JPH07336054A - Interlayer insulating resin material for multilayer board printed circuit board and manufacture of the same board - Google Patents

Abstract

PURPOSE:To obtain an interlayer insulating resin material for a multilayer printed circuit board in which two-stage curings of light and heat are executed by using specific quantities of epoxy resin curing agent and optical curable resin for epoxy resin and a specific quantity of photopolymerization initiator for optically curable resin. CONSTITUTION:Epoxy resin is preferably bisphenol A epoxy resin having a mean molecular weight of 300-500. Optically curable resin is preferably liquid acrylic resin and contains 1-100 pts.wt. in 100 pts.wt. of the epoxy resin. Epoxy resin curing agent is preferably imidazole, and its using quantity is 1-30 pts.wt. in 100 pts.wt. of the epoxy resin. The mixing quantity of the initiator is 1-10 pts.wt. in 100 pts.wt. of the curable resin. After the roughed inner layer circuit surface is coated with the interlayer insulating resin and once optically cured, when a copper foil is adhered, it is laminated by a heated roller, etc., thereby remelting the resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an interlayer insulating resin material for a multilayer printed wiring board, and more particularly to a new type of photo-thermosetting interlayer insulating resin material capable of two-step curing of light and heat. The present invention further provides a method for manufacturing a multilayer printed wiring board using the interlayer insulating resin material.

[0002]

2. Description of the Related Art As a conventional manufacturing method for a multilayer printed wiring board, a circuit is first formed on a double-sided copper clad board by etching, the circuit surface is roughened, and a glass cloth base material is impregnated with an epoxy resin. One or more sheets of semi-cured prepreg sheets were superposed, a copper foil or a single-sided copper clad plate was further laminated thereon, and they were integrated by heating with a heating press. In this process, the glass cloth base material must be impregnated with epoxy resin and semi-cured once in order to make a prepreg sheet, and since heat and pressure molding is performed with a press, enormous equipment and a long time are required. there were. In addition, since the copper foil residual rate of the patterned inner layer material is different, it is necessary to prepare various kinds of prepregs with different resin amounts and melting behaviors to adjust the interlayer thickness, and moreover, glass cloth is used for the prepreg sheet. Since a base material is used, it is difficult and expensive to make the interlayer thickness extremely thin, and there is a problem in that the dielectric constant becomes high due to the glass cloth in electrical characteristics.

In order to solve these problems, many techniques have recently been reported which do not use a glass cloth base material for the interlayer insulating layer. For example, a method using a thermosetting epoxy resin coating agent or film, a polyimide resin coating agent or film, a thermoplastic heat resistant resin film, or a photocurable epoxy interlayer insulating film can be used.

[0004]

First, in the above method, when a film-type insulating material is used as the interlayer insulating material, the inner layer circuit board has unevenness of the patterned circuit, so that no bubbles remain. In order to do so, film lamination must be performed under a reduced pressure environment, and large-scale equipment is required. Further, since the film follows the irregularities of the circuit, the surface smoothness cannot be obtained, which causes peeling of the etching dry film at the time of pattern processing and defective soldering at the time of mounting components.

Next, when a thermosetting resin coating agent is used for the interlayer insulating material, the processing is performed one by one in the case of screen printing and the like, so that the substrate is warped due to curing shrinkage of the resin, and processing of an ultra-thin plate is performed. Will be difficult. Further, in the simultaneous double-sided treatment such as the dip method, it is possible to suppress warpage to some extent, but in both cases, heat curing requires a long time.

Since the present invention uses a liquid photo-thermosetting type interlayer insulating resin material, the copper foil circuit gap of the core material can be easily filled without leaving air bubbles, and is temporarily cured by light irradiation. Warp of the substrate can be suppressed, and then the copper foil with adhesive or copper foil can be laminated or pressed with a heated roll or hot plate to remelt the interlayer insulating resin material and smooth the surface. it can. In addition, thereafter, by heat-curing, it is possible to increase the adhesive force between the inter-layer insulating resin material in the temporarily cured state and the adhesive-attached copper foil or the copper foil.

Particularly when laminating or pressing a copper foil with an adhesive, the provisionally cured interlayer insulating resin material is fluidized so that it is filled only in the concave portion of the circuit. The thickness of the adhesive layer of the foil can be precisely and easily controlled, so that the interlayer thickness can be made extremely thin. When the copper foil is directly laminated, the resin surface after photocuring has tackiness, so that the work can be simplified and the adhesion with the copper foil can be enhanced by the subsequent heat curing.

[0008]

According to the present invention, 1 to 30 parts by weight of an epoxy resin curing agent, 1 to 100 parts by weight of a photocurable resin, and 100 parts by weight of a photocurable resin are used with respect to 100 parts by weight of an epoxy resin. On the other hand, the present invention relates to a photo-thermosetting resin material comprising 1 to 10 parts by weight of a photopolymerization initiator, and a method for producing a multilayer printed wiring board using the photo-thermosetting resin material as an interlayer insulating layer. In the above, the photocurable resin is an epoxy-based, excellent compatibility with the epoxy resin, and when the epoxy resin and the photocurable resin are both liquid, it does not require a solvent and can be easily It is preferable in the present invention because it can be mixed in a short time and has high reliability as a printed wiring board. Also, by using a solvent-free system, the amount of curing shrinkage after heating is suppressed,
It becomes extremely easy to maintain the surface smoothness without depending on the copper foil circuit pattern of the core material.

The epoxy resin used here is preferably a bisphenol A type epoxy resin having an average molecular weight of 300 to 500, and when the average molecular weight is more than 500, the viscosity becomes high or solidifies, which is not preferable in handling.
Further, the photocurable resin is preferably a liquid acrylate resin, and among them, bisphenol A type epoxy acrylate, bisphenol F type epoxy acrylate, novolac type epoxy acrylate, urethane acrylates and the like are more preferable, and epoxy resin 1
1 to 100 parts by weight with respect to 00 parts by weight.
The average molecular weight of the acrylate resin is preferably from 500 to 1500, and when the molecular weight is higher than that, the acrylate resin becomes highly viscous and solidified like the epoxy resin. The tackiness and hardness of the resin surface after photocuring are adjusted by the amount of acrylate, and if the amount of the acrylate resin is more than 100 parts by weight, mechanical properties, heat resistance and chemical resistance deteriorate, which is not preferable.

The epoxy resin curing agent is preferably an imidazole type which is excellent in heat-hardening property, and more specifically, it is liquid 2-
Ethyl-4-methylimidazole or microencapsulated 2-methylimidazole can be used. The amount of the epoxy resin curing agent used is 1 to 30 parts by weight based on 100 parts by weight of the epoxy resin. If it is 1 part by weight or less, there is almost no effect of the compounding, and if it is 30 parts by weight or more, the crosslink density after curing becomes too high, and it tends to be hard and brittle as an interlayer insulating layer. The photopolymerization initiator is a radical polymerization initiator,
Benzoin ether-based, benzophenone-based, ketal-based, acetophenone-based, thioxanthone-based, etc. can be used, and particularly 1-hydroxycyclohexylacetophenone and 2,2-dimethoxy-1, which are excellent in moldability and cured product characteristics,
2-diphenylethan-1-one is preferred. The amount of the photopolymerization initiator compounded is 1 to 10 parts by weight based on 100 parts by weight of the photocurable resin. If it is 1 part by weight or less, the compounding effect will be small, and if it is 10 parts by weight or more, it will cause deterioration of properties after curing.

The above epoxy resin, acrylate resin,
When applying a photo / thermosetting interlayer insulation resin consisting of an epoxy resin curing agent and a photopolymerization initiator to the surface of the roughened inner layer circuit, use screen printing, a roller coater, a curtain coater, etc. After coating, it is once photocured by an exposure device such as a UV irradiation conveyor. Then, a copper foil or copper foil with an adhesive is adhered to the photo-cured surface, but by laminating with a hard roll heated at this time, the resin is re-melted,
Surface smoothness can be obtained. The photo-cured resin is
It is completely cured by the subsequent heat curing and firmly adheres to the copper foil with an adhesive or the copper foil.

[0012]

By using the light / thermosetting type interlayer insulating resin material of the present invention, conventional coating equipment can be used.
An interlayer insulating layer having improved surface smoothness can be formed by heating lamination or pressing without leaving bubbles. This is because the liquid epoxy resin and the acrylate resin are used without solvent to enhance the filling property between circuits and at the same time minimize the shrinkage amount after thermosetting. Further, the reason why the copper foil with an adhesive or the copper foil can be firmly adhered is that the photo-curing is a semi-curing treatment and the two layers can be completely integrated by the subsequent heat curing. In particular, in the case of copper foil laminate, a new interlayer adhesive is not required and a multilayer printed wiring board can be manufactured by a short process.

[0013]

EXAMPLES The present invention will now be described in detail based on examples. (Example 1) 100 parts by weight of bisphenol A-type epoxy resin (Oilized Shell Epoxy: Epicoat 828), 10 parts by weight of bisphenol A-type epoxy acrylate resin (Showa Polymer: Lipoxy SP-1507), epoxy resin curing agent ( Made of oiled shell epoxy: EMI-24-C
N) 10 parts by weight and a composition comprising 0.5 parts by weight of a photopolymerization initiator (manufactured by Ciba Geigy: Irgacure 184) were sufficiently stirred with a homomixer, and degassed under vacuum at 50 ° C.

A glass epoxy double-sided copper clad laminate having a substrate thickness of 0.1 mm and a copper foil thickness of 35 μm was patterned to prepare an inner layer circuit board. Then, sodium chlorite 31 g / l,
Sodium hydroxide 15g / l, sodium phosphate 12g
/ L in an alkaline aqueous solution at 95 ° C for 2 minutes to roughen the circuit surface, and apply the above mixed resin on the surface with a curtain coater to a thickness of about 50 µm.
Two W / cm high-pressure mercury lamps were used to irradiate ultraviolet rays under the conditions of about 2 J / cm to photo-cure.

100 parts by weight of bisphenol A type epoxy resin (epoxy equivalent: 6400, weight average molecular weight: 30,000) and bisphenol F type epoxy resin (epoxy equivalent: 175, manufactured by Dainippon Ink and Chemicals: Epicron 830)
Dissolve 80 parts by weight in MEK while stirring, and then add 15 parts by weight of dicyandiamide as a curing agent, 10 parts by weight of microencapsulated 2-imidazole as a curing accelerator, and a silane coupling agent (manufactured by Nippon Unicar: A-187).
An adhesive varnish was prepared by adding 5 parts by weight. Next, this varnish was applied to a copper foil anchor surface having a thickness of 18 μm with a thickness of 5
It was coated with a roller coater so as to have a thickness of 0 μm and dried. This was roll-laminated on the photo-cured resin on the surface of the inner layer circuit board described above at 100 ° C. and heat-cured at 180 ° C. for 20 minutes to prepare a multilayer printed wiring board.

Example 2 As a glass epoxy double-sided copper clad laminate having a substrate thickness of 0.1 mm for producing an inner layer circuit board, a double-sided roughening using a copper foil having a thickness of 35 μm, which was previously roughened on both sides, was used. An interlayer insulating resin was applied and light-cured in exactly the same manner as in Example 1 except that a copper-clad laminate was used, and a copper foil with an adhesive was laminated thereon and heat-cured.

(Example 3) In the same manner as in Example 1, an interlayer insulating resin material was applied to an inner layer circuit board obtained from a glass epoxy double-sided copper clad laminate and light-cured, and then a thickness of 18 was applied thereon.
A copper foil having a thickness of μm was roll-laminated and cured by heating at 180 ° C. for 20 minutes.

(Comparative Example) A solvent-based undercoat polyimide resin (resin content 70%) was applied onto an inner layer circuit board in the same manner as in Example 1, and cured by heating at 180 ° C for 60 minutes. The copper foil with an adhesive produced in Example 1 was laminated and further cured by heating at 180 ° C. for 20 minutes.

The multilayer printed wiring boards thus obtained have the characteristics shown in the following table.

────────────────────────────── Example 1 Example 2 Example 3 Comparative Example ──────────────────────── Surface smoothness (μm) 3.0 3.0 5.0 25.0 Peel strength (KN / m) − − 2.1 − Moisture absorption solder heat resistance ○ ○ ○ ○ ──────────────────────────────

(Measurement method) 1. Surface smoothness: JIS B 0601 R (max) 2. Peel strength: According to JIS C 6486 3. Moisture absorption solder heat resistance test: Moisture absorption condition Pressure cooker treatment 125 ° C, 30
Min Test conditions n = 5, all 120 at 280 ° C
Those that did not swell for more than a second were rated as ○.

[0022]

As described above, a multilayer print in which an insulating resin layer is formed on both surfaces of a double-sided copper clad board whose circuit surface has been roughened, and a copper foil with an adhesive or a copper foil is laminated thereon. In the method of manufacturing a wiring board, the interlayer insulating resin is a two-step curing type of light and heat, which allows rapid curing by light immediately after coating and no thermal stress, so warping or twisting can occur even on an extremely thin substrate. Copper foil with adhesive or copper foil can be laminated without it. Also, when laminating the copper foil with the adhesive or the copper foil, the surface can be smoothed by a heated hard roll or press, and because it is completely cured by heating, the interlayer insulating resin and the copper foil with the adhesive or It is possible to increase the adhesion with the copper foil.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H05K 1/03 610 L 7511-4E 3/38 B 7511-4E

Claims (5)

[Claims] 1. An epoxy resin curing agent of 1 to 30 parts by weight and a photocurable resin of 1 to 1 with respect to 100 parts by weight of the epoxy resin.
00 parts by weight and 1 to 10 parts by weight of a photopolymerization initiator with respect to 100 parts by weight of the photocurable resin, a photo-thermosetting interlayer insulating resin material for a multilayer printed wiring board. 2. The epoxy resin has an average molecular weight of 300 to 50.
2. A light for a multilayer printed wiring board according to claim 1, which is made of a liquid bisphenol A type epoxy resin of 0.
Thermosetting interlayer insulating resin material. 3. The photocurable resin has an average molecular weight of 500 to 15
2. An optical / thermosetting interlayer insulating resin material for a multilayer printed wiring board according to claim 1, which is made of an acrylate resin of No. 00. 4. A method for manufacturing a multilayer printed wiring board comprising the following steps (A) to (D). The photo-thermosetting according to claim 1, wherein (A) a step of etching a double-sided copper clad board to form an inner layer circuit, (B) a step of roughening the inner layer circuit surface, and (C) both sides or one side of the inner layer circuit board. A step of applying a mold interlayer insulating resin material and then curing by irradiating with light, (D) a step of laminating or pressing an adhesive-attached copper foil or a copper foil on the interlayer insulating resin, and heat curing to integrate them. , 5. A method for manufacturing a multilayer printed wiring board comprising the following steps (A) to (C). (A) a step of etching a double-sided roughened copper clad plate obtained by laminating and forming using a copper foil roughened on both sides in advance to form an inner layer circuit; and (B) claiming on both sides or one side of the inner layer circuit board. A step of applying the light / thermosetting interlayer insulating resin material according to 1 and then curing by irradiating light, (C) laminating or pressing an adhesive-attached copper foil or a copper foil on the interlayer insulating resin, and heating. Curing and integrating,