JPS61143122A - Manufacture of laminated sheet - Google Patents

Abstract

PURPOSE:To prevent bubbles from remaining and a surface from being soiled, by lowering the temperature of the peripheral section of a laminate than that of the central section thereof in the early stage of molding when the laminate is pressed and molded under heating, and making the temperature of that peripheral section the same as or equal to that of that central section in the latter stage of the molding. CONSTITUTION:When a laminate 3 is pressed and molded under heating, and if, in the early stage of the molding, the softening temperature of the resin is 60-120 deg.C, the temperature of part or all of the peripheral section of the laminate 3 is made lower than that of the central section by 2-50 deg.C. If, at the softening temperature of the resin, the temperature of the laminate is uniform or the peripheral temperature is higher than that of the remaining part, bubbles 4 at the central section must pass through the melted resin for a long distance to the peripheral section of the laminate, but if the peripheral temperature is lower, the peripheral section is not melted, and is porous, so that he bubbles easily pass through the resin for a short distance to complete the passage without the flow of the resin. In the latter stage of the molding, the temperature of the peripheral section of the laminate 3 is made the same as or higher than that of the central section.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing laminates that require highly uniform properties, such as copper clad boards for printed circuits and laminates for circuits made by additive methods. It is related to.

[Prior art]

The laminate is prepared by impregnating base material C2 with resin as shown in Figure 1 (-).
A laminate (3) made by laminating the required number of dried prepregs is sandwiched between mirror plates (1), (1) as it is or using silver foil or release paper (2), and then heated and pressure-molded. It will be done. During molding, when the resin is made to flow in order to remove air bubbles (4) inside the laminate (3) to the outside, the resin flows out from the edges of the laminate (3), which causes the laminate (3) to flow out.
3) The plate thickness accuracy (uniformity) deteriorates.

In addition, the resin cannot flow completely (:uniform), and internal distortion remains, resulting in large warpage of the laminate (1).

Further, the resin that has flowed out remains attached to the end of the mirror plate (1). Normally, mirror plates are used repeatedly, so when the next time they are laminated, resin remaining at the end of the mirror plate may be left between the laminate (3) or the copper foil or release paper (2) and the mirror plate (1). Since the laminate is molded while being sandwiched, unevenness occurs on the surface of the laminate after molding. Such unevenness becomes a major hindrance when forming a circuit on the surface of the laminate, making it impossible to form a normal circuit.

Conventionally, in order to solve this problem, if the resin hardens too much before hot-pressure molding, the air bubbles inside the laminate cannot be removed during molding, so the degree of curing of the resin is determined by adjusting the degree of hardening of the resin. Although it was controlled within the limit where no residue remained,
Controlling the degree of hardening was extremely difficult.

[Purpose of the invention]

The purpose of the present invention is to prevent air bubbles from remaining inside the laminate even if the flow of resin is small in the heat forming process of the laminate, to prevent surface contamination, and to have good thickness accuracy. It is an object of the present invention to provide a method for manufacturing a laminate having excellent features such as small warpage.

[Structure of the invention]

In the present invention, when pressurizing and heating a laminate, in the initial stage of molding, for example, at a temperature of 60 to 120°C at which the impregnated resin softens, part or all of the periphery of the laminate is 2 to 5 degrees lower than the central part.
By lowering the temperature to 0°C, air bubbles can be removed even without resin flow, and in the latter half of molding, the degree of hardening of the resin within the laminate is kept constant at C2 (=, the temperature of the surrounding area is kept constant). This is a method for manufacturing a laminate, characterized in that the central part is the same as or higher than the central part.

Considering the mechanism by which air bubbles in the laminate are released during molding,
The temperature at which the resin softens (:) If the temperature of the laminate is uniform or the ambient temperature is high, the central air bubble must pass through the molten resin a long distance to the periphery of the laminate. On the other hand, if the temperature of the surrounding area is low, the surrounding area is not melted and is porous, so degassing is completed by passing through a short distance.For this reason, degassing is possible even if there is no flow of resin. It can form bubbles.

Various methods can be considered for making part or all of the peripheral part of the laminate at a lower temperature than the central part in the initial stage during pressure and heat molding. For example, as shown in Figure 2, we created 22 parts of circuits (5) and (6) inside the C nibbles heating plate, and in the initial stage (= we introduced the heat medium only in circuit (5)). , lowering the temperature of the peripheral part of the laminate (2),
In the latter half of the molding process, a heating medium is passed through the circuits (5) and (6) to make the temperature of the peripheral part of the laminate (2) the same or higher than that of the central part.

〔Effect of the invention〕

As described above, the present invention makes the temperature of the periphery of the laminate lower than the center in the early stage when hot-pressing forming the laminate, and in the latter half of forming (==) the temperature of the periphery is lower than that of the center. By making it the same or higher, the occurrence of flashing in the laminate after forming is eliminated, which significantly improves the appearance of the laminate.Also, the thickness accuracy of the laminate is improved.In the case of conventional laminates, The variation in the thickness of a 1000 x 1000 ttrm laminate was about 0.30 mtth at maximum, but the variation in the laminate made by the method of the present invention was 0.1511 mtth.
．． It can be halved to less than m.

Ru.

Warpage is further improved. Said 1000 x 1000
When a laminate of mm thick is mounted on a flat plate, the conventional maximum of 10 yen becomes less than 5 yen.

〔Example〕

The present invention will be explained with the following (= Examples and Comparative Examples).

Comparative Example Eight sheets of prepreg impregnated with epoxy resin to a resin content of 45% by weight were layered on glass woven fabric, and then a surface (copper foil) and a release film on one surface (C2) were layered, and this laminate was pressed. C2 was inserted.The press was operated at a pressure of 50 degrees, and the temperature was raised from room temperature to 180°C.Heating and pressurization was continued at 180°C for 2 hours, and then cooled to room temperature.

Example When raising the temperature, heating was performed only by circuit (5) in FIG.

Thereafter, the temperature was raised to 180° C., and heating and cooling were performed in the same manner as in the comparative example.

The properties of the obtained laminate (1000×1000=x) were as follows.

Example Comparative example Visual defective appearance rate (%) 0.01 or less 0.
2 Thickness of laminate (III) 1.6-11-0.
13 Warpage of 1.6*3.0 laminate (m)
3.2 9.6

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a state in which a laminate is laminated and molded. FIG. 2 is a plan view of a circuit diagram inside a heating plate as an embodiment of the present invention. (1) Mirror plate (2) Copper foil or release film (3) Laminate (4) Air bubbles Figure 1 ■ Figure 2

Claims (2)

[Claims] (1) In the production of a laminate by heating and press-molding a laminate obtained by stacking one or more prepregs obtained by impregnating and drying a laminate base material with a laminate resin, A laminate characterized in that during hot-pressure molding, part or all of the periphery of the laminate is lower in temperature than the center in the early stages of molding, and in the latter stages of molding, the temperature is the same as or higher than the center. Method of manufacturing the board. (2) At the initial stage of molding on the hot platen for heating and pressure molding,
2. The method of manufacturing a laminate according to claim 1, wherein the heating medium is introduced only into the central portion.