JPH0257018B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD OF THE INVENTION The present invention relates to a method for producing composite laminates with improved formability. Conventional technology Composite laminates are made by impregnating and drying a glass nonwoven fabric base material and a glass fabric base material with resin varnish to obtain a prepreg, as is well known, and then forming the core layer by laminating a predetermined number of glass nonwoven fabric prepregs on both sides. It is manufactured by layering glass cloth prepreg as a surface layer and applying heat and pressure. Problems to be Solved by the Invention However, since the glass nonwoven fabric used for the core layer has a low density, a large amount of air is included in the prepreg, and air cannot be removed sufficiently during lamination molding. As a result, voids remained in the formed laminate, and delamination was likely to occur during processing steps for producing a printed wiring board. An object of the present invention is to provide a composite laminate that is sufficiently defoamed during molding, has good moldability, and has few residual voids. Means for Solving the Problems The present inventors conducted studies to solve the problems and found that the gelling time of the glass nonwoven fabric base material prepreg of the core layer is It has been found that by shortening the curing time by 10 to 90 seconds, it is possible to produce a composite laminate with good moldability and fewer residual voids. Function Defoaming is performed while the resin in the prepreg is in a molten state before it gels, but by slowing down the gelation of the glass fabric base prepreg in the surface layer, the glass nonwoven fabric in the core layer Air contained in the base material prepreg is defoamed through the surface layer of the glass cloth base material prepreg that has not yet gelled. If the difference between the gelation time of the glass nonwoven fabric base material prepreg of the core layer and the gelation time of the glass fabric base material prepreg of the surface layer is less than 10 seconds, defoaming will not be performed smoothly and the amount of remaining voids will increase. do. On the other hand, if the difference exceeds 90 seconds, the resin of the glass cloth base material prepreg of the surface layer will flow out of the laminate during molding, so the peel strength of the surface layer The interlayer adhesion strength of the core layer decreases significantly. Examples The resin used in the present invention may be any ordinary thermosetting resin and is not particularly limited. Further, the glass nonwoven fabric base material to be used is preferably one using a thermosetting or thermoplastic resin or cellulose fiber as a binder, but is not particularly limited. The resin used for the surface layer and the resin used for the core layer may be the same or different. Next, examples and comparative examples of the present invention will be described. Product name Epicote 1001 (epoxy resin manufactured by Yuka Ciel, mp70℃) 100 parts by weight, dicyandiamide
3.5 parts by weight and 0.4 parts by weight of dimethylbenzylamine were blended to prepare an epoxy resin varnish with a resin solid content of 65%. This is coated on plain-woven glass cloth to a resin content of 41% and dried to form a surface layer prepreg. In addition, the amount of resin is 78% in glass nonwoven fabric (weight 75g/m ² ).
The coating was dried to obtain a core layer prepreg. Each prepreg was adjusted to the gelation time shown in Table 1. The gelation time was adjusted by varying the drying temperature between the glass cloth base material and the glass nonwoven base material in the coating and drying process described above. The higher the temperature, the faster the crosslinking reaction of the resin will proceed, and the gelling time of the prepreg will be shorter. To measure the gelation time, the resin scraped off from the prepreg was heated to 160 to 180℃.
The material was heated and stirred on a heating plate, and the time taken until the softened resin stopped stringing between the stirring rod and the resin was measured. With the combination of core layer prepreg and surface layer prepreg shown in Table 1, six core layer prepregs are stacked, one surface layer prepreg is placed on each side on the outermost layer, and copper foil is further stacked on both sides, and the temperature is 170 °C, pressure 20
Lamination molding was carried out for 2 hours at Kg/cm ² to obtain a double-sided copper-clad laminate with a thickness of 1.6 m/m.

【table】 Table 2 shows the physical properties of each laminate obtained above.

[Table] Effects of the Invention As is clear from Table 2, according to the present invention, a composite laminate with good moldability, sufficient degassing, few residual voids, and excellent interlaminar strength can be obtained. In fact, its industrial value is extremely large.

Claims (1)

[Claims] 1 When heat-pressing molding is performed by arranging a glass nonwoven fabric base prepreg in the core layer and a glass fabric base prepreg in the surface layer, the gelation time of the glass nonwoven fabric base prepreg is determined by the gelation time of the glass fabric base prepreg. A method for manufacturing a composite laminate, characterized in that the manufacturing time is 10 to 90 seconds shorter.