JPS60203438A - Laminated board for printed circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of industrial application] The present invention relates to a printed circuit laminate having excellent heat resistance and good workability.

[Prior art]

In recent years, as copper-clad laminates for printed circuits, laminates (hereinafter referred to as composite laminates) have been produced in large quantities with a structure in which a glass nonwoven fabric is used as an intermediate layer and a glass woven fabric is used as a surface layer base material, impregnated with epoxy resin and used as a binder. K became used.

The laminate, which is made by impregnating only the woven glass fabric base material with epoxy resin, has excellent mechanical strength, dimensional stability, moisture resistance, and heat resistance, and is highly reliable for through-hole plating. It is widely used in industrial electronic equipment such as woven glass fabric.However, since only glass woven fabric is used as the base material, punching is not possible in the drilling process, which is one of the processing steps for printed circuit boards, and drilling is required. The reality is that this is the case.

On the other hand, composite laminates have attracted attention as glass-based laminates with good workability because they are economically cheaper than laminates made of glass woven fabric and can be punched and punched, but they have not been successful. The reliability of hole plating was evaluated to be lower than that of glass woven fabric base laminates. The reason is that
The composition of the glass woven fabric base epoxy laminate is such that the weight ratio of organic epoxy resin and inorganic glass woven fabric is approximately 4.
It is 0260. In this case, it is thought that the epoxy resin mainly provides excellent electrical performance, and the glass woven fabric provides excellent mechanical performance such as bending strength and dimensional stability. However, in general composite laminates, the total amount of inorganic base materials that contribute to mechanical performance, that is, glass woven fabric and glass nonwoven fabric, is smaller than that in glass woven fabric laminates.

The ratio of organic matter to inorganic matter is about 60:40, which is the opposite of that of a glass woven fabric laminate, so it was evaluated that the dimensional stability and reliability of through-hole plating were low.

The inventors took advantage of the excellent characteristics of composite laminates while studying to improve these drawbacks, and by adding a large amount of inorganic filler to the composition of general composite laminates, they were able to create a structure that could not be obtained with a single composition. A new composite laminate with unique characteristics has been obtained (Patent application 115118/1986)
issue). Furthermore, the inventors investigated the characteristics of the crystal structure of aluminum hydroxide, which is used as an inorganic filler in composite laminates, and found that when aluminum hydroxide, which has a boehmite crystal structure, is added to composite laminates, it becomes more like gibbsite than K. It has also been found that the solder heat resistance is significantly improved compared to composite laminates containing aluminum hydroxide (Japanese Patent Application No. 167608/1982).
.

Alumina hydrate (so-called aluminum hydroxide) has
Gibbsite (α-type trihydrate AI, 0
．．・aH, 0), payerite (β-type trihydrate), nordstrandite, boehmite (α-type monohydrate AI, O
, 0), diaspore (β-type monohydrate), and todite (5Al, O, -H, 0) are known.

Gibbsite-type aluminum hydroxide (hereinafter referred to as gibbsite) releases water in the range of 200°C to 500°C. Since the amount of heat absorbed at this time is large, it is used as a filler in general synthetic resins to maintain flame retardancy. However, since laminates are frequently exposed to high heat conditions during printed circuit and assembly processes, for example during soldering processes, they are typically immersed in a 260°C solder bath, so composite laminates using Gibbsite as a filler may have better soaking times. Defects occur due to looseness. The cause of this was found to be the release of water from the gibbsite due to heat.

On the other hand, boehmite aluminum deuteroxide with good crystallinity (
It is known that dehydration begins at 500°C (hereinafter referred to as K), and when it is filled in resin for composite laminates, the soldering heat resistance is significantly improved compared to K, but it is better than laminates filled with gibbsite. However, it is inferior in terms of transparency, drill bit life in drilling, and cost.

[Purpose of the invention]

The present invention was developed as a result of research aimed at solving the problems of poor heat resistance when filled with conventional gibbsite, transparency of laminates when filled with boehmite, and life span of drill blades. Based on this knowledge, we focused on the thermal changes in K and found that when heat-treated gibbsite is filled into the resin for composite laminates, the soldering heat resistance is significantly improved without reducing transparency. This is what we have come to complete.

[Structure of the invention]

In the present invention, the surface layer is made of epoxy resin glass woven fabric,
The intermediate layer is a laminate for printed circuits, characterized in that the intermediate layer is made of an epoxy resin nonwoven fabric containing heat-treated gibbsite type aluminum hydroxide in an amount of 10 to 200% by weight based on the resin of the intermediate layer.

The heat-treated gibbsite type aluminum hydroxide used in the present invention is such that the dehydrated part of the bound water of the particles is rearranged to boehmite aluminum hydroxide, and the remaining part is composed of gibbsite type aluminum hydroxide as it is. It is heat-treated in air so that the apparent number of moles of bound water that binds to one molecule of alumina falls within the range of 1.8 to 2.9.

The heat-treated gibbsite has a C10 to intermediate layer resin.
200% (same below weight%), preferably 20-200
%included. If it is less than 10%, the effect of improving soldering heat resistance is small, and if it is more than 200%, the resin viscosity when mixed with gibbsite becomes too high, making it difficult to impregnate the glass nonwoven fabric base material. When it is 20% or more, the effect of improving solder heat resistance becomes more reliable. Inorganic fillers other than aluminum hydroxide (eg silica) can also be used in the intermediate layer.

The ratio of the entire inorganic filler to the intermediate layer resin is 80-2
00% is preferred. If it is less than 80%, the dimensional stability and the reliability of through-hole plating decrease, which is not preferable. 200
% or more, the viscosity becomes too high when the inorganic filler is mixed with the resin, making it difficult to impregnate the glass nonwoven fabric.

Such fillers are used in epoxy resins as so-called mamako-K.
K is distributed evenly when the filler is impregnated into a glass non-woven fabric.
It is preferable that the particle size is 10 μm and the maximum particle size is 40 prn or less. If the particle size is larger than 40 μm, when the glass nonwoven fabric is impregnated with the inorganic filler-containing epoxy resin, the inorganic filler will be unevenly distributed in the glass nonwoven fabric of the laminate due to the filtration effect of the nonwoven pressure. Become. On the other hand, if most of the particles of the inorganic filler have a particle size smaller than 5 μm, the fine powder of the inorganic filler tends to remain solid and remain in this state, resulting in uneven distribution of the inorganic filler.

In addition, ultrafine particle silica is added to the inorganic filler by 2 to 30% of the total amount.
Blending 10% of K has a great effect in preventing the sedimentation of the inorganic filler in the epoxy resin varnish and also in making the distribution of the inorganic filler uniform when it is impregnated into a glass nonwoven fabric.

〔Effect of the invention〕

The printed circuit laminate of the present invention has the following features: (1) It has significantly better resistance to °C and soldering heat than conventional laminates that use unheated gibbsite as a filler. ing.

(11) Compared to the conventional drill using boehmite as a filler, the wear of the drill blade is less and the transparency is excellent.

0+b The heat-treated gibbsite of the present invention can be easily produced by simply heating commercially available gibbsite, and is considerably cheaper in °C than boehmite.

〔Example〕

Examples of the present invention and comparative examples (conventional examples) are shown below.

Example The composition of the epoxy resin-containing varnish is as follows.

(1) Primed epoxy resin (Ep-10 manufactured by Yuka Shell Co., Ltd.)
46) 100 parts (2) dicyandiamide 4 (3) 2-ethyl 4-methylimidazole 0.15 (4)
Methyl cellosolve 36 (5) Acetone 60 The above materials were mixed to prepare a uniform varnish.

Next, apply the varnish to a glass woven fabric (Nittobo WE-18-R).
B84) Glass woven fabric prepreg was obtained by impregnation and drying so that the K resin content was 42 to 45%. Subsequently, an inorganic filler in the following formulation was added to 100 parts of the resin to the epoxy resin-containing varnish, and the mixture was stirred and mixed to prepare an inorganic filler-containing varnish.

(1) Silica (Tatsumori Crystallite VX-3) 25
Part (2) Gibbsite type aluminum hydroxide heat treated product (#
tO, -2.48. O) 70 (3) Ultrafine powder silica (Jiotsugi #! Carplex made by a certain company) 5 Vilene $I Ep-4075) Glass nonwoven fabric is impregnated and dried so that the content of K resin and inorganic filler is 90%. Got prepreg.

Next, the glass non-woven fabric prepreg was used as an intermediate layer, the glass woven fabric prepreg was placed on the upper and lower surface layers, and a copper layer was layered thereon, and the molding temperature was 165°C.

Lamination molding was performed for 90 minutes at a pressure of 60 Kp/st to a thickness of 1.
A glazed laminate of No. 6 was obtained.

Comparative example (conventional example) The blending ratio of the inorganic filler added to the epoxy resin varnish was 1 (1) 25 parts of silica (Crystallite VX-3 manufactured by Tatsumori) (2) Gibbsite per 100 s of resin content in the varnish. W aluminum hydroxide (Showa Light Metal Heidi 2I) H-42) Not heat treated
70 (3) Ultrafine powder crimp strength (Carplex, manufactured by Geotsugi Pharmaceutical) Copper-clad laminates were obtained in the same manner as in the examples except that 5. In the above examples and comparative examples, the measurement results of solder heat resistance are shown. Show IK.

In addition, dimensional stability, reliability of through-hole plating, electrical insulation properties, etc. were also measured, and no difference was found between the example and the comparative example.

As described above, the printed circuit laminate of the present invention maintains the transparency of the laminate, significantly improves solder heat resistance, and has excellent workability with less wear on the drill blade.

Claims (1)

[Claims] Printing characterized in that the surface layer is made of an epoxy resin glass woven fabric, and the middle layer is made of an epoxy resin nonwoven fabric containing 10 to 200% by weight of heat-treated gibbsite-type aluminum hydroxide based on the resin of the middle layer. Circuit laminate.