JPH0453714A - Manufacture of laminated sheet - Google Patents

Abstract

PURPOSE:To reduce the development of warpage, twisting and dimensional change, the adhesion of foreign matter and the generation of scratch and hammering by a method wherein pressure is released at the stage, at which the hardening reaction of resin is completed after the heating and pressurizing of the laminated sheet concerned, and the laminated sheet is held at an elevated temperature higher than glass transition temperature. CONSTITUTION:Structural body produced, for example, by piling up a required number of prepregs, each of which is obtained by impregnating glass cloth base material with epoxy resin varnish and drying it, and further piling up copper foils having the thickness of 0.035mm on both sides of the piled-up prepregs, are formed under heat and pressure with a press under the condition being pinched between stainless steel mirror plates. After hardening-forming, the pressure applied to the structural body is lowered in succession down to 0-20kg/cm<2>, and, after being held at the temperature higher than the glass transition temperature of the hardened matter for a certain period of time, the structural body is cooled down. As a result, some part of residual strain is removed and warpage, twisting and dimensional change are reduced. Further, the discoloration, adhesion of foreign matter, scratch and hammering on the surface of the laminated sheet are reduced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a laminate that can be used for printed wiring boards Kt' and has less warping, twisting, and method changes. [Prior Art] Conventional laminate board In this case, distortion of the base material due to resin flow during molding FI8, or internal distortion caused by the difference between the linear expansion coefficient of the stainless steel spring board and the linear tensile coefficient of the laminate, may remain, resulting in warpage, twisting, or processing. It is recognized that dimensional changes occur during the process.

As a countermeasure to this problem, there has been an attempt to stack the laminates in an open space and heat them at 120 to 170° C. for 1 hour and 6 hours to perform an annealing treatment.

[Problem that the invention seeks to solve]

Despite the above measures, the stack of laminates has poor thermal conductivity, so the annealing effect is not uniform.
It is inevitable that foreign matter will adhere to the open inner edge, and scratches and dents will occur when the laminate is taken in and out.

In view of the above-mentioned problems, an object of the present invention is to provide a method for manufacturing a laminate that causes less warping, twisting, or dimensional changes (and less occurrence of foreign matter layer, scratches, and dents). [Means for Solving the Problems] In order to achieve the above object, the present invention consists of stacking a plurality of prepregs obtained by impregnating and drying a thermosetting resin into a fiber base material, and coating the outer surface with km of metal foil. In the production of a laminate in which the combined structure and mirror plate are stacked alternately and cured under heat and pressure, the pressure is lowered to 70 to 20 kg/aIF after curing, and the temperature is higher than the glass transition temperature of the cured product. This is a method for producing a laminate, which involves holding it for one hour and then cooling it.

The pressure after curing of the present invention is 0 to 2 o kg/alF, preferably 0 to 3 kg/-, and the cured product is heated for at least 10 minutes at a temperature higher than the glass transition temperature, preferably 20 to 80 °C higher than the glass transition temperature. It is preferably held for 30 to 60 minutes or longer. After that, it is cooled down to below the glass transition temperature, preferably below 30°C, and then taken out from the press.The fiber base materials used include paper, natural fibers such as cotton links, polyamide, polyvinyl alcohol, polyester, and polyacrylic. Woven fabrics, non-woven fabrics, or emmats are made of synthetic fibers such as glass, asbestos, etc., and thermosetting resins are used, such as epoxy resin, unsaturated polyester resin, polyimide resin, polybutadiene resin, etc. .

As the metal foil, copper, aluminum, nickel, etc. can be used, but there is no limitation to the percentage according to the conditions of the present invention. In general, the thickness is preferably α018 to [LO7O2O3,
An adhesive layer may be provided on the back side if necessary.0 [Operation] When the laminate is heated and pressure-molded by press&1 and cooled, distortion remains in the fiber base material and the boundary between the fiber base material and the cured resin. This distortion causes warping, twisting, and dimensional changes in the laminate.In the present invention, the laminate is heated and pressurized to complete the curing reaction of the resin, and then the pressure is removed and the laminate is heated to a high temperature above the glass transition temperature. This condition removes some of the residual distortion and reduces warping, twisting, and dimensional changes. [Example] Next, the present invention will be explained in detail. (Example 1) Glass cloth base @ A predetermined number of prepregs obtained by soaking and drying 1kt of Evo medium-sized tree bear varnish, and both TIjJV
A structural body made of steel with a thickness of [10351111] was sandwiched between stainless steel plates and heated and pressed using a press.

That is, after heating and pressure forming at 170°C and 60kJl/- for 60 minutes, the pressure was increased to kOkg/rye, the temperature was held at 170°C for 50 minutes, and the laminate was further cooled to room temperature to form a 1B thick laminate. Obtained.

(Example 2) Following heating and pressure forming, the pressure was set to Okg/aII, and the temperature was
A laminate plate having a thickness of 1a+s was obtained in the same manner as in Example 1, except that the temperature was maintained at 170°C for 60 minutes.

(Comparative Example 1) After hot-press molding in the same manner as in Example 1, the product was cooled to room temperature to obtain a laminate having a thickness of 1 pongee.

(Comparative IpH2) The laminate obtained in Comparative Example 1 was placed in an open container at 160°C.
After heating for a period of time, the mixture was cooled to room temperature to obtain a laminate having a thickness of 1 as.

(Test) *mf! Table IK shows the measured values of warpage, twist, and dimensional change rate, and surface condition of the laminates obtained in Comparative Examples. Exam 41
．． T-etch the entire surface of a 500 x 250 M test piece,
After heating at 40°C for 60 minutes, warping, twisting, and dimensional changes before and after heating were measured. The amount of warping, amount of twisting, and rate of dimensional change are all smaller compared to the comparative example of the conventional method. It has been confirmed that the method of the present invention also has less discoloration, foreign matter adhesion, scratches, and dents on the 0-1 surface. As shown in comparison 912, the conventional annealing method has the worst performance.

Claims (1)

[Claims] 1. In the production of laminates, in which a plurality of prepregs made by impregnating and drying a thermosetting resin into a fiber base material are stacked, and a structure in which metal foil is superimposed on the outer surface and a mirror plate are alternately stacked and cured under heat and pressure. , After curing and molding, the pressure is continued from 0 to 20 kg.
/cm^3, the cured product is maintained at a temperature higher than the glass transition temperature for a certain period of time, and then cooled.