JP2001298253A - Base film for printing, method of printing using the same, and wiring board manufactured thereby - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a base film for printing whereon a fine pattern can be printed easily and at a low cost and also provide a method of printing using the base film and a wiring board manufactured by the method. SOLUTION: The base film 60 for printing formed between an object 52 to be printed with a printed matter and a printed matter 53 is formed of a porous material having a smaller surface energy than that of the object to be printed with a printed matter. Since the surface energy of the base film is smaller than that of the object to be printed with a printed matter, the printed matter is less pulled outwards and the width of a line part of even a fine pattern can be maintained, preventing the generation of bleeding. Since the base film is porous, the printed matter is likely to be absorbed more by the base film than by the object to be printed with a printed matter, reducing a ratio of a quantity of bleeding to the width of the line part of the fine pattern.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing base film formed between a substrate and a printed material, a printing method using the printing base film, and a wiring board manufactured by the method. is there.

[0002]

2. Description of the Related Art A method of manufacturing a printed circuit board is classified into a typical method for forming a conductor pattern, and is classified into an additive method and a subtractive method.

FIG. 10 is a process chart showing a general additive method. First, an insulating substrate (laminated plate) 1 having no copper foil is prepared (see FIG. 10A), and a plating resist 2 is printed in a predetermined pattern on the surface of the insulating substrate 1 (FIG. 10B). reference).

After a conductive pattern 3 is formed between the plating resists 2 on the surface of the insulating substrate 1 by electroless copper plating or the like (see FIG. 10C), the plating resist 2 is peeled off. After that, the solder resist 4 is printed and cured between the conductor patterns 3 on the surface of the insulating substrate 1, the symbols are printed and cured, and the insulating substrate 1 is punched into a predetermined printed circuit board 5 (FIG. 10). (D)).

FIG. 11 is a process chart showing a general subtractive method. First, a substrate (single-sided copper-clad laminate) 11 having a copper foil 12 on one side is prepared (FIG. 11A).
), Etching resist ink 1 on the surface of copper foil 12
3 is printed in a predetermined pattern (see FIG. 11B).
Next, portions of the copper foil 12 that are not covered with the etching resist ink 13 are removed by etching (FIG. 11).
(C)).

Then, the remaining etching resist ink 13 is peeled off to form a conductor pattern 14 on the substrate 11 (see FIG. 11D). Thereafter, a solder resist 15 is printed and cured between the conductor patterns 14 on the substrate 11, a symbol is printed and cured, and the substrate 11 is punched to form a predetermined printed circuit board 16 (FIG. 11).
(E)).

[0007]

At present, the subtractive method, which allows a printed circuit board to be manufactured relatively easily, has become mainstream. In the step of printing the etching resist ink 13 in a predetermined pattern on the surface of the copper foil 12 shown in FIG. 11C in the subtractive method, a screen printing method is used.

[0008] Here, the screen printing method means that eyes other than necessary image lines on a screen woven with fibers such as nylon or Tetron (registered trademark) or a wire such as stainless steel are covered with a resist formed by a photo process. This is a method in which printing is performed by rubbing ink and passing through a required image line. However, in the pattern formation of the etching resist ink 13 by the conventional screen printing method, the width of the line portion of the circuit pattern shown in FIG. 12 and the width of the space portion sandwiched between the lines, that is, the line and space (L / S) are 130. / 130 μm is the limit.

The reason is that as the L / S becomes smaller, the balance of the surface energy (surface tension) between the copper foil 12 and the etching resist ink 13 makes it impossible to maintain the width of the line portion, causing bleeding. This is considered to be due to two causes of an increase in the ratio of the amount of blur to the width of the line portion. When the width of the line portion cannot be maintained and bleeding occurs, or when the ratio of the bleeding amount to the width of the line portion increases, not only does the design specification not be satisfied, but also the occurrence of short circuit and noise There is a problem that causes.

A method of forming a fine pattern having an L / S of 100/100 μm or less can be performed by a photo process such as mask exposure or laser drawing, but is expensive.
Since it is necessary to arrange a pattern exposure machine, a laser plotter, and the like, and two steps of an ink coating step and a pattern forming step are required, there is a problem of adhesion of dust during transportation. Furthermore, UV pattern exposure must be performed after the entire substrate is coated with the etching resist ink, so that there is a problem in that it requires much labor and cost as compared with the screen printing method in which the etching resist ink has to be applied only to the pattern portion.

In view of the above, the present invention has been made to solve the above problems, and provides a printing base film capable of printing a fine pattern easily and at low cost, a printing method using the same, and a wiring board manufactured by the method. It is intended to be.

[0012]

According to the present invention, an object of the present invention is to provide a printing base film formed between a printing material and a printing material, wherein the surface energy is smaller than the surface energy of the printing material. This is achieved by being formed of a porous material having a film.

According to the above construction, since the surface energy of the printing base film is smaller than the surface energy of the printing substrate,
The amount by which the printed matter is pulled outward is also reduced. For this reason, even if it is a fine pattern, generation | occurrence | production of bleeding can be suppressed by keeping the width of a line part. Further, since the printing base film is porous, the printed matter is more easily absorbed than the printed matter. For this reason, even in the case of a fine pattern, the ratio of the bleed amount to the width of the line portion can be reduced.

[0014]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Note that the embodiments described below are preferred specific examples of the present invention,
Although various technically preferable limits are given, the scope of the present invention is not limited to these modes unless otherwise specified in the following description.

FIGS. 1 to 3 are process diagrams showing an embodiment of the printing method of the present invention. First, a substrate (single-sided copper-clad laminate) 51 having a copper foil (substrate to be printed) 52 stretched on one side is prepared (see FIG. 1 (A)). 0.5 μm on the surface of
An amine compound having a particle group having a particle diameter of 1 μm, for example, an organic material such as Alpha Prep (trade name: Cook Prem Electronics Co., Ltd., 1.5 μm to 2 μm)
A film having a thickness of μm is formed as a printing base film 60 (FIG. 1).
(B)).

Next, an etching resist ink (printed matter), for example, a UV etching resist ink 53, which is a mixture of a polyester acrylate resin and an inorganic filler, is applied on the surface of the printing base film 60 in a predetermined pattern to a thickness of 15 μm.
Printing is performed with a thickness of 20 μm (see FIG. 1C).

That is, as a preparatory stage, the printing base film 60 is formed.
The substrate 51 so that the substrate faces upward.
The screen is mounted and fixed thereon, and a screen-stretched frame, that is, a screen mask 22 is arranged on the substrate 51 at predetermined intervals. Further, the squeegee vertical cylinder 23 and the scraper vertical cylinder 24 are raised, and the squeegee 25 and the scraper 26 are arranged at one end on the screen mask 22 at a predetermined interval. Then, a predetermined amount of the etching resist ink 53 is dropped on one end of the surface of the screen mask 22 (see FIG. 2A).

Next, a work stage is entered. The scraper vertical cylinder 24 is lowered to bring the tip of the scraper 26 into contact with the screen mask 22. Scraper 2 at this time
The downward force 6 is an extremely weak force that does not allow the screen mask 22 to contact the printing base film 60 on the substrate 51.
Subsequently, the squeegee vertical cylinder 23 and the scraper vertical cylinder 24 are simultaneously moved to move the scraper 26 together with the squeegee 25 along the screen mask 22 toward the other end, and the etching resist ink 53 is spread thinly on the surface of the screen mask 22. (Fig. 2 (B)
reference).

When the scraper 26 reaches the other end of the screen mask 22, the scraper vertical cylinder 24 is raised to separate the scraper 26 from the screen mask 22 (see FIG. 3A). Then, the squeegee vertical cylinder 2
3 is lowered to bring the tip of the squeegee 25 into contact with the screen mask 22. The downward force of the squeegee 25 at this time is such that the screen mask 22 slightly contacts the printing base film 60 on the substrate 51.

Subsequently, the squeegee vertical cylinder 23 and the scraper vertical cylinder 24 are simultaneously moved to move the squeegee 25 along with the scraper 26 toward one end along the screen mask 22. At this time, the etching resist ink 53 penetrates the eyes of the required image of the screen mask 22, that is, the eyes that are not covered by the resist, and is extruded onto the surface of the printing base film 60 on the substrate 51 to perform printing. (See FIG. 3B).

Thereafter, the portion of the printing base film 60 not covered with the etching resist ink 53 and the portion of the copper foil 52 thereunder are removed by etching (see FIG. 1D). Then, the remaining printing base film 60 and the etching resist ink 53 are peeled off to form a conductor pattern 54 on the substrate 51 (see FIG. 1E). Then, the substrate 51
Solder resist is printed and cured between the upper conductor patterns 54, and symbols are printed and cured, and the substrate 51 is punched to form a predetermined printed circuit board.

FIG. 4 is a diagram when the etching resist ink 13 is dropped on the surface of the copper foil 12 on the conventional substrate 11, and FIG. 5 is a diagram when the etching resist ink 13 is dropped on the surface of the copper foil 52 on the substrate 51 of this embodiment. FIG. 7 is a diagram when an etching resist ink 53 is dropped on the surface of a formed printing base film 60. Note that the same material is used for each material. Here, γs is copper foil 1
2 is the surface energy of the etching resist ink 1
3, 53 are surface energies, γsl is an interface energy between the copper foil 12 and the etching resist ink 13, γst is a surface energy of the printing base film 60, and γstl is a printing base film 6.
0 and the interface energy of the etching resist ink 53,
α and β represent contact angles.

As shown in FIG. 4, conventionally, since the surface energy γs of the copper foil 12 is larger than the surface energy γl of the etching resist ink 13, the etching resist ink 13 is pulled outward on the copper foil 12 to cause bleeding. appear. On the other hand, as shown in FIGS. 4 and 5, in the present embodiment, the surface energy γst of
2 is smaller than the surface energy γs, and the amount of the etching resist ink 53 pulled outward on the printing base film 60 is small. The occurrence of bleeding of the resist ink 53 can be suppressed.

FIGS. 6 (A) and 6 (B) are a 1000 × and 5000 × micrographs of the surface of the conventional copper foil 12 on the substrate 11 when observed microscopically.
(A) and (B) show a copper foil 52 on a substrate 51 of the present embodiment.
10A and 10B are a photomicrograph of 1000 times and a photomicrograph of 5000 times when the surface of the undercoating film for printing 60 formed on the surface of No. 1 is observed with a microscope.

As is apparent from FIG. 6, the surface of the copper foil 12 is a metal solid surface having almost no holes.
As is clear from FIG. 7, the surface of the printing base film 60 is a porous surface on which particles having a particle size of 0.5 μm to 1 μm are overlapped. For this reason, the etching resist ink 13 conventionally applied on the surface of the copper foil 12 is liable to bleed in the surface direction of the copper foil 12, but in this embodiment, the etching resist ink 53 applied on the surface of the printing base film 60 is It is easily absorbed in the thickness direction of the printing base film 60.

Therefore, even in the case of a fine pattern, the ratio of the bleed amount of the etching resist ink 53 to the width of the line portion can be reduced. Further, since the etching resist ink 53 enters the inside of the hole,
The adhesive strength of the etching resist ink 53 can be increased. For this reason, the yield in the subsequent etching process can be improved.

FIGS. 8 (A) and 8 (B) show that the surface of a copper foil 12 on a conventional substrate 11 is
FIG. 6 is a diagram when a concentric test pattern and an L-type test pattern having a / S of 100/100 μm are printed,
FIGS. 9A and 9B show L / S of 100/100 μm with etching resist ink 53 on the surface of printing base film 60 formed on the surface of copper foil 52 on substrate 51 of the present embodiment.
FIG. 9 is a diagram when an m-type concentric test pattern and an L-type test pattern are printed. In the drawing, the darker portions are the etching resist inks 13 and 53.

As shown in FIG. 8, when the etching resist ink 13 is printed on the surface of the copper foil 12 on the conventional substrate 11, bleeding of the etching resist ink 13 occurs and the line width becomes 100 μm or more. ing. On the other hand, as shown in FIG. 9, when the etching resist ink 53 is printed on the surface of the printing base film 60 formed on the surface of the copper foil 52 on the substrate 51 of the present embodiment, the etching resist ink 53 No bleeding, line width 1
It can be kept at 00 μm.

According to the printing method using such a printing base film 60, a fine pattern having an L / S of 100/100 μm or less can be printed without bleeding of the etching resist ink 53. Further, in the photo process, the steps divided into the ink applying step and the pattern forming step can be simplified to one, and clean printing can be easily performed. Further, an inexpensive UV exposing machine with low specifications can be sufficiently used instead of an expensive UV pattern exposing machine or laser plotter required for the photo process, and the cost can be reduced.

In the photo process, the etching resist ink has to be applied to the entire substrate. However, since the etching resist ink only needs to be applied to the pattern portion, the labor and cost can be reduced. In the above-described embodiment, the organic material is used as the printing base film 60. However, the present invention is not limited to this. Any porous material having a surface energy smaller than the surface energy of the copper foil 52 can be used. Can be used. Also,
The present invention can be applied to not only a single-sided copper-clad laminate but also a double-sided copper-clad laminate.

[0031]

As described above, according to the present invention,
Fine patterns can be printed easily and at low cost.

[Brief description of the drawings]

FIG. 1 is a first process chart showing an embodiment of a printing method of the present invention.

FIG. 2 is a second process chart showing an embodiment of the printing method of the present invention.

FIG. 3 is a third process diagram showing an embodiment of the printing method of the present invention.

FIG. 4 is a diagram when a conventional etching resist ink is dropped on the surface of a copper foil on a substrate.

FIG. 5 is a diagram when an etching resist ink is dropped on a surface of a printing base film formed on a surface of a copper foil on a substrate of the embodiment.

FIG. 6 shows a micrograph of × 1000 and a micrograph of × 5,000 when a surface of a conventional copper foil on a substrate is observed with a microscope.

FIG. 7 is a micrograph (× 1000) and a micrograph (× 5,000) of a surface of a printing base film formed on a surface of a copper foil on a substrate according to the present embodiment when observed by a microscope.

FIG. 8 is a diagram when a concentric test pattern and an L-type test pattern having an L / S of 100/100 μm are printed on the surface of a conventional copper foil on a substrate with etching resist ink.

FIG. 9 is a diagram showing an example in which the surface of a printing base film formed on the surface of a copper foil on a substrate of the present embodiment is L / L with an etching resist ink.
FIG. 9 is a diagram when a concentric test pattern and an L-type test pattern having S of 100/100 μm are printed.

FIG. 10 is a process chart showing a general additive method.

FIG. 11 is a process chart showing a general subtractive method.

FIG. 12 is a diagram showing a width of a line portion of a general circuit pattern and a width of a space portion interposed between the lines.

[Explanation of symbols]

51 ... substrate, 52 ... copper foil, 53 ... etching resist ink, 54 ... conductor pattern, 60 ...
・ Printing base film

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Tetsuya Komine 6-35 Kita-Shinagawa, Shinagawa-ku, Tokyo F-term within Sony Corporation (reference) 2H113 AA01 AA06 BA10 BB07 BB10 BB22 BC00 BC10 CA17 DA33 DA68 FA10 5E339 BC02 BD03 BD06 BD11 BE11 CC01 CD01 CE13 CE18 DD04 GG01

Claims (5)

[Claims] 1. A printing base film formed between a substrate and a printed material, wherein the substrate film is formed of a porous material having a surface energy smaller than the surface energy of the substrate. Printing base film. 2. The undercoating film for printing according to claim 1, wherein the porous material is an organic material. 3. The undercoat film for printing according to claim 2, wherein the organic material is an amine compound having a particle group having a particle size of 0.5 μm to 1 μm. 4. A method of printing a pattern on a copper foil with an etching resist ink, comprising: an amine having a particle group having a particle size of 0.5 μm to 1 μm on the surface of the copper foil while micro-etching the surface of the copper foil. A printing method, comprising: forming a base compound in a thickness of 1.5 μm to 2 μm to form a printing base film; and printing a pattern on the surface of the printing base film with the etching resist ink. 5. A wiring board manufactured by printing a pattern on a copper foil with an etching resist ink, wherein the surface of the copper foil is micro-etched and a particle size of 0.5 μm to 1 μm is simultaneously formed on the surface of the copper foil. An amine-based compound having a particle group of 1.5 to 2 μm is formed into a film having a thickness of 1.5 μm to 2 μm as a printing base film, and a pattern is printed on the surface of the printing base film with the etching resist ink to form the pattern. A wiring board, wherein a conductive pattern made of the copper foil is formed.