JPH0632919A - Production of prepreg for printed circuit board - Google Patents

Abstract

PURPOSE:To form markings on a unit sheet of prepreg which indicate, without fail, the direction in which the sheet will deform. CONSTITUTION:A conveyor 3 is provided with a belt having many openings of a shape with which the transverse and longitudinal directions are clearly distinguished. For example, the belt has many arrow-shaped openings oriented to the lengthwise direction of a continuous prepreg sheet. A unit prepreg sheet 2 which is being transferred on the conveyor 3 is heated with a far-infrared heater 6 through the openings to eliminate the cracks in the heated regions which cracks were developed by rolling in the preceding step. Thus, markings are formed which indicate the direction of deformation based on a difference in reflectance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a prepreg used as a bonding sheet in manufacturing a printed wiring board.

[0002]

2. Description of the Related Art A prepreg used as a bonding sheet in the production of a printed wiring board has a glass cloth as a base material and a thermosetting epoxy resin or the like applied thereto.

The prepreg as described above has a dimensional change after molding in the longitudinal direction and the width direction of the prepreg due to the tension acting on the glass cloth base material when the thermosetting epoxy resin is applied and the structure of the cloth. different. That is, there is directionality in the deformation after molding. Therefore, the direction of the deformation needs to be confirmed before molding is performed. In this way, the direction of deformation has been confirmed, and if it is displayed, the shape after molding can be made exactly the desired one by determining the mode of molding according to the display.

In order to display the direction of the above deformation,
Scratch (mark) on either end surface of the prepreg,
I also print the mark on the glass cloth. Further, for example, even in the case of a prepreg which should originally be a square, it is also possible to form the prepreg into a correct shape regardless of the direction of deformation by changing the vertical and horizontal lengths.

[0005]

Problems to be Solved by the Invention It is difficult to understand the indication of any of the above-mentioned directions, and it may be completely unclear especially when cutting. Further, the determination of the vertical and horizontal dimensions in consideration of the directionality of deformation does not always give the desired result.

The present invention has been made based on the above circumstances, and the direction of the deformation is clearly and surely displayed at the time of manufacturing the prepreg, and the prepreg including the directional display means does not remain after molding. A method for manufacturing the same is provided.

[0007]

A method of manufacturing a printed wiring board prepreg according to the present invention comprises a conveyor belt which conveys a unit sheet obtained by cutting a continuous sheet of the prepreg toward a cradle to prevent deformation of the prepreg. Providing a large number of window holes showing the directionality, heating the unit sheet being conveyed through these window holes, eliminating the cracks in this heating area and displaying a shape corresponding to the shape of the window holes, It is characterized in that the unit sheet is formed.

[0008]

In the method of manufacturing a prepreg for a printed wiring board according to the present invention having the above-mentioned structure, the cracks generated during the passage of the rollers in the previous step are eliminated in the heating zone, and the reflectance of the zone is changed. As a result, it becomes easy to distinguish the area from other portions, and a display indicating the direction of deformation is formed.

[0009]

EXAMPLE The present invention provides a prepreg obtained by impregnating a glass cloth substrate with a thermosetting resin such as epoxy resin or polyimide resin, and then curing the prepreg. It is utilized that a crack is generated and the crack disappears by heating. That is, the prepreg having the above cracks is heated by far infrared rays through a window hole which can be distinguished vertically and horizontally such as an arrow shape, a long and narrow isosceles triangle shape, and the area facing the window hole of the prepreg. To eliminate the crack.
Due to the disappearance of the cracks, the reflectance of the area becomes different from the other parts of the prepreg, and the area can be discriminated from the other parts. As a result, a display indicating the direction of deformation is formed on the prepreg.

FIG. 1 is a schematic perspective view of an example of a manufacturing apparatus for carrying out the above-described prepreg manufacturing method of the present invention, FIG. 2 is an enlarged perspective view of an essential part thereof, and FIG. 3 is a specific example of a window hole. It is a figure which shows an objective size. In FIG. 1, a prepreg formed by impregnating and heating a long glass cloth with a resin in a first step (not shown) is cut into a predetermined size by a cutter 1, and a unit sheet 2 is conveyed by a conveyor 3. On the pedestal 4 provided on the outlet side of the conveyor 3, the pedestals 4 are stacked manually or by an unillustrated unloading mechanism. In the figure, reference numeral 5 indicates a laminated body of prepreg sheets laminated on the pedestal 4.

A far infrared heater 6 is provided below the upper running portion 3a of the conveyor 3. Furthermore, conveyor 3
The belt of FIG. 3 has, for example, an arrow-shaped window hole 7 as shown in FIG.
Are evenly distributed. As shown in FIG. 3, when the width of the arrow-shaped arrow head portion is 20 mm and the total length is 30 mm, for example, as shown in FIG. 2, one window hole per belt area of 100 mm × 100 mm has the arrow-shaped length. Are provided so as to match the longitudinal direction of the belt of the conveyor 3.

In the manufacturing apparatus having the above-mentioned structure, the unit sheet 2 is made to fall onto the belt of the conveyor 3 while the longitudinal direction of the prepreg before cutting is aligned with the longitudinal direction of the belt of the conveyor 3, and the unit sheet 2 is conveyed as it is. 3 is conveyed toward the exit side. Then, the area facing the window hole 7 formed in the belt of the conveyor 3 during the transportation is heated by the far infrared heater 6. In this heated area, the cracks generated during the passage of the roll in the previous step disappear, the reflectance of the surface becomes different from that of the other part of the unit sheet 2, and the shape corresponding to the shape of the window hole 7 is obtained. That is, an arrow-shaped display is formed.

Since the display is formed so as to indicate the direction of deformation of the unit sheet 2, the unit sheet 2 on which the display is formed as described above is oriented according to the display, for example, bonding. If it is used as a sheet, it is possible to control the deformation of the obtained printed wiring board during molding.

(Example 1) 180 micron thickness, 500 m
A m-width glass cloth was impregnated with a thermosetting epoxy resin to obtain a continuous prepreg sheet. This continuous sheet was cut into a length of 500 mm to obtain a unit sheet 2. The unit sheet 2 was conveyed by the conveyor 3, and the unit sheet 2 was heated to 80 ° C. to 100 ° C. by the far infrared heater 6 through the window 7 of the belt of the conveyor 3 during the conveyance. Using this unit sheet 2, copper foil of 18 microns was brought into contact with both sides of the unit sheet 2, and 1,000 double-sided plates were manufactured by manual preparation.

In this embodiment, there was no error in the direction of the unit sheet 2.

(Comparative Example 1) In the above-mentioned Example 1, the heating step was omitted and a conventional prepreg unit sheet was used.
A double-sided plate was manufactured under the same other conditions.

In the comparative example, the misdirection of 107 sheets out of 1000 sheets was observed.

[0018]

As is apparent from the above, in the method of manufacturing a printed wiring board prepreg of the present invention, since it is possible to surely form an indication indicating the direction of deformation on the unit sheet of the prepreg, this is bonded. It is possible to easily and reliably control the deformation of the printed wiring board that is used as a sheet and is manufactured, and improve the product yield.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an example of an apparatus for carrying out the present invention.

FIG. 2 is an enlarged perspective view showing a part of an apparatus for carrying out the present invention.

FIG. 3 is a diagram showing an example of the shape and dimensions of a window hole of a conveyor belt in the above apparatus.

[Explanation of symbols]

1 ... Cutter, 2 ... Unit sheet, 3 ... Conveyor, 4 ... Cradle, 5 ... Laminated body, 6 ... Far infrared heater, 7 ... Window hole.

Claims (1)

[Claims] 1. A belt of a conveyor which conveys a unit sheet formed by cutting a continuous sheet of prepreg toward a receiving table is provided with a large number of window holes showing the direction of deformation of the prepreg. Of the printed wiring board prepreg, characterized in that the unit sheet being conveyed is heated through the unit, an indication of a shape corresponding to the shape of the window hole is formed by extinguishing cracks in the heating area, and the unit sheet is formed. Production method.