JPH0234310B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to a method for manufacturing metal foil laminates using unsaturated polyester resins for use as printed circuit boards.

BACKGROUND TECHNOLOGY AND PROBLEMS A laminate made of paper, glass cloth, glass paper, etc. as a base material, laminated with a plurality of resin-impregnated base materials impregnated with a resin liquid, and cured; Metal foil laminates, which are made by laminating metal foils on both sides, are used as insulating boards and printed wiring boards.

Conventionally, these laminates were manufactured using a batch method in which prepregs obtained by impregnating the base material with resin varnish and drying were stacked and molded by pressurizing and heating. A continuous method has been developed that performs resin impregnation, lamination, curing, etc. while continuously conveying materials, and is attracting attention. For example, see Japanese Patent Laid-open Nos. 55-4838 and 56-98136 by the present applicant.

A paper-based unsaturated polyester resin copper-clad laminate manufactured by a continuous process is commercially available under the trade name "Excelite" by the applicant.
It is widely used primarily in consumer electronics products due to a number of superior features compared to traditional paper phenolic resin copper clad laminates.

In recent years, the tolerance limits for printed circuit boards used in consumer electronic products have become increasingly strict due to the spread of automation in the processing process and the automation of parts insertion into the board, and the amount of warpage has become more and more limited. It is desired to supply fewer products.

Under these circumstances, the present invention provides a product with improved warpage characteristics.

Solution It was found that the warpage of metal foil-clad laminates manufactured by the continuous method is related to the moisture content of the uncured unsaturated polyester resin present in the base material layer after impregnation and before curing. . That is, if the water content of the resin at this time is below a certain value, the amount of warpage of the product will increase, and if it is too excessive, other properties of the product, such as bending strength, will be reduced.

Therefore, the present invention involves impregnating a plurality of sheet-like base materials with a liquid unsaturated polyester resin while continuously conveying the base materials, combining the plurality of impregnated base materials, and dissolving the combined base materials. In a continuous manufacturing method for metal foil-clad laminates, which includes a continuous process of laminating metal foil on at least one side and then curing the entire board, the water content of the unsaturated polyester resin in the base material layer after impregnation and before curing is reduced to 500 to 2000 ppm. It is characterized by being adjustable within the range of .

DESCRIPTION OF THE PREFERRED EMBODIMENTS The drawing is a schematic side view of an example of an apparatus for carrying out the method of the invention to produce single-sided metal foil-clad laminates.

A base material, for example kraft paper 2 made of cellulose fibers, wound around a roll 1 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 increased or decreased as appropriate 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, passes between a pair of squeeze rolls 5, and is combined. At that time, roll 7
A metal foil 8 fed out from the roll 9 is coated with an adhesive and laminated on the top surface of the laminate of impregnated base materials, and a carrier sheet 10, such as a polyester film, fed out from the roll 9 is placed on the bottom surface of the laminate onto the roll 5. It is twisted and pasted together. The uncured laminate thus obtained is placed in a curing furnace 1.
2, and as it travels through it, it is heated and hardened. The lower carrier sheet 10 is peeled off from the laminate 14 leaving the curing furnace 12 by a roll 13 and wound up as a roll 11. Next, the laminated plate 14 is trimmed at both end portions by a rotary cutter 18, and cut to a required length by a guillotine cutter 19. The previous part of this device was published in Japanese Patent Application Laid-Open No. 1983-1999 by the applicant, as cited above.
No. 4838 and No. 56-98136.

In the present invention, the "substrate layer after impregnation and before curing" means:
In the drawing, reference is made to the base material layer 2 being conveyed from the impregnation chamber 4 to the rolls 5, 5. The moisture content of the resin in the base material layer between these layers is reduced to 500 to 2000 ppm, preferably
To adjust within the range of 500 to 1000ppm,
The impregnation chamber is humidified or dehumidified depending on the moisture content already contained in the resin liquid to be supplied to the impregnation chamber 4, and while the base material layer advances through the chamber, the humidity in the chamber and the moisture content of the resin are maintained. It is sufficient that an equilibrium state is established.

However, in general, the applicant's JP-A-56-
As disclosed in No. 13136, the resin liquid supplied to the impregnation chamber is degassed under reduced pressure to eliminate the formation of fine bubbles in the product, so dissolved gas is removed and moisture is removed at the same time. has also been removed. Therefore, the relative humidity in the impregnation chamber 4 may be adjusted so that the inside of the impregnation chamber 4 is humidified and the resin liquid in the base material layer immediately after impregnation absorbs moisture and reaches an equilibrium within the above-mentioned moisture range. As a result, the water content of the resin in the base layer is maintained substantially within the desired range as it progresses from the impregnation chamber 4 to the rolls 5,5.

If the moisture content of the resin is too low, the warpage of the product will exceed the allowable value; on the other hand, if it is too high, the strength of the product will be adversely affected. It was found that the moisture content must be within the range.

Example An unsaturated polyester resin liquid was prepared consisting of 100 parts by weight of a commercially available unsaturated polyester (Polymer 3311, manufactured by Takeda Pharmaceutical Co., Ltd.), 1 part by weight of cumene hydroperoxide, and 0.2 parts by weight of 6% cobalt naphthenate.

Using the apparatus shown in the drawing, five sheets of crust paper (Sanyo Kokusaku Pulp ZBS-135, 10 mil) pretreated with melamine resin in the pretreatment chamber 3 were impregnated with the resin liquid in the impregnation chamber 4, and then squeezed. Copper foil coated with epoxy adhesive is laminated on the upper surface, a polyester film is laminated as a carrier sheet on the lower surface, and heated at 110°C in a curing furnace 12.
curing for 30 minutes at 150°C for 15 minutes.
A single-sided copper foil-clad laminate with a thickness of 1.6 mm was obtained.

At this time, the temperature inside the impregnation chamber 4 was maintained at 40° C. and the relative humidity was 95%, and the water content of the resin liquid in the base material layer immediately after leaving the impregnation chamber was adjusted to 800 ppm.

The obtained laminate was cut into pieces of 300 mm in length and 240 mm in width.
After leaving it in a constant temperature and humidity room at 40℃ and 85%RH for 4 days,
It was placed on a surface plate with the convex side facing down, the heights of the four corners were measured, and the average value was taken as the amount of warpage.

When the moisture content of the resin in the base material layer after impregnation and before curing is within the above range, the amount of warpage is -1.5 mm (concave with the metal foil surface inside);
The amount of warpage for those with 200 ppm or less was -3.0 mm.

Further, the bending strength of the laminate according to the present invention is 17
Kg/mm ² , but when the water content exceeded 2000 ppm, the bending strength decreased to 14 Kg/mm ² , and it also contained fine air bubbles, which were thought to be caused by evaporation of water during curing. .

[Brief explanation of drawings]

The drawing is a schematic diagram of an apparatus for implementing the invention. 2 is a base material, 4 is an impregnating chamber, 5 is a laminating roll, 8 is a metal foil, 10 is a carrier sheet, and 12 is a curing chamber.

Claims (1)

[Scope of Claims] 1 A plurality of sheet-like base materials are impregnated with a liquid unsaturated polyester resin while being conveyed continuously, and the plurality of impregnated base materials are combined to form a combined base material. In a continuous manufacturing method of a metal foil-clad laminate, which includes a continuous step of laminating metal foil on at least one side of the substrate and then curing the entire substrate, the atmosphere through which the substrate layer passes after impregnation and before curing is controlled to control the humidity of the atmosphere through which the substrate layer passes through, and 500 to 2000 ppm by balancing the moisture content of the unsaturated polyester resin in the material layer with the humidity of the atmosphere.
The above method, characterized in that the adjustment is made within the range of . 2. The method of item 1, wherein the base material is paper. 3. The method of item 1, wherein the unsaturated polyester resin is subjected to reduced pressure treatment before impregnation.