JPH0470334A - Laminated sheet composed of sheet like pulp base material - 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 [Industrial Application Field] The present invention relates to a laminate made of a sheet-like pulp base material used for manufacturing a phenolic resin copper-clad laminate for printed wiring boards.

[Prior Art] Ordinary laminates, especially phenolic resin copper-clad laminates for printed wiring boards, are semi-cured by impregnating a sheet pulp base material such as kraft paper or linter paper with phenolic resin varnish and drying it. (this is called a prepreg), a plurality of prepregs are laminated, adhesive-coated steel foil is laminated on one or both sides depending on the use, and the prepreg is heated and press-formed.

Such laminates are relatively inexpensive and meet the performance requirements for use in ordinary electrical or electronic equipment, so they are widely used in household electrical appliances.

However, in recent years, with the miniaturization, weight reduction, and high performance of electronic devices, the usage conditions for printed wiring boards have become harsher, and there has been a strong tendency for the physical properties required of sheet-like pulp base materials for laminates to become more sophisticated. It's coming.

In particular, in order to cope with high-density wiring, there is a need for a sheet-like pulp base material for laminates that has good punching workability, heat resistance, dimensional stability, etc. in laminates. Furthermore, the impregnation process for phenolic resin faces tends to be faster, and it is also desired to improve the impregnation speed for phenolic resin faces.

Conventionally, bleached kraft pulp has been mainly used as a raw material for sheet-like pulp base materials for laminates, but sheet-like pulp base materials made from this pulp have poor dimensional stability and punching workability, and have a high density. There were problems as a base material for laminated boards for wiring.

Further, by using linter pulp as a raw material, it is possible to improve the impregnating property and punching workability of the sheet-like pulp base material, but this is not preferable because it causes a decrease in the strength of the base material and a decrease in the strength and dimensional stability of the laminate.

On the other hand, the resin impregnation rate can be improved by lowering the density of the base material and increasing the porosity in the base material, but the density of the base material used conventionally is 0.45 to 0. 5
The level is already low at 5 g/cm', and lowering it further will also significantly reduce the strength of the base material, so it is important to consider the lack of strength of the base material and laminate, especially the sheet pulp base when impregnated with resin. This method cannot be used as it will lead to serious trouble due to cutting of the material.

In order to solve these problems, a method of improving impregnating properties by selecting the fiber length of the pulp used (Japanese Patent Application Laid-Open No. 63-211395), a-pulp fibers with a cellulose content of 90% or more are used. How to do it (Tokuko Showa 63
-8885) etc., but pulp MA
The affinity between the fiber and the phenolic resin is not sufficient, and the punching properties, soldering heat resistance, and dimensional stability are not satisfactory.

On the other hand, regarding phenolic resins, resin modification, additives,
Concentration, viscosity, solvent, etc. have been studied, and impregnation treatment under optimal conditions has been proposed (Japanese Patent Laid-Open No. 607226).
Publication No. 531).

However, the impregnability of resin still largely depends on the essential characteristics of the base paper, and there is currently a need for further improvement of the base paper.

For this reason, conventional laminates are not suitable for use in printed wiring for electrical devices with higher component density, or for printed wiring in electronic devices such as computers that require high precision. .

[Problems to be Solved by the Invention] In view of the current situation, the present inventors have conducted extensive research on the impregnation phenomenon of phenolic resin faces into sheet-like pulp base materials, and have found that the speed and uniformity of impregnation of phenolic resin faces into base materials has been determined. In order to obtain impregnating properties, the surface properties of the pulp fibers that make up the base material are changed from hydrophilic to lipophilic.
They came to the conclusion that it would be sufficient to improve the affinity between the pulp fibers and the phenolic resin face, and completed the present invention.

[Means for Solving the Problems] The present invention provides a sheet-like pulp base material containing a lipophilic agent in an amount of 0.02 to 2.0% by weight based on the base material, and a thermosetting resin in a weight ratio of l:
It is a prepreg impregnated with 0.8 to 1:1.2, and two or more sheets of the prepreg are laminated and pressure-bonded.

In general, lipophilic agents are used to introduce lipophilic properties into pulp fibers, such as maleated rosin emulsion type, alkyl ketene dimer, alkenylsuccinic anhydride, styrene-acrylic copolymer, etc. can be mentioned.

The present invention uses at least one of these substances in an amount of 0.02 to 2.0%, preferably 0.1 to 2.0%, per pulp.
0.5% by weight is added together with a fixing agent for the pulp suspension, such as at least one cationic resin such as polyamide polyamine evichlorohythrin resin, acrylamide cationic monomer copolymer, or cationized starch.

If the addition rate is less than 0.02% by weight, the surface of the cellulose fibers remains hydrophilic and does not have sufficient affinity for alcohols, ketones, etc., which are solvents for phenolic resin varnishes.

Further, even if the addition rate exceeds 2% by weight, the impregnating properties of the phenolic resin varnish are not effectively improved and tend to become saturated, which is not preferable because it causes process troubles such as foaming and staining in the papermaking process.

All of the lipophilic agents are known as paper-making sizing agents, and are easy to add and mix into the pulp suspension.

The addition ratio of the lipophilic agent and fixing agent for imparting lipophilicity to the pulp fibers is 1:D, 5 to 1:2.

In order to manufacture a laminate from the sheet-like pulp base material of the present invention, a known method for manufacturing a laminate can be directly applied.

In addition, thermosetting resins such as phenol resin, melamine resin, diallyl phthalate resin, epoxy resin, and unsaturated polyester resin are used as the resin for the laminate, and the solid content weight ratio of pulp base material: resin is I: 0. .8~1
: An impregnation range of 12 is preferred.

The present invention improves the impregnating properties of a sheet-like pulp base material by adding a substance that imparts lipophilicity to pulp fibers into the 5-pulp suspension instead of into the phenolic resin, and the laminate produced from the sheet-like pulp base material The punching properties, heat resistance and dimensional stability of the plate can also be improved. This is because the substance that imparts lipophilicity is adsorbed by the fixative not only on the pulp #a fiber surface but also in the fiber cell wall or lumen, improving the affinity between the phenolic resin varnish to be impregnated and the pulp base material, and increasing the impregnation rate. This is considered to be a result of improving the water content and making impregnation uniform, which in turn promotes the integration of the pulp base material and the phenolic resin as a composite material.

[Examples] The present invention will be specifically explained below with reference to Examples, but the present invention is not limited to the same extent by these Examples.

Example 1 Bleached kraft pulp made from Hokkaido hardwood chips (
A suspension of LBKP) with a concentration of 0.4% was prepared. To this suspension, as a fixing agent, polyamide polyamine epichlorohydrin resin (manufactured by Toyo Kagaku Kogyo Co., Ltd., trade name, ARAFIX 100) was added in an amount of 0.2% based on the weight of bone-dry pulp in terms of solid content, and the mixture was thoroughly mixed and dispersed. Next, an emulsion of maleated rosin (manufactured by Yoyo Kagaku Kogyo Co., Ltd., trade name, Size Pine N705) was sufficiently mixed and dispersed with respect to the weight of the absolutely dry pulp in terms of solid content.

Using this pulp suspension, a sheet-like pulp base material for a laminate having a basis weight of 135 g/m 2 and a thickness of 270 μm was prepared using a known paper machine, and the degree of immersion in castor oil was measured.

Furthermore, this base material was impregnated with phenol resin (manufactured by Showa Kobunshi Co., Ltd., trade name, Showol BLS-3122) at a weight ratio of base material: lIl fat = 1:l, and heated at 135°C.
The prepreg was prepared by heating and drying for 3 minutes.

Next, eight sheets of this prepreg were laminated and heated and press-molded to produce a laminate, and the punching characteristics, solder heat resistance, and dimensional stability of the laminate were evaluated.

In the examples, the castor oil immersion mode measurement method and the evaluation of punching characteristics, dimensional stability, and soldering heat resistance were as follows.

1. Cut out 10 test pieces of 620w+m square from the sheet pulp base material to be subjected to the constant test. Place a container containing castor oil in a constant temperature bath kept at a water temperature of 30℃, and adjust the temperature of the castor oil to 30℃.
Hold the test piece at a constant temperature, drop the test piece horizontally onto the surface of the castor oil liquid, and use a stopwatch to measure the time from the moment the test piece comes into contact with the castor oil until the castor oil uniformly permeates the upper surface of the test piece. . Measurements are taken using five test pieces on both the front and back sides of the paper, and the average value is calculated. The lower this value is, the better the impregnating property is.

The distance between the hole walls of the die is 0.8.1.0.1.2.1.6m
It has a pair of round holes with a diameter of 1.0.1.2.1.7.2.1 mm and a pair of square holes with a diameter of 1 mm x 2 mm, and the clearance on one side between the punch and the die is 0.05... constant. Using a certain test mold, the surface temperature of the laminate was set at room temperature, 35°C, and 55°C.
Punching was performed at ℃, and the condition of the surface, holes, and cut edges after punching was judged according to AS Cho M 0617.
Evaluation was made on a four-level scale of fair and poor.

1. Support 1. Sheet-like pulp base material for laminates Thermosetting resin, that is, resol type phenolic resin as base material: solid content weight ratio of resin is l=
1 and dried at a temperature of 135° C. for 3 minutes to create a prepreg. A laminate is produced by stacking these 8 sheets of prepreg and compressing them at 2165°C and LOOKg/cm for 60 minutes.The laminate is conditioned for 24 hours in an environment with a temperature of 20°C and a relative humidity of 65%. span 200mm
Mark the mark with . Subsequently, it was heated at 80°C for 30 minutes, further heated at 120°C for 15 minutes, and then heated again at 20°C and relative humidity 6.
The humidity was adjusted for 24 hours in a 5% environment, and the distance Lmm between gauges was measured using a high-precision two-dimensional coordinate measuring device (for example, DR-550-D).
, manufactured by Dainippon Screen Manufacturing Co., Ltd.).

Calculate the dimensional change rate α using the following formula.

σ= (200-L) /200 X100 (%)
The dimensional change rate of the laminate is shown as an average value in the longitudinal direction and in the lateral direction. The smaller the dimensional change rate, the higher the dimensional stability of this laminate.

Good) Manufacture a laminate using the same method as used in the measurement method for J1 dimensional stability, and prepare 6 test pieces of 50 x 100 mm from this laminate.
Create one. 50X 50mm area of the test piece 260
When immersed in a solder bath maintained at ±2°C, the longer it takes for blistering to occur, the better the soldering heat resistance.

Example 2 Acrylamide cationic monomer copolymer (manufactured by Dick Vercules, trade name, Evinox DS-51 (1) was added to the same pulp suspension as in Example 1 as a fixing agent.
) was added in an amount of 0.04 times as solids based on the superposition of bone dry pulp, thoroughly mixed and dispersed, and then an emulsion of maleated rosin (manufactured by Dick Vercules Co., Ltd.: trade name,
T500Jl is 0 relative to the absolute dry pulp weight in terms of solid content.
2% by weight was added and thoroughly mixed and dispersed.

A sheet-like pulp base material for a laminate was prepared from this pulp suspension in the same manner as in Example 1, and the degree of immersion in castor oil was measured.

A laminate was produced from this base material in the same manner as in Example 1, and its punching characteristics, soldering heat resistance, and dimensional stability were evaluated.

Comparative Example The same pulp suspension as in Example 1 was prepared without adding a fixing agent and a lipophilic agent.
A sheet-like pulp base material for a laminate was prepared, and the degree of castor oil immersion was measured.

A laminate was prepared from this base material in the same manner as in Example 1, and its punching characteristics, soldering heat resistance, and dimensional stability were evaluated.

Table 1 shows the measurement results of Example 1.2 and Comparative Example.

As is clear from Table 1, the impregnation properties of the sheet-like pulp base materials of the present invention obtained in Examples 1 and 2 are better than those of the comparative examples, and the punching properties and solder heat resistance of the laminates of the present invention are The properties and dimensional stability were also good.

[Effects of the Invention] As described above, the present invention includes a lipophilic agent in a sheet-like valve base material to make the pulp base material surface lipophilic.
Compared to conventional pulp base materials, it is possible to significantly improve the uniformity and impregnation speed of phenolic resin varnish on pulp base materials, making it possible to speed up the impregnation process, increasing production efficiency, and improving punching characteristics and solderability. It can be made into a laminate that has both heat resistance and dimensional stability.

Claims (1)

[Claims] A thermosetting resin is added to a sheet-like pulp base material containing 0.02 to 2% by weight of a lipophilic agent to the base material in a weight ratio of 1:0.8 to 1.
:1.2: A laminate board characterized in that two or more sheets of the prepreg are laminated and pressure-bonded using prepreg impregnated with the above.