JP3261471B2 - Manufacturing method of metal mask - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used, for example, for manufacturing lead frames for IC chips and wiring pattern printed boards for hybrid ICs, and for filling through-hole conductor pastes for ceramic wiring boards for computers. that, metal mask for screen printing
And a method for producing the same.

[0002]

2. Description of the Related Art This type of metal mask is composed of C, Au, Ag.
8 has a hole through which a conductive ink such as copper or Cu or a conductive paste (hereinafter, referred to as an ink paste) passes.
As shown in FIG. 1, there is a mask substrate 2 having a through hole 3 opened.

It is also known that electroforming is used as a method for producing this type of metal mask. During the electroforming,
For example, as shown in FIGS. 9A to 9D, a process chart of the manufacturing process is shown. First, as shown in FIG. And a film 12 having a pattern corresponding to a mask pattern is closely adhered onto the photoresist 11 and baked and developed to form a resist film 13 as shown in FIG. Next, as shown in FIG. 2C, an electrodeposited metal 21 is electrodeposited on the surface of the electroformed matrix 10 which is not covered with the resist film 13, and thereafter, as shown in FIG. The electrodeposited metal 21 is peeled off from the electroformed mold 10 and the resist film 13 is removed to obtain an electroformed product of a metal mask.

[0004]

However, in the above-described metal mask formed by etching, the inner surface of the through-hole 3 is rough and not smooth, so that the ink paste has poor permeability. When plating is performed to improve the transmissivity, there is a disadvantage that the number of steps is increased. In particular, when an ink paste is placed on the squeegee mounting surface 4 side of the mask substrate 2 for squeegee printing, the squeegee printing pressure is applied to the mask substrate 2.
The non-porous portion 5 is pressed against the surface of the printing material, but the pressing load spreads and acts on the entire flat back surface of the non-porous portion 5 on the printing surface 6 side, so that the load per unit area is reduced. For this reason, the adhesion to the surface of the printing substrate is poor, and the bleeding of the ink paste and the wraparound to the back surface of the non-porous portion 5 are likely to occur.

On the other hand, in the metal mask formed by electroforming, since the inner surface of the through hole 3 is a contact surface with the resist film 13, the inner surface is not rough and smooth, but is rough. bad. When the metal mask is relatively thick, the photoresist 11 is overlapped with two or three layers as shown in FIG. 9 (A). The ultraviolet rays hardly reach the position of the electroformed matrix 10, and the amount of ultraviolet rays reaching the lower layer 13 a of the resist film 13 on the side of the electroformed matrix 10 is reduced. Since the lower layer 13a tends to be uncured due to the surface hardening, defects such as the lower layer 13a of the resist film 13 being easily peeled off or floating from the electroforming mold 10 are generated. When electroforming is performed in this state, electrodeposition is performed on the resist film 1.
9 escapes to the peeling or floating portion of the lower layer portion 13a of FIG.
(D), burrs (flakes) f tend to occur. For this reason, the adhesion of the metal mask to the surface of the printing material is deteriorated, and the ink / paste oozes during printing of the ink / paste or easily wraps around to the back surface of the metal mask, resulting in poor printing accuracy. In particular, it is necessary to increase the ratio (a: b) between the entrance on the squeegee surface side and the exit on the printing surface side of the through hole 3 in order to make it easier to draw the ink paste into the through hole 3. Photoresist 11
The ratio cannot be made large due to the adhesion of the ink paste to the electroforming mold 10, and therefore, it is difficult to draw the ink paste into the through hole 3. Also in this case, the pressing load due to the squeegee spreads over the entire flat back surface of the non-porous portion 5 during printing, so that the adhesion to the surface of the printing material is poor,
Bleeding of the ink paste and wraparound to the back surface of the non-porous portion 5 are likely to occur.

[0006] An object of the present invention is to improve the cross-sectional shape of the through-holes and non-through-holes of the metal mask as described above, thereby improving the attraction and passage of the ink paste into the through-holes. Another object of the present invention is to prevent the ink paste from bleeding and wrapping around the back of the mask, thereby obtaining an excellent metal mask capable of performing high-precision printing. Another object of the present invention is to easily obtain such an excellent metal mask by further developing and improving the electroforming method of the metal mask.

[0007]

As shown in FIG. 1, a metal mask according to the present invention has a cross-sectional shape of an ink paste passage hole 3 provided in a mask substrate 2 on a squeegee mounting surface 4 side. The counter sink 7 is formed on the printing surface 6 side of the non-perforated portion 5 surrounding the perforated hole 3.

In manufacturing the metal mask of the present invention, as shown in FIGS. 3 and 5, a step of forming a resist film 13 having a pattern corresponding to the mask pattern on the surface of the electroformed matrix 10 A step of electrodepositing a countersink-forming electrodepositing layer 14 having a substantially arc-shaped cross section projecting beyond the thickness of the resist film 13 on a surface of the electroforming mold 10 not covered with the resist film 13; A step of subjecting the surface of the countersink forming electrodeposition layer 14 to a release treatment and then electrodepositing the non-porous portion electrodeposition layer 15; And a step of peeling off the metal mask.

[0009]

According to the through-hole 3 having a funnel-shaped cross section that expands toward the squeegee mounting surface 4 side, the ink paste P placed on the squeegee mounting surface 4 is applied with the squeegee S. It is smoothly and easily guided into the through hole 3.

Since the countersink 7 is formed on the printing surface 6 side of the non-porous portion 5, the countersink 7 is formed on the printing surface 6 side of the non-porous portion 5 as illustrated in FIG. Does not come into contact with the surface of the printing material 8 at the location where the squeegee S contacts only the peripheral edge 5a of the non-porous portion 5, and the pressing load by the squeegee S acts on the peripheral edge 5a. The adhesion of the ink paste P to the surface and the sneaking of the ink paste P to the back surface of the non-porous portion 5 can be prevented.

When the non-porous portion electrodepositing layer 15 is electrodeposited on a substantially arc-shaped cross-section projecting from the resist film 13 of the countersink forming electrodeposition layer 14, the electrodeposition is substantially circular in cross section. Since it grows along the radius of the arc-shaped protrusion, the through-hole 3 can be formed in a funnel shape that expands toward the squeegee mounting surface 4 side as the cross-sectional shape.

The non-porous portion 5 having the countersink 7 can be obtained by peeling the non-porous portion electrodeposition layer 15 from the countersink forming electrodeposition layer 14.

Since the entire inner surface of the through hole 3 is formed in a mirror-like shape on the electroformed surface, the permeability of the ink paste P is improved, and the cleaning effect after printing is enhanced.

[0014]

Therefore, according to the metal mask of the present invention,
The ink paste can be easily guided into the through-holes 3 and can be easily passed without leaving it, and the washing effect after printing can be enhanced. In particular, the metal mask is pressed against the periphery 5 of the non-perforated portion 5 by a pressing load by a squeegee.
a can be firmly adhered to the surface of the printing substrate 8, so that the ink paste can be prevented from bleeding or sneaking into the back surface of the non-porous portion 5 during printing, and high-precision screen printing can be performed. I do.

Further, according to the metal mask manufacturing method of the present invention, the non-porous portion electrodeposited layer 15 is formed on the substantially arc-shaped projection of the countersink forming electrodeposited layer 14 projecting from the resist film 13. Then, in order to peel off the non-porous portion electrodeposited layer 15 to form a metal mask, the non-porous portion 3 has a funnel-shaped through-hole 3 and a countersink 7 that expands toward the squeegee mounting surface 4 side. A metal mask having the holes 5 and having no burrs can be easily obtained.

[0016]

FIG. 1 shows an embodiment of a metal mask according to the present invention.
A description will be given with reference to FIG. The metal mask 1 is formed by patterning a mask substrate 2 with through-holes 3 for passing ink and paste in correspondence with a desired print pattern. For example, as the substrate 8 to be printed, a ceramic wiring board for a computer as shown in FIG. 2A having a circuit pattern (not shown) printed on both front and back surfaces thereof is exemplified. As shown in (B), through-holes 9 for filling conductive paste P such as tungsten or molybdenum for conducting the circuit patterns on the front and back surfaces are formed in a desired pattern. The through holes 3 are formed in the mask substrate 2 by patterning. The cross-sectional shape of the through hole 3 is formed in a funnel shape that expands toward the squeegee mounting surface 4 side,
A counter sink 7 is formed on the printing surface 6 side of the non-perforated portion 5 surrounding the perforated hole 3.

The metal mask 1 having such a sectional shape
For example, as shown in FIG. 2A, a through-hole 9 and a through-hole 3 are formed on the surface of the printing substrate 8 on the positioning table T.
The ink paste P is placed on the squeegee mounting surface 4 and the squeegee S is applied to draw the ink paste P into the through hole 3 and fill the through hole 9. At this time, the through-hole 3 is formed in a funnel shape that expands toward the squeegee mounting surface 4 side.
The paste P is easily introduced into the through hole 3. Further, since the counter sink 7 is provided on the lower surface of the non-porous portion 5, the pressing load by the squeegee S during printing is reduced by the printing surface 8 of the non-porous portion 5.
In order to improve the adhesiveness to the surface of the printing material 8 by intensively acting only on the peripheral edge 5a on the side, the bleeding of the ink paste P and the wraparound of the non-porous portion 5 toward the printing surface 6 are suppressed. And
High-precision printing is now possible.

If the non-porous portion 5 is formed with a radius R on the squeegee mounting surface 4 side, it is possible to prevent the tip of the squeegee S from being caught and to enable smooth sliding. This is preferable because the resistance can be reduced and the set of the squeegee S can be reduced.

The metal mask 1 can be manufactured by electroforming as follows. First, as shown in FIG. 3A, a uniform film of, for example, 5 to 25 μm is formed on the surface of an electroformed mold 10 made of stainless steel by using a film-like or liquid photoresist 11. Photoresist 11
For example, "TPR" manufactured by Tokyo Ohka Kogyo Co., Ltd.
−101 REA ”is used.

Next, as shown in FIG. 1B, a film 12 having a pattern corresponding to a desired mask pattern is brought into close contact with the photoresist 11 and irradiated with an ultraviolet lamp for baking, developing, and drying. By performing the processing, a resist film 13 is formed as shown in FIG.

Next, the electroforming mold 10 is transferred to an electroforming tank such as a nickel sulfamate bath and electroformed with nickel or a nickel-cobalt alloy, and as shown in FIG. On the surface of the mold 10 that is not covered with the resist film 13, an electrodepositing layer 14 for forming a counter sink having a substantially arc-shaped cross section is formed at a height of about 7 to 30 μ so as to protrude beyond the thickness of the resist film 13. .

Next, the surface of the electrodeposition layer 14 for forming the countersink is subjected to a release treatment, and then subjected to a secondary electroforming to form the non-porous portion electrodeposition layer 15 as shown in FIG. (For example, 50-100 μm thick). At this time, the growth direction of the electroforming can be controlled in the vertical and horizontal directions by adding a brightener to the nickel electroforming bath. For example, by adding a first-class brightener such as saccharin, it can be spread laterally (in a direction perpendicular to the thickness direction), and has a small thickness.
Ratio of the squeegee surface side entrance and the printing surface side exit a: b
(See FIG. 1) can be increased. By adding a second type brightener such as butynediol, it can be expanded in the vertical direction (thickness direction) and has a thickness, and the ratio of the through holes 3 can be reduced.

Finally, the non-porous portion electrodeposited layer 15 is peeled off from the electrodeposited layer 14 for forming the countersink, so that the non-porous portion electrodeposited layer 15 spreads toward the squeegee application surface 4 side as shown in FIG. An electroformed product of the metal mask 1 having the funnel-shaped through-hole 3 having a cross-sectional shape and the non-through-hole portion 5 having a countersink 7 is obtained.

The electrodeposition layer 14 for forming the countersink
As shown in FIG. 3 (D), the cross-section is formed in a substantially arc-shaped cross-section projecting beyond the thickness of the resist film 13, so that the ink-paste P can be easily attracted. The holes 3 can be easily formed, and the countersink 7 is easily formed on the lower surface of the non-porous portion electrodeposited layer 15 electrodeposited on the surface side of the electrodeposited layer 14 for forming the countersink. The cross-sectional shape of the countersink 7 may be, for example, a round shape as shown in FIG. 4 instead of the pan shape as shown in FIG.

In the above embodiment, the non-porous electrodeposition layer 15 of the metal mask 1 is composed of a single layer of nickel or a nickel-cobalt alloy. The layer 15 can also be constituted. 5 (A) to 5 (H) show that the non-porous electrodeposition layer 15 is made of nickel / copper / electrode.
The steps of a manufacturing process for obtaining a metal mask 1 composed of three layers of nickel will be described. First, as shown in FIG. 5A, a uniform film is formed on the surface of the electroformed mold 10 using a film-like or liquid photoresist 11 as in the case of the above embodiment. As shown in (B), a film 12 having a pattern corresponding to a desired mask pattern is brought into close contact with the photoresist 11 and is baked, developed, and dried, and as shown in (C) of FIG. Then, a resist film 13 is formed. Next, as shown in FIG. 3D, the electrodeposition layer 14 for forming a countersink is formed by primary nickel electroforming. Next, as shown in FIG. 3E, the surface of the electrodeposition layer 14 for forming a countersink is subjected to a release treatment, and then nickel secondary electroforming is performed to form a secondary electrodeposition layer 16. Further, as shown in FIG.
Is subjected to copper tertiary electroforming to form a tertiary electrodeposition layer 17.
Further, as shown in FIG. 3G, a fourth electrodeposition layer 18 is formed on the third electrodeposition layer 17 by performing nickel fourth electroforming.
Finally, the secondary, tertiary, and quaternary electrodeposited layers 16, 17, and 18 are peeled off from the electrodeposited layer 14 for forming the countersink to form a non-transparent layer having the countersink 7 as shown in FIG. The metal mask 1 in which the hole electrodeposition layer 15 is formed of three layers of nickel, copper, and nickel is obtained.

In this case, as shown in FIG. 6, a concave portion 19 is formed by dissolving a part of the copper tertiary electrodeposition layer 17 facing the printed surface 6 side with an etching solution for selectively corroding only copper.
Further, as shown in FIG. 7, when the groove 19 is filled with a water-repellent substance 20 such as ethylene tetrafluoride, the ink paste P wraps around the printing surface 6 of the non-porous portion 5. It can be more effectively prevented. Instead of the water-repellent substance 20, a resin mixed with a foaming agent may be filled and then foamed by heating or ultraviolet irradiation.

[Brief description of the drawings]

FIG. 1 is a partially enlarged sectional view of a metal mask.

FIG. 2 is a cross-sectional view showing an example of using a metal mask.

FIG. 3 is a process explanatory view of a manufacturing process of a metal mask.

FIG. 4 is a partially enlarged sectional view of a metal mask showing another embodiment.

FIG. 5 is a process explanatory view of a manufacturing process of a metal mask showing another embodiment.

FIG. 6 is a partially enlarged sectional view of a metal mask showing another embodiment.

FIG. 7 is a partially enlarged sectional view of a metal mask showing another embodiment.

FIG. 8 is a partially enlarged cross-sectional view of a conventional metal mask.

FIG. 9 is a process explanatory view of a manufacturing process of a metal mask of a conventional example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 metal mask 2 mask substrate 3 through hole 4 squeegee surface 5 non-porous portion 6 printing surface 7 counter sink 10 electroforming mold 13 resist film 14 countersink forming electrodeposition layer 15 non-porous portion electrodeposition layer

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B41N 1/24 B41C 1/14

Claims (1)

(57) [Claims] 1. A mask pattern is formed on the surface of an electroforming mold 10.
For forming a resist film 13 having a pattern corresponding to
The surface of the electroformed mold 10 not covered with the resist film 13
A cross section projecting beyond the thickness of the resist film 13;
An electrodeposited layer 14 for forming an arc-shaped countersink is formed by electrodeposition.
And applying a release treatment to the surface of the electrodeposition layer 14 for forming a countersink.
After the application, the step of electrodepositing the non-porous portion electrodeposited layer 15 and the step of depositing the non-porous portion electrodeposited layer 15 on the
4. A method of manufacturing a metal mask, comprising:
Law.