WO2018105176A1

WO2018105176A1 - Entry sheet, entry sheet production method, and flexible substrate production method

Info

Publication number: WO2018105176A1
Application number: PCT/JP2017/030404
Authority: WO
Inventors: 悠赤尾; 田中　秀明; 保之伊藤; 充貴浦; 栄一梅澤
Original assignee: 日本メクトロン株式会社
Priority date: 2016-12-09
Filing date: 2017-08-24
Publication date: 2018-06-14
Also published as: JP6351865B1; CN108419432A; TW201822601A; CN108419432B; TWI650054B; JPWO2018105176A1

Abstract

The purpose of the present invention is to provide: a drilling entry sheet, which extends the service life of a drill by inhibiting drill breakage and improves the quality of the through hole after drilling; a drilling entry sheet production method; and a flexible substrate production method. This drilling entry sheet is formed by coating a non-water soluble lubricating layer made of a lubricant and a binder on at least one surface of a base substrate.

Description

Entry sheet, entry sheet manufacturing method, and flexible substrate manufacturing method

The present invention relates to an entry sheet, an entry sheet manufacturing method, and a flexible substrate manufacturing method.

Roll-to-roll method is known as a method for mass production of flexible printed circuit boards (Flexible Printed Circuit, FPC). There are a through-hole drilling process and a through-hole plating process as the first stage of the manufacturing process of a flexible substrate having a through-hole structure. Thereafter, a flexible substrate is manufactured through a resist coating process, a pattern formation process, an etching process, a terminal surface treatment process, and the like.

Among these processes, the through-hole drilling process is the first process for manufacturing a flexible substrate having a through-hole structure. However, a drilling method using an NC drilling apparatus with a roll-to-roll conveyance function (drill drilling process). Method) has been put to practical use. NC drilling equipment is capable of drilling holes as small as about 40μm, equipped with a spindle, and can drill holes by stacking multiple copper clad laminates (Flexible Cupper Clad Laminate, FCCL). ing. The number of copper-clad laminates to be stacked is generally 2 (2 levels), 4 (4 levels), 5 (5 levels), or 8 (8 levels).

The copper-clad laminate is a main member constituting a flexible printed circuit board, and an adhesive layer is formed on a thin film insulator “base film (for example, polyimide film)” having a thickness of 12 μm to 100 μm. And a conductive foil (for example, copper foil) having a thickness of about 12 μm to 50 μm. Other than the terminals and soldered parts, they are covered with an insulator for protection. Many plastics such as polyimide and polyester (PET: Polyethylene Terephthalate) are used as insulator materials. Copper foil is generally used as the conductor. For the adhesive layer, an epoxy resin-based adhesive or an acrylic resin-based adhesive is mainly used. Since a flexible printed circuit board can be folded, it is an indispensable material for connection parts of mobile phones, personal computers, digital cameras, and the like.

As a drilling method for this copper-clad laminate, a method is generally employed in which a copper-clad laminate is stacked and an aluminum foil or the like is placed on the uppermost part to perform drilling. In recent years, with the demand for improved reliability and increased density of printed wiring board materials, high-quality drilling has been required, such as improved hole location accuracy and reduced hole wall roughness. For this purpose, a drilling method using a polyethylene glycol drilling entry sheet (see, for example, Patent Document 1) and aluminum sheet coatings are proposed as entry sheets mainly composed of a water-soluble lubricant for ease of recycling.・ Practical use. In recent years, a PET (Polyethylene Terephthalate) film having a high hardness is used for an entry sheet for NC punching of a flexible printed circuit board in order to prevent flexibility and dents.

Japanese Unexamined Patent Publication No. 4-92488

However, water-soluble lubricants are sticky, and when touched, fingerprints are formed and handling properties are deteriorated. In recent years, the resin component used in PET film has adhered to the wall of the drill bit as the printed circuit board has become smaller and lighter, and the finer wiring pattern and the smaller diameter of the through hole have been extended. In particular, when drilling a small diameter of 0.1 mmφ or less, breakage of the drill bit may be recognized, leading to poor drill breakage, shortening the life, and concavity and convexity on the wall surface of the through-hole.

An object of the present invention is to provide a drilling entry sheet that extends the life of a drill by suppressing drill breakage, improves the irregularities of the wall surface of the through hole after drilling, and improves burrs, and an entry sheet for drilling. It is to provide a manufacturing method and a manufacturing method of a flexible substrate.

In order to solve the above-mentioned problems, the entry sheet for drilling according to the present invention is formed by applying a water-insoluble lubricating layer comprising a lubricant and a binder to at least one surface of a base substrate. And

In the above invention, the lubricant preferably comprises polyethylene as a main component, has an average particle diameter of 5 to 7 μm, a molecular weight of 4000 to 5000, and a melting point of 95 to 130 ° C.

In the above-described invention, the lubricant preferably contains polyethylene and polytetrafluoroethylene as main components.

In the above-described invention, it is preferable that the thickness of the water-insoluble lubricating layer composed of the lubricant and the binder is 5 to 30 μm.

In the above-described invention, it is desirable that the ratio of the solid content of the lubricant is 13.0 to 23.1% by weight of the total solid content of the lubricant layer.

In the above-described invention, examples of applicable base substrates include metal thin films (0.1 to 0.2 mm) and paper phenol plates in addition to resin composition films (thickness 125 to 250 μm).

In addition, in order to solve the above-described problem, the method for manufacturing an entry sheet for punching according to the present invention is a method in which a water-insoluble lubricating layer composed of a lubricant and a binder is applied to at least one surface of a base substrate and then dried. It is characterized by being formed.

In addition, in order to solve the above-described problem, the flexible printed circuit board manufacturing method of the present invention includes a water-insoluble lubricating layer comprising a lubricant and a binder on at least one surface of a base substrate in a through-hole drilling step. It is characterized in that it is applied to form an entry sheet for drilling.

According to the present invention, it is possible to extend the life of the drill by suppressing drill breakage (breakage) and improve the quality of the through hole after drilling.

It is sectional drawing which shows the structure of the entry sheet for hole punching which concerns on this invention. (A) is sectional drawing which showed the laminated body after a pilot hole processing and a through hole processing, (b) The cross section which showed the laminated body after performing a through hole processing without a pilot hole processing FIG. (A) And (b) is the figure which illustrated through-hole quality, (c) is the figure which showed the abrasion state of the drill. It is the figure which showed the state of the surface of the through hole after the drilling process of the entry sheet of test No1. It is the figure which showed the state of the surface of the through hole after the drilling process of the entry sheet of test No2. It is the figure which showed the state of the surface of the through hole after the drilling process of the entry sheet of test No3. It is the figure which showed the state of the surface of the through hole after the drilling process of the entry sheet of test No4. It is the figure which showed the state of the surface of the through hole after the drilling process of the entry sheet of test No5. It is the figure which showed the state of the surface of the through hole after the drilling process of the entry sheet of test No6. It is the figure which showed the state of the surface of the through hole after the drilling process of the entry sheet of test No7. It is the figure which showed the state of the surface of the through hole after the drilling process of the entry sheet of test No8. It is the figure which showed the state of the surface of the through hole after the drilling process of the entry sheet of test No9. It is the graph which showed the relationship between the number of drill holes, a drill breakage rate, and through-hole quality.

[entry sheet]
Hereinafter, an entry sheet according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic cross-sectional view of a state in which an opening entry sheet 10 of the present invention is coated on a copper clad laminate 20 made of a plurality of copper clad laminates. The opening entry sheet 10 of the present invention comprises a PET film 14 and a water-insoluble lubricating layer 12 formed on the upper surface of the PET film 14. When the drill bit 5 moves downward, the lubricant layer 12, the PET film 14 and the copper clad laminate 20 are penetrated in this order, and after reaching a predetermined depth, the drill bit 5 moves upward to form a hole (through hole). Escape from). In FIG. 1, a PET film 30 is formed on the lower surface of the copper clad laminate 20.

The thickness of the PET film 14 constituting the entry sheet 10 of the present invention is 125 to 250 μm, more preferably 125 μm. The thickness (coating thickness) of the water-insoluble lubricating layer composed of the lubricant and the binder is preferably 5 to 30 μm.

Lubricating layer 12 is composed of a lubricant and a binder, and butyl acetate, ethyl acetate, and toluene are preferable as a solvent. The lubricant is polyethylene and the average particle size is preferably 5 to 7 μm. As the binder, isocyanate-modified polybudadiene or boil-modified polybutadiene is preferable. These mixing methods are not particularly limited as long as they are known methods used industrially. Specifically, the composition is heated or heated as appropriate using a roll, kneader, or other kneading means to obtain a uniform mixture.

[Entry sheet manufacturing method]
The entry sheet is generated through a stirring process, a coating / drying process. First, the mixture is obtained by stirring for 10 minutes using a kneading means in such a ratio that the solid content of the lubricant becomes 13.0 to 23.1% by weight of the total solid content of the lubricant layer. At this time, the lubricant is dispersed in the solvent. Next, a coating / drying step of the stirred mixture is performed using a coater machine (Kobayashi Seisakusho KS-001), and the solvent in the mixture is volatilized to obtain an entry sheet having a film thickness of 5 to 20 μm. In manufacturing the entry sheet, the coater is set to the following conditions, but is not limited thereto.

<Coating machine condition settings>
The line speed 7 (m / min), MR / AR rate 6.5 / 8.0, the first unwinder for tension 7 kg, the dryers 12 kg, the DR at 3 kg / cm ^2, 1N winding And the dryer temperature was set to 120 ° C. and 150 ° C. The applied coater machine had the dryer temperature in the first zone and the second zone, and the first zone was 120 ° C and the second zone was 150 ° C. Here, MR is an abbreviation for a metalling roll, AR is an abbreviation for an applicator roll, and there is no unit for speed, which is a relative value to the line speed (a value specific to the applied coater machine). DR is an abbreviation for Dancer Laura.

Incidentally, polyethylene having an average particle diameter of 5 to 7 μm can be suitably used as the lubricant used in the entry sheet of the present invention. If the particle size is too small, the function of imparting the lubricity of the lubricating layer is reduced, while if the particle size is too large, the cutting scraps are likely to adhere to the drill. In addition, the shape of the polyethylene particles can be spherical, square, columnar, needle-like, plate-like, indefinite shape, etc., but in the present invention, from the viewpoint of imparting lubricity of the lubricating layer, It is preferable to take a form, and it becomes difficult for cutting waste to adhere to the drill while providing excellent lubricity. By setting the average particle diameter of the polyethylene within the above range, the polyethylene protrudes from the surface of the lubricating layer, so that the entry sheet can have appropriate lubricity.

The polyethylene particles are preferably contained at a blending ratio of 13.0 to 23.1% by weight with respect to the total solid content (100% by weight) of the lubricating layer. If the content is too small, the lubricity of the lubricating layer is lowered, and if the content is too large, cutting waste tends to adhere to the drill. The melting point of polyethylene is preferably 95 to 130 ° C. If the melting point is too low, the preservability of the entry sheet is lowered, or the polyethylene itself melts in the drying process after the lubrication layer is applied, which inhibits the lubricity of the lubrication layer, while the melting point is high. If it is too much, the surface irregularities of the lubricating layer become conspicuous. The melting point can be measured using a conventionally known method such as a differential scanning calorimeter (DSC). The molecular weight of polyethylene is preferably 4000 to 5000.

[Method for manufacturing flexible printed circuit board]
A roll-to-roll system is used as a system for mass-producing flexible printed boards by laminating the entry sheet of the present invention on the copper clad laminate 20. A flexible substrate is manufactured through a through-hole drilling process, a through-hole plating process, a resist coating process, a pattern baking process, an etching process, a terminal surface treatment process, and the like.

The through-hole drilling process is performed using an NC drilling device (not shown) with a roll-to-roll conveyance function. This NC drilling device can drill up to about 0.1 mm and is equipped with a spindle. After the entry sheet 10 of the present invention is stacked on the upper side of the copper clad laminate 20 and the PET 30 is stacked on the lower side, a drill (not shown) is rotationally driven as shown in FIG. The through hole 17 is formed by moving the entry sheet 10 from above to below. Conventionally, the through hole processing is performed after the pilot hole processing (processing for forming the pilot hole 16) as shown in FIG. 2 (a) is performed. However, the copper-clad laminated with the entry sheet 10 of the present invention is used. The laminate 20 can be directly subjected to through-hole processing without preparing a pilot hole. Therefore. Since the pilot hole machining process can be omitted, the manufacturing process time can be shortened and the cost can be reduced accordingly.

When drilling a flexible printed circuit board using a drill, the entry sheet of the present invention is placed on the uppermost layer (intrusion side of the drill) of the flexible printed circuit board, etc. It is also called a backup board), and these are overlapped and drilled. The flexible printed circuit board to be processed is not particularly limited, and may be a single-sided board, a double-sided board, or a multilayer board. The material of the flexible printed circuit board may be any of phenol resin, epoxy resin, polyimide resin, polyester resin, triazine resin, fluorine resin, etc., and these may be fiber reinforced resin reinforced with glass fiber or the like. .

In addition, the entry sheet of the present invention has a small side slip even when drilling with a drill having a small diameter as described later, and can perform drilling with high positional accuracy (high centrogenicity), so the diameter is about 1 to 6 mm. Of course, it can also be used for drilling, but it can also be preferably used for drilling with a small diameter. Particularly, the diameter is 0.1 to 0.4 mm, more preferably 0.1 to 0.3 mm, and most preferably 0. Used for drilling of 1 to 0.2mm.

[Entry sheet performance test 1]
Below, NC drilling is performed on the entry sheet without the lubricant, the mixing ratio of the three kinds of lubricants, the coating thickness is changed, and the drying conditions are changed, and the first hole, the 5000th hole, and the 10,000th hole. Presence / absence of wall surface unevenness in hole and 100,000th hole, presence / absence of burr on wall surface, presence / absence of interface peeling, presence / absence of through-hole plating peeling in 1st hole and 100,000th hole, and through-hole copper foil in first hole and 100,000th hole The presence or absence of deformation, the presence or absence of bending of the drill (drill durability), the degree of sticking of cutting waste to the drill, the degree of wear of the drill, and the centripetality (drill hole position accuracy) were evaluated. All nine types of entry sheets (test sheets No1 to No9) were tested, and the evaluation results are shown in Table 1 below.

Next, the evaluation criteria will be described. For wall surface unevenness evaluation, ◎ for those with almost no wall surface unevenness, ○ for those with unevenness but less impact on the drill, etc. For △, there were irregularities, and those that could not be applied due to fear of plating defects due to the influence of scraps adhering to the drill, etc. were represented by ×. For example, the left figure in FIG. 3A has no wall surface irregularities, and the right figure has wall surface irregularities.

Regarding evaluation of burrs, ◎ for those without burrs, ◯ for those with some burrs but no effect on through-hole quality, △ for those with burrs but little effect on through-hole quality, △, Those that have a significant impact on through-hole quality are marked with x.

As for interface peeling, all entry sheets No. 1 to No. 9 did not peel off, copper foil deformation did not break in all No. 1 to No. 9 entry sheets, and drill breakage did not break in all No. 1 to No. 9 entry sheets.

<Example 1 (test sheet No. 1)>
Polyethylene (trade name: ZJ-22, manufactured by Gifu Seratec) is used as the lubricant constituting the entry sheet according to Example 1, and isocyanate-modified polybutadiene (trade name: TP-1001, manufactured by Nippon Soda) is used as the binder. The content ratio of the lubricant was 50%. This entry sheet has a coating thickness (film thickness) of 20 μm, and is produced by stirring at 150 ° C. for 5 minutes after stirring the polyethylene and the binder.

FIG. 4 (a) is a view of the through hole in the first hole as seen from above, and FIG. 4 (b) is a view as seen from diagonally above. FIG. 4C is a view of the through hole at the 5000th hole as viewed from above, and FIG. 4D is a view as viewed from obliquely above. FIG. 4E is a view of the through hole at the 10,000th hole as viewed from above, and FIG. 4F is a view as viewed from obliquely above. FIG. 4G is a view of the through hole at the 100,000th hole as seen from above, and FIG. 4H is a view as seen from obliquely above.

Referring to Table 1, the entry sheet according to the test sheet No1 has almost no wall surface irregularities up to the 5000th hole (see FIGS. 4B and 4D), the presence or absence of through-hole plating peeling, the amount of cutting waste on the drill The degree of adhesion and the degree of wear of the drill were good.

<Example 2 (test sheet No. 2)>
Polyethylene (trade name: ZJ-22, manufactured by Gifu Serask) is used as the lubricant constituting the entry sheet according to Example 2, and isocyanate-modified polybutadiene (trade name: TP-1001, manufactured by Nippon Soda) is used as the binder. The lubricant content was 33%. This entry sheet has a coating thickness (film thickness) of 10 μm, and is produced by agitating the polyethylene and the binder, drying at 120 ° C. for 2 minutes, and further drying at 150 ° C. for 3 minutes.

FIG. 5 (a) is a view of the first through hole seen from above, and FIG. 5 (b) is a view seen obliquely from above. FIG.5 (c) is the figure which looked at the through hole in the 5000th hole from upper direction, and FIG.5 (d) is the figure seen from diagonally upward. FIG. 5E is a view of the through hole at the 10,000th hole as viewed from above, and FIG. 5F is a view as viewed from obliquely above. FIG. 5 (g) is a view of the through hole at the 100,000th hole as viewed from above, and FIG. 5 (h) is a view as viewed from obliquely above.

Referring to Table 1, the entry sheet according to test sheet No. 2 has slight wall surface irregularities up to the 10,000th hole (see FIGS. 5B, 5D, and 5F). The presence or absence of through-hole plating peeling and centripetality were generally good. The degree of adhesion of the cutting scraps to the drill is a little larger than that of Example 1, but has a small effect on the quality of the through hole. About the wear degree of a drill, it is a grade which is a little worn but is not enough to replace | exchange.

<Example 3 (test sheet No. 3)>
Polyethylene (trade name: ZJ-22, manufactured by Gifu Seratec) is used as a lubricant constituting the entry sheet according to Example 3, and isocyanate-modified polybutadiene (trade name: TP-1001, manufactured by Nippon Soda) is used as a binder. The lubricant content was 33%. This entry sheet has a coating thickness (film thickness) of 20 μm, and is produced by stirring the polyethylene and the binder, drying at 120 ° C. for 2 minutes, and further drying at 150 ° C. for 3 minutes.

FIG. 6 (a) is a view of the through hole in the first hole as seen from above, and FIG. 6 (b) is a view as seen from diagonally above. FIG. 6 (c) is a view of the through hole at the 5000th hole as viewed from above, and FIG. 6 (d) is a view as viewed from obliquely above. FIG. 6 (e) is a view of the through hole at the 10,000th hole as viewed from above, and FIG. 6 (f) is a view as viewed from obliquely above. FIG. 4 (g) is a view of the through hole at the 100,000th hole as viewed from above, and FIG. 6 (h) is a view as viewed from obliquely above.

Referring to Table 1, the entry sheet according to test sheet No. 3 shows slight wall surface irregularities up to the 10,000th hole (see FIGS. 6B, 6D, and 6F). The presence or absence of through-hole plating peeling, the degree of sticking of cutting waste to the drill, the degree of wear of the drill, and the centering property were generally good.

<Example 4 (test sheet No. 4)>
Polyethylene (trade name: ZJ-22, manufactured by Gifu Serask) is used as the lubricant constituting the entry sheet according to Example 4, and isocyanate-modified polybutadiene (trade name: TP-1001, manufactured by Nippon Soda) is used as the binder. The content ratio of the lubricant was 50%. This entry sheet has a coating thickness (film thickness) of 10 μm, and is produced by agitating the polyethylene and the binder, drying at 120 ° C. for 2 minutes, and further drying at 150 ° C. for 3 minutes.

FIG. 7 (a) is a view of the through hole in the first hole as seen from above, and FIG. 7 (b) is a view as seen from diagonally above. FIG. 7C is a view of the through hole at the 5000th hole as viewed from above, and FIG. 7D is a view as viewed from obliquely above. FIG. 7E is a view of the through hole at the 10,000th hole as viewed from above, and FIG. 7F is a view as viewed from obliquely above. FIG. 7 (g) is a view of the through hole at the 100,000th hole as viewed from above, and FIG. 7 (h) is a view as viewed from obliquely above.

Referring to Table 1, the entry sheet according to test sheet No. 4 showed almost no wall surface irregularities up to the 10,000th hole, and was slightly seen at the 10,000th hole (FIGS. 7B, 7D and 7F). (See (h)). The presence of burrs is only slightly recognized but has little effect on through-hole quality. In addition, as for the presence or absence of through-hole plating peeling, some peeling is seen, but the influence on the through-hole quality is small.

<Example 5 (test sheet No. 5)>
Polyethylene (trade name: ZJ-22, manufactured by Gifu Seratec) is used as the lubricant constituting the entry sheet according to Example 5, and isocyanate-modified polybutadiene (trade name: TP-1001, manufactured by Nippon Soda) is used as the binder. The content ratio of the lubricant was 50%. This entry sheet has a coating thickness (film thickness) of 20 μm, and is produced by stirring the polyethylene and the binder, drying at 120 ° C. for 2 minutes, and further drying at 150 ° C. for 3 minutes.

FIG. 8 (a) is a view of the through hole in the first hole as seen from above, and FIG. 8 (b) is a view as seen from diagonally above. FIG. 8 (c) is a view of the through hole at the 5000th hole as viewed from above, and FIG. 8 (d) is a view as viewed from obliquely above. FIG. 8E is a view of the through hole at the 10,000th hole as viewed from above, and FIG. 8F is a view as viewed from obliquely above. FIG. 8 (g) is a view of the through hole at the 100,000th hole as viewed from above, and FIG. 8 (h) is a view as viewed from obliquely above.

Referring to Table 1, the entry sheet according to test sheet No5 showed almost no wall surface irregularities up to the 5000th hole, and was slightly seen at the 10,000th and 100,000th holes (FIGS. 8B and 8D). , (F), (h)). The presence or absence of through-hole plating peeling was generally good. The degree of adhesion of the cutting scraps to the drill is a little larger than that of Example 1, but has a small effect on the quality of the through hole. About the wear degree of a drill, it is a grade which is a little worn but is not enough to replace | exchange.

<Example 6 (test sheet No. 6)>
Polyethylene (trade name: ZJ-24FA, manufactured by Gifu Serask) is used as the lubricant constituting the entry sheet according to Example 6, and isocyanate-modified polybutadiene (trade name: TP-1001, manufactured by Nippon Soda) is used as the binder to be mixed. The polyethylene (lubricant) content was 33%. This entry sheet has a coating thickness (film thickness) of 10 μm, and is produced by agitation treatment of polyethylene and a binder, followed by drying at 120 ° C. for 2 minutes and then drying at 150 ° C. for 3 minutes.

FIG. 9 (a) is a view of the through hole in the first hole as seen from above, and FIG. 9 (b) is a view as seen from diagonally above. FIG. 9C is a view of the through hole at the 5000th hole as viewed from above, and FIG. 9D is a view as viewed from obliquely above. FIG. 9 (e) is a view of the through hole at the 10,000th hole as viewed from above, and FIG. 9 (f) is a view as viewed from obliquely above. FIG. 9 (g) is a view of the through hole at the 100,000th hole as viewed from above, and FIG. 9 (h) is a view as viewed from obliquely above.

Referring to Table 1, the entry sheet according to test sheet No. 6 has a slight unevenness on the wall surface at the 5000th hole, but is hardly seen at the 10,000th hole (FIGS. 9B, 9D, 9F). (See (h)). The presence or absence of through-hole plating peeling was generally good. Although the presence of burrs is only slightly observed, the effect on the through-hole quality is small. The degree of adhesion of the cutting scraps to the drill is a little larger than that of Example 1, but has a small effect on the quality of the through hole.

<Example 7 (test sheet No. 7)>
Polyethylene (trade name: XD-448 (microcrystalline wax), manufactured by Gifu Seratec) is used as the lubricant constituting the entry sheet according to Example 7, and isocyanate-modified polybutadiene (trade name: TP-1001, Nippon Soda) is used as the binder. And the lubricant content was 33%. This entry sheet has a coating thickness (film thickness) of 10 μm, and is produced by drying at 120 ° C. for 2 minutes after stirring treatment of polyethylene and binder, and further drying at 150 ° C. for 3 minutes.

FIG. 10 (a) is a view of the through hole in the first hole as seen from above, and FIG. 10 (b) is a view as seen from diagonally above. FIG. 10 (c) is a view of the through hole at the 5000th hole as viewed from above, and FIG. 10 (d) is a view as viewed from obliquely above. FIG. 10E is a view of the through hole at the 10,000th hole as viewed from above, and FIG. 10F is a view as viewed from obliquely above. FIG. 10G is a view of the through hole at the 100,000th hole as viewed from above, and FIG. 10H is a view as viewed from obliquely above.

Referring to Table 1, in the entry sheet according to test sheet No7, the wall surface unevenness is slightly seen at the 5000th hole, but is hardly seen at the 10,000th and 100,000th holes (FIGS. 10B and 10D). (Refer to (f) and (h)). Although the presence of burrs is only slightly observed, the effect on the through-hole quality is small. With respect to the presence or absence of through-hole plating peeling, some peeling is seen, but the effect on the through-hole quality is small. With respect to the deformation of the through-hole copper foil, the deformation portion is slightly scattered at the 10,000th hole, but the influence on the through-hole quality is small. The degree of adhesion of the cutting scraps to the drill is a little larger than that of Example 1, but has a small effect on the quality of the through hole. About the wear degree of a drill, it is a grade which is a little worn but is not enough to replace | exchange.

<Example 8 (test sheet No. 9)>
Polyethylene (trade name: ZJ-22, manufactured by Gifu Seratec) is used as the lubricant constituting the entry sheet according to Example 8, and isocyanate-modified polybutadiene (trade name: TP-1001, manufactured by Nippon Soda) is used as the binder. The lubricant content was 33%. This entry sheet has a coating thickness (film thickness) of 30 μm, and is produced by stirring the polyethylene and the binder, drying at 120 ° C. for 2 minutes, and further drying at 150 ° C. for 3 minutes.

FIG. 12 (a) is a view of the through hole in the first hole as seen from above, and FIG. 12 (b) is a view as seen from diagonally above. FIG. 12C is a view of the through hole at the 5000th hole as viewed from above, and FIG. 12D is a view as viewed from obliquely above. FIG. 12E is a view of the through hole at the 10,000th hole as seen from above, and FIG. 12F is a view as seen from obliquely above. FIG. 12G is a view of the through hole at the 100,000th hole as seen from above, and FIG. 12H is a view as seen from obliquely above.

Referring to Table 1, the entry sheet according to the test sheet No. 9 has slight wall surface irregularities up to the 10,000th hole (see FIGS. 12B, 12D, and 12F). The presence or absence of through-hole plating peeling, the degree of sticking of cutting waste to the drill, the degree of wear of the drill, and the centering property were generally good.

<Comparative example 1 (test sheet No. 8)>
The entry sheet according to Comparative Example 1 is produced using 250 μm PET and does not contain a lubricant.

FIG. 11 (a) is a view of the through hole in the first hole as seen from above, and FIG. 11 (b) is a view as seen from diagonally above. FIG. 11C is a view of the through hole at the 5000th hole as viewed from above, and FIG. 11D is a view as viewed from obliquely above. FIG. 11 (e) is a view of the through hole at the 10,000th hole as viewed from above, and FIG. 11 (f) is a view as viewed from obliquely above. FIG. 11 (g) is a view of the through hole at the 100,000th hole as seen from above, and FIG. 11 (h) is a view as seen from obliquely above.

Referring to Table 1 and FIG. 11, in the entry sheet according to test sheet No8, wall surface unevenness is seen from the first hole, and wall surface unevenness is also seen in the 5000th, 10000th and 100,000th holes (FIG. 11 ( b), (d), (f), (h)). The presence of burrs was observed, and the presence or absence of peeling of through-hole plating was observed. It was confirmed that the degree of wear of the drill was relatively high and the amount of misalignment of the through-hole was large.

[Evaluation results and discussion]
The test items described above of the entry sheets according to Examples 1 to 7 obtained by mixing the lubricant and the binder (the presence or absence of wall surface irregularities, the presence or absence of wall surface burrs, the presence or absence of through-hole plating peeling, the amount of cutting waste on the drill) Consideration is based on the evaluation results of the degree of adhesion and the degree of wear of the drill.

In addition, there is almost no deformation of the copper foil, and the through hole quality can be improved and the quality of the flexible printed circuit board can be improved. In addition, the PET positioned below the lubrication layer can be made thinner as compared with the conventional entry sheet made of only PET, so that the material cost can be reduced.

Regarding the wall surface unevenness, Examples 4 and 5 were good at the 5000th hole, and Examples 4, 6, and 7 were good at the 10,000th hole. When the lubricant is ZJ-22, it can be seen that the unevenness of the wall surface can be reduced by setting the lubricant content to 50%. Regarding the presence or absence of through-hole plating peeling, Examples 3, 5, and 6 were good at the 10,000th hole. It can be seen that when the lubricant is ZJ-22, the coating thickness of 20 μm can further reduce the through-hole plating peeling.

Examples 1 and 3 were good with respect to the degree of adhesion of cutting waste to the drill. It can be seen that when the lubricant is ZJ-22, the coating thickness of 20 μm can further reduce the degree of adhesion of cutting waste to the drill.

[Entry sheet performance test 2]
Next, the test which evaluates the drill breakage rate and drill hole quality in this invention and the conventional entry sheet was done. Polyethylene (trade name: ZJ-22, manufactured by Gifu Seratech) is used as the lubricant constituting the entry sheet of the present invention, and isocyanate-modified polybutadiene (trade name: TP-1001, manufactured by Nippon Soda) is used as the binder. The material content was 33%. This entry sheet has a coating thickness (film thickness) of 5 μm, and is produced by stirring at 150 ° C. for 5 minutes after stirring the polyethylene and the binder. The conventional entry sheet consists of a 250 μm PET layer and does not contain a lubricant.

Evaluation results are shown in FIG. In FIG. 13, the horizontal axis represents the number of drill holes (× 1000), the vertical axis represents the drill breakage rate (%), and the through hole quality, and the relationship between the number of drill holes, the drill breakage rate (%), and the through hole quality. It is the graph which showed. Through-hole quality is a comprehensive evaluation of unevenness, plating peeling, deformation, etc. on the wall surface of the through-hole. The higher the numerical value, the better the quality. The through hole quality is indicated by a numerical value quantified according to a predetermined standard. The -O- line is a graph showing the drill breakage rate (%) of the entry sheet of the present invention, and the-□-line is a graph showing the through-hole quality of the entry sheet of the present invention. The line-△-is a graph showing the drill breakage rate (%) of the conventional entry sheet (comparative example), and the line -x- is a graph showing the through-hole quality of the conventional entry sheet.

[Evaluation results and discussion]
Regarding the drill breakage, in the case of the entry sheet of the present invention, the drill breakage does not occur even when the number of holes exceeds 10,000 holes, but it can be seen that the drill breakage rate of the conventional entry sheet increases from the point of exceeding 10,000 holes. As for through-hole quality, there is a slight difference between the entry sheet of the present invention and the conventional entry sheet in the initial stage, but both the quality gradually deteriorates as the number of drill holes increases. I can't see it.

As described above, according to the entry sheet of the present invention, drill breakage can be suppressed while maintaining a constant through-hole quality, and the drill life can be extended.

Although one embodiment of the present invention has been described above, the present invention can be variously modified in addition to this.

5 ... Drill bit 10 ... Entry sheet 12 ...

Lubrication layer

14,15 ... PET
16 ... Pilot hole 17 ... Through hole 20 ... Copper-clad laminate 30 ... PET

Claims

Formed by applying a water-insoluble lubricating layer comprising a lubricant and a binder to at least one surface of the base substrate,
This is an entry sheet for drilling.
The perforated material according to claim 1, wherein the lubricant comprises polyethylene as a main component, has an average particle diameter of 5 to 7 µm, a molecular weight of 4000 to 5000, and a melting point of 95 to 130 ° C. Entry sheet for processing.
The lubricant is mainly composed of polyethylene and polytetrafluoroethylene,
The entry sheet for drilling according to claim 1, wherein:
The water-insoluble lubricating layer composed of the lubricant and the binder has a thickness of 5 to 30 μm.
The entry sheet for drilling according to any one of claims 1 to 3, wherein
The drilling process according to any one of claims 1 to 4, wherein the ratio of the solid content of the lubricant is 13.0 to 23.1 wt% of the total solid content of the lubricant layer. entry sheet.
Formed by applying a water-insoluble lubricating layer consisting of a lubricant and a binder to at least one surface of the base substrate and then drying it.
A method for manufacturing an entry sheet for boring, characterized in that.
The lubricant comprises polyethylene as a main component, has an average particle size of 5 to 7 μm, a molecular weight of 4000 to 5000, and a melting point of 95 to 130 ° C.
The method for manufacturing an entry sheet for punching according to claim 6.
The lubricant is mainly composed of polyethylene and polytetrafluoroethylene,
The method for manufacturing an entry sheet for punching according to claim 6.
The water-insoluble lubricating layer composed of the lubricant and the binder has a thickness of 5 to 30 μm.
The method for producing an entry sheet for drilling according to any one of claims 6 to 8.
The drilling process according to any one of claims 6 to 9, wherein the ratio of the solid content of the lubricant is 13.0 to 23.1 wt% of the total solid content of the lubricant layer. Entry sheet manufacturing method.
In the manufacturing method of the flexible printed circuit board including the through-hole drilling process,
In the through-hole drilling step, a water-insoluble lubricating layer composed of a lubricant and a binder was applied to at least one surface of the base substrate to form an entry sheet for drilling.
A method for producing a flexible printed circuit board.
The lubricant comprises polyethylene as a main component, has an average particle size of 5 to 7 μm, a molecular weight of 4000 to 5000, and a melting point of 95 to 130 ° C.
The method for producing a flexible printed board according to claim 11.
The lubricant is mainly composed of polyethylene and polytetrafluoroethylene,
The method for producing a flexible printed board according to claim 11.
The water-insoluble lubricating layer composed of the lubricant and the binder has a thickness of 5 to 30 μm.
The method for producing a flexible printed circuit board according to any one of claims 11 to 13, wherein:
The flexible printed circuit board according to any one of claims 11 to 14, wherein a ratio of the solid content of the lubricant is 13.0 to 23.1 wt% of the total solid content of the lubricant layer. Production method.