JPS6018540B2 - Method of manufacturing laminates - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a laminate having a novel configuration, and more specifically, a laminate with a heat-resistant insulating layer formed by applying a heat-resistant resin solution to one side of metal foil and drying and hardening it. The present invention relates to a method for manufacturing a laminate board, which comprises obtaining a metal foil, rolling a prepreg with the insulating coat layer of the metal foil as the inner surface, and heat-pressing the prepreg to form a single laminate.

Conventional methods for manufacturing double-sided metal-clad laminates include prepreg and metal foil, which are made by impregnating glass cloth, glass woven cloth, paper, etc. with thermosetting resin varnish and drying to harden the resin to the B-stage. The common method is to laminate the sheets and heat and press them together to make a laminate. If the adhesion between the metal foil and the prepreg is poor, it is necessary to apply thermosetting resin to one side of the metal foil. Foil coated with adhesive or metal foil coated on one side is used.

On the other hand, with recent advances in electronics, there has been a strong demand for heat resistance of circuit boards used therein. To address this problem, metal clad plates made of various heat-resistant resins have begun to be used.

That is, polyimide resin-based steel clad plates, polysulfone resin-based steel clad plates, fluororesin-based steel clad plates, and the like are commercially available. However, when manufacturing these heat-resistant 9-grade boards, a special high-temperature press is required because heat-stopping E is required under high temperature conditions, and the materials are expensive, making them uneconomical. Furthermore, in the case of polyimide-based copper foil, the adhesion with metal foil is poor, so methods such as using specially treated steel foil or modifying imide resin with epoxy resin are recommended. In the case of using polysulfone resin, various complicated methods are used because the adhesion is poor. Furthermore, if metal foil is directly laminated using heat-resistant resin prepreg, the pinholes in the prepreg will have a direct negative effect on the withstand voltage characteristics, so there will be a limit to how thin the prepreg can be made. Defects such as the inability to obtain a functional substrate also occur. The present inventors clearly understood the problems in manufacturing these heat-resistant circuit boards, and investigated various methods to solve them.

As a result, it was discovered that some of the problems could be solved if there was a heat-resistant resin layer under the metal foil that tightly adhered to the metal foil, and this led to the completion of the present invention. That is, a heat-resistant resin solution is cast coated on one side of the metal foil to the desired thickness, and if the resin is a thermosetting resin, it is cured, and if the resin is a thermoplastic resin, it is heated and melted to completely insulate the metal foil. Attach the layers. Thereafter, the obtained metal foil insulating resin layer with an insulating layer is mirror-layered with various types of adhesive base material Bripreg, and this is molded under normal heat and pressure conditions. The thus obtained laminate having a heat-resistant insulating layer under the metal foil is a double-sided metal clad plate with the following characteristics. In other words, '1' Since the heat-resistant resin layer is directly under the metal foil, when a circuit is created by etching, the exposed board surface is smooth and at the same time, the circuit adhesion is excellent and there is little deterioration of circuit adhesion over time. , '21 Because it has an excellent surface layer,
It is possible to significantly improve the performance required for the surface such as surface insulation and arc resistance.{3; Excellent solder heat resistance; The core layer can be made as thin as possible as long as it does not interfere with adhesion.
It is now possible to manufacture flexible double-sided plates (heat resistant), and the interlayer voltage withstand reliability is excellent.The '51 heat and pressure conditions are sufficient to form the prepreg used for the core layer, and a special press molding machine is required. It is an energy-saving board that does not require
[6] A laminate with excellent economical efficiency can be obtained. '7' Since there is an insulating layer with excellent performance under the circuit, phenomena such as plating measling, which can be seen in epoxy resin to glass laminates, can be completely prevented. '81 Because the metal foil has a heat-resistant resin surface, it has features that are not found in conventional metal foils, such as excellent beer retention properties when heated and excellent dimensional stability.

The details of the present invention will be described below.

As the metal foil used in the present invention, all metal foils such as electrolytic steel foil, rolled steel foil, single-sided laminated steel foil, aluminum foil, iron foil, stainless steel foil, etc. can be used.

Metal foil with adhesive can also be used in production, but it is not preferred because the bottom of the metal foil will ultimately become an adhesive layer after circuit processing. Next, a resin solution is applied to one side of these metal foils.

Although any resin may be used in principle as this resin, a heat-resistant resin having a glass transition point of 130 qo or higher is used in view of the purpose of the present invention. A resin having a glass transition point lower than this is essentially useless as a substrate for a heat-resistant circuit board. Even if the heat-resistant resin is a thermosetting resin,
Thermoplastic resins can also be used, and even if the varnish is a solution whose shape can be controlled, an emulsion or a dispersion can be used as long as it has film-forming properties. Furthermore, if necessary, addition of fillers, key fuel agents, surface smoothing agents, antifoaming agents, colorants, plasticizers, etc. to the varnish may be used as appropriate. Further, the method of applying these varnishes to the metal foil is not particularly limited, but as a general application method, methods such as roll coater, flow coater, screen coating, doctor blade coating, etc. are used. The coating thickness can be selected as appropriate, but when considering pinholes etc., the idea of forming an insulating layer is the gist of the present invention, not the concept of adjustable surface treatment, so an insulating layer of 5 or more layers is formed. It is necessary to apply as much as possible. Moreover, if a thicker layer is required, repeated coating several times can be carried out by a conventional method.・Polyimide resin as heat-resistant resin,
Varnishes using resins with high glass transition points such as imide resins such as polyamideimide resins, polyesterimide resins, and bismaleimide resins, or polysulfonate resins such as fluorine resins, polysulfide resins, and polyethersulfone resins are preferred. used.

The metal foil thus applied is fired under desired conditions, but
In the case of thermoplastic resins, treatment with heat above the softening or melting point of the resin is necessary to improve adhesion.

Next, the obtained two metal foils are laminated with a prepreg with the insulating layer side facing inside.

In this case, the prepreg includes glass cloth, glass nonwoven fabric,
Paper, cloth, carbon fiber cloth, etc. impregnated with a resin capable of forming a B-stage are used. In particular, epoxy resin prepreg and epoxy-modified pismaleimide resin prepreg are preferably used to improve adhesion to metal foil. In addition, the number of prepreg sheets to be used is the number that will obtain the desired laminated board thickness, but in order to obtain a flexible circuit board that makes the most of the performance of the surface heat resistance report, it is recommended to use a thickness of 1 to 3 sheets of prepreg. 500 or less is most preferable.

The obtained laminate is then heated and pressed under desired conditions to form a laminate.

The thus obtained laminate was a completely new and unprecedented substrate having excellent performance as described above, and was particularly useful as a circuit board substrate.

This will be described in more detail with reference to Examples below. Example 1 Polyimide varnish (PYreML manufactured by DuPont) was applied by roll coating using the roughened surface of a single-sided assembled steel foil with a thickness of 35 mm.
After spraying one powder of solvent at 130 degrees Celsius, heat one powder at 200 degrees Celsius, then one powder at 25 degrees Celsius, and heat to completely harden the resin. A copper foil with a heat-resistant insulating layer of No. 12 was obtained.

On the other hand, a glass cloth was impregnated with a heat-resistant epoxy resin composition to a semi-cured state to obtain an epoxy resin prepreg with a thickness of 100 mm.

Next, the two sheets of steel foil with the heat-resistant insulating layer were arranged so that the insulating layer was on the inner surface, one sheet of epoxy resin prepreg was sandwiched between them, and a pressure of 50 k9/ground was applied, and the heating was carried out at 170°C for 8 pm. The prepreg was heated under pressure to completely cure it, and an integrated laminate was obtained.

The performance of the obtained laminate was determined by the steel foil peeling strength (180
℃ direction) remained 1.3k9f/skin, 1.2k9f/skin even after heat treatment at 150 pm for 24 hours. The solder heat resistance was 320 qo, 6 eC, and the noble layer withstand voltage was 11 V/mm, making it a laminate with extremely excellent thermal stability and electrical performance. Example 2 Thickness 3
A polysulfone solution (Sumitomo Chemical Polyethersulfone 10 Mosquito) was applied to the roughened surface of the single-sided roughened steel foil.
1,1,2-trifluoroethane dissolved in a methanol mixed solution to make a 25 wt% solution) was applied using a roll coater, dried at 70°C for 10 minutes, the solvent was evaporated, and nitrogen was added. Heat brazing was performed at 400° C. for 15 minutes in a gas circulation dryer to obtain a steel foil with a polysulfone insulation coating layer having a thickness of 22 μm.

Next, arrange the two pieces of copper foil so that the insulating layer is on the inside,
Between this, two sheets of epoxy resin prepreg obtained in the same manner as in Example 1 were sandwiched and
The prepreg was heated under pressure for 8 minutes at 0 to completely harden the prepreg, and an integrated laminate was obtained.

The obtained laminate had an initial steel foil peeling strength (18000 direction) of 0.35k9f/skin, but at 150°C,
Even after heat treatment for 240 hours, it maintains 0.34k9f/, solder heat resistance is 290q○, 6eC, noble layer withstand voltage is 127KV/mm, and military force is 3.
It maintained a value of 3.26 even at 1 mm and 200 qo, and was a laminate with unprecedented performance in terms of heat resistance stability.

Claims (1)

[Claims] 1. A step of applying a heat-resistant resin solution having a glass transition point of 130° C. or higher to one surface of metal foil and drying and curing it to form an electrically insulating coating film with a thickness of 5 μm or more (Step I) ), Using the coated metal foil obtained in Step I, one or more sheets of prepreg made of a resin having a relatively lower glass transition point than the coated insulating coat are inserted and laminated with the insulating coated film side inside. The method is characterized by consisting of the following steps: a step (step II) of heating and pressurizing the laminate obtained in step II to cure the inner layer prepreg and simultaneously bonding the metal foil with the insulating coating (step III). A method for manufacturing a laminate having a surface heat-resistant resin layer. 2. The method for manufacturing a laminate according to claim 1, wherein the heat-resistant resin solution is an imide resin solution. 3. The method for producing a laminate according to claim 1, wherein the heat-resistant resin solution is a polysulfone resin solution. 4. The method for manufacturing a laminate according to claim 1, 2 or 3, wherein the prepreg is an epoxy resin prepreg obtained by impregnating glass cloth and/or glass mat with epoxy resin.