JPH10242607A - Metal base board and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal base board having high adhesive properties and processibility by forming of insulating adhesive material having high relative dielectric constant and low dielectric loss tangent. SOLUTION: In the metal base board in which insulating adhesive material with a copper foil obtained by disposing the material on the foil is laminated on a metal plate, the adhesive material containing 40 to 80vol.% of inorganic filler having relative dielectric constant of 50 or more is used. And, the adhesive material is constituted by at least two layers or more of the material so that the adhesive material containing 50 to 80vol.% of inorganic filler is used for a first layer in contact with the foil and the adhesive material containing 40 to 50vol.% of the filler is used for an outermost layer of a second layer without contact with the foil in such a manner that the first layer becomes curing degree of B or C stage and the second layer becomes curing degree of A or B stage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a metal base substrate using an insulating adhesive material having a high dielectric constant and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, electronic equipment has been reduced in size and density, and the operating frequency has been increased. In response to these, the object is to reduce high-frequency noise and reduce the size of wiring boards. There is a demand for increasing the dielectric constant of the insulating adhesive material. As a method for obtaining a laminated substrate having a high relative dielectric constant, for example, JP-A-55-57212, JP-A-61-13
No. 6,281, Japanese Unexamined Patent Publication No. 3-221448, etc., have included a method of including a high dielectric substance in an insulating layer.

[0003]

All of these require a step of impregnating the glass cloth with an insulating material, and the adhesiveness to the metal foil and the accuracy of the thickness of the laminate in the heating and pressing step of forming the laminate. Fluidity is necessary for the insulating material for improvement. However, an insulating material containing a large amount of a high dielectric has a low fluidity, so that a large amount of a high dielectric cannot be contained, and the relative dielectric constant cannot be sufficiently increased. Producing a high dielectric constant metal-based substrate is described in Printed Circuit Society No. 8
The abstract of the 110th Annual Meeting of the JSCE is described as "High Dielectric Constant Copper Base Board" on page 117, but has a relative dielectric constant of about 26, which is sufficient for reducing the size of wiring boards and reducing high-frequency noise. Was not. When the frequency is 500 MHz or more, the dielectric loss tangent (tan δ) becomes large, and there is a problem that the use at 500 MHz or more is not sufficient. It is well known that there is a high dielectric constant inorganic filler as a high dielectric substance, and it is well known that an insulating material contains a high dielectric constant inorganic filler to increase the dielectric constant. In such a case, the melt viscosity of the insulating material increases, the fluidity is poor, the adhesiveness to the metal plate is reduced, the flexibility is reduced, voids remain in the insulating layer, and many problems occur, so that it is put into practical use. Has not been reached. Conventionally, there is a ceramic substrate having a high dielectric constant obtained by sintering an inorganic powder having a high dielectric constant. However, the workability with respect to external processing or the like has not been sufficient.

[0004]

The present invention has been made in view of such circumstances, and has a high relative dielectric constant, a low dielectric loss tangent,
It is an object of the present invention to obtain a metal base substrate having excellent adhesion to metal and good workability. In order to solve this problem, the present inventors have conducted intensive studies, and as a result, by selecting the filler content, the resin component, and the degree of curing of each layer of the insulating adhesive material, a metal base substrate having a high dielectric constant can be obtained. Was. The present invention relates to a metal base substrate in which an insulating adhesive material with a copper foil obtained by arranging an insulating adhesive material on a copper foil is laminated on a metal plate. % Of the metal base substrate. Then, among the insulating adhesive material layers formed in at least two layers on the copper foil, the insulating adhesive material layer in contact with the copper foil contains an inorganic filler having a relative dielectric constant of 50 or more from 50% by volume to 80% by volume. The outermost insulating adhesive material layer not in contact with the copper foil contains an inorganic filler having a relative dielectric constant of 50 or more in the insulating adhesive material by 40% by volume to 50% by volume.
Preferably, the metal base substrate contains at least 20% by volume or more of an epoxy resin having a molecular weight of 500 or less in at least the outermost insulating adhesive material layer. In addition, the present invention applies an insulating adhesive material varnish containing an inorganic filler having a relative dielectric constant of 50 or more so as to be 40% by volume to 80% by volume on a copper foil, and then dried to produce an insulating adhesive material with a copper foil. A method for manufacturing a metal base substrate, characterized by laminating and forming a metal plate. Further, an insulating adhesive material varnish containing an inorganic filler having a relative dielectric constant of 50 or more so as to be 50% by volume to 80% by volume is applied to a copper foil, dried, and then further coated with an inorganic filler having a relative dielectric constant of 50 or more. An insulating adhesive material varnish containing the filler in an amount of 40% by volume to 50% by volume is applied to the copper foil, and the degree of curing of the insulating adhesive material layer on the side in contact with the copper foil is B.
Or a metal base substrate which is a C-stage, which is made by drying an insulating adhesive material with a copper foil so that the outermost insulating adhesive material layer not in contact with the copper foil is at the A or B stage, and is laminated with a metal plate and molded. And a method of manufacturing a metal base substrate using a varnish containing an epoxy resin having a molecular weight of 500 or less to be at least 20% by volume as an outermost insulating adhesive varnish not in contact with the copper foil.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The insulating adhesive material of the present invention mainly comprises a resin component and an inorganic filler. As the resin component, an epoxy resin type, a polyimide resin type, a phenol resin type, or the like can be used. To this, a flexibility-imparting component which is a polymer substance having good electric insulation can be added. Preferred are, for example, acrylic rubber, NBR, epoxy-modified acrylic rubber, epoxidized polybutadiene, phenoxy resin and the like. Further, it is preferable to use a coupling agent in order to improve the adhesiveness between the copper foil and the insulating adhesive material. As the coupling agent, a silane coupling agent is preferable, and γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-ureidopropyltriethoxysilane, N-β -Aminoethyl-γ-aminopropyltrimethoxysilane and the like.

[0006] The outermost insulating adhesive material layer preferably contains 20% by volume or more of a low molecular weight epoxy resin having a molecular weight of 500 or less in order to improve fluidity during molding. Examples of such an epoxy resin include a bisphenol A type or a bisphenol F type liquid resin having two or more epoxy groups in one molecule.
7, marketed under the trade name Epicoat 828.
In addition, Dow Chemical Japan Co., Ltd. E. FIG. R.
330, D.I. E. FIG. R. 331; E. FIG. R. 361. Further, they are commercially available from Toto Kasei Co., Ltd. under the trade names of YD128 and YDF170. The curing agent for the epoxy resin is not particularly limited, but a curing agent having a long varnish life and a high potential is desirable. Examples of this are tertiary amines, acid anhydrides,
One or more of imidazole compounds, polyphenol resins, masked isocyanates and the like can be used. Further, in order to prevent a decrease in insulation resistance at the time of moisture absorption due to impurity ions, it is preferable to add an ion-adsorbing inorganic substance.

The following are examples of inorganic fillers having a relative dielectric constant of 50 or more.
More than one species can be used in combination. That is,
There are powders of titanium dioxide, barium titanate, calcium titanate, strontium titanate, lead titanate, barium zirconate, calcium zirconate, barium stannate, calcium stannate and the like. Further, by using a powder obtained by firing and pulverizing a ceramic capacitor raw material as the inorganic filler and having a relative dielectric constant of 300 or more, a substrate having a higher dielectric constant can be obtained. The shape and particle size of the inorganic filler are not particularly limited, but the use of a spherical filler improves the fluidity of the insulating adhesive material at the time of molding, and the use of a crushed or fibrous material provides mechanical strength. Is improved. It is necessary that the amount of such an inorganic filler is from 40% by volume to 80% by volume of the insulating adhesive material. The reason for this is that if the blending amount is less than 40% by volume, the effect of increasing the dielectric constant is small, and 80% by volume.
If the ratio exceeds, the fluidity of the insulating adhesive material is reduced, and the withstand voltage is reduced due to generation of voids.

Next, regarding the layer structure of the insulating adhesive material with copper foil, an insulating adhesive material varnish is applied as a first layer on the copper foil, and this is heated and cured to a B or C stage to obtain a fluidized material. To reduce the nature. Further, a second layer is applied on the insulating adhesive material, and this is heated to the A or B stage having a curing degree. With such a two-layer structure, a decrease in insulation reliability due to coating film defects such as voids, craters, and foreign matter in the insulating adhesive material is prevented. Although a two-layer structure has been described, the same operation may be repeated to form a three-layer structure or more. In this case, the outermost insulating adhesive material not in contact with the copper foil has a degree of curing of A or B stage. A, B, and C stages indicate the degree of curing of the adhesive, and the A stage is in a state of being almost uncured and not gelling, and has finished generating 0 to 20% of the total curing calorific value. It is in a state where it is. The B stage is in a state in which curing and gelation have progressed slightly, and a state in which heat generation of 20 to 60% of the total curing calorific value has been completed. The C stage is considerably hardened and gelled, and 60 to 100% of the total curing heat generation
This is the state in which heat generation has been completed. In the case of a two-layer insulating adhesive material, the first-layer insulating adhesive material varnish provided on the copper foil contains an inorganic filler having a relative dielectric constant of 50 or more so as to be 50% by volume to 80% by volume. The amount of the inorganic filler when applied and dried is adjusted to 50% by volume to 80% by volume. The first layer of the insulating adhesive material is applied and dried on the second layer of the insulating adhesive material, so that the application and drying conditions are anticipated. Further, an insulating adhesive material varnish containing an inorganic filler having a relative dielectric constant of 50 or more so as to be 40% by volume to 50% by volume is further applied thereon and dried, and the degree of curing becomes the B or C stage. So that In the case of a three-layer structure or more, the outermost insulating adhesive layer not in contact with the copper foil is made to have an inorganic filler content of 40% by volume to 50% by volume.

As a method for applying the insulating adhesive material varnish to the copper foil, there are a bar coater, a lip coater, a roll coater, etc., which have few defects such as craters and voids and can uniformly apply the thickness at the time of coating. If there is, it is not restricted. The metal base substrate of the present invention can be used as a multilayer wiring board. The method for manufacturing the multilayer wiring board can be performed as follows. A metal base substrate is obtained by pressure-heating and integrating the insulating adhesive material with copper foil and the metal plate. For this, a press, a vacuum press, a hot roll laminator, a vacuum laminator, or the like can be used. The obtained metal base substrate is processed by a usual method,
Outer shape processing is performed to obtain a metal-based wiring board. An insulating adhesive material with a copper foil is further laminated on the copper foil wiring layer of the metal wiring board and integrated under pressure and heat to form a multilayer wiring board. In this case, as the insulating adhesive material with copper foil to be laminated on the metal base substrate, an insulating adhesive material with copper foil containing no inorganic filler may be laminated, or via a prepreg or an adhesive film of a glass base material. They may be stacked. Hereinafter, the present invention will be specifically described based on examples.

[0010]

【Example】

(Experimental Example 1) (1) A copper foil having a thickness of 35 μm was used, and an insulating adhesive material varnish A shown in Table 1 was applied thereon as a first layer of the insulating adhesive material so that the thickness after drying was 35 μm. , 150 ° C
For 10 minutes, and the thickness after drying as a second layer of the insulating adhesive material is 70
The insulating adhesive material varnish B shown in Table 1 was applied to a thickness of μm, and dried at 110 ° C. for 10 minutes to produce an insulating adhesive material with a copper foil. (2) Laminate the above-mentioned insulating adhesive material with copper foil and an aluminum plate having a surface thickness of 2 mm, which has been polished, and 170 ° C., 30 kg
Heat and pressure molding was performed at f / cm ² for 60 minutes to produce a metal base substrate. (3) The copper foil of the metal base substrate was subjected to an etching treatment by a conventional method to obtain a metal base wiring substrate.

(Experimental Example 2) Using a copper foil having a thickness of 35 μm,
On this, a first layer of an insulating adhesive material having a thickness after drying of 1
The insulating adhesive material varnish C shown in Table 1 was applied so as to have a thickness of 8 μm, dried at 150 ° C. for 10 minutes, and further dried thereon as a second layer of the insulating adhesive material having a first layer and a second layer. Insulating adhesive material varnish A of Table 1 was applied so that the total thickness of the two layers became 35 μm, and dried at 150 ° C. for 10 minutes to produce an insulating adhesive material with a copper foil. Further, a varnish B of the insulating adhesive material shown in Table 1 is further applied thereon as a third layer of the insulating adhesive layer so that the thickness after drying becomes 70 μm in total from the first layer to the third layer. After drying for 10 minutes, an insulating adhesive material with a copper foil was prepared. A metal base substrate and a metal base wiring board were obtained in the same manner as in Example 1 except that this insulating adhesive material with a copper foil was used.

(Experimental Example 3) Using a copper foil having a thickness of 35 μm, apply an insulating adhesive material varnish A shown in Table 1 on the copper foil so that the thickness after drying becomes 70 μm, and then apply the coating at 110 ° C. for 10 minutes. After drying, an insulating adhesive material with a copper foil was prepared. Example 1 was repeated except that this insulating adhesive material with copper foil was used.
In the same manner as in the above, a metal base substrate and a metal base wiring substrate were obtained.

(Experimental Example 4) Using a copper foil having a thickness of 35 μm, an insulating adhesive material varnish B shown in Table 1 was applied on the copper foil so that the thickness after drying became 70 μm, and the coating was performed at 110 ° C. for 10 minutes. It dried and the insulating adhesive material with a copper foil was produced. A metal base substrate and a metal base wiring board were obtained in the same manner as in Example 1 except that this insulating adhesive material with a copper foil was used.

(Experimental Example 5) Using a copper foil having a thickness of 35 μm, the insulating adhesive material varnish A shown in Table 1 was coated on the copper foil as the first layer of the insulating adhesive material so that the thickness after drying was 35 μm. Coating, drying at 150 ° C. for 10 minutes, and further, as a second layer of an insulating adhesive material,
The insulating adhesive material varnish A of Table 1 is applied so that the total thickness of the layers and the second layer is 70 μm, and dried at 150 ° C. for 10 minutes.
An insulating adhesive material with a copper foil having a degree of curing of C for both the first and second layers was produced. A metal base substrate and a metal base wiring board were obtained in the same manner as in Example 1 except that this insulating adhesive material with a copper foil was used.

The measurement of the relative dielectric constant and the dielectric loss tangent are based on JIS C
6481, LCR meter (Model 4274)
A, manufactured by Hewlett-Packard) and a triplate structure straight line resonator method at room temperature (25 ° C.). As for the withstand voltage, the withstand voltage between the copper foil sandwiching the insulating adhesive material and the aluminum plate was measured. Copper foil of metal base substrate with diameter 20
The copper foil of mm was removed by etching so as to remain, and the measurement was performed using a withstand voltage meter. The withstand voltage failure rate was defined as the number of tests showing a withstand voltage of less than 2 KV / the number of test pieces evaluated. The adhesion between the insulating adhesive material and the aluminum plate is 260
When immersed in a solder bath at 3 ° C. for 3 minutes, those with peeling were evaluated as poor, and those without peeling were evaluated as good.

Table 2 shows the test results of the metal base substrates manufactured in Experimental Examples 1 to 5. Experimental Examples 1 and 2 have a large relative dielectric constant, good withstand voltage, and good adhesion between the insulating adhesive material and the aluminum plate. Experimental Example 3 has a large relative dielectric constant,
The adhesion between the insulating adhesive material and the aluminum plate is poor,
In Experimental Example 4, the relative dielectric constant was low as a result of reducing the amount of the inorganic filler to improve the adhesion between the insulating adhesive material and the aluminum plate. In Experimental Example 5, the degree of curing of the insulating adhesive material was out of the preferred range, and the withstand voltage and the adhesion between the insulating adhesive material and the aluminum plate were also poor.

[0017]

[Table 1] ―――――――――――――――――――――――――――――――― Item Item Varnish A Varnish B Varnish C ―― ―――――――――――――――――――――――――――――― Epoxy resin Ehcoat 828 60 60 0 Ehcoat 1007 0 0 60 Flexible agent Phenoxy resin 40 40 40 Curing agent Phenol novolak 30 30 15 Curing accelerator 2PZ-CN 0.5 0.5 0.5 Silane cuff A187 202 Linking agent Inorganic filler Perium titanate 800 450 450 Volume% of valium titanate 55.6 41.7 44.6 ――――――――――――――――――――――――――――――――――― Echicoat 828: Bisphenol A type epoxy resin (epoxy equivalent = 190, oil Shell Epoxy Co., Ltd. ) Ehjicoat 1007: bisphenol A type epoxy resin (epoxy equivalent = 2000, trade name of Yuka Shell Epoxy Co., Ltd.) phenoxy resin: YP-50 (trade name of Toto Kasei Co., Ltd.) phenol novolak: LF-2882 (Dainippon Ink Inc. Company brand name, hydroxyl equivalent = 118) potassium titanate: manufactured by Fuji Titanium Industry Co., Ltd., particle size 1.4 μm
m, relative permittivity = 1150

[0018]

[Table 2] ――――――――――――――――――――――――――――――――― Item Unit Experimental example 1 Experimental example 2 Experimental example 3 Experiment 4 Experiment 5 ――――――――――――――――――――――――――――――――― Relative permittivity ― 54 45 65 36 65 Dielectric loss tangent 1MHz 0.001 0.001 0.002 0.003 0.002 Dielectric loss tangent 100MHz 0.002 0.002 0.022 0.013 0.011 Dielectric loss tangent 1000MHz 0.004 0.004 0.032 0.020 0.023 Withstand voltage kV 5.6 6.6 4.5 6.1 4.0 Withstand voltage failure% 0.1 0.1 2.4 0.1 1.2 Ratio Aluminum plate-Insulation-Good Good Poor Good Poor Adhesion between layers (peeling between layers (peeling between layers) peeling) ――――――――――――――――――――――――――――――――― -

[0019]

When the metal base substrate of the present invention is used to form a metal base wiring substrate, the insulating adhesive material has a high dielectric constant and the substrate itself has a large capacitance. A capacitor function can be provided, and high-frequency noise mixed into a power supply line can be removed in a digital circuit without newly providing a capacitor, contributing to miniaturization and high density. Further, in the present invention, a metal plate having a high thermal conductivity is used as an essential component. The metal plate has excellent heat radiation properties, has a small local temperature rise, and can achieve a uniform temperature over the entire substrate. For this reason, even when a component having a large temperature dependence of the characteristic is used, the instability of the characteristic due to the temperature rise can be resolved. The relative permittivity varies greatly with temperature, and was particularly remarkable in those having a high relative permittivity.However, the change in relative permittivity due to temperature decreases due to temperature uniformity due to the heat conduction of the metal plate, and the It can be operated stably. When a metal base substrate having a large relative dielectric constant is used for an AD converter, a hybrid IC, or the like, high-frequency noise mixed into a power supply line can be removed and an increase in the temperature of the IC can be suppressed. Further, when used for a high-frequency circuit used in a wireless transceiver or the like, the width of a circuit pattern for matching impedance is reduced, and the size of the entire circuit can be reduced. Further, since the temperature can be made uniform over the entire area of the substrate, the characteristics are stabilized.

Claims (6)

[Claims] 1. A metal base substrate in which an insulating adhesive material with a copper foil in which an insulating adhesive material is arranged on a copper foil is laminated on a metal plate, wherein an inorganic filler having a relative dielectric constant of 50 or more is added to the insulating adhesive material. A metal base substrate containing from about 80% by volume to about 80% by volume. 2. An insulating adhesive material layer formed in at least two layers on a copper foil, wherein the insulating adhesive material layer in contact with the copper foil contains an inorganic filler having a relative dielectric constant of 50 or more from 50% by volume to 80% by volume. %, Wherein the outermost insulating adhesive material layer not in contact with the copper foil contains an inorganic filler having a relative dielectric constant of 50 or more in the insulating adhesive material by 40% by volume to 50% by volume. . 3. The method according to claim 1, wherein at least the outermost insulating adhesive material layer comprises:
3. An epoxy resin having a molecular weight of 500 or less at least 20% by volume or more.
A metal-based substrate according to claim 1. 4. An inorganic filler having a relative dielectric constant of 50 or more is 40 or more.
A metal base substrate characterized in that an insulating adhesive material varnish containing from 80% by volume to 80% by volume is applied to copper foil, dried to produce an insulating adhesive material with copper foil, laminated with a metal plate and molded. Manufacturing method. 5. An inorganic filler having a relative dielectric constant of 50 or more is 50 or more.
After coating and drying an insulating adhesive material varnish contained so as to have a volume percentage of 80 to 80% by volume, an inorganic filler having a relative dielectric constant of 50 or more is further coated on the copper foil.
The insulating adhesive material varnish contained so as to have a volume% is applied, and the degree of curing of the insulating adhesive material layer on the side in contact with the copper foil is B or C stage, and the outermost insulating adhesive material layer not in contact with the copper foil is A method for producing a metal base substrate, comprising: preparing an insulating adhesive material sheet with a copper foil which is dried so as to form an A or B stage; and laminating and forming the sheet with a metal plate. 6. The method for manufacturing a metal-based substrate according to claim 5, wherein an epoxy resin having a molecular weight of 500 or less is at least 20% by volume in an insulating adhesive varnish serving as an outermost layer not in contact with the copper foil. A method for producing a metal-based substrate, characterized by using a varnish containing the same.