JPH08252988A - Paste printing plastic mask and paste printing method using the mask - Google Patents

Abstract

PURPOSE: To provide a paste printing plastic mask having excellent electrification property of static electricity and abrasion resistance, and a paste printing method using the mask. CONSTITUTION: As a paste printing mask, a paste printing plastic mask having a conductive layer 5 formed on a bottom face or both top and bottom faces of a plastic plate 3 having an opening 6 consisting of a predetermined pattern is used. The paste printing plastic mask is attached to a body to be printed 13, and a paste 14 is extended from its top so as to fill the opening 6 with the paste. Next, the paste printing plastic mask is removed from the top of the body to be printed 13, so that a paste pattern having the same shape as that of the opening 6 is formed on the body to be printed 13. The static electricity to be generated at the time of printing is freed to an earth through the conductive layer 5, a clamper 10 of a printing machine, and an earth wire 11. Thus, as electrification does not occur, electrostatic breakdown of mounted parts is eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paste printing plastic mask and a paste printing method using the same.

[0002]

2. Description of the Related Art Conventionally, a screen has been used as a paste printing mask for printing cream solder, ink, adhesive, paste-like resin (hereinafter referred to as "paste") on a substrate such as a printed circuit board. Although masks and metal masks are known, the present inventor has proposed a plastic mask as a paste printing mask which eliminates the drawbacks of these conventional masks (Japanese Patent Application No. 5-1653).
No. 91, Japanese Patent Application No. 5-230010).

This plastic mask is used in the same manner as a conventional metal mask, but since the material is a plastic that is softer than metal, it adheres to the unevenness of the surface to be printed flexibly. It is excellent and has the advantage of less bleeding of the paste. In addition, the manufacturing method is also ablation using an excimer laser, which makes it possible to make very fine and fine holes and improve the ease of removing the paste. Further, a so-called half-etching mask in which a plastic plate surface is partially dug in accordance with a fine pitch component to make it thin and a minute opening is formed in this thinly dug portion can be easily manufactured.
Therefore, it is possible to perform paste printing with higher quality and higher definition than the conventional metal mask.

However, on the other hand, since the mask material is an insulator and is a plastic softer than metal, static electricity is generated due to friction during paste printing.
In terms of abrasion resistance, the following new problems not found in conventional metal masks occur. That is, FIG. 12 and FIG.
As shown in FIG. 3, paste 51 is applied to the plastic mask 5
Most of the squeegees 53 for rubbing the second plate surface are usually made of a soft squeegee such as urethane so that they can be adhered to the surface of the thin half-etched portion 54. Since this urethane squeegee 53 is plastic, it is electrically an insulator. Therefore, when the urethane squeegee 53 is rubbed against the plate surface of the plastic mask 51 during paste printing, static electricity is generated and charged on the surfaces of the urethane squeegee 53 and the plastic mask 51.

In the case of a metal mask, since the metal mask itself is conductive, this electrostatic charging problem hardly occurs. However, in the case of a plastic mask, the plastic mask is an electrical insulator. ,
The problem of electrostatic charging cannot be avoided. In particular, this has caused a serious problem in the work of mounting electronic components on a printed circuit board by the double-sided reflow soldering method. The double-sided reflow soldering method is to print cream solder on one side of the printed circuit board, use the viscosity of this cream solder to mount components on it, and pass it through an electric furnace called a reflow furnace. After melting the solder by heating and mounting the component on one side of the printed circuit board, flip the printed circuit board upside down and solder the remaining opposite side in the same process to solder the component to both sides of the printed circuit board. Is the way to complete.

When a plastic mask is used for the double-sided reflow soldering, the following problems occur. That is, the static electricity generated by the use of the plastic mask is accumulated and becomes a high potential each time the triboelectric charging by printing is repeated. Then, when the electric potential of the charged static electricity reaches a certain voltage or more, it flows into the electronic component already mounted on one surface by double-sided reflow,
There is a risk of electrostatic damage to minute circuits inside parts.

Some components soldered by double-sided reflow are extremely vulnerable to static electricity. For example, RO
It is known that M, RAM, CMOS products, CCD, etc. can be destroyed by static electricity of about a hundred and several tens of volts. When cream solder is printed on a glass epoxy board with a urethane squeegee using a plastic mask that does not take measures against static electricity, the actual value of static electricity charged on the plastic plate surface is a large value exceeding 1000 volts after printing 3 to 4 times. Therefore, the parts and the like may be electrostatically destroyed. Moreover, it is not possible to judge the occurrence of defects in the parts that have been electrostatically destroyed by their appearance,
It will be discovered in the functional inspection, which is the final step of mounting, and a great loss will occur. In addition, ROM, RAM
The electrostatic breakdown inside the memory circuit such as is not found in the normal function test, and a situation where a defective product leaks to the outside may occur.

As a measure against the above-mentioned electrostatic problem, it is possible to use a metal squeegee. This uses a metal blade such as phosphor bronze as a squeegee, and tries to let static electricity generated on the plastic plate surface escape to the outside through a conductive metal squeegee. However, as shown in FIG. 14, since the metal squeegee 55 is not as soft as the urethane squeegee,
At the time of printing the half-etched portion 54, the lower edge of the metal squeegee 55 having a large width is supported by the plate surface 56 which is not half-etched, so that the surface of the half-etched portion 54, which is dug into a concave shape, cannot be adhered. .

As a result, as shown in FIG. 15, when the plastic mask 52 is peeled off, the cream solder 51 remains in a film form on the half-etched portion 54, which impedes the removability of the cream solder. Therefore, the metal squeegee cannot be used for paste printing with a plastic mask having a half-etched portion, and a plastic squeegee such as a urethane squeegee must be used.

Further, since the plastic mask is soft, there is a new problem that it is inferior in abrasion resistance to the metal mask. In particular, if the printing target has a large surface roughness, such as a ceramic plate or glass epoxy laminated substrate, or if there are chips of fine plate material on the substrate surface, the abrasion of the plastic mask will be further accelerated and the abrasion resistance will increase. There is room for consideration in terms of wear resistance.

[0011]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and a paste printing plastic mask excellent in electrostatic charging characteristics and abrasion resistance,
It is an object to provide a paste printing method using this.

[0012]

In order to achieve the above object, a plastic mask for paste printing according to claim 1 comprises:
In a plastic mask for paste printing in which a plastic plate is used as a mask material and an opening having a predetermined pattern is formed in the plastic plate, a conductive layer is formed on the surface of the plastic plate.

The plastic mask for paste printing according to a second aspect of the present invention is characterized in that a conductive layer is formed only on the surface of the plastic plate that is in contact with the object to be printed.

The plastic mask for paste printing according to a third aspect of the invention is characterized in that conductive layers are formed on the upper and lower surfaces of the plastic plate, and the conductive layers on the upper and lower surfaces are electrically connected.

The plastic mask for paste printing according to a fourth aspect is characterized in that the conductive layers on the upper and lower surfaces are electrically connected by a conductive adhesive.

Further, the plastic mask for paste printing according to a fifth aspect is characterized in that a wear-resistant conductive layer is adopted as the conductive layer.

The plastic mask for paste printing according to a sixth aspect of the invention is characterized in that a titanium coating layer is adopted as the conductive layer.

Further, the paste printing method of claim 7 is
A paste printing mask having an opening formed of a predetermined pattern is brought into close contact with an object to be printed, and the paste is spread on the paste printing mask to fill the opening with the paste, and then on the object to be printed. The paste according to any one of claims 1 to 6, wherein the paste printing mask is removed to form a paste pattern having the same shape as the opening on the substrate to be printed, as the paste printing mask. The present invention is characterized in that a printing plastic mask is used and printing is performed in a state where the conductive layer of the paste printing plastic mask is electrically grounded.

When printing is performed by the paste printing method according to the present invention using the plastic mask for paste printing according to the present invention, static electricity generated by friction between the urethane squeegee and the plastic plate surface is transmitted through the conductive layer formed on the surface of the plastic plate. It is released to the ground and discharged. Therefore, static electricity is not charged on the paste printing plastic mask. Therefore, there is no fear that the mounted components will be electrostatically damaged by the charged static electricity.

In the above-mentioned printing, when the paste printing plastic mask in which the conductive layer is formed only on the surface of the plastic plate which is in contact with the substrate to be printed is used as the paste printing plastic mask, the generated static electricity is converted into the conductive paste. Since it can be led to the conductive layer on the lower surface through, it is possible to eliminate static electricity generated when the conductive paste is printed.

When a conductive mask is formed on both upper and lower surfaces of a plastic plate and the conductive layers on the upper and lower surfaces are electrically connected to each other as a plastic mask for paste printing, the conductive layer on the upper surface is used as a mask. Since static electricity generated in the conductive layer on the lower surface can be conducted, static electricity generated when printing an insulating paste that cannot be a conductor by itself can be eliminated.

If the conductive layers on the upper and lower surfaces of the plastic plate are electrically connected with a conductive adhesive, the structure of the plastic mask for paste printing can be made simpler.

Further, as a conductive layer, a titanium coating layer, a chromium coating layer, a nickel coating layer, an aluminum coating layer, stainless steel (for example, SUS
304) When a wear-resistant conductive layer such as a coating layer is adopted, static electricity generated during paste printing can be removed, and the wear resistance of the plastic mask for paste printing can be further increased. Therefore, the life of the plastic mask for paste printing can be further extended. As the abrasion resistant conductive layer, a titanium coating layer is particularly preferable in terms of hardness.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. 2 to 4 show a first example of a plastic mask for paste printing (hereinafter, abbreviated as "plastic mask") of the present invention. FIG. 2 is a side view showing the overall configuration, and FIG. 3 is the overall configuration. FIG. 4 is a partially enlarged sectional view of FIG. This first example shows an example of a plastic mask in which a conductive layer is coated only on the lower surface of a plastic plate, and is used when printing a conductive paste.

In FIGS. 2 and 3, the mask frame 1 is made of aluminum square pipe, and the mask frame 1 has 180 to 22 pieces.
A polyester mesh film 2 of about 5 mesh is attached under a constant tension. A 125 μm-thick polyimide plastic plate 3 is attached to the central cut-out portion of the gauze membrane 2 with an adhesive 4.

On the lower surface of the plastic plate 3, as shown in FIG. 4, a conductive coating layer 5 of titanium is sputter-deposited to a thickness of about 2000Å. Polyimide is used as the material of the plastic plate 3 in consideration of mechanical strength and chemical resistance. Further, the reason why titanium is used as the conductive coating layer 5 is in consideration of improvement of abrasion resistance.

In FIG. 4, 6 is a large opening for large parts formed on the plastic plate surface, 7 is a middle opening for medium-sized parts, and 8 is a minute opening for fine pitch parts formed in the half-engaging part 9. It is an opening. These openings 6
8 to 9 and the half-etched portion 9 can be formed, for example, by the method shown in the above-mentioned Japanese Patent Application No. 5-230010 proposed by the present inventor.

Next, with reference to FIG. 1, a method of printing conductive cream solder on a printed circuit board for mounting electronic parts using the plastic mask of the first example will be described.

When printing is performed using the plastic mask of the present invention, as shown in FIG. 1, the metal structure such as the metal clamper 10 of the printing machine is previously grounded to the ground wire 11.
It is necessary to ground appropriately by the method. This is because static electricity generated at the time of printing is released to the ground to prevent charging as described later.

After the metal structure such as the clamper 10 of the printing machine is grounded as described above, the printing operation is performed as follows. First, the printed circuit board 13 to be soldered is placed on the left and right clampers 10 of the printing machine, and then the plastic mask is attached to the printed circuit board 1 by the conductive coating layer 5.
3 is placed on the printed circuit board 13 in a direction of contacting the printed circuit board 3, and the entire plastic mask is pressed by a pressing means (not shown) so that the surface of the printed circuit board 13 and the metal structure such as the clamper 10 of the printing machine are brought into close contact with each other.

Next, after placing a predetermined amount of the conductive cream solder 14 on the plastic plate 3, the urethane squeegee 1
2 and the opening 6 (7, 7) of the plastic plate 3
8) is filled with the conductive cream solder 14. When the filling of the conductive cream solder is completed, the plastic mask is peeled off from the printed circuit board 13 and removed. As a result, a paste pattern having the same shape as the opening 6 (7, 8) is formed on the printed board 13.

As described above, when the cream solder is printed by the urethane squeegee 12, the tip of the urethane squeegee 12 and the surface of the plastic plate 3 are rubbed. As a result, as shown in FIG.
As shown therein, positive and negative static electricity is charged. Which side is positive or negative is determined by the triboelectrification train of the substances to be rubbed, but when the urethane squeegee 12 is used as the squeegee and the polyimide is used as the plastic plate 3 as in the illustrated example, As shown in the figure, the urethane squeegee 12 side is positively (plus) charged and the plastic plate 3 side is negatively (minus) charged.

The static electricity thus generated remains on the surfaces of the urethane squeegee 12 and the plastic plate 3 which are insulators, and is not discharged as it is. However, in the case of the present invention, the conductive cream solder 14 that is in close contact with the source of the triboelectricity cancels some of them to eliminate the static electricity, and the remaining static electricity is indicated by an arrow in FIG. So that conductive cream solder 1
4 through the opening 6 (7, 8) of the plastic plate 3, the conductive coating layer 5 on the lower surface, the clamper 10 of the printing machine and the earth wire 11 which are in close contact with the plastic plate 3.
It is released to the ground through and the electricity is removed.

Therefore, even if an insulating plastic squeegee such as the urethane squeegee 12 is used, static electricity will not be charged, and the mounted component will not be mounted in the mounting work of the electronic component on the printed circuit board by the double-sided reflow soldering method. It will not be electrostatically destroyed.

On the other hand, as shown in FIG. 6, when the plastic mask is peeled off from the printed circuit board 13 after printing is completed, peeling charge is generated. However, in general, on the surface of the printed circuit board 13, as shown in FIG.
5, there are fine irregularities such as the resist 16, the display ink 17, the pattern projections 18, and the like, and there is a gap 19 between the printed board 13 and the plastic plate 3, and they are completely in close contact microscopically. Not not. Therefore, the static electricity generated by the peeling charge is small, and the static electricity caused by the peeling charge does not destroy the mounted components. Even if static electricity is generated by this peeling charge,
In the case of the present invention, until the conductive coating layer 5 is completely separated from the clamper 10 of the printing machine, the conductive coating layer 5 is released to the ground and discharged, so that no problem occurs.

Even if the conductive coating layer 5 is separated from the clamper 10 of the printing machine, if the contact portion between the plastic mask and the printed circuit board remains, peeling electrification occurs due to peeling that occurs thereafter. However, the potential is so small that it does not pose a problem. Moreover, since this charging potential is diffused over the entire surface of the conductive coating layer 5 and averaged, even if static electricity due to peeling charging remains on the surface of the plastic plate 3, it does not become a high voltage, and the mounted component There is no such thing as destroying. Further, even if static electricity due to peeling electrification remains on the surface of the plastic plate 3 in this way, it is released to the ground through the conductive coating layer 5, the clamper 10 and the ground wire 11 each time at the next cream solder printing, Static electricity will not accumulate as the number of operations increases.

As shown in FIG. 5, the peeling charge described above is applied not only to the side of the plastic plate 3 but also to the printed circuit board 13.
The peeling electrification on the printed circuit board side is at a level of 50 V or less per peeling, and at a potential of this level, it is likely to occur in ROM, RAM, etc., which are susceptible to static electricity. Even if it flows to the internal minute circuit, it does not lead to electrostatic breakdown. By the way, even in the double-sided reflow soldering method using a metal mask that is widely used at present, the conditions of this peeling electrification are the same, and the same peeling electrification occurs on the printed circuit board. There is no electrostatic damage caused by.

On the other hand, regarding the abrasion resistance, in the case of the present invention, since the conductive coating layer 5 made of hard titanium having excellent abrasion resistance is formed on the lower surface of the plastic plate 3, there is a problem. It never happens. For example, about 20
Using a 125 μm-thick plastic plate 3 made of polyimide resin on which a conductive coating layer 5 made of titanium having a thickness of 00Å was sputter-deposited, a printing durability test was conducted under the same conditions as the metal mask, and even after printing 15,000 times. Almost no abrasion of the conductive coating layer 5 was observed. As a result, it was estimated that it could endure printing at least tens of thousands of times, and it was confirmed that there was no problem in practical use.

By the way, among the conventional metal masks, the half-etching mask having a stepped portion is used most closely to the plastic mask of the present invention.
Usually, this mask material is nickel, which is considerably softer than the SUS304 spring material used as a material for an etching mask. Therefore, as shown in FIG. 7A, if there is a foreign material 20 or a convex portion 21 due to uneven solder plating on the pad 15 of the printed board, as shown in FIGS. 7B and 7C, Metal mask 22
Deformation 24 easily occurs in the rib portion of the opening 23 of the above, and as shown in FIG. 7D, the paste 25 leaks from this deformed portion during the next printing, and as shown in FIG. To
A defect such as a short 27 or a solder ball 28 occurs in the printed paste pattern 26.

On the other hand, when the plastic plate 3 is used as in the present invention, as shown in FIG. 8 (a), the printing plate flexibly adheres to the surface of the printed circuit board during printing, and FIG. As shown in Fig. 3, when it is peeled off from the printed circuit board, it immediately returns to the original flat plate, so the occurrence of printing defects as described above is much less than with metal masks, and high-quality, high-definition paste Printing can be performed.

By the way, in addition to the conductive paste, an insulating paste is often used as the paste. When printing this insulating paste, it is necessary to take measures against static electricity, but when the insulating paste is used, the vest itself is used as a static elimination path to lead the static electricity to the ground as in the case of the conductive paste described above. Cannot be used. Therefore, as a second example, FIG. 9 shows an example of the plastic cook mask of the present invention suitable for printing such an insulating paste.

In the plastic cook mask of the second example shown in FIG. 9, not only the conductive coating layer 5 is formed on the lower surface of the plastic plate 3, but also a similar conductive coating layer 29 is formed on the upper surface, The conductive coating layers 5 and 29 on the upper and lower surfaces are electrically connected by a conductive adhesive 30 at the edge of the plastic plate 3.

FIG. 10 shows a method of printing the insulating cream solder 31 on the printed board using the plastic mask of the second example. In FIG. 10, the same parts as those in FIG. 1 are designated by the same reference numerals.

Also in the case of printing using the plastic mask of the second example, the tip of the urethane squeegee 12 and the conductive coating layer 29 on the surface of the plastic plate 3 are rubbed, and positive and negative static electricity is generated between them. However, these static electricity are also grounded via the upper conductive coating layer 29, the conductive adhesive 30, the lower conductive coating layer 5, the clamper 10, and the ground wire 11, as shown by the arrow in FIG. Is discharged to and is discharged. Therefore, the static electricity generated when the insulating cream solder 31 is printed can be surely removed, and the mounted components are not electrostatically destroyed.

The plastic mask of the second example can be used not only for printing the insulating paste, but also for the conductive paste described in the first example.

FIG. 11 shows a third example of the plastic mask of the present invention. In the plastic mask of the third example, instead of the conductive adhesive 30 in FIG. 10, metal foil 32 is used to form conductive coating layers 5, 29 on both upper and lower surfaces.
Is connected. In this case, an ordinary non-conductive adhesive is sufficient as the adhesive 4 for adhering the plastic plate 3 and the gauze film 2, but if the same conductive adhesive 30 as shown in FIG. The conduction between the coating layers 5 and 29 can be made more reliable.

As a method of conducting the conductive coating layers 5 and 29 on the upper and lower surfaces, for example, a metallic foil in which a metal foil or a conductive wire from the conductive coating layers 5 and 29 is adhered and fixed to the printer main body is used. Various methods such as pulling out to the position of the mask frame 1 (see FIG. 1) and connecting these metal foils and conductive wires through the mask frame 1 can be adopted.

In the above examples, the case where the cream solder is printed has been described, but the same can be applied to other pastes other than the cream solder. Furthermore, in the above example, the case where a titanium coating layer was used as the conductive coating layer was taken as an example, but in addition to this,
Chrome coating layer, nickel coating layer, aluminum coating layer, stainless steel (eg SUS304)
A coating layer or the like can be used.

[0049]

As described above, according to the plastic mask for paste printing of claim 1, a plastic plate is used as a mask material, and the plastic plate for paste printing is formed with openings having a predetermined pattern in the plastic plate. In the above, since a conductive layer is formed on the surface of the plastic plate, static electricity generated during paste printing can be released to the outside through this conductive layer, and static electricity can be removed, and plastic characteristics can be maintained even for parts and boards that are sensitive to static electricity. It is possible to perform fine paste printing with high quality by making good use of it. Furthermore, the conductive layer formed on the surface of the plastic plate also improves abrasion resistance and can extend the life of the plastic mask for paste printing, thus increasing the practicality and reducing the cost of the printing mask. You can

Further, according to the plastic mask for paste printing of the second aspect, since the conductive layer is formed only on the surface of the plastic plate which is in contact with the object to be printed, the static electricity generated during the printing of the conductive paste can be effectively used. It can be removed.

According to the plastic mask for paste printing of the third aspect, since the conductive layers are formed on the upper and lower surfaces of the plastic plate and the conductive layers on the upper and lower surfaces are electrically connected, the insulating paste and the conductive layer are formed. It is possible to effectively eliminate static electricity generated when printing the paste.

According to the plastic mask for paste printing of the fourth aspect, since the conductive layers on the upper and lower surfaces are electrically connected by the conductive adhesive, the structure of the plastic mask for paste printing can be simplified. it can.

According to the plastic mask for paste printing of the fifth and sixth aspects, since the abrasion-resistant conductive layer, especially the hard titanium coating layer is adopted as the conductive layer, a greater abrasion resistance is realized. Therefore, the life of the paste printing plastic mask can be further extended.

Further, according to the paste printing method of claim 7, the paste printing plastic mask according to any one of claims 1 to 6 is used, and the conductive layer of the paste printing plastic mask is electrically grounded. Since paste printing is performed with, it is possible to perform printing while removing the triboelectricity that occurs during paste printing and the peeling electricity that occurs when the plastic mask for paste printing is separated from the material to be printed, and there is no electrostatic charge. Good paste printing can be realized.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a paste printing method using a paste printing plastic mask of a first example.

FIG. 2 is a side view showing the overall configuration of the plastic mask for paste printing of the first example.

FIG. 3 is a plan view showing an overall configuration of a plastic mask for paste printing of a first example.

FIG. 4 is a partially enlarged cross-sectional view of the paste printing plastic mask of the first example.

FIG. 5 is an explanatory diagram of peeling charging that occurs between a paste printing plastic mask and a printed circuit board.

FIG. 6 is an explanatory diagram of a contact state between a paste printing mask and a printed circuit board.

FIG. 7 is an explanatory diagram of an influence of a foreign substance on a pad on a paste printing metal mask.

FIG. 8 is an explanatory diagram of the influence of foreign matter on the pad on the plastic mask for paste printing.

FIG. 9 is a partial enlarged side sectional view of a plastic mask for paste printing of a second example.

FIG. 10 is an explanatory diagram of a paste printing method using the paste printing plastic mask of the second example.

FIG. 11 is a partial enlarged cross-sectional view of a paste printing plastic mask of a third example.

FIG. 12 is a front view showing a state of the urethane squeegee at the time of printing the half-etched portion.

FIG. 13 is a side view showing a state of a urethane squeegee during printing of a half-etched portion.

FIG. 14 is a front view showing a state of a metal squeegee during printing of a half-etched portion.

FIG. 15 is an explanatory diagram of a print solder shape when residual solder is present on the upper surface of the half-etched portion.

[Explanation of reference numerals] 1 mask frame 2 gauze film 3 plastic plate 4 adhesive 5 conductive coating layer on the lower surface 6 to 8 openings 9 half-etched portion 10 printer clamper 11 ground wire 12 urethane squeegee 13 printed circuit board 14 conductive Cream solder 29 conductive coating layer on the upper surface 30 conductive adhesive 31 insulating cream solder 32 metal foil

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location // H05K 3/12 7511-4E H05K 3/12 D

Claims (7)

[Claims] 1. A plastic mask for paste printing in which a plastic plate is used as a mask material and an opening having a predetermined pattern is formed in the plastic plate, wherein a conductive layer is formed on the surface of the plastic plate. Printing plastic mask. 2. The plastic mask for paste printing according to claim 1, wherein a conductive layer is formed only on the surface of the plastic plate that is in contact with the object to be printed. 3. The plastic mask for paste printing according to claim 1, wherein conductive layers are formed on both upper and lower surfaces of the plastic plate, and the conductive layers on the upper and lower surfaces are electrically connected. 4. The plastic mask for paste printing according to claim 3, wherein the upper and lower conductive layers are electrically connected by a conductive adhesive. 5. The paste printing plastic mask according to claim 1, wherein an abrasion resistant conductive layer is used as the conductive layer. 6. The plastic mask for paste printing according to claim 1, wherein a titanium coating layer is used as the conductive layer. 7. A paste printing mask in which an opening having a predetermined pattern is formed is brought into close contact with an object to be printed, and the paste is spread on the paste printing mask to fill the opening with the paste. A paste printing method in which a paste pattern having the same shape as the openings is formed on the printing object by removing the paste printing mask from the printing object; Using the plastic mask for paste printing according to any of the following,
A paste printing method comprising: printing with a conductive layer of the paste printing plastic mask electrically grounded.