JPS6151329A - Manufacture of laminated sheet - Google Patents

Abstract

PURPOSE:To prepare a thermosetting resin laminated sheet free from warpage and torsion, good in dimensional stability and excellent in water resistance and electric performance, by using the paper base specifying warpage and torsion after heat treatment, in manufacturing a laminated sheet by heating and pressing required sheets of prepreg obtained by impregnating paper base with thermosetting resin and then drying them. CONSTITUTION:After heattreatment the warpage and torsion of the paper base used shall not exceed 40mm.. When the laminated sheet exceeds this value, they will become larger. The density of paper should be as small as possible to increase impregnated resin. However, the paper and prepreg require certain strengths in their manufacturing processes and a range 0.4-0.6g/cm is desirable. Further, it is desirable to use the paper base wherein, in the tensile strength of the paper base, the ratio of the longitudinal/strength the lateral strength is within 1.0-1.4:1.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing a laminate used for manufacturing printed wiring boards and the like.

(Prior Art) Filter paper base materials made from linter pulp and kraft pipes are widely used for filter paper base thermosetting resin laminates or copper clad laminates used in electronic devices.

In recent years, there has been a strong demand for these steel clad laminates to have not only water resistance and electrical performance, but also higher performance in terms of warpage, twisting, and dimensional stability.

In other words, due to the remarkable spread of automation of printed wiring board processing and parts insertion, and due to the increased use of printed wiring boards, which have resulted in more complex shapes and uneven residual copper ratios, it is becoming increasingly difficult to use wood pulp with less warpage and dimensional changes. More and more paper base materials have been used as raw materials, and linter pulp has been used in combination with paper base materials. However, the prepreg made by impregnating the paper base material of the laminate with a thermosetting resin and drying it is
More than one sheet of prepreg is used. This is to improve the impregnation of resin into the paper base material, drying efficiency, and thickness accuracy of the laminate in the prepreg manufacturing process. When a laminated board is formed by heating and pressurizing, the printed wiring board's warping and twisting and dimensional stability are not fully satisfactory, and changes occur in the shape and residual copper ratio of the printed wiring board. In such cases, warping and dimensional changes become so large that they cannot be used for disaster relief.

(Objective of the Invention) An object of the present invention is to provide a method for producing a thermosetting resin laminate having good warp/twist resistance, dimensional stability, water resistance, and electrical performance.

(Structure of the Invention) The present invention provides a method for producing a laminate in which a required number of dried prepreg sheets impregnated with a thermosetting resin are heated and pressed into a paper base material, and the warpage or twisting after heat treatment is within JQ mm. It is characterized by using a filter paper base material.

The raw material pulp for the filter paper base material used in the present invention is a type of pulp made from hardwoods such as oak, maple, beech, and birch, softwoods such as red pine, rainbow pine, Todomatsu, and fir, and cotton.
Two or more types may be used in combination (the mixing ratio can be changed as necessary).

Paper base material is manufactured through a papermaking process in which pulp slurry is poured onto a rotating wire mesh to form a paper layer, then compressed and dried. Become.

Warp and twist of the paper base material after heat treatment are measured as follows. That is, from the paper base material, the vertical direction 42011
A sample measuring 1 m and 500 mm in the horizontal direction is cut out, suspended in a constant temperature bath at 95° C. with the vertical direction of the specimen, heated for 2 minutes, and then cooled to room temperature. Next, the sample was placed on a jig at an angle of 85 degrees to the horizontal direction,
Measure the distance between the four corners of the sample and the jig cut,
Let the maximum value be the sled. Also, the absolute difference between the maximum value and the minimum value is defined as the twist.

In the present invention, a filter paper base material is used that exhibits warping and twisting of 40 degrees or less after heat treatment.

If the warp or twist exceeds 40 mm, the warp or twist of the laminate increases. It is more preferable that the warp or twist is within 30 lungs.

The density of the paper is a factor that affects the impregnability of the resin, and if the resin impregnation is insufficient, fine voids will remain inside the laminate, resulting in a decrease in water resistance and electrical performance when the laminate is humidified. become the cause. For impregnation, it is advantageous for the paper density to be as low as possible, but since a certain degree of strength is required in paper making and prepreg manufacturing processes, a range of 0.4 to 0.6 g/tan is preferred. In addition, if there is a large difference in the permeability of the machine oil between the front and back sides of the paper base material, the amount of resin impregnated will differ and the amount of molding shrinkage of the laminate due to heating and pressure will differ, resulting in warpage, twisting, and insufficient dimensions. There is a tendency to have

To measure the permeability of castor oil, a cut sample of size 15mm x 15mmvc is floated on Japanese Pharmacopoeia castor oil maintained at 60±0.5℃, and the time taken for castor oil to permeate the entire surface of the sample is measured as the permeability of castor oil. However, in the present invention, it is preferable to use a paper base material in which the difference in permeability of mustard oil between the front and back sides is in the range of 0 to 5 seconds.

In addition, if the ratio of the tensile strength of the paper base material in the vertical direction to the horizontal direction is large, there will be a difference in dimensional expansion and contraction between the prepregs that make up the laminate, resulting in disadvantages such as warpage and unsatisfactory dimensional change characteristics. tends to occur. From this point of view,
In the present invention, the ratio of the tensile strength of the paper base material in the vertical direction to the horizontal direction is 1.0 to 1.4 in the vertical direction: in the horizontal direction.
It is preferable to use one within the range of 1.

The test method for tensile strength of paper base material is JIS P8113.
is stipulated as follows: In other words, the sample is clamped between two grips with surfaces parallel to the direction in which the load is applied, so that the sample does not slip and is kept on one plane during the test. The vertical and horizontal VC width from the test paper to the test device is 15. [l±Q,
After attaching a sample cut to a length of 1 mm and approximately 250ffIfll, a load is applied, and the load indication value when the sample breaks is taken as the tensile strength of the paper base material.

In order to impart flame resistance and wet strength to paper base materials, inorganic substances such as antimony trioxide, clay, and aluminum hydroxide, or organic compounds such as halogen, phosphorus, and nitrogen, and resin compositions such as melamine and phenol are used during paper making. can be added or applied by impregnation.

The thermosetting resin used in the present invention is, for example, a resin made by reacting a phenol such as phenol, cresol, or xylenol with formaldehyde, and if necessary modified with an alkylphenol, drying oil, xylene resin, toluene resin, etc. during the reaction. Heat treatment of polyester resins, including mixtures of phenol resins, or mixtures of one or more of bisphenol epoxy resins, novolac epoxy resins, and alicyclic epoxy resins, and amine hardeners or acid anhydride hardeners. General thermosetting resins used in the manufacture of curable resin laminating machines can be used.

Further, in order to impart flame retardancy to these resins, phosphorus compounds such as triphenyl phosphate and flame retardants such as antimony trioxide are used.

Phenol resins and epoxy resins used as thermosetting resins are relatively polymeric, so impregnating them is difficult and can cause a decline in the water resistance and electrical performance of the laminate. An effective method is to impregnate the material with a mono- or dinuclear phenol resin that has good affinity for the material.

In the present invention, a conventional method can be used for laminating the laminate, and a steel foil with an adhesive can be placed on one or both sides of the prepreg to form a laminate.

Example 1゜ 700 g of phenol, 300 g of cresol.

Formalin (37% formaldehyde aqueous solution) 100g
A mixture of 35 g of 25% ammonia water was heated and reacted, then dehydrated under reduced pressure, and an organic solvent was added thereto to obtain a phenolic resin varnish. This varnish is made of hardwood pulp and has a warpage and twist of 25 mm after heat treatment, and a density of 0.51.
g/an', the ratio of the tensile strength in the vertical direction to the horizontal direction is 1
．． 25. A paper base material with a castor oil permeability difference of 3.0 seconds between the front and back sides was impregnated and dried to obtain a prepreg with a total resin content of M850%. The required number of prepreg sheets and adhesive-coated copper foil were combined and held at 165° C. and 85 kg/aIII for 40 minutes to obtain a copper-clad laminate with a thickness of 1.6 ff 1 m. Its performance is shown in the table below.

Example 2 Made of hardwood pulp with warpage and twist of 38 after heat treatment
1T1m, a density of 0.51 g/an', a ratio of tensile strength in the vertical direction to the horizontal direction of 1.25, and a difference in castor oil permeability between front and back sides of 3.0 seconds. A copper-clad laminate was obtained in the same manner. Its performance is shown in the table below.

Comparative Example Warp twist after heat treatment made of hardwood pulp is 55m
A paper base material having a density of 0.51 g/af, a ratio of tensile strength in the vertical direction to the horizontal direction of 1.25, and a castor oil permeability difference of 50 seconds between the front and back sides was used in the same manner as in Example 1. A copper-clad laminate was obtained. Its performance is shown in the table below.

The test method was as follows.

(1), (2) ; ■Sample size 500 (horizontal direction) and 250 (vertical direction) mm (remaining copper rate 50%) ■Processing Normal → Etching - 160 3 10 minutes drying process ■Measurement method 4 by standing method Measure the corners and take the maximum value as the warpage. Furthermore, the difference between the absolute values of the maximum value and the minimum value is defined as the twist.

(3); ■Sample size 140 (vertical or horizontal direction) Measure the dimensions after treatment and divide the difference by the normal value to determine the rate of change.

(Effects of the Invention) By the method of the present invention, it was possible to produce a thermosetting steel-clad laminate with excellent warpage and dimensional stability.

Claims (1)

[Claims] 1. In a method for producing a laminate in which a required number of prepregs prepared by impregnating a paper base material with a thermosetting resin and drying are heated and pressurized, warping and twisting after heat treatment are within 40 mm. A method for manufacturing a laminate, characterized by using a paper base material. 2. Production of a laminate according to claim 1, using a paper base material having a density of 0.4 to 0.6 g/cm^3 and a castor oil permeability difference between the front and back sides of 0 to 5 seconds. Law. 3. Claim 1, which uses a paper base material whose tensile strength ratio in the vertical direction and the horizontal direction is in the range of vertical direction: horizontal direction = 1.0 to 1.4: 1.0. Or the method for manufacturing a laminate according to item 2.