JP2001259911A - Backup board for drill machining - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress wear of a drill cutting edge when a drill enters a backup board for drill machining used for drilling in a manufacturing process of a printed wiring board. SOLUTION: A mixture prepared by evenly mixing crushed articles of paper base material thermosetting resin hardened material and uncured phenolic resin is put between pre-impregnations with thermosetting resin impregnated in the paper base material and a backup board for drill machining is composed of laminating plates molded by heating and pressurizing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backup board for drilling used in drilling in a printed wiring board manufacturing process.

[0002]

2. Description of the Related Art In a drilling process, which is one of the manufacturing processes of a printed wiring board, an entry board is provided on a drill entry side of a substrate to be a printed wiring board, and a drilling laminated board called a backup board is provided on the opposite side. Hole processing has been performed.

As a back-up board for drilling used in a drilling process, a thermosetting resin laminate of a paper base material is most often used. Not yet.

In the drilling process, it is necessary to keep the copper foil of the printed wiring board flat. Therefore, it is desirable that the surface of the backup board for drilling be as hard and smooth as possible. Considering the wear of the drill and the straightness of the drill,
It is desirable that the load on the drill is as small as possible.

[0005] However, in the conventional backup board for drilling comprising a thermosetting resin laminate of a paper base material, there is a strong tendency that the smoothness of the surface when the drill enters is emphasized, and the lamination is uniform in the traveling direction of the drill. Due to the structure, the internal composition of the laminate is also made of a hard material, and there is a problem that the drill bit is worn when the drill enters.

[0006] Therefore, the present invention is to solve the problem of wear of the drill bit when the drill enters.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a mixture of a pulverized cured paper-based thermosetting resin and an uncured phenolic resin,
A back-up board for drilling was formed by a laminated plate that was inserted between prepregs in which a paper base material was impregnated with a thermosetting resin and was heated and pressed.

The surface layers 1 on both sides of the drilling backup board are formed by heating and pressing a prepreg in which a paper base material is impregnated with a thermosetting resin. It becomes a layer with high burrs suppressing effect.

The intermediate layer 2 inside the drilling backup board is made of a mixture obtained by uniformly mixing a pulverized hardened paper base thermosetting resin and an unhardened phenol resin. No fiber orientation. Due to this, the occurrence of warpage when made into a laminate is extremely small,
Further, the wear of the drill bit at the time of drill penetration is small, the drill is not bent, and the processing accuracy is improved.

As the pulverized product of the cured thermosetting resin of the paper base material for forming the intermediate layer 2, a molded article or a laminate using the paper base material can be used. In addition, when a material obtained by crushing a used backup board for drilling is used for the intermediate layer 2,
It can be obtained at a low price and resources can be reused.

The particle size of the pulverized product of the cured paper base thermosetting resin is 50 mesh under.

By using a pulverized material having a mesh size of less than 50, the intermediate layer 2 has a fine and uniform structure, and the load on the drill can be reduced. In addition, when a material having a particle size larger than 50 mesh under is used, the rigidity of the pulverized material is increased, and the straightness is likely to be impaired when the drill bit comes into contact.

Further, the ratio of the pulverized product of the cured paper base thermosetting resin to the uncured phenolic resin is preferably 80 to 80% by weight in order to uniformly cure at the time of subsequent heat and pressure molding.
95 / 20-5 is the best. If the ratio of the pulverized product of the cured paper base thermosetting resin is large, the adhesion of the pulverized product becomes insufficient, and powder of the pulverized product may fall. On the other hand, when the ratio is low, the uncured phenol resin flows easily, the thickness of the end of the plate becomes thin, and it becomes difficult to form a product having a uniform thickness.

In a prepreg obtained by impregnating a paper base material with the above-mentioned thermosetting resin, a mixture of a pulverized product of a cured paper-based thermosetting resin and an uncured phenol resin can be easily used as a powder in a predetermined amount. Prepreg / mixed powder /
The prepreg can be integrally molded at one time.

The prepreg constituting the surface layer 1 is not particularly limited as long as it is a thermosetting resin impregnated in a paper substrate, and a phenol resin, a melamine resin, a urea resin, an epoxy resin, or the like may be used. it can.

[0016]

EXAMPLES Example 1 Basis weight 200 g / m 2, density 0.
65 paper substrates were impregnated with phenolic resin,
Heat in a dryer, C. Make 45% prepreg A.

Next, the cured paper base thermosetting resin obtained by pre-curing the prepreg A is finely pulverized to 50 mesh under, and the pulverized substance and the uncured phenol resin are mixed at a ratio of 9%.
A mixture uniformly mixed at a ratio of 0/10 was placed on the prepreg A at 2 kg / m2, and the prepreg A was further placed on the prepreg A. After heating and pressurizing for a time, a backup board for drilling was manufactured, and the drillability of this backup board was confirmed. The results are as shown in Table 1. [Comparative Example 1] A paper base material having a basis weight of 200 g / m2 and a density of 0.65 was impregnated with a phenol resin, and this was heated with a dryer. C. Make 45% prepreg A.

Eight of the prepregs A are laminated and heated and pressed by a press at a temperature of 160 ° C. and a pressure of 1000 N / cm 2 for 1 hour to produce a backup board for drilling.
The drill workability of this backup board was confirmed. The results are as shown in Table 1.

The test data and evaluation method in Table 1 are as follows.

Working substrate: FR-4 1.6 mm, 2 pieces Drill: 0.3 mm diameter, Number of working shots: 4,000 shots [Drilling workability evaluation method] Drill blade wear: Used after drilling. Measured the width of the drill blade and compared it with before processing Copper foil burr: After drilling, 5 holes from the start of drilling of the board in contact with the entry board, and 5 holes before the end of processing The amount of burr generated around the copper foil was measured, and the average value was calculated. Warp amount: A plate cut to a size of 300 × 500 mm was placed on a surface plate, and the maximum lift amount was measured.

[0021]

[Table 1]

[0022]

The back-up board for drilling according to the present invention has a hard and smooth surface, so that the copper foil can be held flat and the inside is configured so that the load on the drill is small. Also, the wear of the drill bit at the time of penetration of the drill is small and the straightness of the drill is good.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a backup board for drilling according to the present invention.

[Explanation of symbols]

 1 surface layer 2 intermediate layer

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Tomoji Sakata 2-9-1 Dojima, Kita-ku, Osaka-shi Risho Kogyo Co., Ltd. F-term (reference) 3C036 AA01 GG00

Claims (2)

[Claims] 1. A mixture obtained by uniformly mixing a crushed product of a cured paper-based thermosetting resin and an uncured phenolic resin is placed between prepregs in which a paper-based material is impregnated with a thermosetting resin.
Drilling backup board made of heat-pressed laminated board. 2. The particle size of the pulverized product of the cured paper base thermosetting resin put between the prepregs is set to 50 mesh under, and the mixing ratio of the pulverized product and the uncured phenol resin is 80 to 95/20. The backup board for drilling according to claim 1, wherein the backup board is in the range of ~ 5.