown voltage Region of first insulating layer 10.1 10.6 Region of second and third insulating layers 7.25 13.60 (Example 2)

Reference will be made to FIGS. 2A and 2B. here,
2A is a cross-sectional view of the circuit metal substrate, and FIG. 2B is a plan view of the insulating layer of FIG. 2A. The same members as those in FIG. 1 are designated by the same reference numerals and the description thereof is omitted.

Reference numeral 21 in the drawing denotes a third insulating layer formed between the insulator 12 having a thickness of 0.30 mm and the copper foil pattern 13. This third insulating layer 21 has a basis weight of 20 g / m ^2. ， The thickness is 0.05m
m of aromatic polyamide fiber nonwoven fabric is coated with the epoxide resin B.

In the metal substrate of FIG. 2, the thermal conductivity (Kcal / m · h · ° C.) and the dielectric breakdown voltage of the regions of the first insulating layer 14, the second insulating layers 15a and 15b, and the third insulating layer 21. (K
V) was as shown in Table 2 below. Table 2 Thermal conductivity Dielectric breakdown voltage Region of the first insulating layer 8.90 12.5 Region of the second and third insulating layers 7.10 14.7 Note that the insulating member used for the third insulating layer is the above-mentioned. Besides the epoxy resin B, the epoxy resin A or a filler containing these resins can be used. (Example 3)

Reference will be made to FIGS. 3 (A) and 3 (B). here,
3A is a cross-sectional view of the circuit metal substrate, and FIG. 3B is a plan view of the insulating layer of FIG. 3A. The same members as those in FIG. 1 are designated by the same reference numerals and the description thereof is omitted.

In the circuit metal board according to the third embodiment, the first insulating layer 14 has a round shape (rectangular shape in FIG. 1) and the second insulating layer 15a, as compared with the circuit metal board of FIG. The shapes are the same except that the shapes of 15b and the third insulating layers 16a and 16b have a relative shape to the shape of the first insulating layer.

In the metal substrate of FIG. 3, the region of the first insulating layer 14, the second insulating layers 15a and 15b, and the third insulating layers 16a and 16b.
The thermal conductivity (Kcal / m · h · ° C) and the dielectric breakdown voltage (KV) in the region b were as shown in Table 3 below. Table 3 Thermal conductivity Dielectric breakdown voltage Region of first insulating layer 10.5 10.55 Region of second and third insulating layers 7.25 14.0 (Example 4) Reference is made to FIG.

Reference numeral 41 in the figure denotes an uneven surface formed on the back surface of the metal base 11 located below the first insulating layer (high thermal conductive insulating layer) 14 in the central portion. It should be noted that the second insulating layer (voltage resistant insulator) 15 provided on both sides of the first insulating layer 14
The back surfaces of a and 15b are smooth. In FIG. 4, the first insulating layer 14 has a glass transition point higher by 5 ° C. or more and a thermal expansion coefficient of 90% or less than the second insulating layers 15a and 15b.

According to the circuit metal substrate of the fourth embodiment,
Since the back surface of the metal base 11 located below the first insulating layer 14 is the uneven surface 41, the area of the back surface of the metal base 11 can be made large, and thus the heat dissipation is further improved as compared with the first embodiment. it can. (Example 5) Referring to FIG.

In the insulating layer 12 of the fifth embodiment, the thickness of the first insulating layer 14 is 0.26 mm, and the second insulating layers 15a and 15b.
Has a thickness of 0.3 mm. The thickness of the first insulating layer 14 is 90% or less of the thickness of the second insulating layers 15a and 15b. Further, as in the case of the fourth embodiment, the uneven surface 41 is formed on the back surface of the metal base 11 located below the first insulating layer 14.

According to the circuit metal substrate of the fifth embodiment,
Since the thickness of the first insulating layer 14 is formed thinner than the thickness of the second insulating layers 15a and 15b, the heat dissipation can be further improved as compared with the case of the fourth embodiment. (Comparative Example) As compared with Example 1, an insulator obtained by impregnating a glass fiber non-woven fabric with the epoxy resin containing no filler was used.

In this case, the thermal conductivity (Kcal / m · h · ° C.) in the region of the first insulating layer was 5.85, respectively. The dielectric breakdown voltage (KV) in the region of the first insulating layer was 14.8, respectively.

From the above test results, it was confirmed that in the case of the present invention, the thermal conductivity is higher than that in the prior art, that is, the heat dissipation through the metal base is excellent and the withstand voltage is excellent. Further, in the above embodiment, the case where the synthetic resin alone and the insulator formed by applying the inorganic filler to the glass fiber non-woven fabric and the aromatic polyamide fiber non-woven fabric are combined as the base material of the insulator is described. Not limited to this, an aromatic polyamide fiber nonwoven fabric may be used. A woven fabric may be used instead of the non-woven fabric.

[0036]

As described in detail above, according to the present invention, by disposing the insulating layer between the metal base and the conductive layer from a plurality of insulators having different thermal conductivities on the same plane, the heat dissipation and the withstand voltage can be improved. An excellent metal substrate for a circuit can be provided.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a metal substrate for circuits in which a three-layer structure and a four-layer structure according to a first embodiment of the present invention are formed on the same plane.

FIG. 2 is an explanatory diagram of a circuit metal substrate having a four-layer structure according to a second embodiment of the present invention.

FIG. 3 is an explanatory diagram of a metal substrate for a circuit in which a three-layer structure and a four-layer structure in which the mode of the insulating layer according to the third embodiment of the present invention is changed are formed on the same plane.

FIG. 4 is a cross-sectional view of a circuit metal substrate provided with an uneven surface according to a fourth embodiment of the present invention.

FIG. 5 is a cross-sectional view of a circuit path metal substrate according to a fifth embodiment of the present invention, in which an uneven surface is provided and an insulating layer has a different thickness.

[Explanation of symbols]

11 ... Heat dissipation metal base, 12 ... Insulator, 13 ... Copper foil pattern, 14, 15a, 15b, 16a, 16b, 21 ... Insulating layer, 41 ... Uneven surface.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Yukio Nakajima 1-1, Tanabe Nitta, Kawasaki-ku, Kawasaki-shi, Kanagawa Fuji Electric Co., Ltd. No. 1 in Fuji Electric Co., Ltd. (72) Inventor Ryozo Karatsu 1-1 No. 1 Tanabe Nitta, Kawasaki-ku, Kawasaki City, Kanagawa Prefecture Fuji Electric Co., Ltd.

Claims (4)

[Claims] 1. A circuit metal substrate comprising a heat-dissipating metal base and a conductive layer provided on at least one surface of the metal base via an insulator, wherein the insulator is a first insulating layer, and A second insulating layer formed adjacent to the first insulating layer and having a height lower than that of the first insulating layer; and a second insulating layer formed on the second insulating layer so as to be flush with the first insulating layer. 3 insulating layers, wherein the first insulating layer is a glass fiber non-woven fabric 50-70 parts by weight aluminum oxide, 1-10 parts by weight silicon dioxide, 1-10 parts by weight magnesium silicate, 20-50 parts by weight thermosetting resin. Wherein the second insulating layer is a glass nonwoven fabric containing 10 to 20 parts by weight of aluminum hydroxide, 10 to 20 parts by weight of magnesium silicate, and 1 to 5 parts by weight of silicon dioxide. Thermosetting resin 60- 0
A metal substrate for a circuit, characterized in that an inorganic filler mixed resin composed of parts by weight is applied, and the third insulating layer is an aromatic polyamide fiber nonwoven fabric applied with a thermosetting resin. 2. The metal substrate for a circuit according to claim 1, wherein the back surface of the heat-dissipating metal base corresponding to the area for providing heat dissipation is an uneven surface. 3. The back surface of the heat-dissipating metal base corresponding to the area for providing heat dissipation is an uneven surface, and the thickness of the insulating layer corresponding to the uneven surface is the same as the thickness of the insulating layer in other areas. The metal substrate for a circuit according to claim 1, which is smaller than the metal substrate. 4. A circuit metal substrate comprising a heat-dissipating metal base and a conductive layer provided on at least one surface of the metal base via an insulator, wherein the insulator comprises a first insulating layer and a first insulating layer. A second insulating layer formed on the same surface as the first insulating layer; and a third insulating layer formed on the same surface of the first and second insulating layers, wherein the first insulating layer is glass fiber A non-woven fabric is coated with an inorganic filler mixed resin comprising 50 to 70 parts by weight of aluminum oxide, 1 to 10 parts by weight of silicon dioxide, 1 to 10 parts by weight of magnesium silicate, and 20 to 50 parts by weight of a thermosetting resin. The second insulating layer is a glass nonwoven fabric containing 10 to 20 parts by weight of aluminum hydroxide, 10 to 20 parts by weight of magnesium silicate, 1 to 5 parts by weight of silicon dioxide, and 60 to 80 thermosetting resins.
A metal substrate for a circuit, characterized in that an inorganic filler mixed resin composed of parts by weight is applied, and the third insulating layer is an aromatic polyamide fiber nonwoven fabric applied with a thermosetting resin.