JPH10250032A - Metal mask for printing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal mask for printing capable of eliminating tailings of printing ink which may cause a function of the mask to be lowered by being stuck to the metal mask in the printing operation, of largely increasing the number of repeating times of continuously using the metal mask without lowering the accuracy of the printing and of markedly reducing the number of washing times and processes of cleaning. SOLUTION: Nickel/PTFE composition plating 2 is applied to an electroforming metal mask 1. The composition plating is stuck to a side for supplying printing ink and an inner section of an opening section that forms a printing section 3. The electroforming metal mask is brought into contact with an insulation substrate and solder printing is applied thereto to form a wiring substrate. Since the nickel/PTFE composition plating film is applied thereto, tailings of the printing ink or the like is eliminated so that the number of repeating times of continuously using the metal mask can be markedly increased without lowering the printing accuracy. The number of washing times and processes of cleaning can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a metal mask for printing on a wiring board or the like.

[0002]

2. Description of the Related Art Conventionally, most wiring boards are made by corrosion, and copper plating is applied to an insulating substrate, and a plating portion other than a circuit portion is dissolved and removed using a printing or photographic emulsion. Those which make a desired wiring board by this are widely marketed as electronic circuit kits. In a mass-produced product, a circuit is composed of a highly integrated device such as an IC, and therefore, a wiring substrate is often formed by solder printing using a metal mask.

[0003] There are two methods of manufacturing a metal mask: one by corrosion and one by electroforming. A dry film emulsion is stuck on a stainless steel substrate, and a film base plate of a pattern is brought into close contact therewith and irradiated with light to dissolve and remove either the exposed or unexposed portions. The processes up to this point are the same for both the processes by corrosion and electroforming. Fig. 4 in case of corrosion
It is made by a process as shown in FIG. In the above process, as shown in FIG. 4A, an opening of the metal mask is a dry film removing portion 7 where no dry film emulsion 6 is attached, and the stainless substrate 5 in this portion is dissolved by the corrosive liquid. You. The progress of the corrosion is as shown in FIG. 4 (b), and the opening is formed when the corrosion progressing portion 7a reaches the back surface. Corrosion leaves a large gradient in the vertical direction as shown by the dotted line.

[0004] Therefore, when precision is required, dry films 9a and 9b are stuck on the front and back surfaces of the stainless steel substrate 8 as shown in Fig. 4 (c) to promote corrosion from both sides. . Figure 4 shows the finished metal mask
As shown in FIG. 4D, the vicinity of the center of the thickness of the opening becomes the narrowest, and the dimensional accuracy of the opening is the same as that of the single-sided corrosion method shown in FIGS. To improve. In this method of corroding from both sides, the pattern of the photographic original plate to be brought into close contact with both sides must be accurately aligned, and the positioning operation is considerably difficult in obtaining the required dimensional accuracy. When the completed metal mask is used as a printing mask, since the inner wall cross section of the opening has an inclined shape as shown in FIG. 4D, printing ink easily remains in this portion, and printing is repeated. Not suitable for work. Therefore, the frequency of cleaning the mask must be increased.

On the other hand, when a metal mask is formed by electroforming, it is performed in a process shown in FIG. The photographic original plate 13 is brought into close contact with the dry film 11 on the stainless steel substrate 10, exposed to light, the dry film of the unexposed portion is removed, and the dry film of the portion that becomes the opening 12 of the mask is left on the stainless steel substrate 10 as the remaining portion 15. Remains (Fig. 5 (a)
(B)). Then, as shown in FIG. 5C, nickel electroforming is performed on the stainless substrate 10 from which the dry film has been removed to form a nickel plating layer 14 having a predetermined thickness. The thickness of the nickel plating layer 14 is often about 0.15 mm in an actual metal mask. Thereafter, the stainless substrate 10 is peeled off, and the dry film remaining portion 15 is further removed.
Is removed to complete a metal mask as shown in FIG.

In the case of corrosion and the case of electroforming, the steps after the photographic original plate, exposure, and dissolution and removal of the dry film are applied in the reverse of negative and positive applications. That is, in the electroforming, a dry film is left in a portion corresponding to an opening, and the dry film other than the opening is dissolved and removed to grow nickel plating on the surface of the stainless steel substrate. FIG.
In the exposure in (a), the photochemical change received by the dry film generally has a tapered shape that slightly tapers from the front surface to the back surface. Therefore, the opening of the finished metal mask shown in FIG. 5D generally has a taper that tapers from the front side to the back side. The electroformed metal mask formed in this manner has several dimensions higher than the metal mask formed by corrosion, and the inner wall of the opening has a shape in which, for example, a residue of solder printing is hard to adhere and stick.

[0007]

However, if the number of times of repeated use increases, it is still unavoidable that the residue such as solder printing adheres and adheres, the dimensional accuracy decreases, and cleaning is required. The object of the present invention is to eliminate the residue of printing inks that cause the function of the mask to deteriorate by adhering and sticking to the metal mask in a printing operation,
To provide a printing metal mask capable of significantly increasing the number of continuous repetitive use of the metal mask without deteriorating the printing accuracy, and significantly reducing the frequency of cleaning and the number of man-hours of the cleaning work as compared with the conventional method. It is in.

[0008]

According to the present invention, there is provided a metal mask for printing according to the present invention, wherein a dry film is adhered to a metal substrate, a photographic original plate is brought into close contact with the metal film, and exposed to light. After dissolving and removing any of them, nickel / PTFE (polytetrafluoroethylene, commonly known as Teflon) is applied to the other parts of the metal mask except for the surface to be in close contact with the printing object in the printing metal mask formed by a predetermined process. It is configured to perform plating.

[0009] According to the above configuration, the high quality printing can be realized with the improvement of the productivity by the lubricating property, the abrasion resistance, the non-adhesiveness, and the repellency of the nickel / PTFE composite plating film. it can.

[0010]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a partial cross-sectional view illustrating an embodiment of a printing metal mask according to the present invention. In this figure, a nickel / PTFE composite plating film is applied to the electroformed metal mask of FIG.
Composite plating is applied to the printing ink supply side and the inner wall portion of the opening forming the printing section 3.

FIG. 2 is a diagram showing an example of a printing metal mask according to the present invention. For example, 700mm x 600mm
Nickel of about 3-6 μm /
PTFE composite plating is applied. FIG. 3 is a cross-sectional view showing a state in which solder printing is performed on a wiring board using an electroformed metal mask. The electroformed metal mask shown in FIG. 2 is brought into close contact with the insulating substrate 4, and solder printing is performed from the front side.

Since the electroformed metal mask is for printing contacts such as semiconductors and ICs, the ink is a mixture of paste and fine particles of solder. When the printing process is completed, the mask is peeled off from the insulating substrate 4. Insulating substrate 4
Solder is printed on the opening of the mask to complete the wiring board. Thereafter, the foot of an IC or the like is put on the wiring board together, and the printed portion and the semiconductor are soldered by heating or the like to complete the circuit.

Since the nickel / PTFE composite plating film is applied to the surface of the electroformed metal mask and the inner wall of the opening, there is little residue of solder adhesion and sticking, and the abrasion resistance is increased. Therefore, the adhesion of solder residue on the mask surface is reduced, and the change in dimensional accuracy due to the adhesion / sticking of the solder residue to the inner wall of the opening and the wear is significantly reduced. Therefore, the number of times of continuous repetition printing increases, for example, as compared with a conventional mask not coated with nickel / PTFE composite plating, the number of times of use can be secured several times (at least three times or more), and the cleaning frequency of the mask during that time. Can also be reduced.

In the above-described embodiment, an example has been described in which nickel / PTFE composite plating is applied to an electroformed metal mask as a metal mask for printing, and solder printing is performed by closely contacting the metal substrate with an insulating substrate. The same applies to printing other than the above.

[0015]

As described above, according to the present invention, nickel / P is applied to the surface of the printing metal mask and the inner wall of the opening.
By applying the TFE composite plating film, it is possible to eliminate residues such as printing inks and the like, which cause deterioration of the function of the mask in the printing operation. Therefore, the number of continuous repetitive uses of the metal mask can be greatly increased while maintaining the finishing accuracy of printing, and the frequency of cleaning and the number of man-hours for the cleaning work can be significantly reduced as compared with the related art, so that the durability can be improved. Thus, it is possible to manufacture a wiring board or the like with high quality and improve productivity.

[Brief description of the drawings]

FIG. 1 is a partial sectional view illustrating an embodiment of a printing metal mask according to the present invention.

FIG. 2 is a view showing an example of a printing metal mask according to the present invention.

FIG. 3 is a cross-sectional view showing a state in which solder printing is performed on a wiring board using an electroformed metal mask.

FIG. 4 is a view for explaining a step of forming a metal mask by a corrosion method.

FIG. 5 is a view for explaining a step of forming a metal mask by electroforming.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Electroformed metal mask 2 ... Nickel / PTFE composite plating 3 ... Printing part 4 ... Insulating substrate 5, 8, 10 ... Stainless steel substrate 6 ... Dry film emulsion 7 ... Dry film removal part 9a, 9b, 11 ... Dry film 12, 12a Opening 13 Photographic plate 14 Nickel plating layer 15 Dry film remaining portion

Claims (1)

[Claims] 1. A printing metal mask formed by a predetermined process after a dry film is stuck on a metal substrate, a photographic original plate is brought into close contact and exposed, and either the exposed or unexposed portion is dissolved and removed. A metal mask for printing, characterized in that nickel / PTFE plating is applied to other parts of the metal mask except for a surface to be in close contact with a printing object.