JP2000218758A - Manufacture of metal mask and metal mask manufactured by the method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a metal mask having a recessed part with a specified film thickness regardless of the film thickness of a mask material and the metal mask. SOLUTION: A half-etching fabricated part A as a recessed part is formed using an electrical discharge machining process to discharge electricity between a metal mask 10 as an anode and a discharge electrode 20 as a cathode. The electrical discharge machining process enables a mask material to be engraved to a specified level regardless of the film thickness of the mask material. Thus it is possible to correctly control the film thickness of the half-etching fabricated part A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a metal mask and a metal mask, and more particularly, to a metal mask as a printing mask in which a printing pattern having a through opening is formed and a recess is partially formed. And a metal mask manufactured by the manufacturing method.

[0002]

2. Description of the Related Art Conventionally, cream solder, ink, adhesive,
As a printing mask material for a paste printing mask for printing a paste-like resin or the like (hereinafter, referred to as a “paste”) on a printing medium such as an electronic circuit board or a semiconductor package, stainless steel, copper, and copper alloys are used. Alternatively, a metal mask made of a so-called metal plate such as an electroformed product of iron, steel, nickel, or an alloy thereof is widely used.

As a method of manufacturing the metal mask, an etching method and an additive method are known, but a metal mask formed by the additive method has the best print quality and is most often used in the field of electronic component manufacturing. .

FIGS. 6 (a), (b), (c), (d),
(E) shows a method of manufacturing a metal mask by the additive method. In FIG. 6 (a), a dry film 2 which is a slightly thicker photosensitive resin is overlaid on a stainless steel plate 1 as a plating base material and adhered. 6 (b) and 6 (c), the exposed portion is exposed through the opening of the print pattern of the design film 3 as a photomask, and then the portion corresponding to the opening is removed by chemical treatment to remove the female mold. 4
To form Next, as shown in FIG. 6D, a portion other than the female mold 4 on the stainless steel plate 1 is subjected to electrolytic plating (mainly nickel) to form a plating layer 5. Next, by removing the female mold 4 and the stainless steel plate 1, a metal mask 10 having a through-opening for a print pattern as shown in FIG. 6E is obtained.

However, in the metal mask obtained by the additive method, the plating layer 5 is not formed uniformly as shown in FIGS.
There is a problem that the thickness of 0 varies.
That is, in the additive method, as the design pattern formed on the female mold 4 becomes denser, that is, the portion where the fine openings 11 are concentrated at a fine pitch, the agitation of the plating solution and the oscillation of the female mold 4 increase. As a result, a new plating solution is easily supplied and the dry film 2 serving as an insulator is provided.
The current is easily concentrated because it is surrounded by For this reason,
The denser the design pattern, the more the plating is promoted and the thickness of the plating layer 5 becomes larger, and conversely, the larger the plating layer thickness 5 of the sparse and large portion of the design pattern. This difference in the thickness of the plating layer, that is, the difference in the film thickness in the mask was very large, and sometimes caused a difference of about ± 20% from the intended film thickness. Further, since the plating solution is consumed, it is difficult to keep plating conditions such as temperature and concentration constant at all times, and there is a problem that a difference in film thickness occurs depending on a mask.

Meanwhile, conventionally, a metal mask in which a concave portion is formed in a part of a mask material is known. For example,
In particular, in the case of a metal mask as a printing mask in which fine openings are perforated, in order to improve the removability of the printing paste during printing, a half-etched portion as a recess is formed by digging a fine opening portion of the mask material. May form. This half-etching process forms a recess in the mask material by filling the through-opening with a resin for surface protection having resistance to an etching solution, masking the portion other than the half-etched portion, and performing etching with the etching solution. Is what you do.

However, when the above-described mask material having a varied thickness is subjected to a half-etching process using an etchant, it has been difficult to dig into a predetermined desired depth. This is because the film thickness in the mask varies, there is also a difference in film thickness depending on the mask, and there are many variations in the etching itself such as the temperature, PH value, concentration, or etching time of the etching solution. It is because of that.

As described above, it is very difficult to form a half-etched portion having a uniform thickness in a metal mask, which has been a major problem in the quality of a half-etched product.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object the following:
An object of the present invention is to provide a method of manufacturing a metal mask having a concave portion having a constant thickness regardless of the thickness of a mask material, and a metal mask.

[0010]

In order to achieve the above object, an object of the present invention is to provide a metal mask as a printing mask which forms a printing pattern comprising a through opening and partially forms a recess. In the manufacturing method, the concave portion is formed by electric discharge machining in which the metal mask is used as an anode and the discharge electrode is used as a cathode, and discharge is performed between the anode and the cathode.

In the method of manufacturing a metal mask according to the first aspect, in the process of discharging between the metal mask as an anode and the discharge electrode as a cathode, a discharge mark is formed on a portion of the metal mask facing the discharge electrode. Then, by repeating this electric discharge machining, a concave portion composed of a collection of electric discharge traces can be formed. In the electric discharge machining, it is possible to dig down to a predetermined desired position regardless of the film thickness of the mask material, so that the film thickness of the concave portion can be accurately controlled. Further, since only the portion facing the discharge electrode is dug down, the electric discharge machining can be selectively performed only in an arbitrary range without performing a masking process.

According to a second aspect of the present invention, in the method for manufacturing a metal mask according to the first aspect, an electrode having a planar shape corresponding to a range of the concave portion is used as the discharge electrode. It is assumed that.

In the method for manufacturing a metal mask according to the second aspect, electric discharge machining is performed using a discharge electrode formed in a planar shape corresponding to the range of the concave portion. This eliminates the need to relatively move the metal mask and the discharge electrode to perform the processing as in the case of the step processing or the scanning processing, so that the processing can be performed in a short time. This is particularly effective when the range of the concave portion is a special shape in which step processing or scanning processing is difficult, or when it is necessary to form a large number of concave portions having the same shape.

According to a third aspect of the present invention, in the method for manufacturing a metal mask according to the first aspect, an electrode formed in a planar shape smaller than the range of the concave portion is used as the discharge electrode. .

In the method for manufacturing a metal mask according to a third aspect of the present invention, electric discharge machining is performed using a discharge electrode formed in a planar shape smaller than the range of the concave portion. This allows
By performing the step processing or the scanning processing, an arbitrary concave portion can be formed. In particular, when it is necessary to form a large number of concave portions having different shapes, it is more advantageous in terms of cost than preparing a flat discharge electrode corresponding to each concave portion.

According to a fourth aspect of the present invention, in the method of manufacturing a metal mask according to the first aspect, the concave portion is a half-etched portion formed after forming a print pattern including the through-opening portion. Is what you do.

In the method for manufacturing a metal mask according to the fourth aspect, half etching is performed on the metal mask after the printing pattern including the through openings is formed by electric discharge machining. Here, in a conventional half-etching process using an etching solution, an etching solution oozes between the protective resin filled in the through-opening and the mask material during the etching, so that the etching is performed. Jagging sometimes occurred at the edge of the opening. When printing is performed using a mask material in which the through-holes are jagged, the printing paste spreads on the printing medium, and good printing may not be performed. In the method of manufacturing a metal mask according to the fourth aspect, since the half-etching process is performed by the electric discharge machining, the through-opening portion is not sharpened due to the penetration of the etchant unlike the half-etching process using the etchant.

According to a fifth aspect of the present invention, in the method for manufacturing a metal mask according to the fourth aspect, as the discharge electrode, the tip end surface of the electrode is flat or substantially flat, and the peripheral side of the electrode is formed into a tapered shape. Characterized in that the electrode is used.

In the method of manufacturing a metal mask according to the present invention, the tip surface of the discharge electrode is flat or almost flat.
In addition, electric discharge machining is performed using an electrode in which the peripheral side portion of the electrode is formed into a tapered shape. When the workpiece is dug down by electric discharge machining, since the shape of the discharge electrode and the shape of the workpiece have a negative / positive relationship, the peripheral side portion of the electrode is previously formed into an arbitrary tapered shape. In addition, the peripheral portion of the half-etched portion of the metal mask can be processed into an arbitrary tapered shape. Accordingly, since the peripheral edge of the half-etched portion formed on the metal mask is not formed at a step having a substantially right angle, when the printing paste is squeezed into the through-opening, the step is not formed. The squeegee will not be damaged.

Here, when the projection is formed on the printing medium, for example, when an electronic component is previously mounted on an electronic circuit board as the printing medium, a metal mask is used during printing. In order to make the metal mask adhere to the printing medium, it is desirable to form a concave portion as a relief for the projection in a portion of the metal mask corresponding to the projection on the printing medium.

According to a sixth aspect of the present invention, in the method for manufacturing a metal mask according to the first aspect, the concave portion is a relief portion corresponding to a protruding portion on the printing medium.

In the method for manufacturing a metal mask according to the sixth aspect, a relief portion of the projection is formed at a portion of the metal mask corresponding to the projection on the printing medium by electric discharge machining. As a result, a relief portion having a constant depth can be efficiently formed without performing a masking process. Then, since the escape portion of the protruding portion is formed, the metal mask and the printing medium come into close contact during printing.

According to a seventh aspect of the present invention, there is provided the first, second, third,
It is characterized by being manufactured by 4, 5, or 6 metal mask manufacturing methods.

In the metal mask according to the present invention,
Since the metal mask is manufactured by the metal mask manufacturing method according to the first, second, third, fourth, fifth, or sixth aspect, a metal mask in which the thickness of the concave portion is accurately controlled can be obtained.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment in which the present invention is applied to a method of manufacturing a metal mask in which a concave portion serving as a half-etched portion is formed in a metal mask after a print pattern including a through opening is formed. Will be described.

In FIG. 1A, reference numeral 10 denotes a metal mask formed by the additive method (see FIG. 4A).
Through (e)). As shown in FIG. 4E, the metal mask 10 has a large variation in film thickness within the mask, and in particular, a portion where fine openings having a fine pitch are concentrated is formed thick. Using the metal mask 10 as an anode and the discharge electrode 20 as a cathode,
Install inside. When performing electric discharge machining, machining is performed in a state where the machining fluid 22 is stored. Here, in electric discharge machining, the machining speed increases as the current value increases, but the surface roughness of the machining surface formed thereby increases as the current value increases. Therefore, as a method for increasing the processing speed and increasing the surface roughness of the processing surface, it is preferable to use a processing liquid mixed with fine particles such as silicon as the processing liquid 22. This fine particle-mixed working fluid is capable of improving the surface roughness of the machined surface of the workpiece by causing a large number of discharges due to the discharge being dispersed by the fine particles in the working fluid. is there. In the present embodiment, an electric discharge machining oil (“Picut” manufactured by Sodick) into which silicon fine particles are mixed is used as the machining fluid 22.

In the above configuration, a portion having a fine opening of the metal mask 10 is provided with a half-etched portion A
Is formed by electric discharge machining. Here, the discharge electrode 2
The opposing portion 20a opposing the metal mask at the leading end is formed in a planar shape corresponding to the range of the half-etched portion A as shown in FIG. Then, when a voltage is applied between the metal mask 10 and the discharge electrode 20, a discharge is generated, and a discharge mark is formed on the metal mask 20. By repeating this discharge, a half-etched portion A composed of a collection of discharge traces is formed on the metal mask 10.

At this time, as shown in FIG. 1 (b), the electric discharge machining can be dug down to a certain height from the mask bottom surface regardless of the film thickness of the mask. The film thickness can be accurately controlled to a desired film thickness. In addition, according to this electric discharge machining, since the etching solution is not used, the edge of the opening due to the infiltration of the etching solution does not occur. Further, in the electric discharge machining, only the portion facing the facing portion 20a is dug down, so that selective etching can be performed only in the range of an arbitrary half-etched portion A without performing a masking process.

Here, the facing portion 20a of the discharge electrode 20
Is formed in the same shape as the range of the half-etched portion A, so that there is no need to perform the process by relatively moving the metal mask 10 and the discharge electrode 20 as in a step process or a scanning process. In addition, the processing time can be reduced. As described above, forming the facing portion 20a in advance in the same shape as the range of the half-etched portion A is effective, for example, when the half-etched range is a special shape in which step processing or scanning is difficult. This is effective when there are a large number of processing ranges having the same shape.

In this embodiment, the discharge electrode 2
0 The opposite part 20a at the tip is
Used in a planar shape corresponding to the range of
It is not limited to this. For example, as shown in FIG. 2B, by using an electrode having an opposing portion 20a formed in a planar shape smaller than the range of an arbitrary half-etched portion A, the above-described step processing and the above-described scanning process are performed. An arbitrary half-etched portion A may be formed. According to this, for example, even when there are a large number of processing ranges having different shapes, it is more advantageous in terms of cost than preparing a planar discharge electrode corresponding to each range. Further, a scanning process using a wire discharge electrode may be performed.

As the discharge electrode 20, for example, FIG.
As shown in (a), (b), and (c), the discharge electrode 20 whose peripheral side is processed into a tapered shape by an arbitrary tapered router 30 may be used. In addition, from the viewpoint of processing time, it is desirable that the electrode tip surface has a planar shape or a substantially planar shape as described above, but is not limited thereto. By performing discharge machining of the metal mask 10 using the discharge electrode 20 having such a tapered peripheral portion, the shape of the peripheral portion of the half-etched portion A of the metal mask 10 is formed into an arbitrary tapered shape. be able to. Therefore, a step having a substantially right angle is not formed on the peripheral edge portion, so that it is possible to prevent the squeegee from being damaged when the printing paste is squeezed.

As described above, in the present embodiment, the case where the concave portion as the half-etched portion is formed in the metal mask has been described, but the present invention is not limited to this. For example, the present invention can be applied to a case where there is a protrusion on a printing medium and a recess is formed as a relief for the protrusion. A specific example will be described below.

For example, as shown in FIG. 4, when an electronic component 50a is previously mounted on an electronic circuit board 50 as a printing medium, the metal mask 10 and the electronic circuit board 50 are printed on the electronic circuit board 50 at the time of printing. Do not adhere to each other, and the printing paste is not transferred well. Therefore, as shown in FIG. 5, a concave portion 60 is formed in a portion of the metal mask 10 corresponding to the electronic component 50a as a clearance for the electronic component 50a. The formation of the concave portion 60 by the above-described electric discharge machining allows the concave portion 60 having a certain depth to be formed.
Can be efficiently formed without performing a masking process. By forming the recesses 60 in the metal mask 10 as described above, the metal mask 10 and the electronic circuit board 50 are in good contact with each other at the time of printing, and the printing paste can be satisfactorily transferred onto the electronic circuit board 50. .

[0034]

According to the first to sixth aspects of the present invention, the recess is formed by electric discharge machining, so that the recess can be dug down to a predetermined desired position regardless of the thickness of the mask material. The film thickness can be accurately controlled. Therefore, it is possible to obtain a metal mask having a recess having a constant thickness. Further, since no masking process is required, the formation of the concave portion can be performed efficiently.

In particular, according to the second aspect of the present invention, by performing electric discharge machining using a discharge electrode formed in a planar shape corresponding to the range of the concave portion, compared with the case of performing step machining or scanning machining. In addition, the processing time can be reduced. In particular, it is more effective when the range of the concave portion is a special shape in which step processing or scanning processing is difficult, or when it is necessary to form many concave portions having the same shape.

In particular, according to the third aspect of the present invention, by performing the electric discharge machining using the discharge electrode formed in a planar shape smaller than the area of the concave portion, the electric discharge machining can be performed by the step machining or the scanning machining. Can be formed. In particular, when it is necessary to form a large number of concave portions having different shapes, it is more advantageous in terms of cost than preparing a flat discharge electrode corresponding to each concave portion.

In particular, according to the invention of claim 4, there is an excellent effect that by performing the half-etching process by electric discharge machining, it is possible to prevent the penetration opening portion from being entangled due to seepage of the etching solution.

In particular, according to the fifth aspect of the present invention, electric discharge machining is performed by using an electrode in which the tip end surface of the discharge electrode is flat or substantially flat and the peripheral side of the electrode is tapered. By doing so, the shape of the peripheral portion of the half-etched portion can be formed into an arbitrary tapered shape.
Therefore, there is an excellent effect that the squeegee is not damaged when the printing paste is squeezed into the through-opening.

In particular, according to the invention of claim 6, by forming the escape portion of the projecting portion above the printing medium by electric discharge machining, the escape portion having a constant depth can be efficiently processed without performing a masking process. Can be formed. In addition, the formation of the escape portion has an excellent effect that the metal mask and the printing medium can be brought into close contact with each other at the time of printing, and the paste can be satisfactorily transferred onto the printing medium.

According to the seventh aspect of the present invention, there is an excellent effect that a metal mask having a concave portion having a constant film thickness can be provided.

[Brief description of the drawings]

FIG. 1A is a diagram illustrating a half etching process by electric discharge machining of a metal mask according to an embodiment. (B)
3 is an enlarged cross-sectional view of a metal mask half-etched by the electric discharge machining.

FIGS. 2A and 2B are diagrams showing examples of the surface shape of a discharge electrode used in the electric discharge machining.

FIGS. 3A to 3C are diagrams showing examples of a three-dimensional shape of a discharge electrode used in the electric discharge machining.

FIG. 4 is an explanatory diagram for explaining a problem when a projection is present on a printing medium.

FIG. 5 is a cross-sectional view of a metal mask in which a relief portion corresponding to the protrusion is formed by the electric discharge machining.

FIGS. 6A to 6E are schematic cross-sectional views illustrating a method for manufacturing a metal mask by an additive method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stainless plate 2 Dry film 3 Design film 4 Female type 5 Plating layer 10 Metal mask 11 Fine opening 20 Discharge electrode 21 Processing tank 22 Processing liquid 30 Router 50 Electronic circuit board 50a Electronic component 60 Concave part

Claims (7)

[Claims] 1. A method of manufacturing a metal mask as a printing mask in which a printing pattern comprising a through-opening is formed and a recess is partially formed, wherein the metal mask is used as an anode, the discharge electrode is used as a cathode, and A method for manufacturing a metal mask, wherein the recess is formed by electrical discharge machining for discharging between the cathodes. 2. The method of manufacturing a metal mask according to claim 1, wherein an electrode having an end surface formed in a planar shape corresponding to the range of the recess is used as the discharge electrode. Production method. 3. The method for manufacturing a metal mask according to claim 1, wherein an electrode having a flat surface whose tip end surface is smaller than the range of said recess is used as said discharge electrode. Production method. 4. The method of manufacturing a metal mask according to claim 1, wherein the recess is a half-etched portion formed after forming a print pattern including the through-opening. Method. 5. The method for manufacturing a metal mask according to claim 4, wherein the discharge electrode is an electrode having a flat or substantially flat tip end surface and a tapered peripheral portion of the electrode. A method for manufacturing a metal mask, comprising: 6. The method for manufacturing a metal mask according to claim 1, wherein said concave portion is a relief portion corresponding to a protruding portion on a printing medium. 7. A metal mask manufactured by the method for manufacturing a metal mask according to claim 1, 2, 3, 4, 5, or 6.