JPS592397B2 - Manufacturing method for wiring boards using insulated wires in the required wiring pattern - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a flame-retardant high-density wiring board using insulated wires for necessary wiring patterns.

Manufacturing methods for printed wiring boards include the saputracto method, in which unnecessary copper parts of copper-clad laminates are dissolved and removed using chemicals to form wiring patterns, and the wiring is deposited with electroless plating on the necessary parts of non-copper-clad laminates. There are additive methods for forming patterns. In both of these methods, the wiring is formed on a plane, so it is not possible to cross the wiring on the same plane.For crossing wiring, different planes are used and through holes are provided between the plane layers, and the through holes are filled with electroless plating etc. Since interlayer connections are made using a gold layer, it is difficult to increase the density of wiring patterns. To improve these shortcomings, we have created a high-density wiring board suitable for high-mix, low-volume production by providing an adhesive layer on an insulating substrate and wiring the wires by holding them in the adhesive layer (hereinafter referred to as multi-wire wiring board). Hitachi Chemical Co., Ltd. (product name)).

This type of multi-wire wiring board uses a thermosetting adhesive that maintains thermoplasticity when bonding (wiring) the wires to an insulating substrate such as a thermosetting resin laminate. Using a numerically controlled wiring machine, wire an insulated wire coated with heat-resistant resin such as polyimide resin onto the material laminated or coated with the agent, fix the wiring wire with a press, etc., and cross the wire at the end of the wire. The through hole is raised, the cut end of the wire is exposed on the peripheral wall of the through hole, and an electroless plating metal layer is formed on the inner wall of the through hole to connect to the cut end of the wire.

Multi-wire wiring boards use insulated wires, so they have high insulation even when the wiring intersects or is placed in close parallel, making it suitable for high-density wiring. Adhesives used for multi-wire wiring boards are thermally softened when heated, making it easy to embed wires under pressure, and immediately solidified when air-cooled to fix wires, while hardening when heated and pressurized in the post-process. A rubber-based thermosetting adhesive (for example, trade name HA-05 manufactured by Hitachi Chemical Co., Ltd.) is used to improve heat resistance, electrical properties, and the like.

This adhesive contains a plating catalyst necessary for electroless plating on the inner walls of through holes, etc. Adhesive is 1
Not only is it formed on an insulating substrate to a thickness of 00 μm or more, but it is also usually laminated on an insulating substrate in the form of an adhesive sheet containing glass cloth as shown in the drawing. The glass cloth 1 also has the function of preventing the wires from penetrating too deeply and coming into close contact with the circuits on the board when embedding the wires. The adhesive sheet is made by impregnating glass cloth with adhesive and then coating the surface with a thickness necessary for embedding the wire (100μ or more for hard cedar) and the thickness necessary for adhering it to the insulating substrate side. (approximately 50μ in solid form). Printed wiring boards are used to miniaturize electrical equipment, etc.
Although densities have been increased to improve performance, the demand for improved flame retardancy (71J) has also increased.

The insulating substrate is usually of a flame-retardant type, but in the case of multi-wire wiring boards, the flame resistance of the adhesive layer and wiring adhesive sheet bonded to the surface of the insulating substrate has a significant effect. That is, in the case of an adhesive layer of 100μ or more on both sides of the insulating substrate and a wiring adhesive sheet, a thickness of 100μ of the adhesive layer for wiring
This is because a thick bonding layer of about 150 microns in total, which is 50 microns of adhesive layer for adhesion to the insulating substrate, is introduced. The simplest countermeasure is to make the internal combustible adhesive layer thinner. For example, if the thickness of the adhesive layer for wiring is halved by 100μ, the flame retardance will certainly be improved, but this will increase the number of wiring errors in which the wires become misaligned or removed from their predetermined positions, which is impractical. In addition, the use of halogen-based materials and antimony trioxide, which is commonly used, makes the adhesive layer hard, which results in insufficient heat softening properties with ultrasonic waves during wiring, and the way the wire is buried becomes opaque. This will result in a wiring error.

The present invention has been made in view of the above points, and involves forming an adhesive layer on an insulating substrate, placing insulated wires on the adhesive layer, and simultaneously bonding them to form a wiring pattern. In the manufacturing method of wiring boards that uses insulated wires for the necessary wiring pattern, which involves drilling through holes across the holes and metallizing the insides of the through holes, synthetic rubber, which is solid at room temperature, is used as the adhesive constituting the adhesive layer. 30 to 70% by weight of synthetic rubber mixed with synthetic rubber that is liquid at room temperature, and 70% by weight of thermosetting resin.
It is characterized by using an organic component having a halogen content of 5% by weight or more and a halogen content of 5% by weight or more. In other words, in the present invention, a halogen compound is introduced into the organic component constituting the adhesive in order to make it flame retardant, so the adhesive becomes hard and the heating ability of the wire wiring machine due to ultrasonic waves is reduced by the adhesive layer being This problem was solved by introducing a synthetic rubber that is a mixture of synthetic rubber that is solid at room temperature and synthetic rubber that is liquid at room temperature. be.

As the halogen compound for making the organic component of the adhesive flame retardant, compounds such as bromine and chlorine are used, and bromine is particularly suitable.

Reactive type brominated epoxy resins, brominated vinylphenol resins, and the like are preferred in terms of electrical properties, soldering heat resistance, and the like.
If the halogen content is less than 5% by weight, the desired flame retardant grade will not be achieved. For example, aluminum hydroxide may be used in combination as an optical filler. Antimony trioxide, which is often used as a flame retardant aid, acts as a chemical plating inhibitor when the amount is increased, so it cannot be applied in large enough quantities to be more effective than aluminum hydroxide. The greater the amount of halogen compound added, the better the flame retardancy will be, but if too much is added, it will be unfavorable in terms of cost and the electrical properties will deteriorate. It is meaningless to add more than 15% by weight.

When a halogen compound is introduced into the adhesive in this way, the adhesive becomes hard and a problem arises in the wiring properties of the wire by ultrasonic heating. That is, although wiring is carried out in a predetermined pattern, the wire embedding depth decreases due to insufficient softening, and the number of defective points per number of wire intersections is considered to be a wiring error, and correction after the fact is not preferable. As a countermeasure to these problems, we investigated the use of synthetic rubber that is a mixture of synthetic rubber that is solid at room temperature and synthetic rubber that is liquid at room temperature, and found that the adhesive strength was greatly improved and wiring errors were significantly reduced. I understood.

The liquid rubber undergoes vulcanization of the phenol resin, etc. in the curing process (160 to 170° C., about 1 hour) after wiring, and does not cause any problems. If the amount of synthetic rubber is less than 30% by weight in the organic composition, the adhesion to the wire will decrease, and if it exceeds 70% by weight, it will become too soft and the soldering heat resistance will deteriorate.

Since the adhesive also serves as a base for chemical plating, acrylonitrile-butadiene rubber is preferred as the main synthetic rubber component in terms of adhesion to chemically plated copper. The synthetic rubber that is liquid at room temperature is preferably added in an amount of 5 to 40% by weight based on the total synthetic rubber.

If it is less than 5% by weight, it will not be very effective;
If it exceeds % by weight, the adhesion of the dried adhesive sheet will deteriorate and workability will deteriorate.

Phenol resins and epoxy resins are mainly used as thermosetting resins. Addition of epoxy resin improves electrical properties, but if it exceeds 40% by weight in the thermosetting resin, solder heat resistance deteriorates. If the amount is less than 10% by weight, the effect of use will not be achieved.

As the phenol resin, it is best to use alkyl phenol resin and self-crosslinking noporak type phenol resin in combination.
Alkylphenol resin is effective in improving adhesive strength, and noporak type resin is effective in improving soldering heat resistance.

In order to improve the cohesive force of the adhesive at high temperatures and prevent tackiness, optical fillers such as aluminum hydroxide, zirconium silicate, zirconium oxide, silica, and talc can be used.

If it exceeds 70 parts by weight per 100 parts by weight of the organic component, it will become hard and the wireability will deteriorate, and if it is less than 2 parts by weight, the effect of use will be small. In addition, a plating catalyst such as palladium is appropriately added to serve as a plating base. As an adhesive layer, the first adhesive layer in which 4 insulated wires are embedded, ◎Glass cloth for reinforcement, O
When using an adhesive sheet composed of a second adhesive layer for adhesion to an insulating substrate, the reinforcing glass cloth should be one impregnated with 25±10% by weight of flame-retardant epoxy resin;
Alternatively, by impregnating 15±10% of the adhesive of the present invention thereon, wire wiring properties and electrical characteristics are improved.

Example 1 Acrylonitrile-butadiene rubber (Nippon Zeon 9
28 parts (parts by weight, the same applies hereinafter) of liquid acrylonitrile-butadiene rubber (manufactured by Kogyo Co., Ltd., trade name Nipol 1032)
Product name Hytanol 2501) 1 manufactured by Nippon Zeon Industries Co., Ltd.
0 parts, thermosetting ferer resin (trade name SP-6600 manufactured by Schenectaday Chemical Co., Ltd.) 10 parts, brominated polyparavinylphenol resin (trade name Resin MB manufactured by Maruzen Oil Industries Co., Ltd., bromine content 500!)) 10 parts of brominated epoxy resin (trade name: DER542, manufactured by Gu Co., Ltd., bromine content: 500 tons), 22 parts of zirconium silicate, and 3 parts of Metsuki catalyst (trade name: PEC-8, manufactured by Hitachi Chemical Co., Ltd.) were added to cellosolve. An adhesive was prepared by dissolving and dispersing it in acetate.

The bromine content is 1001). After applying this adhesive to a release polypropylene film and drying it, apply a flame-retardant epoxy resin (trade name: VE-627 manufactured by Hitachi Chemical Co., Ltd.) to a 96 g/M3 glass cloth so that the resin impregnation amount is 25%.
NC), dried at 150℃ for 10 minutes, further impregnated with adhesive to approximately 15%, dried at 150℃ for 10 minutes, and laminated on resin-impregnated glass cloth, as shown in the drawing. An adhesive sheet was created.

The thickness of the adhesive was 140 μm on the surface where the wire was embedded, and 50 μm on the surface to be bonded to the insulating substrate. This adhesive sheet was used as an insulating substrate (manufactured by Hitachi Chemical Co., Ltd., product name E-168, 0).
．． Laminate 1 on 8 [1m thick], wiring mistake when fixing the wire with the wiring machine, peeling strength of the wire, and Audora prepreg meat (trade name: GEA-168N, manufactured by Hitachi Chemical Co., Ltd.) .0.12 thickness) with 177
℃, press at 25k9/CT[i for 30 minutes, 16'C
After curing for 2 hours, a flammability test was conducted.

These test results are summarized in the attached table. Example 2 In Example 1, Hytanol 2501 was changed to 15 parts, Resin MB was changed to 5 parts, and zirconium silicate (Showa Denko Kogyo Co., Ltd.) was added.
The bromine content of an adhesive prepared by adding 30 parts of Hygilite H-42) manufactured by Co., Ltd. (trade name) was 5.5%.

Thereafter, a multi-wire wiring board was created in the same manner as in Example 1. Its characteristics are shown in the attached table. Comparative Example 1 35 parts of acrylonitrile-butadiene rubber (trade name Hiker 1032, manufactured by Nippon Synthetic Rubber Co., Ltd.), alkylphenol resin for rubber vulcanization (trade name S, manufactured by Schenectady Chemical Co., Ltd.)
15 parts of P-126, 15 parts of thermosetting phenolic resin (trade name SP-6600, manufactured by Schenectaday Chemical Company), 15 parts of epoxy resin (Epi J Mete 100, manufactured by Schiel Chemical Company)
1) An adhesive was prepared by dissolving and dispersing 10 parts of zirconium silicate, 22 parts of zirconium silicate, and 3 parts of Metsuki's catalyst (PEC-8 manufactured by Hitachi Chemical) in cellosolve acetate.

Thereafter, a multi-wire wiring board was created in the same manner as in Example 1. Its characteristics are shown in the attached table. Comparative Example 2 In Comparative Example 1, SP-6600 was replaced with resin MB,
An adhesive was prepared by changing the amount of Epikote 1001 to DER-542.

Bromine content is 10%. Thereafter, a multi-wire wiring board was created in the same manner as in Example 1. Its characteristics are shown in the attached table. As explained above, by the method of the present invention, UL-9
It is now possible to manufacture multi-wire wiring boards that meet the 4V0 grade, have an oxygen index of 45 or higher, and eliminate wiring errors.

[Brief explanation of drawings]

The drawing is a cross-sectional view of the adhesive sheet. Explanation of symbols, 1...Glass cloth, 2...
... Adhesive on the side where the wire is embedded, 3... Adhesive on the side to be bonded to the insulating substrate.

Claims (1)

[Claims] 1. An adhesive layer is formed on an insulating substrate, an insulated wire is placed on the adhesive layer and bonded at the same time to form a wiring pattern, a through hole is made across the insulated wire, and a through hole is formed inside the through hole. In the manufacturing method of wiring boards using insulated wires for the necessary wiring pattern, the adhesive constituting the adhesive layer is composed of synthetic rubber that is solid at room temperature and synthetic rubber that is liquid at room temperature. A necessary wiring pattern comprising 30 to 70% by weight of synthetic rubber mixed with 70 to 30% by weight of thermosetting resin, and an organic component having a halogen content of 5% by weight or more. A method for manufacturing wiring boards using insulated wires. 2. Use of insulated wires for the necessary wiring pattern according to claim 1, wherein the adhesive constituting the adhesive layer is composed of 100 parts by weight of an organic component and 70 to 2 parts by weight of a filler. A manufacturing method for printed wiring boards. 3. A method for manufacturing a wiring board using insulated wires as a necessary wiring pattern as set forth in claim 1 or 2, wherein the synthetic rubber is acrylonitrile-butadiene rubber. 4. Claims 1, 2, or 4, characterized in that the synthetic rubber consists of 95 to 60% by weight of synthetic rubber that is solid at room temperature and 5 to 40% by weight of synthetic rubber that is liquid at room temperature. A method for manufacturing a wiring board using insulated wiring for the necessary wiring pattern described in Section 3. 5 Thermosetting resin is phenolic resin 90 to 60% by weight
, 10 to 40% by weight of an epoxy resin, Claims 1, 2, 3, or 4
A method for manufacturing wiring boards using insulated wires for the required wiring patterns as described in Section 1. 6. The adhesive layer is composed of (a) a first adhesive layer in which the insulated wire is embedded, (b) glass cloth for reinforcement, and (c) a second adhesive layer for adhesion to the insulated substrate. Claims 1 and 2, characterized in that the adhesive sheet is an adhesive sheet.
A method for manufacturing a wiring board using an insulated wire for the necessary wiring pattern as described in item 3, item 4, or item 5.