JPH0699569A - Screen printing method - Google Patents

Abstract

PURPOSE:To form a fine resist ink pattern by screen printing by prescribing the expansion of the resist ink layer transferred to a copper foil through a screen. CONSTITUTION:An oil repelling liquid 9 capable of repelling ink such as water or alcohol is applied to the contact surface with an object to be printed of the pattern forming layer 3 provided on the screen mesh 2 of a screen frame 1 by a roller 8 to perform usual screen printing. When a squeezee 6 is moved, the oil repelling liquid 9 on the contact surface with the object of the pattern forming layer 3 is transferred to the copper foil 5 in the same shape as a pattern and the resist ink 7 passed through the screen is transferred to the copper foil 5 to form a resist ink layer 7a but, since the ink layer 7a is brought into contact with the oil repelling liquid 9, the expansion of the ink layer 7a is prescribed by the oil repelling liquid 9 and the ink layer 7a is cured in this state. Therefore, an ink pattern having the same shape as that of the pattern forming layer is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screen printing method and, more particularly, to an improvement of the screen printing method suitable for forming a conductor pattern on a printed circuit board.

[0002]

2. Description of the Related Art In the manufacture of printed circuit boards, screen printing is used for various purposes. For example, in the process of forming a conductor pattern, a copper foil is provided on the substrate, and a portion required as a circuit is screen-printed with a resist (protective film).
Are formed, and unnecessary portions are removed by etching or the like. recent years,
Circuits are becoming finer, and it is required to form fine resists by screen printing. Conventionally, as a screen printing method, the method shown in FIG. 5 (B _{1 to} B ₄ ) is known.

In the figure, 1 is a screen frame, 2 is a screen mesh, 3 is a pattern forming layer made of emulsion or the like provided on the mesh, 4 is a substrate, 5 is a copper foil, 6 is a squeegee, and 7 is a resist ink. The movement of the squeegee 6 causes the resist ink 7 to pass through the mesh 2 to form a pattern of the resist ink layer 7a on the copper foil.

[0004]

In the above screen printing method, the resist ink is once divided by a mesh and spreads on the copper foil to be integrated. Therefore, spread of the resist ink is necessary. However, since the spread of the ink is irregular, the pattern size changes, and it is not possible to form a fine pattern.

Conventionally, in order to prevent the spread of the resist ink, the thixotropy of the resist ink is made high. However, according to this, the mesh shape remains and the edge portion of the pattern becomes jagged. Such a shape is not preferable for insulation between patterns. Further, when the width of the pattern is small, the resist ink is not integrated and there is a high risk of disconnection. Further, in the conventional method, there is also a problem that the ink wraps around the printed material contact surface of the pattern forming layer of the screen being printed, which causes stepwise bleeding of the resist ink at the edge portion of the pattern, which deteriorates printing accuracy. .

[0006]

SUMMARY OF THE INVENTION The present invention has been made in order to solve all the problems of the conventional screen printing method described above, and provides a screen printing method capable of controlling the spread of the resist ink transferred onto the copper foil. Its main purpose is to provide.

[0007]

According to the present invention, in a screen printing method in which ink is applied to a substrate to be printed through a screen mask by moving a squeegee, ink is prevented from passing through a surface of the screen mask facing the substrate to be printed. The gist of the present invention is to provide a pattern forming layer for blocking and to print by applying an oil repellent liquid that repels the ink on the surface of the pattern forming layer that contacts the printing medium.

[0008]

According to the above screen printing method, the oil repellent liquid previously applied to the contact surface of the pattern forming layer on which the printing material is to be transferred is transferred to the surface of the printing material in the printing step. Therefore, the spread of the ink formed on the surface of the printing object after passing through the screen mask is regulated by the oil repellent liquid transferred to the surface of the printing object, so that a fine pattern can be printed with high accuracy.

[0009]

EXAMPLE FIG. 1 (A _{1 to} A ₄ ) shows a screen printing process according to an example of the present invention. In the figure, the same or similar members as those in FIG. 5 are designated by the same reference numerals. In this embodiment, first, as shown in FIG. 1 (A ₁ ), for example, a roller 8 is used, and a contact surface of the pattern forming layer 3 provided on the screen mask side is exposed to water or alcohol. An oil-repellent liquid 9 that can repel ink is applied. FIG. 1 (A ₂ ) shows the screen mask after the application of the oil repellent liquid. Next in FIG.
As shown in (A ₃ ), when the squeegee is moved,
The oil-repellent liquid 9 on the surface of the pattern forming layer 3 that contacts the printing medium is transferred onto the copper foil 5 in the same shape as the pattern, and the resist ink that has passed through the screen is transferred onto the copper foil 5 to form the resist ink layer 7a. Becomes Therefore, immediately after printing,
As shown in FIG. 1 (A ₄ ), since the ink layer 7a is placed in contact with the oil repellent liquid 9, the spread of the ink layer 7a is restricted by the oil repellent liquid 9 and the ink layer 7a is cured in that state.
The oil-repellent liquid 9 is volatilized as it is, but may be volatilized by a treatment such as air drying or heat drying if necessary.

FIGS. 2, 3 and 4 show the features of the method of the present invention in comparison with the conventional method. That is,
In the conventional method shown in FIGS. 2 (B ₅ ), (B ₆ ), and (B ₆ ′), when the thixotropy of the resist ink is small, FIG.
As in _6), likely to occur a short circuit spreads out ink layer 7a to the copper foil portions corresponding to the pattern forming layer, when thixotropy of the resist ink conversely large, as shown in FIG. (B _6),
The ink layer that should be integrated may not spread sufficiently due to the spread of the ink, and it may not be integrated, as shown in FIG. 2 (A ₅ ),
In the method of the present invention shown in (A ₆ ), since the oil repellent liquid 9 is transferred to the copper foil portion corresponding to the pattern forming layer,
As a result, the spread of the ink layer is regulated and the short circuit of the ink layer does not occur. Moreover, the ink layer can be easily integrated by using an ink having a small thixotropic property.

Further, in the conventional method shown in FIGS. 3 (B ₇ ) and (B ₈ ), when the ink divided by passing through the mesh spreads and is integrated to form the ink layer 7a, the edge of the ink layer becomes Although it becomes jagged and a pattern having the same shape as the pattern forming layer cannot be formed, in the method of the present invention shown in FIGS. 3 (A ₇ ) and 3 (A ₈ ), the spread of the ink causes the oil repellent liquid 9 transferred onto the copper foil 9 to be spread. As a result, the pattern having the same shape as the pattern forming layer can be obtained.

Further, in the conventional method shown in FIGS. 4 (B ₉ ) and 4 (B ₁₀ ), the ink 7b wraps around the printed material contact surface of the pattern forming layer 3 of the screen at the time of printing, and ink is applied to the edges of the pattern. Although bleeding occurs and printing accuracy deteriorates, in the method of the present invention shown in FIGS. (A ₉ ) and (A ₁₀ ), the oil-repellent liquid 9 that repels ink adheres to the contact surface side of the pattern forming layer 3 to be printed. There is no ink wraparound.

[0013]

As described above, according to the present invention,
Since the spread of the resist ink transferred onto the copper foil through the screen can be regulated, a fine resist can be easily formed by screen printing.

[Brief description of drawings]

FIG. 1 is a process drawing of a screen printing method showing an embodiment of the present invention.

FIG. 2 is a process diagram showing the method of the present invention in comparison with a conventional method.

FIG. 3 is a process diagram showing the method of the present invention in comparison with a conventional method.

FIG. 4 is a process diagram showing the method of the present invention in comparison with a conventional method.

FIG. 5 is a process diagram of a conventional screen printing method.

[Explanation of symbols]

 1 Screen Frame 2 Screen Mesh 3 Pattern Forming Layer 4 Substrate 5 Copper Foil 6 Squeegee 7 Resist Ink 7a Ink Layer 9 Oil Repellent Liquid

Claims (1)

[Claims] 1. In a screen printing method in which ink is applied to an object to be printed through a screen mask by moving a squeegee, a pattern forming layer for blocking passage of ink is provided on a surface of the screen mask facing the object to be printed. A screen printing method, which comprises applying an oil-repellent liquid that repels the ink to a surface of the pattern forming layer that contacts the printing medium to perform printing.