JPH07336002A - Wiring board and manufacture thereof - Google Patents

Abstract

PURPOSE:To manufacture simply and conveniently a wiring board being excellent in migration resistance by a method wherein a base is constructed of a layer formed by impregnating glass cloth with thermosetting resin and by setting it and of a layer of high-molecular-weight epoxy resin and an insulating material coming into contact with a wiring is constituted of the high-molecular-weight epoxy resin. CONSTITUTION:This wiring board is composed of a base and a wiring 4 and the base is constructed of a layer 1 formed by impregnating glass cloth with thermosetting resin and by setting it and of a high-molecular-weight epoxy resin layer 2, while an insulating material coming into contact with the wiring 4 is constituted of high- molecular-weight epoxy resin. In this wiring board, the wiring 4 may be provided on either one or both surfaces of the base and also it may be provided in one or more layers on both surfaces of the base and at least inside of it. The viscosity of the high-molecular-weight epoxy resin is very high and the fluidity thereof is low even at a temperature at the time of lamination bonding. Even when the resin is laminated adjacently to a prepreg and subjected to pressure and heat, therefore, no mutual mixing of the resin takes place and fibers of the glass cloth are prevented from coming into contact with a copper leaf.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring board having excellent migration resistance and a method for manufacturing the same.

[0002]

2. Description of the Related Art As a typical method for manufacturing a wiring board, there is a subtractive method in which wiring is formed by etching using a metal-clad laminate having a metal foil attached to an insulating base material as a starting material. In this method, wiring can be formed only by etching, and the manufacturing is easy. Further, also in the case of forming a multi-layer wiring, it can be easily formed by forming an inner layer plate which is a plurality of double-sided wiring formed products and performing multi-layer bonding through a prepreg or the like. A wiring board using a laminated plate of a base material containing a glass cloth is widely used because it can obtain high strength of the support and is relatively low in cost.

[0003]

By the way, printed wiring boards have become disadvantageous in terms of electrical insulation such as lighter, thinner, shorter and smaller, and narrower wiring intervals with the development of electronic equipment. In particular, in a place where the wiring interval is narrow, a migration phenomenon in which a metal, which is a wiring material, moves due to an electric potential occurs, and there is a problem that the insulating property is lowered. The easiness of occurrence of the migration is determined by the relationship between the wiring interval and the potential difference between the wirings. When glass cloth is used in the substrate, the migration speed at the interface is particularly high. , Is known to accelerate insulation degradation. Therefore, in the case of wirings having a certain potential difference from each other, it has been attempted that the wiring interval cannot be made too narrow and the potential difference between the wirings is taken into consideration in the design stage.

If such measures cannot be taken, measures have been taken such as plating a metal that is unlikely to cause migration, such as nickel plating, and then providing copper wiring thereon.

However, these methods reduce the merits of the subtractive method in that the degree of freedom of the wiring is lost and the wiring can be formed only by etching the metal-clad laminate.

As another method, it is conceivable not to use glass cloth or the like for the laminated plate, but not only the strength of the support is insufficient, but also in the case of a high-density wiring board, particularly important dimensional stability is impaired. There were challenges. Therefore, in order to secure the strength and dimensional stability of the support, it may be possible to use a substrate made of glass cloth or the like and provide a layer of only resin between the substrate and the metal foil. With this method, there is no glass cloth,
Although the migration resistance is improved, when a prepreg containing a glass cloth impregnated with a general resin and a metal foil provided with an uncured resin layer are laminated and bonded, the resin of the prepreg resin and the resin of the resin layer provided on the metal foil are It is mixed and cannot achieve the original purpose. To achieve the purpose, the resin layer provided on the metal foil may be pre-cured, but a resin having excellent heat resistance, such as an epoxy resin, becomes hard and brittle when cured, and when wound on a roll or There are problems that the resin layer is cracked or peeled off during handling.

It is an object of the present invention to provide a wiring board having excellent migration resistance and a method for easily manufacturing the wiring board.

[0008]

The wiring board of the present invention comprises a base material and wiring 4, and the base material is a layer 1 in which a glass cloth is impregnated and cured with a thermosetting resin and a high molecular weight epoxy resin layer 2. The insulating material in contact with the wiring is a high molecular weight epoxy resin.

In this wiring board, the wiring 4 can be provided on one side of the base material as shown in FIG. 1, and the wiring can be provided on both sides of the base material as shown in FIG. As shown in FIG. 5, the wiring may be provided on both sides and at least inside of the base material in one or more layers. The thermosetting resin with which the glass cloth used in the present invention is impregnated is preferably substantially an epoxy resin.

In order to manufacture such a wiring board, a base material composed of a layer obtained by impregnating and curing a glass cloth with a thermosetting resin, a high molecular weight epoxy resin layer, and a metal foil are bonded to each other on the side of the adhesive surface. A method including a step of laminating and adhering so as to form a high molecular weight epoxy resin layer and a step of forming wiring on the laminated plate can be used.

In order to produce a single-sided or double-sided wiring board, a high molecular weight epoxy resin film and a metal foil are pressure-heated and laminated on one or both sides of a prepreg obtained by impregnating a glass cloth with a thermosetting resin. You can form wiring on the
In order to manufacture a multilayer wiring board, a base material is composed of a glass cloth impregnated with a thermosetting resin and cured, and a high molecular weight epoxy resin layer, and a metal foil whose adhesive surface is a high molecular weight epoxy resin layer. A step of producing a laminated laminate, a step of forming wiring on the laminate, a high molecular weight epoxy resin film,
A step of laminating a high molecular weight epoxy resin layer formed on a metal foil, a material selected from prepregs, at least one or more of the above laminated plates, and a metal foil if necessary, and laminating and adhering the same; And a step of forming a wiring on the wiring, and the wiring or the metal foil is always brought into contact with the high molecular weight epoxy resin layer or the high molecular weight epoxy resin film at the time of lamination and adhesion.

Further, in the step of forming the wiring, the holes and the metalization of the hole wall can be performed to electrically connect the wirings of the respective layers. It is preferable that at least the portion that comes into contact with the glass cloth is plated with nickel as a main component because migration can be further suppressed.

Furthermore, at the time of making a hole, at least at a portion which comes into contact with the glass cloth, the hole is once filled with resin, and then a hole having a small diameter is made again,
The edge of the glass cloth is not exposed on the inner wall of the hole, which is also preferable in terms of suppressing migration.

More specifically, first, a prepreg made of glass woven cloth or glass nonwoven cloth and a thermosetting resin is prepared. The thermosetting resin is selected from heat resistance, electric characteristics, price, etc., and from the balance of these, epoxy resin is particularly suitable. The thickness is not particularly limited, and the thickness and the number of sheets may be determined according to the purpose.

Next, a metal foil with a high molecular weight epoxy resin layer, or a high molecular weight epoxy resin film and a metal foil are prepared. Generally, copper foil is suitable for the metal foil because of its electrical characteristics. The thickness is not particularly limited, but is generally 5 to 70 microns, and particularly 5 to 18 microns is suitable for forming high density wiring. As the high molecular weight epoxy resin film, a commercially available epoxy resin film AS3000 (manufactured by Hitachi Chemical Co., Ltd., trade name) can be used. When a metal foil with a high molecular weight epoxy resin layer is used, a resin varnish such as AS3000 (manufactured by Hitachi Chemical Co., Ltd.) can be used by directly coating the metal foil. The thickness of the high molecular weight epoxy resin film or the high molecular weight epoxy resin layer is preferably 10 to 50 μm because of its effect and cost.

On one or both sides of the glass cloth / resin prepreg, the above materials are laminated so as to be a high molecular weight epoxy resin and a metal foil, and they are heated and pressure-bonded to obtain a metal-clad laminate. The pressure and heating conditions when using the epoxy resin-impregnated prepreg vary slightly depending on the resin used, but the pressure is 20 to 50 kgf / cm ² , 160 to 1
70 ° C and 50 to 90 minutes are suitable. Note that this condition is an example, and is not a limitation.

In the case of a single-sided wiring board, it can be obtained by forming wiring on this metal-clad laminate. In the case of a double-sided wiring board, a wiring is formed by forming a through hole, metalizing the hole wall by plating, etching, etc. In the case of a multilayer wiring board, wiring is formed on one or more metal-clad laminates on which wiring has been formed and a laminated adhesive in which insulating layer materials are laminated. As the outermost layer, a metal-clad laminate or a metal foil may be used. As the insulating layer material, a prepreg containing glass cloth and a high molecular weight epoxy resin can be selected, but a high molecular weight epoxy resin layer is formed at least on the insulating material in contact with the wiring layer or the metal foil.

That is, the adhesive layer between wiring-formed laminated plates and the metal foil may be only a high molecular weight epoxy resin, or may be a high molecular weight epoxy resin on both surfaces of the prepreg. Incidentally, if the surface in contact with the wiring layer or the metal foil is a high molecular weight epoxy resin,
A high molecular weight epoxy resin may be included between the prepregs.

In the case of a double-sided board or a multilayer wiring board, the through hole and the interlayer connection hole can be provided by a conventional method. If the hole spacing is narrow and there is a potential difference between the holes, the metal on the hole walls will migrate at the interface between the glass cloth and the resin, and the electrical insulation will deteriorate. desirable. As one of the methods, as shown in FIGS. 3 to 5, the hole wall is plated with a metal having a low migration property. Specifically, there is plating containing nickel as a main component, and nickel plating, nickel-phosphorus plating and the like can be mentioned. Alternatively, as another method, once the holes are filled, the holes are filled with a thermosetting resin, and then the holes are made again with a slightly smaller hole diameter. You can prevent it from being exposed. By taking these measures, the migration resistance including the through holes can be easily improved.

[0020]

[Function] Since the high molecular weight epoxy resin has extremely high viscosity and low fluidity even at the time of laminating and bonding, the resins may be mixed with each other even if they are laminated next to the prepreg and heated under pressure. And the fibers of the glass cloth do not come into contact with the copper foil. Therefore, even when the wiring is formed, the wiring does not come into contact with the glass cloth.

[0021]

【Example】

Example 1 (1) A glass woven cloth / polyimide resin prepreg having a thickness of 0.1 mm, GEA-671 (manufactured by Hitachi Chemical Co., Ltd., trade name), has a 50-micron thick epoxy resin film AS3000 (Hitachi). 25 kg by stacking 18 micron thick copper foil TSTO (Furukawa Circuit Foil Co., Ltd., trade name) with Kasei Kogyo Co., Ltd. (trade name)
A laminated plate was prepared by heating under pressure under the conditions of f / cm ² , 180 ° C., 0.5 Torr, and 95 minutes. (2) An unnecessary portion of the copper foil of this laminate was removed by etching to form a circuit, and a solder resist was screen-printed to obtain a single-sided wiring board.

Example 2 (1) On both sides of 0.1 mm thick glass woven cloth / polyimide resin prepreg, GEA-671 (trade name, manufactured by Hitachi Chemical Co., Ltd.), 50 μm thick epoxy Resin film AS3000 (manufactured by Hitachi Chemical Co., Ltd.,
(Trade name) and copper foil TSTO (trade name, manufactured by Furukawa Circuit Foil Co., Ltd.) having a thickness of 18 microns are laminated to form 25
A laminated plate was prepared by heating under pressure under the conditions of kgf / cm ² , 180 ° C., 0.5 Torr, and 95 minutes. (2) A hole was made in this laminated plate, and after electroless copper plating with CUST-201 (manufactured by Hitachi Chemical Co., Ltd., trade name), a plating layer having a thickness of about 7 microns was formed using electro copper sulfate plating. . (3) After laminating Phototec H-K450 (trade name, manufactured by Hitachi Chemical Co., Ltd.), which is a photosensitive dry film having a thickness of 50 microns, it is exposed and developed to form a resist pattern for etching, and etching is performed to form wiring. Formed.

Example 3 (1) A glass woven cloth / polyimide resin prepreg having a thickness of 0.1 mm, GEA-671 (manufactured by Hitachi Chemical Co., Ltd., trade name), was coated with a 50 micron thick epoxy resin film. 25 kg by stacking AS3000 (Hitachi Chemical Co., Ltd., trade name) and 18 micron thick copper foil TSTO (Furukawa Circuit Foil Co., Ltd. trade name)
F / cm ² , 180 ℃, 0.5 Torr, pressurize and heat under conditions of 95 minutes to create a laminated board, remove unnecessary portions of the copper foil by etching, and three inner layer circuit boards with different wiring patterns Was formed. (2) The three inner-layer circuit boards and two 50-micron-thick epoxy resin films AS3000 (manufactured by Hitachi Chemical Co., Ltd., trade name) are alternately laminated, and the outermost layer has two thicknesses. 50 micron epoxy resin film AS300
0 (manufactured by Hitachi Chemical Co., Ltd., product name) is stacked, and two 18-micron-thick copper foil TSTOs are further placed on the outside.
(Furukawa Circuit Foil Co., Ltd., trade name) is overlaid, 25 kgf / cm ² , 180 ° C., 0.5 Torr,
A laminated plate was prepared by heating under pressure for 95 minutes. (3) A hole was made in this laminated plate, and after electroless copper plating with CUST-201 (Hitachi Chemical Co., Ltd., trade name), a plating layer having a thickness of about 7 microns was formed using electro copper sulfate plating. . (4) Phototec H-K450 (trade name, manufactured by Hitachi Chemical Co., Ltd.), which is a photosensitive dry film having a thickness of 50 microns, is laminated, exposed and developed to form a resist pattern for etching, and etching is performed to form wiring. Formed.

Example 4 (1) A glass woven cloth / polyimide resin prepreg having a thickness of 0.1 mm, GEA-671 (trade name, manufactured by Hitachi Chemical Co., Ltd.), and an epoxy resin film having a thickness of 50 μm were used. 25 kg by stacking AS3000 (Hitachi Chemical Co., Ltd., trade name) and 18 micron thick copper foil TSTO (Furukawa Circuit Foil Co., Ltd. trade name)
F / cm ² , 180 ℃, 0.5 Torr, pressurize and heat under conditions of 95 minutes to create a laminated board, remove unnecessary portions of the copper foil by etching, and three inner layer circuit boards with different wiring patterns Was formed. At this time, a hole with a diameter of 0.5 mm was previously drilled in the prepreg,
An epoxy resin film is filled inside the hole. (2) MUS020 (manufactured by Mitsubishi Materials Co., Ltd.), which is a 0.2 mm diameter drill in the hole formed in the prepreg, which is filled with resin in the previous pressure and heating step.
After making a hole under the conditions of 80 krpm, feed speed of 1.5 m / min, and stacking of 5 substrates, Fotec H-K4 which is a photosensitive dry film with a thickness of 50 μm.
After laminating 50 (manufactured by Hitachi Chemical Co., Ltd., trade name), exposure and development were carried out to form a resist pattern for etching, and etching was performed to form wiring to form three inner layer circuit boards. (3) These three inner-layer circuit boards and two 50-micron-thick epoxy resin films AS3000 (manufactured by Hitachi Chemical Co., Ltd., trade name) are alternately laminated, and the outermost layer also has two thicknesses. 50 micron epoxy resin film AS300
0 (manufactured by Hitachi Chemical Co., Ltd., product name) is stacked, and two 18-micron-thick copper foil TSTOs are further placed on the outside.
(Furukawa Circuit Foil Co., Ltd., trade name) is overlaid, 25 kgf / cm ² , 180 ° C., 0.5 Torr,
A laminated plate was prepared by heating under pressure for 95 minutes. (4) A hole was made in this laminated plate, and after electroless copper plating with CUST-201 (manufactured by Hitachi Chemical Co., Ltd., trade name), a plating layer having a thickness of about 7 microns was formed using electro copper sulfate plating. . (5) Phototec H-K450 (trade name, manufactured by Hitachi Chemical Co., Ltd.), which is a photosensitive dry film having a thickness of 50 μm, is laminated, exposed and developed to form a resist pattern for etching, and wiring is performed by etching. Formed.

(Test) (1) Electrolytic Corrosion Test Under conditions of 85 ° C. and 85% RH, a voltage of DC 100 V was applied with a gap of 0.5 mm (hole wall interval was 0.2 mm).
It was applied between the through-holes opened at, and the time when the connection resistance became 10 6 ohm or less was examined. as a result,
In the substrates of all the examples, the insulation did not deteriorate even after 500 hours.

(2) Connection reliability As a result of a thermal shock test (alternate repetition of 125 ° C./30 minutes and −65 ° C./30 minutes), in each of the examples, 300
It was found that the change rate of the connection resistance after the cycle was 10% or less and there was no abnormality.

(3) Heat resistance As a result of being floated in a solder bath at 260 ° C. for 30 seconds, it was found that there was no abnormality such as peeling in any of the examples.

[0028]

According to the present invention, a wiring board having excellent migration resistance can be provided at low cost.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view showing another embodiment of the present invention.

FIG. 3 is a sectional view showing still another embodiment of the present invention.

FIG. 4 is a sectional view showing an aspect of still another embodiment of the present invention.

FIG. 5 is a cross-sectional view showing another aspect of still another embodiment of the present invention.

Claims (12)

[Claims] 1. A base material and wiring, a base material comprising a layer obtained by impregnating and curing a glass cloth with a thermosetting resin and a high molecular weight epoxy resin layer, and the insulating material in contact with the wiring is a high molecular weight epoxy resin. A wiring board characterized by being present. 2. The wiring board according to claim 1, wherein the wiring layer is provided on one surface of the base material portion. 3. The wiring board according to claim 1, wherein wiring layers are provided on both sides of the base material portion. 4. The wiring board according to claim 1, wherein one or more wiring layers are provided on both sides and at least inside of the base material portion. 5. The wiring board according to claim 1, wherein the thermosetting resin with which the glass cloth is impregnated is substantially an epoxy resin. 6. A base material comprising a layer obtained by impregnating and curing a glass cloth with a thermosetting resin and a high molecular weight epoxy resin layer, and a metal foil are laminated so that the adhesive surface side becomes the high molecular weight epoxy resin layer. A method of manufacturing a wiring board, comprising a step of adhering and a step of forming wiring on the laminated board. 7. A wiring is formed by pressing and heating a high molecular weight epoxy resin film and a metal foil on one side or both sides of a prepreg obtained by impregnating a glass cloth with a thermosetting resin, and laminating and integrating them. The method for manufacturing a wiring board according to claim 6. 8. A metal-clad laminate comprising a glass cloth impregnated with a thermosetting resin and cured, and a high molecular weight epoxy resin layer, the adhesive side of which is a high molecular weight epoxy resin layer. A manufacturing step, a step of forming wiring on the laminate, a high molecular weight epoxy resin film, a high molecular weight epoxy resin layer formed on a metal foil, a material selected from prepregs, and at least one or more of the laminates And a metal foil, if necessary, and a step of laminating and laminating, and a step of forming wiring on the laminating adhesive, and at the time of laminating and adhering, the wiring or the metal foil must be made of a high molecular weight epoxy resin. A method for manufacturing a wiring board, wherein the layer or the high molecular weight epoxy resin film is configured so as to be in contact with each other. 9. The method for manufacturing a wiring board according to claim 6, wherein in the wiring forming step, a hole is formed and the hole wall is metallized. 10. The plating containing nickel as a main component is formed at least in a portion in contact with the glass cloth when the hole is formed and the wall of the hole is metallized.
The method for manufacturing a wiring board according to. 11. The method of forming a hole, wherein at least at a portion in contact with the glass cloth, the hole is once made, resin filling is performed, and then a hole having a small diameter is made again.
The method for manufacturing a wiring board according to. 12. The method for manufacturing a wiring board according to claim 6, wherein the metal foil is a copper foil.