JP6281686B2 - Metal mask and manufacturing method thereof - Google Patents

Description

The present invention relates to a metal mask and a method for manufacturing the same for surface mounting of electronic components.

In modern industrial society, electronic devices that apply electrical engineering are widely used in almost all fields, and it is no exaggeration to say that our civilization is supported by the electronics industry.

Generally, an electronic circuit board built in an electronic device is configured by mechanically and electrically joining an electronic component to a printed wiring board having a wiring pattern formed on the board.

An electronic component is mechanically and electrically joined to a printed wiring board to give a function as an electronic circuit. This mounting process is generally performed as follows.
(1) A conductive paste in which metal particles such as solder particles and silver particles are confused with a viscous medium called a flux to form a paste is applied to a predetermined position on the substrate. The conductive paste is called “solder paste” or “silver paste” depending on the type of metal particles contained.
In applying the conductive paste onto the substrate, a printing method using a metal stencil called a “metal mask” is widely used.
(2) The terminal of the electronic component is placed on the conductive paste at a predetermined position of the wiring applied in (1). In mass production, this process is generally performed by an automatic device called a “mounter”.
(3) The printed wiring board on which the electronic components are placed is transported to a high temperature drying furnace called a reflow furnace. By heating at a high temperature of about 150 to 270 ° C., the solvent component contained in the flux in the conductive paste is volatilized, the conductive paste is solidified, and the component can be fixed on the substrate.

In the mass production, the mounting process is modularized in each process, and the modules are connected to function as a single mounting system in many cases.

Here, among the mounting processes of (1) to (3), (1) is a very important process in that it starts the mounting process. The degree of difficulty is very high in that it must be formed in a small amount and in a constant shape with a constant amount.

As described above, in the paste printing process, a metal stencil called a metal mask is widely used. This is done by sliding the squeegee on the back side of the printing surface of the stencil, moving the paste mass in a rotating manner (rolling) on the metal mask, and filling the openings formed in the stencil. The process of printing the paste is taken. This is similar to so-called silk screen printing, but unlike a silk screen, the metal mask has no wrinkles that obstruct printing in the opening, and the accuracy of the thickness of the metal mask is superior to that of the stencil on the silk screen. The accuracy of the shape and amount of the paste to be printed is excellent. Further, a metal mask made of metal also in terms of strength is naturally higher than a stencil on a silk screen formed of a cured photosensitive emulsion, and is excellent in durability against repeated use.

For these reasons, the metal mask is an important item in the surface mounting of the electronic circuit, and it is considered that the performance of the metal mask affects the performance of the electronic device.

The performance and characteristics required for metal masks vary widely in combination with their importance. The accuracy of the shape and size of the opening and the coordinate position determine the shape and amount of the paste to be printed and the position on the substrate. Further, the ability of the paste to be removed from the opening is an important characteristic because the paste filled in the opening is smoothly detached from the opening and is stably placed on the substrate while maintaining a predetermined shape. The hardness and rigidity of the metal mask material are related to damage, wear, and wound due to metal fatigue when used repeatedly, and determine the durability against spreading. Further, the roughness and properties of the surface influence the degree of the spread of the paste on the substrate contact surface side in relation to the adhesion to the substrate. On the other hand, the squeegee side affects the squeegee's slidability, the rolling property, which is the smooth fluidity of the paste during printing, and the scraping residue of the paste described later. Yes.

Here, as an aspect of the use of the metal mask for printing, generally, a metal mask is fixed to an item called a screen frame in which a polyester screen is stretched on a square metal frame such as aluminum, with an adhesive, A so-called “combination mask” is used in which the part of the screen covering the metal mask is cut out, leaving a fixed part (called “combination part”). In addition, what is called a removable mask is also used in which the metal mask is physically engaged with the metal frame, not bonded, and can be repeatedly attached and detached. However, there is no significant difference in physical properties and performance required for metal masks.

In addition, the metal mask manufacturing method can be broadly divided into (1) a resist image of an opening pattern is formed on a plating base made of a conductive metal flat plate such as stainless steel using a photolithography method. , Electroplating method that performs electrolytic nickel plating on the plating substrate, (2) Laser processing method that directly forms an opening in the metal (mainly stainless steel) flat plate that is the material of the metal mask by laser irradiation, (3) Photo An etching method that combines image formation of an opening pattern on a stainless steel substrate by lithography and opening formation by etching is conceivable. A simple flow of each process is shown in FIGS. Although the characteristics of the metal mask vary depending on the manufacturing method, the performance required for the metal mask is required to be the same regardless of which manufacturing method is used.

Here, with the advancement of electronics technology in recent years, the demand for metal masks has increased as electronic components have become smaller and the mounting density has increased. For example, a state-of-the-art 03015 component requires a small opening of about 0.1 mm. In such a small opening, the paste can be filled smoothly into the opening after printing. It is desired that the paste does not stick to the squeegee surface of the metal mask and that it is scraped off as much as possible as the squeegee moves. For this purpose, it is necessary for the paste to flow smoothly with little friction on the squeegee surface of the metal mask.

In addition, as the parts become smaller, the particle size of the conductive paste becomes as small as φ5 μm to 15 μm. However, in this case, the paste is likely to spread from the gap between the metal mask and the substrate, which may cause a defect. . In order to prevent this, the edge of the opening of the metal mask needs to be formed sharply without rounding.

When the aspect ratio, which is the ratio of the metal mask thickness to the opening dimension, is generally greater than 1, the paste is difficult to escape from the opening, and cohesive fracture is likely to occur. Therefore, when the opening shape of the metal mask becomes fine, it is necessary to reduce the mask thickness. However, this is inconsistent with reducing the rigidity of the metal mask and shortening the service life. In order to avoid this, it is necessary to increase the strength of the mask material itself, but the metal materials that can be used are limited to some extent by using any of the above-mentioned manufacturing methods, and it is essentially difficult to improve.

An object of the present invention is to apply a non-electrolytic nickel plating to a metal mask having a sharp edge shape of the opening and to coat the surface and the opening side wall with a high-hardness alloy in order to make it possible to mount fine parts. Thus, a metal mask excellent in printability and durability is obtained. Since the metal mask has low friction between the surface and the side wall of the opening, it has excellent squeegee slidability on the squeegee surface, there is almost no paste remaining on the squeegee surface, and the paste is smoothly released from the opening. , With good printing performance. Moreover, there is little deformation | transformation and wound of the metal mask by printing, and it has the outstanding durability.

The invention according to claim 1 of the present invention is a metal mask for conductive paste printing, which is used for an electronic circuit mounting process or the like, and is provided within the surface of a metal mask base having a thickness of 20 μm to 100 μm. And a printing opening having a sharp edge shape, and an alloy of nickel, boron and phosphorus coated on the surface of the metal mask and the side wall of the printing opening with a thickness of 2 to 3 μm. The surface of the metal mask and the side wall of the printing opening have wettability in which the flux component of the conductive paste remains like a thin film, and the metal mask base has a Vickers hardness of 200 Hv to 600 Hv. There, the coating layer is Vickers hardness 700～900Hv, the opening edge for printing is formed on the sharp surface or edge or side of the opening of the printing Heat affected layer such as an oxide film on, and the foreign matter is not present, such as metal melt, characterized in that.
The invention according to claim 2 is a method of manufacturing a metal mask for use in conductive paste printing, which is a metal mask made of a nickel plate or a stainless plate having a thickness of 20 μm to 100 μm and a Vickers hardness of 200 Hv to 600 Hv. Forming a metal mask base by forming an opening for printing in the surface by laser processing on the material, and mixing the metal mask base with a mixture of nitric acid and hydrogen fluoride, or a mixture of nitric acid and ammonium hydrogen fluoride Penetrating into the treatment liquid, and removing the thermally deteriorated layer and the metal melt from the surface of the metal mask base and the edge or side wall of the printing opening by chemical polishing, and the metal mask base, The edge of the printing opening is not damaged by electrolytic polishing in which a direct current is passed in an acidic solution composed of an aqueous solution of phosphoric acid and sulfuric acid or an aqueous solution of phosphoric acid. A step of treating the approximately have the said surface and the opening side wall of the printing metal mask matrix, by electroless nickel plating, made of nickel and boron and phosphorous alloy, Vickers hardness of the coating layer of 700~900Hv coated with a thickness of 2 to 3 [mu] m, and forming a sharp opening edge for the printing, characterized in that.

The metal mask is particularly effective for mounting minute electronic parts such as 03015 parts.

Furthermore, the metal mask manufacturing method is particularly effective for manufacturing a metal mask on which minute electronic components such as 03015 components are mounted.

The metal mask manufactured by the metal mask and the method for manufacturing the metal mask is not only for surface mounting of electronic components, but also for bump electrode formation for semiconductor packages, electrode formation for solar cells, and conductive paste in printed electronics. It is also effective for circuit printing formation using

According to the metal mask of the present invention, since the conductive paste can be printed at a predetermined position on the printed wiring board with high accuracy, surface mounting of minute electronic parts such as 03015 parts is enabled, and the metal mask is provided. It has the effect of improving the durability and extending its service life.

Manufacturing process flow of metal mask matrix by electrolytic plating Manufacturing process flow of metal mask matrix by etching method Manufacturing process flow of metal mask matrix by laser processing Electroless nickel plating alloy coating process flow on metal mask base Sectional view of a metal mask according to the present invention Examples and comparative examples of printing evaluation of the present invention Form of opening edge when alloy film thickness is 4.0μm or more

Embodiments of the present invention will be described with reference to the accompanying drawings.

The base of the metal mask according to the present invention before coating with the alloy film (hereinafter referred to as “metal mask base”) is an electroplating method, a laser processing method, an etching method using a conventional metal mask manufacturing method. Any material may be manufactured, and as a material, nickel is generally used in the electrolytic plating method, and stainless steel (especially SUS304) is used in the laser processing method or the etching method. That is, the construction method and the material are not limited to these as long as they can form a metal stencil having an opening in the plane.

If foreign matter adheres to the surface of the metal mask base or the side wall of the opening, the alloy film is not sufficiently covered only on that portion, and the effect is impaired. Therefore, it is necessary to remove them by performing appropriate treatment after the production.

In other words, if the electrolytic plating method is used, the residue of the dry film resist is likely to remain in the opening. In the laser processing method, an oxide film is formed on the surface of the metal mask base, the edge of the opening, or the side wall by the heat of the irradiated laser beam. Although a foreign matter such as a thermally deteriorated layer and a metal melt adheres, it is required that these are completely removed.

As a method for removing foreign matter in the opening, in the case of a dry film resist in the electrolytic plating method, there is a method in which a metal mask is immersed in an alkaline stripping solution together with the plating base, dissolved or swollen, and then removed with a high-pressure water stream. It is common.

Further, in the laser processing method, there is an electropolishing method in which a metal melt is electrically removed by passing a direct current in an acidic solution composed of a mixed solution of phosphoric acid and sulfuric acid or a phosphoric acid aqueous solution. Here, when the electropolishing is excessively performed, the corners of the opening edge are cut and blunted to form a rounded shape, which may cause printing bleeding. However, since the heat-affected layer on the side wall of the opening cannot be removed, it is necessary to perform polishing by buffing after the fact and remove it. However, this also requires physical attention because the edge of the opening is also physically removed.
Next, a chemical polishing method is also conceivable in which the thermal alteration layer and the metal melt are chemically removed by dipping in a treatment liquid that is a mixed liquid of nitric acid and hydrogen fluoride, or a mixed liquid of nitric acid and ammonium hydrogen fluoride. .
Unlike the electropolishing method, this method has the advantage that the heat-affected layer can be removed and the edge of the opening is not cut. However, the metal surface may be too rough due to the acid. It is necessary to adjust it so that it is not excessively processed.

In this regard, the metal on the rough textured surface can be made a glossy surface by cutting the surface irregularities by electrolytic polishing treatment, so the metal melt and the heat-affected layer were first removed by chemical polishing. Then, by performing electropolishing to such an extent that the opening edge is not impaired, a sharp opening edge and a smooth metal mask matrix with a surface / opening side wall can be obtained. Here, as will be described later, when the surface slidability is improved by coating with an electroless nickel plating film, it is more effective that the base itself is smooth.

The metal mask base has a Vickers hardness of about 200 Hv or less in the case of a stainless steel plate produced by a laser processing method or an etching method, and about 300 to 600 Hv in the case of a nickel plate produced by an electrolytic plating method.

The entire metal mask base is subjected to electroless nickel plating to form an alloy film having a thickness of 1.0 μm to 4.0 μm on the surface and the opening side wall. A flow chart of film formation is shown in FIG. Here, if it is less than 1.0 μm, it is too thin, and therefore the effect on the enhancement of surface hardness is reduced. On the other hand, if it is thicker than 4.0 μm, the opening edge becomes dull and begins to be rounded. This is because if the opening edge becomes dull and loses sharpness, it causes printing blur. In this respect, the thickness that combines the opening edge shape and the strength of the coating layer is ideally 2.0 to 3.0 μm. By coating the electroless plating alloy film, the size of the opening is reduced according to the thickness and the thickness of the metal mask is increased. Therefore, the amount is calculated and corrected at the design stage. There is a need.

A cross-sectional view of the metal mask thus obtained is shown in FIG.
Here, the film composition of the electroless nickel plating may be nickel-boron-phosphorus (Ni-BP) in addition to typical ones such as nickel-phosphorus (Ni-P) and nickel-boron (Ni-B). ). Also, recently, by adding divalent tin ions to the Ni-BP plating solution, it is possible to form an electroless nickel plating film having similar physical properties while suppressing the use of environmentally hazardous substances such as lead. Are known.
JP 08-1558058 JP2013-14809

Here, the Ni-P alloy film has a Vickers hardness of about 500 Hv at the time of precipitation, but increases to 700 Hv or more by heat treatment at 250 ° C. or higher. On the other hand, in the case of a Ni-BP alloy film, it is advantageous in that a Vickers hardness of 700 to 800 Hv or more can be obtained in a precipitated state without performing a heat treatment after the fact. If a heat treatment is applied to the metal mask by heat treatment, it is desirable to obtain high hardness in the precipitated state because the deformation due to expansion and contraction may change the opening coordinates and adversely affect printing accuracy. It is.

In order to obtain the above effect in the Ni-BP alloy, the component composition ratio in the alloy film is such that Ni is 97.0% by weight or more, P is 0.5 to 3.0% by weight or more, and B is When the amount is 0.05 to 2.0% by weight or less, a particularly remarkable effect is obtained (Patent Document 1).

The metal mask according to the present invention is wrapped in a highly hard outer shell having high slidability, so that scratches and wear due to squeegees are reduced, and metal fatigue due to deformation caused by repeated printing is increased. On the other hand, since the internal electrolytic nickel plating film and stainless steel have lower hardness and flexibility than the outer shell, they can compensate for the brittleness often found in high-hardness films and reduce the occurrence of cracks and chips.

In addition, the electroless plating method has an advantage of being able to uniformly form the plating film thickness without variation because it is excellent in uniform precipitation compared with the electroplating method. Brittleness becomes prominent and weak against impact and deformation. Moreover, since the plating solution is expensive and difficult to manage, the cost performance deteriorates. Furthermore, as with the electroplating method, when an opening pattern is formed by using photolithography together, the photosensitive dry film is weak against the electroless plating solution, so that it tends to lose its shape, making it difficult to form the pattern. There's a problem. For these reasons, the electroless plating method is considered unsuitable for forming a thick film by itself.

Therefore, forming a metal mask base by electrolytic plating and forming only the surface layer that affects the quality and performance of the metal mask by electroless plating means that the entire metal mask is produced by electroless plating. In comparison, it has the advantage that the delivery time can be shortened and production costs can be reduced without degrading the quality and performance of the metal mask.

The following patent document exists as a prior art in which the electroless nickel plating film is applied to the surface of the metal mask and the inside of the opening.
The electroless nickel plating of the invention according to Japanese Patent Application Laid-Open No. 06-183165 is a system of the Ni-P alloy, which is about 300 Hv in the deposited state, but is about 600 Hv by performing heat treatment at 300 ° C. for 1 hour. It is said that the hardness of can be obtained. In addition, the electroless nickel plating contains PTFE, which is a water repellent resin, in the plating solution, which is eutectoidized in the Ni-P alloy. In this patent document, this water-repellent resin improves the slidability and enhances the releasability of the paste. In this case, the above heat treatment causes dimensional fluctuations, resulting in a decrease in positional accuracy. There is a risk of becoming unsuitable for high-precision printing for mounting fine parts. Furthermore, the squeegee surface becomes too slippery due to the water-repellent resin, so that there is a concern that the rolling property of the conductive paste is lowered and the filling property of the conductive paste into the metal mask opening is impaired. Furthermore, there is a risk that worn PTFE may be mixed into the printed paste and adversely affect the performance of the electronic circuit.

On the other hand, when the water-repellent resin is not incorporated in the alloy film as in the present invention, the surface is rather easily wetted, so that flux components such as a solvent of the conductive paste are not formed on the metal mask surface or the opening sidewall. In combination with this, and the slidability of the high hardness metal, the releasability of the conductive paste from the opening is improved. In addition, the squeegee surface is not as slippery as excessively water-containing resin, so that the rolling property of the conductive paste is not lowered and the printability is not deteriorated.

In the metal mask base, an opening was formed in a SUS304 material having a thickness of 0.1 mm by a laser processing method, and then the metal melt on the opening edge and the thermal alteration material on the opening side wall were removed by chemical polishing. In addition to 0603 and 0402, a number of 30015 component mounting patterns are formed in the opening of the metal mask base.

The metal mask base is subjected to electroless nickel plating to form an alloy film. Here, SKB-230 Kaniboron (registered trademark No. 4080761) manufactured by Nippon Kanisen Co., Ltd. was used as the electroless plating solution. It can be used without being limited to.
First, a pretreatment such as degreasing, pickling, electroless nickel plating activation treatment (strike plating, etc.) is performed on the metal mask base, and then immersed in the electroless plating solution according to the specified conditions to form an alloy film. Formed. The total thickness of the metal mask after immersion was measured, and it was confirmed that the thickness of the alloy film was 2.0 μm. Moreover, the Vickers hardness of the alloy film was 715 Hv in the precipitation stage.

The metal mask thus obtained was stretched on a screen plate to form a printing plate, and a solder paste printing test was conducted using a stainless steel squeegee and a solder printer. As a result, the squeegee slidability and solder paste rolling are good, there is no solder paste remaining on the squeegee surface, and there is no problem with the release of the solder paste in any size opening, and the desired printing. The solder paste could be transferred to the pattern and printing position.

In order to check the durability (deformation / wear resistance) of the metal mask, a continuous printing test was conducted. When the appearance and dimensions of the metal mask were inspected after printing 10,000 times, scratches, abrasion, elongation, and deformation of the metal mask surface were not observed.

Evaluation of printability and durability under the same conditions as in Example 1 except that the thickness of the metal mask base is systematically changed in the range of 20 to 100 μm and the thickness of the alloy film is in the range of 0.5 to 8.0 μm. Went. The results are shown in the table of FIG.

In the case of an alloy film thickness of 0.5 μm, the effect of coating the alloy film was not seen in both printability and durability at any metal mask total thickness. First, with regard to printability, the squeegee slidability is not improved, and paste remains on the squeegee surface after printing, hindering smooth filling of the paste inside the opening, resulting in insufficient printing. did. This was particularly noticeable for printing a fine pattern such as a 03015 component mounting pattern.

As for durability, many squeegee wounds occurred during continuous printing. These results suggest that the thickness of the alloy film is insufficient.

When the alloy film thickness is 1 μm, the squeegee slidability is smooth, the paste rolling property is good, and the paste remains on the squeegee surface after printing, regardless of the total thickness of the metal mask. In addition, the printing of the 03015 mounting pattern could be realized without any particular problem, and a significant effect could be confirmed compared with the conventional metal mask not coated with the alloy film.

On the other hand, regarding the durability, scratches and rubbing due to the squeegee were less than 0.5 μm on the metal mask surface after continuous printing 10,000 times. That is, an alloy film thickness of 1 μm exhibits an effect for improving printability, but is insufficient for improving durability.

When the alloy film thickness was 2.0 or 3.0 μm, the effect of improving both printability and durability was exhibited in any total thickness metal mask.

The sliding property of the squeegee and the rolling property of the solder paste were good, and no solder paste remained on the squeegee surface, and a special solder paste could be printed at any size opening.

As for the durability of the metal mask, it was confirmed that the metal mask surface after 10000 times of continuous printing was not damaged, worn, stretched or deformed by the appearance and dimensional inspection.

When the alloy film thickness is 4.0 μm, squeegee sliding and paste releasability are improved in the same way as the alloy film thicknesses of 2.0 and 3.0 μm in any total thickness metal mask. However, slight blur occurred in the solder paste after printing. To confirm the cause, the edge of the opening of the metal mask was confirmed. Unlike the case where the edge was 3.0 μm or less, the edge had a sharp round shape as shown in FIG. It was. That is, the printing blur is caused by this round shape.

As for durability, an improvement effect was observed as in the case of alloy film thicknesses of 2.0 and 3.0 μm.

In the case of the alloy film thickness of 6.0 and 8.0 μm, the durability was improved as in the case of 2.0 to 4.0 μm, but the paste bleeding was larger than that in the case of 4.0 μm. . As a result of confirming the shape of the opening edge, the degree of blunting was larger than that at 4.0 μm.

As described above, the thickness of the alloy film that is evaluated to be effective for both printability and durability varies depending on the thickness of the metal mask matrix, but in the range of 2 to 3 μm, in all matrix thicknesses, It was confirmed that both printability and durability were effective. In the case of 1 μm to 2 μm or 3 μm to 4 μm, the effectiveness with respect to either printability or durability is weak depending on the thickness of the metal mask base, but it is either as compared with a conventional metal mask not coated with an alloy film. One was improved.
(Comparative Example 1)

Under the same conditions as in Example 1, a metal mask using electroless nickel plating as an NP system was produced. The surface hardness at the time of precipitation was about 400 Hv, and this was stretched on a screen frame without being heat-treated, and a printing test was conducted. As a result, the squeegee slidability was not as smooth as in Example 1, and several paste release defects occurred in the openings for the 30015 parts. In the initial stage of continuous printing, squeegee marks were formed on the squeegee side and substrate marks were formed on the print side.
(Comparative Example 2)

On the other hand, when the metal mask manufactured under the same conditions as in Comparative Example 1 was heat-treated at 250 ° C. for 1 hour, the hardness increased to 650 Hv, but a deviation of the opening coordinates due to thermal deformation of the metal mask occurred, and printing was performed. In the test, there was a problem that the solder paste was transferred to a place that was shifted from a predetermined position.
(Comparative Example 3)

The metal mask base was the same as in Example 1, and the alloy film was made of a Ni-P-based metal mask containing PTFE as in Patent Document 3.
Since it was as low as 320 Hv at the precipitation stage, when heat treatment was performed at 300 ° C. for 1 hour, the altitude was improved to about 600 Hv, but the mask was deformed as in Comparative Example 4. In addition, since the friction of the squeegee surface is too low due to the water repellent resin, the solder paste rolling is not as good as in Example 1, and the filling ability of the paste into the opening is poor. As a result, it was not printed.

In the examples and comparative examples described above, the metal mask base material used was prepared by a laser processing method, but the invention of the present application is applicable to those manufactured by other manufacturing methods as well as electrolytic plating methods and etching methods. It is clear that the effects of the above can be obtained in the same manner, and other examples are not meant to be limited thereto.

51 Metal Mask 52 Electroless Nickel Plating Alloy Film 53 Metal Mask Base 54 Opening 71 Opening Edge 72 Opening

Claims (2)

A metal mask for conductive paste printing, which is used for electronic circuit mounting processes, etc.
An opening for printing provided in the plane of a metal mask base having a thickness of 20 μm to 100 μm and having a sharp edge shape;
A coating layer made of an alloy of nickel, boron, and phosphorus, coated on the surface of the metal mask and the sidewall of the printing opening with a thickness of 2 to 3 μm,
The surface of the metal mask and the sidewall of the opening for printing have wettability in which the flux component of the conductive paste remains like a thin film,
The metal mask matrix has a Vickers hardness of 200Hv to 600Hv, the coating layer has a Vickers hardness of 700 to 900Hv,
The edge of the opening for printing is sharply formed,
There is no foreign matter such as a thermally deteriorated layer such as an oxide film and a metal melt on the surface or the edge or side wall of the printing opening ,
A metal mask characterized by this. A method of manufacturing a metal mask used for conductive paste printing,
Forming a metal mask base by forming an opening for printing in a surface by a laser processing method on a metal mask material made of a nickel plate or a stainless steel plate having a thickness of 20 μm to 100 μm and a Vickers hardness of 200 Hv to 600 Hv ;
The metal mask base is infiltrated into a treatment liquid which is a mixed liquid of nitric acid and hydrogen fluoride, or a mixed liquid of nitric acid and ammonium hydrogen fluoride, and the surface of the metal mask base and the opening for printing are formed by chemical polishing. Removing the thermally deteriorated layer and the metal melt from the end or side wall;
Treating the metal mask matrix to an extent that does not impair the edges of the printing openings by electrolytic polishing in which a direct current is passed in an acidic solution composed of an aqueous solution of phosphoric acid and sulfuric acid or an aqueous solution of phosphoric acid;
Wherein the surface and the opening side wall of the printing metal mask matrix, by electroless nickel plating, made of nickel and boron and phosphorous alloy coating Vickers hardness of the coating layer of 700~900Hv a thickness of 2~3μm and, and forming a sharp opening edge for the printing,
A method for manufacturing a metal mask.

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