JPH08332696A - Metal member fitted with insulating adhesive material and production thereof - Google Patents

Abstract

PURPOSE: To form an adhesive layer good in the uneven embedding properties of a circuit conductor when bonded to a circuit board and improving the insulating properties between the circuit conductor and a metal member after bonding on the surface of the radiation metal member of the circuit board. CONSTITUTION: In a metal member having an insulating adhesive layer formed on the surface thereof, the flowability of the insulating adhesive layer is made low on the side of the metal member and large on the surface side thereof. This insulating adhesive layer is obtained by a method wherein an adhesive sheet is obtained by applying an adhesive large in flowability at a time of bonding work to a sheet like support and applying an adhesive low in flowarbility at the time of bonding work thereon and laminated to the surface of the metal member so that the adhesive layer comes into contact with the metal member or a method wherein an adhesive sheet obtained by applying an adhesive to the sheet like support is laminated to the surface of the preheated metal member so that the adhesive layer comes into contact with the metal member.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal body with an insulating adhesive material and a method for manufacturing the same.

[0002]

2. Description of the Related Art As electric equipment becomes smaller and has higher performance, the mounting density of electronic parts becomes higher, and a means for dissipating heat generated from these electronic parts is required. As a means for dissipating heat generated from an electronic component, there is one in which a metal body is bonded to the entire surface or a part of the heat source. In addition,
The heat generation source is meant to include not only an element that directly becomes a heat source during operation, but also a semiconductor element package, a printed board on which electronic components are mounted, and the like. As the metal body, aluminum, copper, 42 alloy (known as an alloy having a low coefficient of thermal expansion) or the like having good heat dissipation is used.

The metal body and the heat source are bonded together by using an insulating adhesive material such as glass epoxy prepreg or an insulating adhesive material containing acrylic rubber as a main component. In order to simplify the work of adhering the metal body and the heat source, it has been proposed to previously form an insulating adhesive layer in a B stage on the surface of the metal body.

[0004]

In the method using the insulating adhesive material, 1) the surface treatment of the metal body needs to be performed immediately before the adhesion, and the process is complicated, and 2) the insulating adhesive material sheet and the metal plate are used respectively. It is necessary to perform punching into a desired shape and alignment during lamination. 3) Glass epoxy prepreg and adhesive sheet have insufficient heat dissipation. There were problems such as.

If a B-staged insulating adhesive layer is formed on the metal body in advance, such a problem can be solved. However, in order to form the B-staged insulating adhesive layer, a step of printing and drying the insulating adhesive material is performed, but when the insulating adhesive material is printed on the metal body, bubbles remain. However, there is a serious problem that the insulation characteristics are deteriorated. Further, a printed circuit is often formed on the surface of the heat source, and there is a recess between the circuit conductors. In order to fill this recess, the fluidity of the adhesive must be increased. If so, the flow of too much at the time of bonding cannot maintain a space required for insulation between the circuit conductor and the metal body, and insulation reliability cannot be maintained. An object of the present invention is to improve the insulating property of a metal body in which a B-staged insulating adhesive layer is formed on the surface of the metal body in advance.

[0006]

DISCLOSURE OF THE INVENTION The present invention provides a metal body having an insulating adhesive layer formed on the surface thereof, wherein the metal body side of the insulating adhesive layer has low fluidity and the surface side has high fluidity. Is.

Next, a method of forming the insulating adhesive layer will be described. The first is a method of laminating an adhesive sheet obtained by applying an adhesive on a sheet-shaped support so that the adhesive layer is in contact with the metal body on the surface of the metal body that has been heated in advance. When the metal body and the insulating adhesive layer are laminated, since the metal body is heated in advance, the side of the insulating adhesive layer to be laminated that is in contact with the metal body is heated, and the surface side is cooled. Curing of the contacting side proceeds from the surface side, and the metal body side of the insulating adhesive layer can have low fluidity and the surface side can have high fluidity. In this method, two insulating adhesive layers are used.
It is not necessary to apply the coating in layers, which is advantageous in terms of process.
The heating temperature of the metal body is preferably 130 to 200 ° C. When the temperature of the metal body is high, the number of layers having high fluidity decreases, and conversely, the number of layers having low fluidity decreases.

The second method of forming an insulating adhesive layer was obtained by applying an adhesive varnish having a high fluidity onto a sheet-shaped support and then applying an adhesive varnish having a low fluidity thereon. This is a method of laminating an adhesive sheet on the surface of a metal body so that the adhesive layer is in contact with the metal body. By doing so, the insulating adhesive material can be laminated by a continuous laminating process such as a hot roll laminator, and the metal body with the insulating adhesive material can be stably manufactured.

As the adhesive, an epoxy resin type, a polyimide resin type, a phenol resin type or the like can be used. It is preferable to add a flexibility imparting component to the adhesive composition. Examples of the flexibility-imparting component include a polymer substance having a good electric insulation property, such as a high molecular weight epoxy resin, an ultra high molecular weight epoxy resin, an acrylic rubber, NBR, an epoxy modified acrylic rubber, an epoxidized polybutadiene, and a phenoxy resin. These may be used alone or in combination of two or more.

Further, in order to improve the adhesiveness to the circuit conductor, it is preferable to add a silane coupling agent such as epoxysilane, aminosilane, ureasilane or the like. Examples of such coupling agents include γ-glycidoxypropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β-aminoethyl-γ-aminopropyltrimethoxysilane, and the like. Is mentioned.

To increase fluidity, a bisphenol A type or bisphenol F type epoxy resin having a molecular weight of 500 or less is contained. The curing agent for the epoxy resin is not particularly limited, but a curing agent having a long varnish life and high potential is desirable. As this example, one or more kinds of tertiary amine, acid anhydride, imidazole compound, polyphenol resin, masked isocyanate and the like can be used.

Further, it is preferable to add imidazoles as a curing accelerator. Examples of such imidazoles include 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-phenylimidazolium trimellitate and the like.

In order to improve heat dissipation, an inorganic filler having a high thermal conductivity is added to the adhesive. Examples of the inorganic filler suitable for this purpose include alumina powder, aluminum nitride powder, and boron nitride powder. The blending amount of the inorganic filler needs to be 10 to 60% by volume of the total adhesive. 1
If it is less than 0%, the effect of improving heat dissipation is small, so that it is unsuitable, and if it is added in excess of 60%, the flexibility of the adhesive sheet, the adhesiveness, and the withstand voltage due to the remaining voids may decrease. It is inappropriate because it occurs. Further, one or more kinds of short fibrous inorganic substances may be added for the purpose of adjusting fluidity and improving crack resistance.

A bar coater, a lip coater, a roll coater and the like can be used as a method for applying an adhesive to a sheet-like support, but if the method has few defects such as craters and voids and the coating film thickness can be applied almost uniformly, Any method will do.

The method for forming the two-layer insulating adhesive material on the sheet-like support is as follows. An insulating adhesive material was applied as the first layer of the coating film on the sheet-like support, and this was in a B stage state (a state in which it was slightly cured and gelled, and the heat generation of 20 to 60% of the total curing heat value was completed. Heat curing to A second layer of coating film is applied on this, and this is
(It is in a state that it is almost uncured and has not gelled, and the heat generation of 0 to 20% of the total amount of heat generated for curing has been completed) or it is heat-cured to the B stage state.

The insulating adhesive material needs to have a certain thickness so that it can fill the irregularities of the adherend such as a single-sided or double-sided wiring board. If the film thickness is too thick,
It is not preferable because the thermal resistance increases. The thickness of the insulating adhesive material required to fill the 35 μm circuit is usually 70
˜120 μm is preferable, and for filling a 70 μm circuit, 120 to 210 μm is preferable.

The insulating adhesive material thus obtained is laminated on a metal body and heated and pressed to be integrated. For this, a hot roll laminator, a vacuum laminator, a press, a vacuum press or the like can be used. The use of a hot roll laminator is preferable in that stacking can be continuously performed at low cost as compared with the case of using a press. In this case, the curing degree of the insulating adhesive material after the insulating adhesive material is laminated needs to be in the A or B stage.

The obtained metal plate with an insulating adhesive material is suitable for the following uses. That is, the metal plate with insulating adhesive material is punched, punched, etc., if necessary,
This is laminated with a single-sided or double-sided copper circuit laminated board, or a multilayer wiring board, a copper foil, a copper plate, a semiconductor chip, a semiconductor package, and the insulating adhesive material is cured. This makes it possible to obtain a wiring board, a semiconductor package, and the like that have excellent heat dissipation and adhesion.

Before forming the insulating adhesive layer on the surface of the metal body, it is preferable to perform a surface treatment in order to improve the adhesion of the insulating adhesive material. The processing method will be described below.

When using an aluminum plate. 1. Polish the surface. 2. Degrease (wash with hot water at about 70 ° C.). 3. Apply the coupling agent to the surface. 4. dry.

When using a copper plate. 1. Polish the surface. 2. Degrease by washing with an aqueous solution of sulfuric acid, an aqueous solution of ammonium persulfate, an aqueous solution containing copper chloride and hydrochloric acid. 3. Oxidize the surface. 4. The copper oxide formed on the surface is chemically reduced. 5. Apply the coupling agent to the surface. 6. dry.

When using 42 alloy. 1. Polish the surface. 2. Wash and degrease in an aqueous solution of sulfuric acid, an aqueous solution of ammonium persulfate, and an aqueous solution containing copper chloride and hydrochloric acid. 3. Apply the coupling agent to the surface. 4. dry.

It is desirable to laminate the insulating adhesive material within 24 hours after the surface treatment. Desirably, it is desirable to laminate the insulating adhesive material immediately after the treatment.

[0024]

The layer having low fluidity secures the thickness of the insulating adhesive layer, and the layer having high fluidity fills the gap of the circuit pattern. Thus, it is possible to improve the embeddability of the inner layer circuit of the wiring board and to secure the insulation reliability between the inner layer circuit and the metal base substrate. Further, by reducing the film thickness of the insulating adhesive material, the effect of lowering the insulation reliability due to coating film defects such as voids, craters, and inclusion of foreign matter can be expected more.

[0025]

【Example】

Preparation of adhesive varnish A 60 parts of bisphenol A type epoxy resin having an epoxy equivalent of 210 (weight part, the same applies hereinafter), 20 parts of phenoxy resin,
30 parts of phenol novolac, 1-cyanoethyl-2-
0.5 part of phenylimidazole, 2 parts of γ-glycidoxypropyltrimethoxysilane and 130 parts of alumina were kneaded in a solvent.

Preparation of Adhesive Varnish B 50 parts of bisphenol A type epoxy resin having an epoxy equivalent of 210, 20 parts of bisphenol A type epoxy resin having an epoxy equivalent of 1750, 40 parts of phenoxy resin, 30 parts of phenol novolac, 1-cyanoethyl-2-phenyl 0.5 parts of imidazole, 2 parts of γ-glycidoxypropyltrimethoxysilane and 230 parts of alumina were kneaded in a solvent.

Preparation of adhesive varnish C 60 parts of bisphenol A type epoxy resin having an epoxy equivalent of 1750, 40 parts of phenoxy resin, 15 parts of phenol novolac, 0.5 part of 1-cyanoethyl-2-phenylimidazole, γ-glycidoxypropyl 2 parts of trimethoxysilane and 130 parts of alumina were kneaded in a solvent.

Example 1 A varnish A was applied as a first layer to a polyester film so that the film thickness after drying was 70 μm, and dried at 110 ° C. for 10 minutes. The film thickness after drying is 7 on the first layer.
Varnish A was applied again to 0 μm and dried at 110 ° C. for 10 minutes. The surface was polished and an aluminum plate having γ-glycidoxypropyltrimethoxysilane attached thereto was placed on a hot roll laminator (linear pressure 98 N / cm, linear pressure 98 N / cm, so that the second layer of the insulating adhesive material sheet was in contact with the surface of the aluminum plate. The layers were laminated at 120 ° C. and a pressing time of 1.5 seconds). The polyester film was peeled from the aluminum plate, and the glass-epoxy double-sided circuit board (copper foil thickness 35 μm, base material thickness 200 μm) on which a circuit was formed was overlaid and heated and pressed at 170 ° C. and 3 MPa for 1 hour.

Example 2 A polyester film was coated with an adhesive varnish A as a first layer so that the film thickness after drying was 80 μm.
It was dried at 0 ° C. for 10 minutes. On the first layer, as the second layer, the film thickness after drying is 200 μm in total for the first layer and the second layer.
Adhesive varnish B is applied so that
Dry for 0 minutes. The surface of the aluminum plate was polished and γ-glycidoxypropyltrimethoxysilane was adhered to the aluminum plate. A hot roll laminator (line pressure 9) was used so that the second layer of the insulating adhesive material sheet was in contact with the surface of the aluminum plate.
The layers were laminated at 8 N / cm, 120 ° C., and a pressing time of 1.5 seconds). The polyester film was peeled from the aluminum plate, and the glass-epoxy double-sided circuit board (copper foil thickness 70 μm, base material thickness 200 μm) on which a circuit was formed was overlaid and heated and pressed at 170 ° C. and 3 MPa for 1 hour.

Example 3 A polyester film was coated with an adhesive varnish A as a first layer so that the film thickness after drying was 80 μm.
It was dried at 0 ° C. for 10 minutes. On the first layer, as the second layer, the film thickness after drying is 200 μm in total for the first layer and the second layer.
Adhesive varnish C is applied so that
Dry for 0 minutes. The surface of the aluminum plate was polished and γ-glycidoxypropyltrimethoxysilane was adhered to the aluminum plate. A hot roll laminator (line pressure 9) was used so that the second layer of the insulating adhesive material sheet was in contact with the surface of the aluminum plate.
The layers were laminated at 8 N / cm, 120 ° C., and a pressing time of 1.5 seconds). The polyester film was peeled from the aluminum plate, and the glass-epoxy double-sided circuit board (copper foil thickness 70 μm, base material thickness 200 μm) on which a circuit was formed was overlaid and heated and pressed at 170 ° C. and 3 MPa for 1 hour.

Example 4 A polyester film was coated with an adhesive varnish A so that the film thickness after drying was 100 μm, and the film was dried at 110 ° C. for 20 minutes.
Dried for minutes. The surface is polished, γ-glycidoxypropyltrimethoxysilane is attached, and the aluminum plate preheated to a surface temperature of 150 ° C. is hot-rolled so that the adhesive layer of the insulating adhesive material sheet is in contact with the aluminum plate surface. Laminator (Line pressure 98N / cm, 12
The layers were laminated at 0 ° C. and a pressing time of 1.5 seconds). The polyester film was peeled off from this aluminum plate, and the circuit-formed glass-epoxy double-sided circuit board (copper foil thickness 70μ
m, substrate thickness 200 μm) and 170 ° C., 3 MPa
It was heated and pressed for 1 hour.

Comparative Example 1 The surface of the aluminum varnish was abraded, and γ-glycidoxypropyltrimethoxysilane was attached to the aluminum plate. Screen printing of the adhesive varnish A was performed at 110 ° C. so that the film thickness after drying was 70 μm. And dried for 10 minutes. This aluminum plate was laminated on a circuit-formed glass-epoxy double-sided circuit board (copper foil thickness 70 μm, base material thickness 200 μm), and 17
It was heated and pressed at 0 ° C. and 3 MPa for 1 hour.

Comparative Example 2 Varnish A was applied to a polyester film so that the film thickness after drying was 200 μm, and dried at 110 ° C. for 20 minutes. The surface of the aluminum plate was polished and γ-glycidoxypropyltrimethoxysilane was attached to the aluminum plate so that the adhesive layer of the insulating adhesive material sheet was in contact with the surface of the aluminum plate.
m, 120 ° C., pressure time 1.5 seconds). This aluminum plate was placed on a circuit-formed glass-epoxy double-sided circuit board (copper foil thickness 70 μm, base material thickness 200 μm) and heated and pressed at 170 ° C. and 3 MPa for 1 hour.

With respect to the multilayer wiring board produced as described above, withstand voltage, withstand voltage failure rate, pattern embedding property, surface smoothness and solder heat resistance (260 ° C.) were examined. Table 1 shows the results.

[0035]

[Table 1] ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Item Item Example 1 Example 2 Example 3 Example 2 ────────────────────────────────── Withstanding voltage (kV) 5.6 6.6 6.0 6 2.2 Failure withstanding voltage ratio (%) 1.8 1.8 1.3 1.2 Pattern embedding property Good Good Good Good Surface smoothness Good Good Good Good Solder heat resistance (s) 180 or more 180 or more 180 or more 180 or more ━ ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ Item Comparative Example 1 Comparative Example 2 ────────── ──────────── Withstand voltage (kV) 3.4 4.4 Withstand voltage defect rate (%) 5.8 4.8 Pattern embedding property is good Defective surface smoothness is good Defective solder heat resistance ( s) 5 6 ━━━ ━━━━━━━━━━━━━━━━━━

From Table 1, it is understood that the multilayer wiring board according to the example of the present invention is superior to the multilayer wiring board of the comparative example in terms of pattern embedding property, surface smoothness, solder heat resistance and the like.

The test method is as follows. Withstand voltage: At 25 ° C., an AC voltage is applied between the upper circuit and the base aluminum plate. Starting from 0V, 100V / s
The voltage is increased at the speed of 1 and the withstand voltage is the voltage when a current of 1 mA flows. Insufficient withstand voltage ratio: The ratio of withstand voltage of 3 kV or less. Pattern embedding property: The presence or absence of voids having a diameter of more than 10 μm is observed with a microscope between the lower layer copper foil and the insulating adhesive material. With voids: bad, without voids: good. Surface smoothness: The unevenness of the copper foil circuit exposed on the surface of the wiring board was measured by a surface roughness meter, and the unevenness of more than 20 μm was evaluated as bad and the unevenness of 20 μm or less was evaluated as good. Solder heat resistance: Samples cut in 25 mm square are 2
Measure the time to float, blister, and peel off in a 60 ° C solder bath.

[0038]

EFFECTS OF THE INVENTION In a heat-dissipating metal body of a circuit board, the surface conductor has good embedding of irregularities in the circuit conductor when it is bonded to the circuit board, and good insulation between the circuit conductor and the metal body after bonding. Can form an excellent adhesive layer.

Claims (3)

[Claims] 1. A metal body having an insulating adhesive layer formed on the surface thereof, wherein the metal body side of the insulating adhesive layer has low fluidity and the surface side has high fluidity. 2. An adhesive sheet obtained by applying an adhesive onto a sheet-shaped support is laminated on a surface of a metal body which has been heated in advance such that the adhesive layer is in contact with the metal body. Of manufacturing a metal body with an insulating adhesive material. 3. An adhesive obtained by coating a sheet-shaped support with an adhesive having a high fluidity during the bonding operation and then applying an adhesive having a low fluidity during the bonding operation on the sheet-shaped support. Sheet,
A method for producing a metal body with an insulating adhesive material, comprising laminating an adhesive layer on the surface of a metal body so as to be in contact with the metal body.