JPH06183165A - Metal mask and production thereof - Google Patents

Abstract

PURPOSE:To enhance abrasion resistance, sliding properties and washing properties, to prevent the generation of static electricity and to enhance the passing properties of solder paste through fine opening parts in a metal mask used when solder paste for bonding the wirings and the external leads of elements formed on a printed wiring board is selectively applied to the printed wiring board. CONSTITUTION:In the metal mask 11 superposed on a printed wiring board 16 and selectively applying a proper amt. of solder pastes 17a, 17b to the printed wiring board 16, a plate-shaped conductive substrate 12, the opening parts 15a, 15b formed to the substrate 12 and filled with the solder pastes 17a, 17b and permitting the pastes to pass and a conductive film 14 containing particles of a resin having water repellency in a dispersed state and applied to at least the surface contact with the printed wiring board 16 of the mask are included.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal mask and a method of manufacturing the same, and more specifically, a solder paste for bonding wiring formed on a printed wiring board and external leads of an element to the printed wiring board. The present invention relates to a metal mask used for selective coating and the like and a manufacturing method thereof.

[0002]

2. Description of the Related Art When a semiconductor device is mounted on a printed wiring board, the wiring formed on the printed wiring board and the external leads of the semiconductor device are connected to each other by pressure bonding by bonding or adhesion by soldering. In particular, when bonding with solder, a metal mask that can apply a fixed amount of solder paste to a large number of places at once has been used.

With the recent miniaturization of semiconductor devices, it is necessary to selectively apply a solder paste to a fine portion. Therefore, the opening of the metal mask in which the solder paste is accommodated has been miniaturized, and the detachability of the solder paste becomes a problem. Further, since the metal mask is reused after the application of the solder paste, the metal mask to which the solder paste is attached is cleaned, but the solder paste needs to be easily removed.

FIG. 11A is a sectional view of a metal mask of the first conventional example, in which reference numeral 1 is a metal mask made of stainless steel or nickel, which is a solder to be applied to a predetermined position of the printed wiring board 3. Openings 2a and 2b through which the pastes 4a and 4b pass are formed.

When the solder paste is applied to the printed wiring board 3, the solder paste is placed on one surface of the metal mask 1 with the metal mask 1 superposed on the printed wiring board 3, and the surface of the metal mask 1 is covered by a squeegee (not shown). The solder paste is embedded in the openings 2a and 2b by strongly pressing and moving while winding the solder paste. Subsequently, when the metal mask 1 is removed, the solder paste 4a,
4b passes through the openings 2a and 2b, and the printed wiring board 3
A certain amount of solder paste 4a, 4b is formed at a predetermined position above.

After that, in order to reuse the metal mask 1, a fluorocarbon-based cleaning agent is used after applying the solder paste.
The metal mask 1 to which the solder paste is attached is washed.
In addition, as a second conventional example, although different from the application of solder paste application, as shown in FIG. 11B, in order to cope with the miniaturization of the printed portion, the printed board is passed through the openings 8a and 8b. In order to reduce the bleeding of the ink 10a, 10b that has reached the upper surface 9, a resin film 7 having water repellency, for example, a resin film 7 of polytetrafluoroethylene (PTFE) or silicon is formed on the contact surface of the mask substrate 6. A metal mask 5 is known (see JP-A-56-67985).

[0007]

By the way, in recent years, the first
In order to prevent environmental damage when cleaning the metal mask 1 of the related art, cleaning agents other than freon-based cleaning agents such as isopropyl alcohol and water have come to be used instead of freon-based cleaning agents. There is. However, according to the metal mask 1, it is difficult to remove the solder paste adhering to the metal mask 1 with a cleaning agent other than a CFC-based cleaning agent, and there is a problem that cleaning takes a long time.

However, when the metal mask 5 having the same structure as the second conventional example is used, the solder paste is easily removed during cleaning, but the presence of the non-conductive resin film 7 causes the contact. Static electricity is generated by sliding in the
Dust may adhere. Therefore, there is a problem that the opening 8a or 8b is closed and the solder paste is not normally formed on the printed wiring board. Further, the surface hardness of the resin film 7 is not sufficient, and there is a problem that the resin film 7 is worn due to sliding in contact with the printed wiring board.

Further, in both of the above metal masks 1 and 5, when the openings 2a, 2b / 8a and 8b are miniaturized, after the solder paste is embedded in the openings 2a, 2b / 8a and 8b, the metal is removed. When removing the masks 1 and 5, it is difficult to separate the metal masks 1 and 5 from the solder paste embedded in the openings 2a, 2b / 8a and 8b, that is, there is a problem that the detachability of the solder paste is deteriorated. .

The present invention was created in view of the problems of the conventional example, and improves abrasion resistance, slidability, and cleanability, prevents generation of static electricity, and is miniaturized. Another object of the present invention is to provide a metal mask capable of improving the detachability of the solder paste from the opening.

[0011]

The above-mentioned problems are as follows. First, in a metal mask which is superposed on a printed wiring board and selectively formed with an appropriate amount of solder paste on the printed wiring board, a plate-shaped conductive mask is used. A base material, an opening formed in the base material for embedding and passing the solder paste, and particles of a resin having water repellency dispersed therein, and at least a surface contacting the printed wiring board is coated with a conductive material. A metal mask having a conductive film and a second
In the third aspect, the conductive film is achieved by the metal mask according to the first aspect of the invention, wherein the surface that contacts the printed wiring board and the side wall inside the opening are covered. The conductive film is coated on the surface that contacts the printed wiring board, the sidewall in the opening, and the surface that does not contact the printed wiring board, by the metal mask according to the first invention. Fourthly, it is achieved by the metal mask according to any one of the first to third inventions, wherein the base is a stainless steel plate or a nickel plate, and fifthly, the conductive film is nickel. And a metal mask according to any one of the first to fourth aspects of the present invention. Sixth, the conductive film is a resin having water repellency. And a water-repellent resin, which is achieved by the metal mask according to the fifth aspect of the invention, which is a conductive film containing nickel as a main component and containing phosphorus in addition to Is achieved by the metal mask according to any one of the first to sixth inventions, which is silicon resin or fluororesin,
Eighth, the content of the particles made of the water-repellent resin in the conductive film is 30 vol% or less, and the metal according to any one of the first to seventh inventions. A ninth aspect of the present invention is achieved by a mask, and a ninth aspect is achieved by the metal mask according to any one of the first to eighth inventions, wherein an adhesion enhancing film is interposed between the base and the conductive film. Tenth, the adhesion enhancing film is achieved by the metal mask according to the ninth invention, characterized in that nickel is the main component, and eleventh, according to any one of the first to tenth inventions. A conductive film is formed by electroless plating using a plating liquid containing at least particles of a resin having water repellency and a conductive substance, and a method of manufacturing a metal mask, comprising: 2. Forming the conductive film by electroless plating using a plating solution containing particles made of the resin having water repellency, a conductive substance, and an additive having a function of promoting hardening of the conductive film. And a conductive film according to any one of the first to tenth inventions, which is made of the resin having water repellency. The present invention is achieved by a method for producing a metal mask, which is characterized in that it is formed by applying a paste containing at least particles and a conductive substance. Fourteenth, the conductive film is formed of the resin having water repellency. The metal mask according to the thirteenth invention, which is formed by applying a paste containing a conductive substance and an additive having a curing-accelerating action on the conductive film. This is achieved by the manufacturing method of the disc.

[0012]

According to the metal mask of the present invention, a resin having water repellency in the conductive film covering the contact surface of the metal mask,
For example, since particles of silicon resin or fluororesin are dispersed and contained, resin particles always appear on the contact surface, and new resin particles always appear even when the contact surface is worn due to sliding. . Therefore, it is possible to maintain the slippery nature of the contact surface of the metal mask due to the action of the resin particles, and it is possible to maintain good slidability.

Further, the side wall in the opening is covered with the conductive film containing the resin particles having water repellency, so that the solder paste and the conductive film are in direct contact with each other in the opening. Therefore, the solder paste is easily separated from the metal mask due to the action of the water-repellent resin particles exposed on the surface of the conductive film. Therefore, the detachability of the solder paste from the miniaturized opening can be improved.

Furthermore, since the resin particles having water repellency are dispersed and exposed on the surface of the conductive film with which the contact surface of the metal mask, the side wall in the opening and the surface which does not contact the metal mask are dispersed and exposed. The surface of the conductive film has water repellency, and the solder paste attached to the metal mask can be easily removed.

Further, since the conductive film has conductivity, it is possible to prevent static electricity from being generated on the surface of the metal mask. As a result, it is possible to prevent dust and the like from adhering to the metal mask, so that the solder paste can be normally embedded in the opening and allowed to pass therethrough to be applied and formed on the printed wiring board.

Further, by using nickel having a high hardness as the main component of the conductive film, the surface hardness is improved as compared with the case of the conventional resin film, and an additive such as phosphorus is contained in the conductive film. By performing the heat treatment on the conductive film, the surface hardness of the conductive film increases due to the hardening promoting action of phosphorus. This reduces wear when the metal mask is slid.

By heat-treating the conductive film, the resin particles are better dispersed and the uniformity of the resin particle distribution is increased. As a result, it is possible to improve slidability and solder paste removal.

Further, according to the method for manufacturing a metal mask of the present invention, the electroconductive plating is used to form the electroconductive film, so that the uniformity of the film thickness of the electroconductive film is improved and the film is formed on the printed wiring board. In-plane uniformity of the amount of solder paste applied and formed can be secured.

[0019]

Embodiments of the present invention will now be described with reference to the drawings. (1) First Embodiment (a) Manufacturing Method of Metal Mask According to First Embodiment of the Present Invention FIG. 2 is a process diagram illustrating a manufacturing method of a metal mask according to the first embodiment of the present invention, 3A to 3D and FIGS. 4A to 4C are cross-sectional views for explaining the method of manufacturing the metal mask according to the first embodiment of the present invention. The method of manufacturing such a metal mask is called an etching method.

First, the thickness 100 to 30 shown in FIG.
A resist film 18 is applied to one surface of a substrate 12 made of a 0 μm stainless plate (FIG. 3B). The solder pastes 17a, 17b selectively applied on the printed wiring board 16
Is determined by the height of the openings 15a and 15b, it is necessary to set the thickness of the substrate 12 in advance within the above range in consideration of the film thickness of the conductive film 14 formed later.

Next, the resist film 18 is selectively exposed and then exposed to a developing solution. This is a region where the openings 15c and 15d of the metal mask 11 are to be formed and has a diameter of about 1
The resist film 18 in the 70 μm circular region is selectively removed, and the resist mask 18a as an etching mask remains in the other regions (FIG. 3C).

Next, the substrate 12 is selectively etched and removed with an aqueous solution of ferric chloride based on the resist mask 18a. As a result, the openings 15c, 15 of the base 12 are
d is formed (FIG. 3D).

Next, after removing the resist mask 18a with a resist stripping solution (FIG. 4A), the substrate 12 is washed in order to perform strike plating on both surfaces of the substrate 12 and the side walls inside the openings 15c and 15d. . That is, the substrate 12 is immersed in an alkaline solution to degrease the surface of the substrate 12 and then immersed in an acid to activate the surface of the substrate 12.

Next, the base 12 is formed by strike plating.
A nickel film (adhesion-strengthening film) 13 having a film thickness of about 1 μm is formed on both surfaces of and the side walls inside the openings 15c and 15d (FIG. 4).
(B)). The nickel film 13 formed by the strike plating is formed in order to improve the adhesion between the base 12 of the metal mask and the conductive film 14 formed later.

Then, an electroless nickel plating solution containing about 30 vol% particles of PTFE (resin having water repellency) and phosphorus (additive having an action of promoting hardening of the conductor film) is heated with stirring. The temperature is maintained at 90 ° C. Subsequently, the substrate 12 having the openings 15c and 15d formed therein is immersed in a nickel plating solution, and the plating solution is held for about 60 minutes while being stirred.
About 25 vol% PTFE on the side walls inside 15c and 15d
A conductive film 14 containing nickel as a main component and having a film thickness of about 10 μm is formed, which contains particles of (1) and (4) in an appropriate dispersion and contains phosphorus. The content of PTFE particles is preferably 30 vol% or less, and more preferably in the range of 20 vol%. This is because when the content of the particles made of PTFE is 30 vol% or more, the conductivity is lowered, and the slidability and abrasion resistance are deteriorated. When the content is too small, the action and effect of PTFE Is smaller. Moreover, since nickel having a high hardness is used as the main component of the conductive film 14, the surface hardness of the metal mask 11 can be improved as compared with the case where only the conventional resin film is used. Further, by forming the conductive film 14 using electroless plating, the uniformity of the film thickness of the conductive film 14 is improved, so that the amount of the solder pastes 17a and 17b applied and formed on the printed wiring board 16 can be reduced. In-plane uniformity can be secured.

After that, when heat treatment is performed at a temperature of 300 ° C. for about 1 hour, a circular opening 15a having a diameter of about 150 μm,
The metal mask 11 having 15b is completed (FIG. 4).
(C)). At this time, due to this heat treatment, the conductive film 1
Curing is promoted by the action of the additive phosphorus in 4, and the surface hardness of the conductive film 14 of about Hv300 is improved to about Hv600 before the heat treatment. This reduces wear when the metal mask 11 is slid. Further, by this heat treatment, the particles made of PTFE are better dispersed, and the uniformity of distribution of the particles made of PTFE is increased. As a result, it is possible to improve slidability and solder paste removal.

(B) Method of selectively forming solder paste on a printed wiring board using the metal mask of the first embodiment Next, the solder paste is selectively formed on the printed wiring board using this metal mask. A method for forming the above will be described with reference to FIG.

First, the printed wiring board 16 and the metal mask 11 are aligned with each other to some extent and overlapped with each other, and then the metal mask 11 is slid on the printed wiring board 16.
Perform precise alignment. At this time, the metal mask 11
Since the particles of PTFE are dispersed and contained in the conductive film that coats, the particles of PTFE are always exposed on the contact surface, and even if the contact surface is worn by sliding, new P particles are always present.
Particles of TFE appear on the contact surface. As a result, PTF
The slipperiness due to the action of the particles of E can be maintained and good slidability can be maintained.

Next, after the solder paste is placed on one surface of the metal mask 11, the metal mask 11 is strongly pressed by a squeegee (not shown), and the solder paste is rolled up and moved on the metal mask 11. As a result, the solder pastes 17a and 17b are embedded in the openings 15a and 15b of the metal mask 11, and a certain amount of the solder paste 17a is provided at a predetermined position on the printed wiring board 16 corresponding to the positions of the openings 15a and 15b. , 17b are formed.

Next, when the metal mask 11 overlaid on the printed wiring board 16 is removed from the surface of the printed wiring board 16, a cylindrical solder paste 17 having a diameter of about 150 μm is formed.
A and 17b are selectively applied and formed at predetermined positions on the printed wiring board 16. At this time, the conductive film 1 in which the side walls inside the openings 15a and 15b contain PTFE particles having water repellency.
By being covered with 4, the openings 15a, 15b
The solder pastes 17a and 17b embedded therein and the conductive film 14 are in direct contact with each other. Therefore, the solder pastes 17a and 17b are easily separated from the metal mask 11 by the action of the water-repellent PTFE particles exposed on the surface of the conductive film 14, and the solder pastes 17a and 17b and the metal mask 11 are easily separated from each other. Can be peeled off.

After that, for reuse, the metal mask 11 is washed with isopropyl alcohol or water to remove the solder paste attached to the metal mask 11. At this time, since the PTFE particles are dispersed and exposed on the surface of the conductive film 14 that covers the contact surface of the metal mask 11, the side walls in the openings 15a and 15b, and the surface that does not contact, the conductivity is increased. The surface of the conductive film 14 has water repellency, and the solder paste attached to the metal mask can be easily removed.

Regarding the printed wiring board 16 on which the solder pastes 17a and 17b are formed, the solder paste 17
After mounting the external leads of the corresponding semiconductor device on a and 17b, heat treatment is performed at a temperature of about 215 ° C. for 30 seconds to 60 seconds. As a result, the solder pastes 17a and 17b are melted, and the wiring on the printed wiring board 16 and the external leads of the semiconductor device are bonded and electrically connected.

As described above, according to the metal mask of the first embodiment of the present invention, the conductive film 14 that covers the contact surface of the metal mask 11 has a water repellent PTFE which is a kind of fluororesin. Since the particles of are dispersed and contained,
PTFE particles are always exposed on the contact surface, and new PTFE particles are always exposed even when the contact surface is worn by sliding. Therefore, since the slippery property of the contact surface of the metal mask due to the action of the PTFE particles can be maintained, good slidability can be maintained.

Further, the side walls inside the openings 15a and 15b are covered with the conductive film 14 containing the PTFE particles having water repellency, so that the solder pastes 17a and 17b embedded in the openings 15a and 15b and the solder pastes 17a and 17b. The conductive paste 14 is in direct contact with the conductive paste 14, and the solder pastes 17a and 17b are easily separated from the metal mask 11 by the action of the water-repellent PTFE particles exposed on the surface of the conductive paste. Therefore, the solder pastes 17a, 17b from the miniaturized openings 15a, 15b
It is possible to improve the detachability of the sheet.

Further, the contact surface of the metal mask 11 and the opening
Since the PTFE particles having water repellency are dispersed and exposed on the surface of the conductive film 14 coated on the side walls and the surfaces not in contact with each other in 15a and 15b, the surface of the conductive film 14 has water repellency. It is possible to easily remove the solder paste attached to the metal mask 11. This improves the cleanability of the metal mask 11.

Further, since the conductive film 14 has conductivity, it is possible to prevent static electricity from being generated on the surface of the metal mask 11. As a result, it is possible to prevent dust and the like from adhering to the metal mask 11, so that the solder pastes 17a and 17b can be normally formed in the openings 15a and 15b and formed on the printed wiring board 16 by coating. .

Furthermore, by using nickel having a high hardness as the main component of the conductive film 14, the surface hardness is improved as compared with the case of the conventional resin film, and phosphorus, which has the action of accelerating the curing by heating, is conductive. By being contained in the film 14, the hardness of the conductive film 14 is increased by heat-treating the conductive film 14. Thereby, the metal mask 11
Wear is reduced when sliding.

By heat-treating the conductive film 14, the PTFE particles are better dispersed, and the uniformity of the distribution of the PTFE particles is increased. As a result, it is possible to improve slidability and detachability of the solder pastes 17a and 17b.

Further, the electroconductive film 14 is formed by electroless plating.
By forming the film, the uniformity of the film thickness of the conductive film 14 is improved, and the in-plane uniformity of the amounts of the solder pastes 17a and 17b applied and formed on the printed wiring board 16 can be secured.

According to the first embodiment, PTFE which is a kind of fluororesin is used as the resin.
Other fluororesins can be used, or silicone resins can be used.

Although the conductive film 14 is mainly composed of nickel, other conductive substances may be used. Furthermore, although phosphorus is used as an additive having a hardening promoting effect on the conductive film 14, other additives having a hardening promoting effect may be used, or may not be added in some cases.

(2) Second Embodiment (a) Method of Manufacturing Metal Mask According to Second Embodiment of the Present Invention FIG. 5 illustrates a method of manufacturing metal mask according to the second embodiment of the present invention. 6A to 6D and 7A to 7C are sectional views for explaining the method for manufacturing the metal mask according to the second embodiment of the present invention. Note that such a metal mask manufacturing method is referred to as an additive method.

First, the resist film 2 is formed on one surface of a base substrate 20 made of a stainless steel plate having a thickness of several mm as shown in FIG.
1 is applied (FIG. 6B). Then, the resist film 21
Is selectively exposed to light and then exposed to a developing solution. As a result, the resist film 2 corresponding to the portion to be left as the metal mask is formed.
1 is selectively removed, and cylindrical resist pattern films 21a and 21b having a diameter of about 150 μm remain in the regions of the substrate 12a where the openings 15g and 15h are to be formed (FIG. 6C).

Next, by electroplating, a film thickness of 100 to 100 is formed on the surface of the base substrate on which the resist pattern films 21a and 21b remain, except for the regions where the resist pattern films 21a and 21b are formed.
Nickel film to be the base 12a of the metal mask of 300 μm
12a is formed (FIG. 6D). Since the amount of the solder pastes 17a and 17b selectively applied on the printed wiring board 16 is determined by the height of the openings 15e and 15f, the above range is taken into consideration in consideration of the film thickness of the conductive film 14a formed later. Therefore, it is necessary to set the thickness of the nickel film 12a in advance.

Next, the resist pattern films 21a and 21b are removed by a resist stripping solution, and the nickel film 12a is removed from the base substrate 20. As a result, the openings 15g, 15
The production of the metal mask substrate 12a having h is completed (FIG. 7A).

Next, both surfaces of the base 12a and the openings 15g,
Strike plating is applied to the side wall within 15h, so the base 12a
To wash. That is, by immersing the substrate 12a in an alkaline solution,
After degreasing the surface of the substrate 12a, it is immersed in an acid to activate the surface of the substrate 12a.

Next, the base 12a is formed by strike plating.
A nickel film (adhesion strengthening film) 13a having a film thickness of about 1 μm is formed on both surfaces of and the side walls inside the openings 15g and 15h (FIG. 7).
(B)).

Next, the electroless nickel plating solution containing fine particles of about 30 vol% PTFE and phosphorus is heated with stirring and maintained at a temperature of 90 ° C. Subsequently, the substrate 12a having the openings 15g and 15h formed therein is dipped in a nickel plating solution, and the plating solution is stirred for about 60 minutes.
When held for a minute, both surfaces of the base 12a and the openings 15g, 15
On the side wall inside h, a conductive film 14a containing about 25 vol% of particles of PTFE dispersed therein and containing phosphorus and having nickel as a main component and a thickness of about 10 μm is formed. Further, since nickel having a high hardness is used as the main component of the conductive film 14a, the surface hardness of the metal mask 11a can be improved as compared with the case where only the conventional resin film is used.

Thereafter, a heat treatment is performed at a temperature of 300 ° C. for about 1 hour to complete the metal mask 11a (FIG. 6).
(C)). At this time, due to the hardening promoting action of phosphorus contained in the heat treatment, Hv300 before the heat treatment.
The surface hardness of the conductive film 14a is improved to about Hv600. Further, by this heat treatment, the particles made of PTFE are better dispersed, and the uniformity of particle distribution is further increased.

(B) Method of selectively forming solder paste on a printed wiring board using the metal mask of the second embodiment Next, on the printed wiring board using the metal mask 11a of the second embodiment. A method for selectively forming the solder paste will be described. That is, by performing the same steps as in the first embodiment, as shown in FIG. 1, the cylindrical solder pastes 17a and 17b having a diameter of about 150 μm are formed into the printed wiring board 1.
6 is selectively applied and formed at a predetermined position on 6. Also in this case, the same operation and effect of the metal mask 11 as those described in the first embodiment can be obtained.

As described above, according to the metal mask of the second embodiment of the present invention, the nickel particles containing PTFE particles having water repellency dispersedly contained on the surface of the metal mask 11a and containing phosphorus. Since the conductive film 14a containing as a main component is formed, the abrasion resistance, the slidability and the cleaning property of the metal mask 11a are improved and the metal mask 11a is improved.
To prevent the generation of static electricity on the
It is possible to improve the detachability of the solder pastes 17a and 17b from e and 15f.

(3) Third and Fifth Embodiments (a) Method for Manufacturing Metal Mask According to Third Embodiment of the Present Invention FIG. 8 (a) shows a metal mask according to a third embodiment of the present invention. 10A is a process diagram for explaining the manufacturing method of FIG.
It is sectional drawing explaining the metal mask which concerns on the 3rd Example of this invention produced by the said manufacturing method. In this case, it is suitable when the size of the opening of the metal mask is relatively large.

The difference from the metal masks of the first and second embodiments is that the conductive film 14b containing nickel as a main component, which contains dispersed PTFE particles having water repellency and contains phosphorus. That is, it is formed only on the contact surface of the metal mask 11b.

The difference from the method of manufacturing the metal mask of the second embodiment is that the nickel film (adhesion strengthening film) is formed by strike plating before the base of the metal mask formed on the base base is removed from the base base. 13b is formed, and further, by electroless plating, water-repellent PTFE particles are dispersed and contained on the nickel film 13b,
In addition, the conductive film 14b containing phosphorus and containing nickel as a main component is formed.

First, the resist pattern film is formed on the surface of the base substrate 20 on which the cylindrical resist pattern films 21a and 21b having a diameter of about 300 μm remain by the same steps as shown in FIGS. 6 (a) to 6 (d). Except for the regions where 21a and 21b are formed, the film thickness is 100 to 300 .mu.
m nickel film is formed (FIG. 6D).

Next, a nickel film 13b having a film thickness of about 1 μm is formed on one surface of the exposed nickel film which will be the base 12b of the metal mask by striking plating and which will be the contact surface.

Next, the electroless nickel plating solution containing particles of about 30 vol% PTFE and phosphorus is heated with stirring and maintained at a temperature of 90 ° C. Subsequently, while the nickel film serving as the metal mask substrate 12b being held by the base substrate 20 is immersed in the nickel plating solution and the plating solution is held for about 60 minutes while stirring, one surface of the substrate 12b And about 25 vol% PTF
A conductive film 14b containing particles of E dispersedly contained and containing phosphorus and having nickel as a main component and a thickness of about 10 μm is formed.

Next, the resist pattern films 21a and 21b are removed by a resist stripping solution, and the nickel film is removed from the base substrate 20. As a result, the openings 15i and 15j are formed and the base 12b on which the conductive film 14b is formed is formed.

Thereafter, when heat treatment is performed at a temperature of 300 ° C. for about 1 hour, a circular opening 15i having a diameter of about 300 μm,
The metal mask 11b having 15j is completed (FIG. 10).
(A)). At this time, due to the hardening promoting action of phosphorus contained in the heat treatment, Hv300 before the heat treatment.
The surface hardness of the conductive film 14b is improved to about Hv600. Further, by this heat treatment, the particles made of PTFE are better dispersed, and the uniformity of distribution of fine particles is further increased.

Although the conductive film 14b is formed by electroless plating, a metal mask base is formed on the base base according to the metal mask manufacturing process diagram of the fifth embodiment shown in FIG. It is also possible to form a nickel film, and after forming the nickel film by strike plating, apply a paste containing PTFE particles and phosphorus having water repellency and containing nickel as a main component.

(B) Method of selectively forming solder paste on a printed wiring board using the metal mask of the third embodiment. Next, using the metal mask of the third embodiment, a solder paste is formed on the printed wiring board. A method for selectively forming the solder paste will be described with reference to FIG. Also in this case, as in the case of the first and second embodiments, a fixed amount of solder paste is selectively applied on the printed wiring board 16b.
17c and 17d can be formed.

According to the metal mask 11b of the third embodiment, the main component of nickel is water-repellent PTFE particles dispersed and contained only in the contact surface of the metal mask 11b. Since the conductive film 14b is formed, the abrasion resistance and the slidability of the metal mask 11b are improved, and the generation of static electricity on the metal mask 11b is prevented as compared with the conventional resin film. can do.

Since it is formed only on the contact surface of the metal mask 11b and no conductive film is formed on the side walls inside the openings 15i and 15j, the solder is different from the first and second embodiments. The pastes 17c and 17d have a slightly poor release property, but the openings 15
Since the dimensions of i and 15j are large, solder pastes 17c and 17d
Poorness is not a problem.

(4) Fourth Embodiment (a) Manufacturing Method of Metal Mask According to Fourth Embodiment of the Present Invention FIG. 8B shows a manufacturing method of metal mask according to the fourth embodiment of the present invention. 10 (b) is a process diagram illustrating
It is sectional drawing explaining the metal mask which concerns on the 3rd Example of this invention produced by the said manufacturing method.

The difference from the metal masks of the first and second embodiments is that the conductive film 14c containing nickel as a main component, which contains dispersed PTFE particles having water repellency and contains phosphorus. It is formed only on the contact surface of the metal mask 11c and the side walls inside the openings 15k and 15l.

The difference from the method for manufacturing the metal mask of the second embodiment is that after the strike plating is formed,
A resist film is formed on the surface that does not come into contact, and further, electroless plating is performed in this state to form nickel containing phosphorus particles containing PTFE particles having water repellency dispersed on the nickel film 13c. This is to form the conductive film 14c containing the main component.

First, FIGS. 6A to 6D and FIG.
By the steps similar to the steps shown in (a) and (b), a film thickness is formed on the exposed one surface of the nickel film having a film thickness of 100 to 300 μm to be the base 12c of the metal mask and the contact surface. A nickel film (adhesion enhancing film) 13c having a thickness of about 1 μm is formed.

Next, after the surface not contacting is covered with a resist film, an electroless nickel plating solution containing about 30 vol% PTFE particles and phosphorus is heated with stirring and kept at a temperature of 90 ° C. Then, the nickel film to be the substrate 12c is dipped in the nickel plating solution, and the plating solution is kept for about 60 minutes while being stirred, so that the contact surface of the substrate 12c and the side wall inside the opening are about 25 vol%. PT
Particles of FE are dispersedly contained, and phosphorus is contained,
Conductive film 14c mainly composed of nickel and having a thickness of about 10 μm
Is formed.

After that, when heat treatment is performed at a temperature of 300 ° C. for about 1 hour, a circular opening 15k having a diameter of about 150 μm,
A metal mask with 15 l is completed (Fig. 10
(B)). At this time, due to the hardening promoting action of phosphorus contained in the heat treatment, Hv300 before the heat treatment.
The surface hardness of the conductive film 14 is improved to about Hv600. Further, by this heat treatment, PTFE particles are better dispersed, and the uniformity of distribution of fine particles is further increased.

(B) Method of selectively forming solder paste on a printed wiring board using the metal mask of the fourth embodiment. Next, using the metal mask of the fourth embodiment, a solder paste is formed on the printed wiring board. A method for selectively forming the solder paste will be described with reference to FIG. Also in this case, as in the case of the first and second embodiments, a fixed amount of solder paste is selectively applied on the printed wiring board 16c.
17e and 17f can be formed.

According to the metal mask 11c of the fourth embodiment, the water-repellent PTFE particles are dispersed on the surface of the metal mask 11c only on the contact surface of the metal mask 11c and the side walls inside the openings 15k and 15l. Since the conductive film 14c containing nickel as a main component and containing phosphorus as a main component is formed, the abrasion resistance and the slidability of the metal mask 11c are improved and the conventional resin film Compared with the case, it is possible to prevent the generation of static electricity on the metal mask 11c and improve the detachability of the solder pastes 17e and 17f.

Since the conductive film 14c is not formed on the contact surface of the metal mask 11c and the sidewalls of the openings 15k and 15l and the contact surface is not formed, the first and second surfaces are not formed.
It is considered that the detergency is slightly inferior to that of the example.

[0073]

As described above, according to the metal mask of the present invention, particles of a water-repellent resin such as a silicone resin or a fluororesin are dispersed in the conductive film covering the contact surface of the metal mask. Since it is contained as a material, good slidability can be maintained.

Further, since the side wall in the opening is covered with the conductive film containing the resin particles having water repellency, it is possible to improve the detachability of the solder paste from the miniaturized opening.

Furthermore, since resin particles having water repellency are dispersed and exposed on the surface of the conductive film with which the contact surface of the metal mask, the side wall in the opening and the surface not contacting the metal mask are dispersed, the metal mask is exposed. The solder paste attached to the can be easily removed, and the cleaning property can be improved.

Further, since the conductive film has conductivity, dust and the like are prevented from adhering to the metal mask due to static electricity, whereby the solder paste is normally embedded in the opening and allowed to pass therethrough, so that the solder paste can be formed on the printed wiring board. Can be formed by coating.

Further, by using nickel having a high hardness as the main component of the conductive film, the surface hardness is improved as compared with the case of the conventional resin film, and an additive such as phosphorus, Due to the hardening promoting effect by heating, the surface hardness of the conductive film is further increased, and the abrasion resistance of the metal mask can be improved. In addition, by heat-treating the conductive film, the resin particles are better dispersed, the uniformity of the distribution of the resin particles is increased, and the slidability and the solder paste removal property can be improved.

By forming the conductive film by electroless plating according to the method for manufacturing a metal mask of the present invention, the uniformity of the film thickness of the conductive film is improved, and the conductive film is formed by coating on the printed wiring board. It is possible to secure the in-plane uniformity of the amount of solder paste to be formed.

[Brief description of drawings]

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

FIG. 2 is a process drawing for explaining the manufacturing method of the metal mask according to the first embodiment of the present invention.

FIG. 3 is a sectional view (No. 1) for explaining the manufacturing method of the metal mask according to the first embodiment of the present invention.

FIG. 4 is a sectional view (No. 2) for explaining the method for manufacturing the metal mask according to the first embodiment of the present invention.

FIG. 5 is a process chart for explaining the manufacturing method of the metal mask according to the second embodiment of the present invention.

FIG. 6 is a sectional view (No. 1) for explaining the method for manufacturing the metal mask according to the second embodiment of the present invention.

FIG. 7 is a cross-sectional view (No. 2) explaining the method of manufacturing the metal mask according to the second embodiment of the present invention.

FIG. 8 is a process chart illustrating a method of manufacturing a metal mask according to third and fourth embodiments of the present invention.

FIG. 9 is a process drawing for explaining a manufacturing method of a metal mask according to a fifth embodiment of the present invention.

FIG. 10 is a cross-sectional view illustrating metal masks according to third to fifth embodiments of the present invention.

FIG. 11 is a cross-sectional view illustrating metal masks according to first and second conventional examples.

[Explanation of symbols]

 11, 11a to 11c Metal mask, 12, 12a to 12c Substrate, 13, 13a to 13c Adhesion strengthening film (nickel film), 14, 14a to 14c Conductive film, 15a to 151, 19a, 19b Opening part, 16, 16b , 16c Printed wiring board, 17a to 17f Solder paste, 18, 21 Resist film, 18a Resist mask, 21a, 21b Resist pattern film.

Claims (14)

[Claims] 1. A metal mask for stacking on a printed wiring board and selectively applying and forming an appropriate amount of solder paste on the printed wiring board, comprising: a plate-shaped conductive base and the solder paste formed on the base. A metal mask having an opening for embedding and passing through, and a conductive film that contains dispersed particles of a resin having water repellency and is coated on at least a surface that contacts the printed wiring board. 2. The metal mask according to claim 1, wherein the conductive film is coated on a surface contacting the printed wiring board and a side wall inside the opening. 3. The conductive film is coated on a surface that comes into contact with the printed wiring board, a sidewall inside the opening, and a surface that does not come into contact with the printed wiring board. Metal mask. 4. The metal mask according to claim 1, wherein the base is a stainless plate or a nickel plate. 5. The conductive film containing nickel as a main component, according to claim 1, wherein the conductive film is a conductive film.
The metal mask according to any one of 1. 6. The metal according to claim 5, wherein the conductive film is a conductive film containing nickel as a main component and containing phosphorus in addition to the particles made of the resin having water repellency. mask. 7. The metal mask according to claim 1, wherein the water-repellent resin is a silicone resin or a fluororesin. 8. The metal mask according to claim 1, wherein the content of the particles of the water-repellent resin in the conductive film is 30 vol% or less. 9. The adhesion enhancing film is interposed between the substrate and the conductive film.
The metal mask according to any one of 1. 10. The metal mask according to claim 9, wherein the adhesion enhancing film contains nickel as a main component. 11. The electroconductive film according to any one of claims 1 to 10 is formed by electroless plating using a plating solution containing at least particles of the water-repellent resin and an electroconductive substance. A method of manufacturing a metal mask, comprising: 12. The electroconductive film is formed by electroless plating using a plating solution containing particles made of the resin having water repellency, an electroconductive substance, and an additive having a hardening promoting action on the electroconductive film. 11. The method according to claim 11, wherein
A method for manufacturing the described metal mask. 13. The conductive film according to claim 1, wherein the conductive film is formed by applying a paste containing at least particles of the water-repellent resin and a conductive substance. A characteristic metal mask manufacturing method. 14. The conductive film is formed by applying a paste containing particles made of the resin having water repellency, a conductive substance, and an additive having a function of promoting hardening of the conductive film. 14. The method of manufacturing a metal mask according to claim 13, wherein the metal mask is manufactured.