JP3976230B2 - Printed circuit board punching sheet and printed circuit board punching method using such a sheet - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a printed wiring board punching sheet useful for drilling (piercing) processing for forming a through hole in a printed wiring board, and a printed wiring board punching method using such a sheet.
[0002]
[Prior art]
When drilling through-holes in a printed circuit board, if the hole diameter is large, the hole is drilled directly on the board. In general-purpose substrates with small hole diameters, a metal thin film such as an aluminum foil is generally formed on the substrate. And various water-soluble compound layers are arranged and penetrated using a drill, a cone, a puncher or the like.
In the above method, the use of the water-soluble compound layer prevents the drill bit from escaping due to the unevenness of the substrate surface and accurately sets the drill tip at the position of the desired through-hole, that is, the processing position. Aluminum foil is used for the purpose of ensuring accuracy. Furthermore, the use of aluminum foil prevents the peeling of the copper surface on the board when the drill is pulled out, and prevents the so-called burrs and generates heat in the through-hole part that occurs during drilling. In order to avoid the clogging of the through-hole part and the trouble of adhesion of cutting debris, drilling is carried out by using the laminated aluminum foil / water-soluble compound layer. In addition, the water-soluble compound layer has an advantage that it can be removed from the substrate by washing the substrate with water after the perforation.
[0003]
As a publicly known document showing a water-soluble compound used for such a purpose, for example, Japanese Patent Laid-Open No. 4-92488 describes that polyethylene glycol, polypropylene glycol, or the like is arranged on one side or both sides of a substrate.
[0004]
[Problems to be solved by the invention]
However, when through holes are punched in a printed wiring board industrially, a large number of printed wiring boards are stacked and punched, and in the conventional method, any through hole on any of the boards is damaged. In addition, in order to obtain a beautifully finished product free from shavings and the like, considerable skill is required, and the quality often varies.
In particular, when continuously drilling with a thin drill such as a drill diameter of 0.15 mm or less, the conventional technology including the above-described method is one of the higher quality requirements in recent times, In other words, it is easy to have defects that the uniform plating workability cannot be sufficiently satisfied when plating is performed in the through hole, so that all through holes on all substrates have a beautiful finish while ensuring processing position accuracy. It must be said that the development of a sheet for manufacturing and a perforation method using the sheet is extremely useful.
[0005]
[Means for Solving the Problems]
As a result of intensive studies by the present inventors in order to solve the above problems, a water-soluble lubricant composed of a polyoxyalkylene compound having a weight average molecular weight of 300 or more and less than 10,000 is laminated on a support composed of a polyvinyl alcohol resin. The present invention has been completed by finding that a printed wiring board perforating sheet can achieve such a purpose.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Examples of the polyoxyalkylene compound having a weight average molecular weight of 300 or more and less than 10,000 used in the present invention include polyalkylene glycols and monoetherified products, monoether monoesterified products, dietherified products, monoesterified products, and diesterified products of polyalkylene glycol. Specific examples of the polyalkylene glycol include polyethylene glycol, polypropylene glycol, polybutylene glycol and the like.
Monoetherified products include polyoxyethylene monooleyl ether, polyoxyethylene monocetyl ether, polyoxyethylene monostearyl ether, polyoxyethylene monolauryl ether, polyoxyethylene monododecyl ether, polyoxyethylene monononylphenol ether, polyoxyethylene Ethylene monooctyl phenyl ether is exemplified. Examples of the monoether monoester product include methoxypolyethylene glycol (meth) acrylate, ethoxypolyethylene glycol (meth) acrylate, and propoxypolyethylene glycol (meth) acrylate. Dietherized products include polyoxyethylene dioleyl ether, polyoxyethylene dicetyl ether, polyoxyethylene distearyl ether, polyoxyethylene dilauryl ether, polyoxyethylene didodecyl ether, polyoxyethylene dinonylphenol ether, polyoxyethylene Examples include dioctyl phenyl ether.
[0007]
Monoesterified products include polyoxyethylene mono (meth) acrylate, polyoxyethylene monooleate, polyoxyethylene monolaurate, polyoxyethylene monostearate, polyoxyethylene mono-bovine fatty acid ester, polyglycerin monostearate, etc. However, diesterified products include polyoxyethylene di (meth) acrylate, polyoxyethylene dioleate, polyoxyethylene dilaurate, polyoxyethylene distearate, polyoxyethylene dibovine fatty acid ester, polygluterin distearate and the like. Each is illustrated.
[0008]
The weight average molecular weight is 300 or more and less than 10,000, preferably 350 to 9000. If the weight average molecular weight is less than 300, the film-forming property may be poor or bleed out may occur. If the weight average molecular weight is 10,000 or more, water solubility may be lowered.
[0009]
In the present invention, a known additive such as an inorganic powder may be added to the water-soluble lubricant, if necessary, in addition to a lubricant such as a nonionic surfactant, a rust inhibitor, a stabilizer such as a phosphate ester. There is no problem.
The water-soluble lubricant layer is used as a laminate laminated with a support made of polyvinyl alcohol resin .
[0010]
In the present invention, a support made of a polyvinyl alcohol resin is used as the support.
[0011]
Such polyvinyl alcohol resin may be modified, and the polyvinyl alcohol is produced by homopolymerizing vinyl acetate and further saponifying it. The modified polyvinyl alcohol is produced by saponifying a polymer of vinyl acetate and another unsaturated monomer, or is produced by post-modifying polyvinyl alcohol.
Examples of other unsaturated monomers include olefins such as ethylene, propylene, isobutylene, α-octene, α-dodecene, α-octadecene, acrylic acid, methacrylic acid, crotonic acid, maleic acid, and maleic anhydride. , Unsaturated acids such as itaconic acid or salts thereof, mono- or dialkyl esters, nitriles such as acrylonitrile and methacrylonitrile, amides such as acrylamide and methacrylamide, ethylene sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, etc. Olefin sulfonic acid or its salt, alkyl vinyl ethers, N-acrylamidomethyltrimethylammonium chloride, allyltrimethylammonium chloride, dimethylallyl vinyl ketone, N-vinylpyrrolidone, vinyl chloride, vinyl chloride Polyoxyalkylenes such as redene, polyoxyethylene (meth) allyl ether, polyoxyalkylene (meth) allyl ether such as polyoxypropylene (meth) allyl ether, polyoxyethylene (meth) acrylate, polyoxypropylene (meth) acrylate, etc. (Meth) acrylate, polyoxyethylene (meth) acrylamide, polyoxyalkylene (meth) acrylamide such as polyoxypropylene (meth) acrylamide, polyoxyethylene (1- (meth) acrylamide-1,1-dimethylpropyl) ester, Polyoxyethylene vinyl ether, polyoxypropylene vinyl ether, polyoxyethylene allylamine, polyoxypropylene allylamine, polyoxyethylene vinylamine, polyoxypropylene Monomer pyrene vinyl amine and various like.
[0012]
Examples of the post-modification method include a method of converting polyvinyl alcohol into acetoacetate ester, acetalization, urethanization, etherification, grafting, phosphoric esterification, and oxyalkylene.
[0013]
Among these polyvinyl alcohol resins, those having a saponification degree of 65 mol% or more are preferable, and 70 to 100 mol%, particularly 72 to 99 mol% is advantageous. If the saponification degree is less than 65 mol%, the water solubility becomes poor, and it is not preferable because it requires labor for washing after drilling.
The viscosity of the 4% by weight aqueous solution at 20 ° C. is preferably 2.5 to 100 mPa · s, more preferably 2.5 to 70 mPa · s, and particularly preferably 2.5 to 60 mPa · s. When the viscosity is less than 2.5 mPa · s, the strength is inferior and the film may be broken during perforation. On the other hand, when the viscosity exceeds 100 mPa · s, the film-forming property on the film or sheet is deteriorated. The viscosity is measured according to JIS K 6726.
[0014]
In order to produce such a laminate, a water-soluble lubricant layer may be laminated on the support by a general film-forming means such as a solution casting method. Alternatively, a water-soluble lubricant layer may be produced in advance and dry-laminated with the support.
The thickness of the water-soluble lubricant layer is preferably set in the range of 60 to 1000 μm.
As for the thickness of a support body, 50-300 micrometers is preferable normally, Furthermore, it is set to 100-250 micrometers.
[0015]
The laminate used in the present invention prevents lateral misalignment between printed circuit boards during use, and ease of separation when individually separating the printed circuit boards that are superposed prior to dissolution and removal by water after drilling For this reason, it is possible to perform adhesive processing on one side and release processing on the other side.
Furthermore, in order to improve the processing position accuracy, it is also possible to form a concavo-convex pattern on the sheet surface by performing satin processing or embossing on one or both sides of the laminate. Examples of the concavo-convex pattern include a lattice pattern, a silk pattern, a turtle shell pattern, and a rhombus pattern. It is practical to provide irregularities with a surface roughness (measured with a laser microscope) of about 1 to 5 μm and a depth of about 1 to 5 μm (measured with JIS B 0601) for embossing. It is.
[0016]
A method of perforating a printed wiring board using the perforating sheet is performed as follows.
First, the printed wiring board used is usually a board in which a metal foil such as copper and an electrical insulator are laminated and integrated, for example, a metal foil-clad laminate such as an epoxy board in which a metal foil is arranged on the outer layer, and an inner layer. Examples include a multilayer laminate having a printed wiring circuit, a metal foil-clad laminate having a printed wiring circuit, and a metal foil-clad plastic film.
[0017]
A punching sheet according to the present invention is arranged on one or both sides of a printed wiring board, and a through hole having a predetermined size is drilled at a predetermined position of the substrate through the sheet by a drill or a cone.
The punching sheet is preferably arranged so that the support surface of the sheet and the printed wiring board surface are in contact with each other from the viewpoint of improving the processing position accuracy. A metal foil such as an aluminum foil may be interposed between the laminate and the printed wiring board surface.
It is also possible to laminate a plurality of printed wiring boards with a sheet interposed between the substrates and perforate them simultaneously.
After drilling, the laminate is dissolved and removed by washing the substrate with water.
[0018]
【Example】
Hereinafter, the present invention will be specifically described with reference to examples.
In the examples, “%” and “part” mean weight basis unless otherwise specified.
Example 1 (Manufacture of punching sheet)
Sheet 1:
30 parts of water and 30 parts of polyethylene glycol (“PEG4000” manufactured by Kishida Chemical Co., Ltd.) having a weight average molecular weight of 3100 were mixed with stirring to obtain an aqueous solution of a water-soluble lubricant.
[0019]
35 mil on a support made of a polyvinyl alcohol resin (“GOHSENOL KM-11” manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) sheet (thickness: 100 μm) having a saponification degree of 78 mol% and a 4% aqueous solution viscosity of 13 mPa · s. And then dried at 65 ° C. for 96 hours to form a coating film having a thickness of 160 μm to obtain a punching sheet.
[0020]
Example 2 (Manufacture of punching sheet)
Sheet 2:
Instead of the polyethylene glycol in the sheet 1, a polyethylene glycol having a weight average molecular weight of 600 [“PEG 600” manufactured by Kishida Chemical Co., Ltd.] was used.
[0021]
Example 3 (Manufacture of punching sheet)
Sheet 3:
Manufactured in the same manner as in Example 1 except that the support in sheet 1 was changed to a polyvinyl alcohol resin (“GOHSENOL KP-08” manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) having a saponification degree of 72 mol% and a 4% aqueous solution viscosity of 7 mPa · s. Went.
[0022]
Example 4 (Manufacture of punching sheet)
Sheet 4:
Same as the above example except that the support in the sheet 2 was changed to a polyvinyl alcohol resin (“GOHSENOL KL-05” manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) having a saponification degree of 80 mol% and a 4% aqueous solution viscosity of 4.5 mPa · s. The same manufacturing was performed.
[0023]
Comparative Example 1 (Manufacture of punching sheet)
Instead of the polyethylene glycol in the sheet 1, polyethylene glycol having a weight average molecular weight of 200 [“PEG200” manufactured by Kishida Chemical Co., Ltd.] was used.
[0024]
Comparative Example 2 (Manufacture of punching sheet)
Instead of the polyethylene glycol in the sheet 1, polyethylene glycol having a weight average molecular weight of 20000 [“PEG20M” manufactured by Kishida Chemical Co., Ltd.] was used.
[0025]
Comparative Example 3 (Manufacture of punching sheet)
The same production as in the above example was performed except that, in the sheet 1, an aluminum foil having a film thickness of 100 μm was used instead of the polyvinyl alcohol resin of the support.
[0026]
The printed wiring board was perforated by the following procedure using the above perforating sheet, and the sheet was evaluated.
Two printed wiring boards with a total thickness of 0.4 mm with 18 μm thick copper foil laminated on both sides are stacked, and a perforating sheet as shown in Table 1 is placed at the top, under conditions of room temperature and 30% RH A 1000-hole through hole penetrating the two substrates was formed with a drill having a diameter of 0.15 mm. Regarding the obtained perforated substrate, the processing accuracy of the through hole and the throwing power with plating were evaluated as follows.
[0027]
(Machining position accuracy)
Measure the center of the hole and measure the deviation from a predetermined position with a digital length measuring device ("DR-555-D" manufactured by Dainippon Screen). The average value of the 750th and 1000th holes was calculated to obtain the standard deviation σ, and the (average value + 3σ) value was calculated and evaluated as follows.
◎ ・ ・ ・ less than 15% of drill diameter ○ ・ ・ ・ less than 15-20% of drill diameter △ ・ ・ ・ less than 20-30% of drill diameter × ・ ・ ・ 30% or more of drill diameter
(Plating coverage)
Copper plating is applied to the perforated substrate (plating bath: “Capper Gream 125” manufactured by Meltex), and the cross sections of the first and second substrates 750, 800, 900 and 1000 are confirmed as follows. evaluated.
○ ... Copper plating in all holes is uniformly attached. Δ ... Copper plating uniformity in any one hole is inferior. × ... Copper plating uniformity in two or more holes is inferior. [0029]
The evaluation results of Examples and Comparative Examples are shown in Table 1.
[Table 1]
Machining position accuracy
Example 1 ◎ ○
Example 2 ◎ ○
Example 3 ◎ ○
Example 4 ◎ ○
Comparative Example 1 × △
Comparative Example 2
Comparative Example 3 ○ ×
[0030]
【The invention's effect】
The printed wiring board perforated sheet of the present invention is formed by laminating a water-soluble lubricant made of a polyoxyalkylene compound having a weight average molecular weight of 300 or more and less than 10,000 on a support made of a polyvinyl alcohol resin, so that the printed wiring board is perforated. When performing, it is excellent in processing position accuracy at the time of drilling and removability with plating, and the removability of the sheet after drilling is also good.

Claims (5)

A printed wiring board perforated sheet comprising a water-soluble lubricant comprising a polyoxyalkylene compound having a weight average molecular weight of 300 or more and less than 10,000 laminated on a support comprising a polyvinyl alcohol resin .   The printed wiring board perforated sheet according to claim 1, wherein the polyoxyalkylene compound having a weight average molecular weight of 300 or more and less than 10,000 is polyethylene glycol. Claim 1-2 sheet according any one, printed circuit board drilling sheet characterized by comprising further stacking a metal foil. A method for punching a printed wiring board, comprising: arranging the sheet according to any one of claims 1 to 3 on a printed wiring board and punching through holes in the board. A method for punching a printed wiring board, wherein the sheet according to any one of claims 1 to 3 is disposed such that a support surface or a metal foil surface thereof is in contact with a printed wiring board surface, and a through hole is punched in the board. .