JPH05124371A - Metal mask for screen printing and production thereof - Google Patents

Abstract

PURPOSE:To form a target mark by electroforming simultaneously with a printing pattern part and to make the same easy to read by a CCD camera, in the target mark provided to a metal mask for screen printing in order to use the mark in the alignment with matter to be printed, by forming the planar shape of the mask into an annular shape. CONSTITUTION:A resist film 11 having a printing pattern part and a pattern for a target mark is formed to the surface of a matrix 16 and the pattern part 11a for the target mark is made thinner than the printing pattern part and formed into an annular shape to perform electroforming. In this way, the target mark can be formed so that the outer diameter thereof is made as large as possible in order to make the mark easy to read by a CCD camera. Further, the target mark can be formed into a blind hole by overhang using electroforming.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to, for example, ICs and LSIs.
TECHNICAL FIELD The present invention relates to a screen printing metal mask that is preferably used for screen printing such as printed wiring for wiring or pattern formation for various display devices and the like, and a manufacturing method thereof.

[0002]

2. Description of the Related Art As a metal mask for screen printing of this type, for example, as disclosed in Japanese Patent Application Laid-Open No. 1-214864, in addition to an opening for passing an ink / paste on a mask substrate, an object to be printed is used. There are some which provide a target mark used for the alignment of the. There, FIG.
As shown in (A), a resist film 20 having a desired pattern is formed on both front and back surfaces of a mask substrate 1 made of stainless steel or the like and then etched to form an opening 2 for ink / paste passage and a target mark 4 by patterning. is doing. As the target mark 4, the mask substrate 1 is formed by double-sided etching as shown in FIG.
There are disclosed through-holes that penetrate both the front and back sides, and those that are formed into blind holes by single-sided etching as shown in FIG. However, with this etching, since the side etch 21 is generated in the opening 2 for passing the ink paste, the ink paste is not sufficiently passable, and not only the ink paste remains but also the opening is generated. Since it is difficult to obtain a part 2 having a constant width, it is difficult to produce a fine line having a constant width particularly in precision printing.
Further, the plate thickness of the base material such as stainless steel is defined by standards and the like, so that the thickness cannot be determined unless it is within the range. Therefore, there is a problem that the thickness of the metal mask is determined by the thickness of the base material, and the degree of freedom in selecting the metal mask product thickness is restricted.

On the other hand, there is an electroformed product as shown in FIG. 7B (unknown document). This is shown in FIG.
As shown in FIG. 1, a resist film 11 having a pattern portion 11b of an ink paste passing opening 2 and a target mark pattern portion 11a is formed on the surface of the electroforming mother die 6, and then the resist of the mother die 6 is formed. Electroplating of nickel or the like is performed on the surface not covered with the film 11 to form the electrodeposited metal layer 12, and finally the electrodeposited metal layer 12 is peeled off to form an ink paste as shown in FIG. A metal mask having a through opening 2 and a target mark 4 is obtained.
According to this, since the spread of the electrodeposited metal layer 12 is suppressed by the thickness (inner wall) of the resist film 11, the opening 2 thereof is prevented.
In addition, since there is no side etch 21 as in the case of etching, the width of the opening 2 can be made substantially constant, the ink paste can be easily removed, and fine line printing of a constant width can be performed. Further, in the case of etching, since the etching is performed from both the front and back sides, the resist films 20 must be formed on both sides thereof. However, according to electroforming, it is sufficient to form the resist film 11 on only one surface of the mother die surface. A metal mask having a desired thickness can be freely obtained, which is also advantageous in this respect.

[0004]

As described above, the metal mask formed by electroforming has various advantages over the one formed by etching. However, in the above-described electroforming method, the opening for ink and paste passage of the resist film 11 is formed. Since electroforming is performed using the pattern portion 2 having the same thickness as the pattern portion of the target mark, the target mark 4 also has a through-hole shape like the opening 2 for passing the ink paste. It is disadvantageous in that it is formed. That is, when the target mark 4 has a through-hole shape, the above-mentioned Japanese Patent Laid-Open No. 1-2148
As described in Japanese Patent No. 64, when performing screen printing on a printed wiring board which is an object to be printed using this metal mask, the target mark of the metal mask for screen printing and the target mark of the printed wiring board are set by a CCD camera. Although it is measured and aligned or positioned, useless solder paste is printed on the target mark of the printed wiring board through the through hole of the target mark of the metal mask during printing, which may cause defects such as bridge formation in the subsequent process. .. In order to solve such a problem, first, as shown in FIG. 8 (A), a resist film 11 having a pattern of openings 2 for passing an ink / paste is formed on the surface of an electroforming mother die 6, and then, The surface of the matrix 6 not covered with the resist film 11 is electroformed with nickel or the like to form an electrodeposited metal layer 12, and then the resist film 11 is washed away as shown in FIG. , Electrodeposited metal layer 1
2 is peeled from the matrix 6. Then, as shown in (C) of the same drawing, a method of forming the blind hole-shaped target mark 4 by bringing the film resist 22 into close contact with both the front and back surfaces of the electrodeposited metal layer 12 and etching it is possible. However, this requires many steps such as an electroforming step and an etching step, resulting in a high cost, and when the film resist 22 is brought into close contact with the metal mask, a positional deviation easily occurs, so that the target mark 4 can be accurately positioned at a predetermined position. It is difficult to form.

Therefore, the present invention has been made in order to solve such a problem, and a metal mask having an opening for passing an ink paste and a blind hole-shaped target mark is manufactured by electroforming. Accordingly, the present invention provides a metal mask for screen printing that can accurately form a target mark at a predetermined position with a small number of steps, and a manufacturing method thereof. Another object of the present invention is to improve the planar shape of the blind hole target mark so that the CCD camera can easily read the target mark.

[0006]

According to the present invention, as shown in the drawings, an ink paste passage opening 2 is formed on a mask substrate 1 made of an electrodeposited metal in a desired printing pattern. In a metal mask for screen printing having a blind hole-shaped target mark 4 used for alignment with an object to be printed, the target mark 4 is formed in an annular shape. Here, the term “ring” is used to mean a shape such as a polygonal ring as well as a circular ring or an elliptical ring.

In the method for producing a metal mask for screen printing of the present invention, the pattern portion 11b of the opening 2 for passing the ink paste and the pattern portion 11a for the annular target mark are formed on the surface of the electroforming mold 6. The step of forming the resist film 11 having the step, the step of cutting the target mark pattern portion 11a of the resist film 11 to a predetermined height according to the depth of the target mark 4, and the step of covering with the resist film 11 of the master block 6. It comprises a step of forming the electrodeposited metal layer 12 by electroforming on the uncoated surface and a step of peeling the electrodeposited metal layer 12 from the matrix 6.

Further, according to the method of manufacturing a metal mask for screen printing of the present invention, the pattern portion 11b of the opening 2 for passing the ink paste and the pattern portion 11a for the annular target mark are formed on the surface of the electroforming mother die 6. A step of forming a resist film 11 having: and a step of forming an electrodeposited metal layer 12 on the surface of the mother die 6 not covered with the resist film 11 to the depth of the target mark 4 by electroforming, the resist film 11, a step of cutting a portion of the target mark pattern portion 11a protruding from the surface of the electrodeposited metal layer 12;
A resist film 11 is formed by further electrodeposition on the electrodeposited metal layer 12.
Of electrodeposition forming to the entire height of the electrodeposited metal layer 1
2 is separated from the mother die 6.

[0009]

Since the target mark 4 is formed in the blind hole, useless solder paste is not printed on the target mark of the printed wiring board during printing. Therefore, it is possible to eliminate the cause of defects such as a bridge at the time of automatic solder paste application in the subsequent process.

Since the target mark 4 is formed in an annular shape, its outer diameter can be formed as large as possible in order to make it easy to read by a CCD camera, and it can be formed in a blind hole by electroforming overhang. If the target mark 4 is formed in a single circle and has a large diameter as shown in FIG. 7B instead of an annular shape, it is easy to read with a CCD camera, but it does not overhang during electroforming, so it becomes a through hole. However, if it is a single circle and its diameter is made small, it will be difficult for the CCD camera to read even if it can be formed in a blind hole due to overhang of electroforming.

The resist film 1 in which the thickness of the target mark pattern portion 11a of the resist film 11 is made thinner than the thickness of the pattern portion 11b of the ink paste passage opening 2 is formed.
Since electroforming is performed using No. 1, the blind hole-shaped target mark 4 can be electroformed at the same time as the opening 2 for passing the ink paste.

[0012]

According to the present invention, the metal mask having the opening 2 for passing the ink and the paste and the target mark 4 in the form of a blind hole is manufactured by electroforming, so that the number of steps is low and the cost is low. Moreover, the target mark 4 can be accurately formed at a predetermined position, and useless printing and bridging can be prevented. Moreover, since the target mark 4 is formed in an annular shape, the outer diameter can be formed as large as possible while being formed as a blind hole, and it is easy to read with a CCD camera.

[0013]

1 and 2, this metal mask for screen printing has a pattern portion for printing having a group of openings 2 for passing an ink and a paste formed on a mask substrate 1 by patterning into a desired printing pattern. 3 and a target mark 4 used for aligning the printed material. The target mark 4 is formed in a blind hole and has a circular annular shape in plan view. The thickness t of the mask substrate 1 is 200 μ
In this case, the circular annular target mark 4 has an inner diameter d of about 800 to 900 μ, an outer diameter D of about 1000 μ, and a depth h of about 20 to 50 μ. Instead of the circular ring, it may be formed into an elliptical or polygonal ring. In order to make it easier to identify the target mark 4 with the CCD camera, the recess of the target mark 4 can be filled with a resin having a reflectance different from the reflectance of the surface of the mask substrate 1. However, when the shadow generated by the depression of the target mark 4 is different from the reflectance of the surface of the mask substrate 1, it is not always necessary to fill it.

This screen printing metal mask is manufactured by electroforming, for example, nickel electroforming. FIGS. 3A to 3E show the manufacturing process, and first, as shown in FIG. 3A, a resist 7 is applied or laminated on the surface of the electroformed mold 6. Then, as shown in FIG. 3B, a pattern film 10 having a pattern of openings 2 for passing ink and paste and a pattern for an annular target mark is adhered on the resist 7, and an ultraviolet lamp is used. After printing, development, and drying are performed by the method described above, and as shown in (C) of the figure, an annular target mark pattern portion 11a and an ink paste passing opening portion 2 pattern portion 11b are provided. The resist film 11 is formed. Then, as shown in FIG. 3D, the target mark pattern portion 11 of the resist film 11 is formed.
According to the required depth h of the target mark 4, a is cut to a predetermined height with a cutter knife or the like. Then, as shown in (E) of the same figure, an electrodeposited metal layer 12 is formed by electroforming on the surface of the mother die 6 which is not covered with the resist film 11.
At this time, in the intermediate stage of the growth process of the electrodeposition, since the pattern portion 11a for the annular target mark of the resist film 11 is thin as shown in FIG. 4, the electrodeposition is for the annular target mark of the resist film 11. The target mark 4 can be formed in a blind hole because it grows so as to protrude beyond the height of the pattern portion 11a and overhangs. Finally, after polishing the surface side of the electrodeposited metal layer 12, the resist film 11 is washed and removed, and the electrodeposited metal layer 12 is peeled from the matrix 6. At this time, the resist film 11a in the blind hole of the target mark 4 may be removed or left as it is. When the resist film 11a is left in the blind hole of the target mark 4, the reflectance can be different from the reflectance of the surface of the electrodeposited metal layer 12, and the target mark 4 can be more easily identified by the CCD camera. Alternatively, after removing the resist film 11a in the blind hole of the target mark 4,
Separately, a synthetic resin or paint having a reflectance different from that of the surface of the electrodeposited metal layer 12 may be filled. As a result, as shown in FIG. 1, it was possible to obtain a screen printing metal mask having an opening 2 for passing an ink paste and a blind target-shaped annular target mark 4 on a mask substrate 1 made of an electrodeposited metal. .. Incidentally, in printing, the master mold side of the electrodeposited metal layer 12 is used as the squeegee surface.

In the above embodiment, the target mark pattern portion 11a of the resist film 11 is cut to a predetermined height before electroforming, but it may be cut during electroforming instead of this. That is, as shown in FIGS. 5 (A) to 5 (F), the pattern of the openings 2 for passing the ink / paste and the pattern for the annular target mark are formed on the surface of the electroforming mold 6. The process of forming the resist film 11 having the above (up to (A) to (C) of the same figure is the same as the case of the above embodiment. As shown in the figure, an electrodeposited metal layer 12 is formed on the surface of the matrix 6 not covered with the resist film 11 by electroforming to a required depth h of the target mark 4. Then, as shown in FIG. Then, the portion of the pattern portion 11a for the target mark of the resist film 11 protruding from the surface of the electrodeposited metal layer 12 is cut with a cutter knife or the like, and then, as shown in FIG. Electrodeposit on top and resist By forming up electrodeposited metal layer 12 to the total height of the height of 11,
As in the case of the above embodiment, the annular target mark 4 is formed in a blind hole shape by the overhang. Finally, the electrodeposited metal layer 12 is peeled off from the matrix 6.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view taken along the line AA in FIG.

FIG. 2 is a perspective view of the entire screen printing metal mask.

FIG. 3 is an electroforming process diagram of a metal mask for screen printing.

FIG. 4 is a cross-sectional view showing a structure of a target mark portion in an electroforming growth process.

FIG. 5 is an electroforming process chart showing another embodiment.

FIG. 6 is an etching process diagram of a conventional screen printing metal mask.

FIG. 7 is an electroforming process drawing of another conventional screen printing metal mask.

FIG. 8 is a manufacturing process diagram of a screen printing metal mask of a comparative example.

[Explanation of symbols]

 1 Mask Substrate 2 Opening for Passing Ink and Paste 4 Target Mark 6 Electroforming Mold 11 Resist Film 12 Electrodeposited Metal Layer

Claims (3)

[Claims] 1. A blind hole-shaped target mark used for aligning an opening 2 for passing an ink paste, which is patterned and formed into a desired printing pattern on a mask substrate 1 made of an electrodeposited metal, and used for aligning with an object to be printed. 4. A metal mask for screen printing, wherein the target mark 4 is formed in an annular shape. 2. A resist film 11 having a pattern portion 11b of an ink paste passage opening 2 and an annular target mark pattern portion 11a on the surface of an electroforming mother die 6.
And a step of cutting the ring-shaped target mark pattern portion 11a of the resist film 11 to a predetermined height according to the depth of the target mark 4, and a step of not being covered with the resist film 11 of the master block 6. A method for producing a metal mask for screen printing, which comprises a step of forming an electrodeposited metal layer 12 on the surface by electroforming, and a step of peeling the electrodeposited metal layer 12 from the matrix 6. 3. A resist film 11 having a pattern portion 11b of an opening 2 for passing an ink paste and a pattern portion 11a for an annular target mark on the surface of an electroforming mother die 6.
And a step of forming an electrodeposited metal layer 12 on the surface of the mother die 6 which is not covered with the resist film 11 by electroforming to a depth of the target mark 4, and an annular target mark of the resist film 11. A step of cutting the portion of the pattern portion 11a for use in projection that protrudes from the surface of the electrodeposited metal layer 12, and further electrodeposition on the electrodeposited metal layer 12 to form the resist film 11
And a step of peeling the electrodeposited metal layer 12 from the matrix 6 to form a metal mask for screen printing.