JPH0577263A - Continuous manufacture of single-sided metal foil clad laminate whose warpage is corrected - Google Patents

Abstract

PURPOSE:To manufacture a laminate with little warpage at the time of molding and processing by cooling down the temperature of the metal foil side of a cured laminate lower than the temperature of the opposite face. CONSTITUTION:Kraft papers pretreated with melamine resin and impregnated with unsaturated polyester resin are laminated integrally. Electrolytic copper foil coated with an epoxy resin bonding agent preliminarily and precured is applied on one face of a base laminate, preheated in a preheating zone 30, cured by a double belt press 31 and cut into pieces of predetermined sizes. The pieces are passed through a cooling double belt at its surface temperature being in contact with metal foil approximately at 30 deg.C and its opposite side surface temperature approximately at 40 deg.C immediately after cutting and then cooled. A single-sided metal foil clad laminate with little plus warpage generated after molding the laminate and during the process of forming the same into a printed wiring board can be manufactured by the arrangement.

Description

Detailed Description of the Invention

[0001] BACKGROUND The present invention relates to a process for the continuous production sided metal foil-clad laminate for a printed circuit board (hereinafter simply referred to as "laminate").

A metal foil-clad laminate is a printed wiring board made of paper, glass cloth, glass paper, etc. as a base material, a plurality of resin-impregnated base materials impregnated with a resin liquid, which are laminated on one surface, and a metal foil attached to one surface. It is used as a substrate.

Conventionally, these laminated plates have been manufactured by a batch type manufacturing method in which a base material is impregnated with a resin varnish and dried, and prepregs are layered and pressed and heated by a press to be molded. A wet continuous method has been developed that impregnates, laminates, and cures the resin while continuously transporting the substrate.
Attention has been paid. For example, Japanese Patent Application Laid-Open No. 55-4
838, 56-98136, etc.

Further, a pressure is applied by using a double belt press which sandwiches the laminate from both sides with a pair of endless belts and pressurizes and heats the laminate while synchronously moving the laminate and the belt in the same direction. A continuous wet method has been developed and disclosed in Japanese Patent Laid-Open No. 56-144151 (Japanese Patent Publication No. 60-58031), and recently, Japanese Patent Laid-Open Nos. 2-6131, 2-59343 and 2-86441.

The one-sided metal foil-clad laminate produced by the above method or the like is likely to warp during molding and processing due to the difference in the coefficient of thermal expansion of the material forming the same and the curing shrinkage of the curable resin.

In recent years, in the process of processing a laminated board into a printed wiring board, the work of inserting parts, soldering, cutting lead wires and the like have been automated by a flow work by a conveyor, so that the requirement for warpage of the laminated board becomes more severe. ing.

Therefore, the present invention proposes a method for producing a single-sided metal foil-clad laminate with improved warpage by a wet continuous method.

DISCLOSURE OF THE INVENTION In the present invention, a plurality of sheet-like base materials impregnated with a curable resin liquid are continuously conveyed and laminated, and a metal foil is attached to one surface of the laminate, and then continuously. In a method for producing a single-sided metal foil-clad laminate including a curing step, cooling the cured laminate from a temperature higher than a glass transition point of a base material impregnated resin to a temperature lower than the temperature while restraining the laminate in a flat state. There is provided said method characterized.

When the laminated plate is cured by the wet continuous method,
Plus, that is, the metal foil surface tends to warp in a convex direction.
According to the present invention, it is possible to obtain a laminated plate which is less warped during molding and processing.

Preferred Embodiment The present invention can be applied to both the wet pressureless continuous method and the wet pressure continuous method. FIG. 1 is a schematic side view of an example of an apparatus for producing a single-sided metal foil-clad laminate by the wet pressureless continuous method.

A base material wound on a roll 1, for example, kraft paper 2 made of cellulose fiber, is continuously conveyed and enters a pretreatment chamber 3. In the drawing, three substrates are shown to be conveyed at the same time, but it goes without saying that the number of substrates can be appropriately increased or decreased depending on the final thickness of the laminate. The base material 2 then enters the resin liquid impregnation chamber 4, is impregnated with the resin liquid, and passes through a pair of squeeze rolls 5 and 5 to be united. At this time, the metal foil 8 unrolled from the roll 7 is coated with an adhesive and laminated on the upper surface of the laminate of the impregnated base material, and the lower surface of the laminate is a carrier sheet 10 unrolled from the roll 9, for example, a polyester film. Are stuck together by the roll 5. The uncured laminate obtained in this way enters the curing furnace 12 and is heated and cured during its progress. The carrier sheet 10 on the lower surface is peeled off from the laminated plate 14 exiting the curing furnace 12 by a roll 13 and wound up as a roll 11. Next, the laminated plate 14 is trimmed at both ends by a rotary cutter 18, and cut to a required length by a guillotine cutter 19.

FIG. 2 is a schematic view of a wet pressure continuous laminating plate manufacturing apparatus.

A plurality of resin-impregnated base material sheets 22 pre-treated and impregnated in the same line as in FIG. 1 or in another line are laminated by a roll 26, and after the metal foil 8 is stretched on one surface thereof. It passes through the preheating zone 30 and is preheated. Next, the laminated plate 14 is compressed and heated at the same time by the double belt press 11, and then the laminated plate 14 released from the double belt press 11 passes through the curing furnace 35, and the remaining curing proceeds in a pressureless state.

In the present invention, as the substrate, a linter paper, a cellulosic substrate such as kraft paper, glass cloth, glass paper, mixed paper, non-woven fabric, etc. can be used, and as the resin, unsaturated polyester resin, epoxy acrylate resin, Unsaturated resins such as polyester acrylate resins can be used.

The cooling process of the cured laminate according to the present invention can be carried out continuously in combination with the pressureless production line of FIG. 1 or the pressure type production line of FIG. It can also be performed after cutting.

In the case of continuous in-line operation, immediately after the carrier sheet 10 is peeled off in the pressureless production line of FIG. 1, and immediately after leaving the curing furnace 35 in the pressure production line of FIG. A double belt press similar to the belt press 11 may be installed, and a cooling liquid may be circulated through the double belt press to cool the laminated plate from both sides.

In the case of processing a laminated plate cut into a predetermined size, if necessary, the laminated plate is once heated to a temperature not lower than the glass transition point of the resin and then passed through a cooling double belt press one after another, or is constantly cooled. A stationary press with circulating liquid can be used to cool the laminate while constraining it to a flat condition. At that time, the pressure applied to the laminated plate is preferably a slight pressure against the internal stress that causes warpage, and is preferable because it does not damage the laminated plate once formed.

It is also desirable then to cool the metal foil of the laminate to a lower temperature than the opposite side. By providing a temperature difference in cooling, the effect becomes more remarkable. The present invention will be illustrated in detail by the following examples and comparative examples.

Example 1 Using the apparatus shown in FIG. 2, seven sheets of kraft paper having a basis weight of 135 g, which had been treated with melamine resin and impregnated with an unsaturated polyester resin having a glass transition temperature of about 80 ° C., were laminated and united. . An epoxy resin adhesive is applied in advance and a pre-cured 35-micron-thick electrolytic copper foil is applied to one side of the substrate laminate, preheated in the preheating zone 30 at 120 ° C. for 2 minutes, and then at 140 ° C. by the double belt press 31. × 1 minute, 7
It was cured under the condition of kg / cm ² , then cured in a curing furnace 35 at 130 ° C. for 6 minutes and cut into a predetermined size. The surface temperature of the belt that contacts the metal foil immediately after cutting is 30 ° C,
The belt on the opposite side was cooled by passing it through a double cooling belt having a surface temperature of 40 ° C.

Example 2 Same as Example 1 except that the surface temperature of the belts on both sides of the cooling double belt press was the same temperature of 30 ° C.

Comparative Example Same as Examples 1 and 2 except that the cut laminated plate was placed on a tray and cooled with cold air in an unrestrained state.

Warpage test The laminated plates of the examples and comparative examples were 340 mm x 255 mm.
The sample was cut into pieces. Sample after molding and residual copper rate 52
% Of the sample was allowed to stand on the surface plate so that the upper surface was concave, the distances from the surface plate at the four corners were measured, and the average value was taken as the amount of warpage. The warp with the copper foil side as the inside was minus, and the warp with the copper foil side as the outside was plus. The results are shown in Table 1.

[0023]

[Table 1]

As is clear from Table 1, according to the present invention, a single-sided metal foil-clad laminate having a small plus warp can be obtained after forming the laminate and in the process of processing the printed wiring board.

[Brief description of drawings]

FIG. 1 is a schematic view of a wet pressureless continuous laminate manufacturing apparatus.

FIG. 2 is a schematic view of a wet pressure continuous laminating plate manufacturing apparatus.

[Explanation of Codes] 2 Base Material 4 Impregnation Chamber 8 Metal Foil 12 Curing Furnace 14 Laminated Plate 31 Double Belt Press

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Claims (2)

[Claims] 1. A one-sided process including a step of laminating and stacking a plurality of sheet-shaped base materials impregnated with a curable resin liquid while continuously conveying the same, applying a metal foil to one side of the laminated body, and then continuously curing the same. The method for producing a metal foil-clad laminate, wherein the cured laminate is cooled from a temperature higher than a glass transition point of a substrate-impregnated resin to a temperature lower than the glass transition temperature while restraining the laminate in a flat state. 2. The method according to claim 1, wherein the temperature of the metal foil side of the cured laminate is cooled to a temperature lower than the temperature of the opposite side.