JPH0745932A - Thick-film forming method - Google Patents

Abstract

PURPOSE:To prevent the printing defect of a wiring pattern by performing the plate separation of a screen in a dummy region. CONSTITUTION:On a material to be printed 100, a wiring region 110 and a dummy region 120 surrounding the wiring region 110 are provided. A dummy pattern 121 is formed in the dummy region 120. In the first step, a screen 210 is brought into close contact with the material to be printed 100. In the second step, paste 240 is printed on the material to be printed 100. At this time, the dummy pattern 121 is printed on the dummy region 120. In the third step, the screen 210 is separated from one end part of the material to be printed 100. The final plate separation occurs in the dummy region 120. Therefore, the printing defect does not occur in a wiring pattern 111 in the wiring region 110.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thick film forming method for forming a wiring layer such as a ceramic substrate on which a semiconductor component is mounted, and more particularly to a thick film forming method for forming a thick film by screen printing.

[0002]

2. Description of the Related Art Generally, a wiring layer is formed by screen printing by off-contact printing.
The structure of off-contact printing is described in "Electronic Materials" Industry Research Committee, April 1992, p. 120, Fig. 10. As shown in this figure, a characteristic of off-contact printing is that a gap is provided between a substrate to be printed and a screen mask (hereinafter, simply referred to as a screen). During printing, the screen is stretched by a squeegee, and after the transfer of the paste, the screen returns to its original state by elasticity. A stainless steel screen or the like is used for this screen.

The off-contact printing has a characteristic that a fine pattern can be formed, but has the following problems. That is, in off-contact printing, since the screen is stretched by the squeegee, there is a problem that the screen is easily worn and the life of the screen is short.

One of the means for solving the problem of forming a wiring layer by off-contact printing is to form a wiring layer by using contact printing. Contact printing is a method of printing by bringing the screen and printed matter into close contact with each other, and is currently used for printing cream solder or the like. In contact printing, since the screen is not stretched, the life of the screen can be greatly extended.

[0005]

However, it has been difficult to use contact printing for forming a wiring layer for the reason described below.

A description of a cream solder printing machine using contact printing is given in "Electronic Technology", published by Nikkan Kogyo Shimbun, June 1991, separate volume, mounting technology series 21 "91".
All of the annual edition and printed wiring boards "(hereinafter referred to as Document 1), pages 182 to 183. In this technique, cream solder is printed using a metal mask having a thickness of 0.1 mm to 0.15 mm.

As described in Document 1, the problem of contact printing is that the print pattern is damaged when the plate is separated. In the technique described in Document 1, the plate separating speed is precisely controlled by the plate separating device to prevent damage to the print pattern when the plate is separated.

However, reference 1, pages 110 to 111
As described on the page, the stainless screen printing plate used for forming the wiring layer is made of stainless steel having a thickness of about 10 micrometers and is easily deformed. For this reason, no matter how precisely the plate separation speed is controlled, pattern damage at the time of plate separation cannot be avoided. For this reason, it has been difficult to use contact printing for forming a wiring layer.

A process in which a print pattern is damaged (hereinafter referred to as a print defect) in wiring layer printing by contact printing will be described.

Referring to FIGS. 7A and 7B, the contact printing mechanism is performed by bringing the screen 210 held by the frame 220 into close contact with the substrate 100.
The frame 220 can move up and down. In addition, C of the frame 220
It is also possible to control the upper and lower positions of the D side and the D side independently. On the other hand, the substrate 100 is fixed on the stage 300.

FIG. 7B is a sectional view of the CD of FIG. 7A.
With reference to FIG.
It is 10. Referring to FIG. 7C, the squeegee 230
Moves past screen 210 and paste 2
40 is printed on the printed material 100, and the wiring pattern 111 is formed on the upper surface of the printed material 100.

FIG. 8 (a) shows a state in which the screen 210 is peeled off from the printing object 100 thus printed. FIG. 8A is a diagram showing the case where the frame 220 is pulled up evenly. Screen 210
Has elasticity, and thus is gradually peeled from both sides of the printing target 100. Finally, at the center 4 of the substrate 100,
30 parts are peeled off. At this time, since the 430 portion is rapidly peeled off, the print defect 114 as shown in FIG. 9 occurs in the wiring pattern 111. Even if the moving speed of the frame 220 is slow, it is difficult to suppress the peeling speed of the final peeling portion 430.

Further, even if the peeling method as shown in FIG. 8B is adopted, the print defect 114 is not improved. Figure 8
In (b), the frame is raised from the C direction. As a result, the final peeling point moves to the 440 portion,
The print defect 114 still occurs at the 0 portion.

[0014]

In order to solve the above-mentioned problems, the thick film forming method of the present invention comprises a first step of bringing a screen mask into close contact with an object to be printed, and a paste in the opening of the screen mask. A second step of forming a wiring pattern used as a circuit on the printed material by passing the dummy pattern that is not used as a circuit at an end portion of the printed material;
A third step of peeling the screen mask from the printing object so that a peeling portion advances toward the dummy pattern of the printing object.

[0015]

Next, a first embodiment of the present invention will be described with reference to the drawings.

First, with reference to FIG. 1 and FIG. 2, the print substrate 100, the screen 210, the frame 220 and the stage 300 of this embodiment will be described.

Referring to FIG. 1, in the present embodiment, the upper surface of the substrate 100 to be printed is the wiring region 1 at the center of the substrate 100 to be printed.
10 and a dummy area 120 at the periphery of the printing material 100 are divided into two areas.

In the wiring area 110, a wiring pattern 111 that is actually used as a circuit is formed. The wiring pattern 111 is composed of signal wiring 112, lands 113, etc. as shown in FIG. In this embodiment, the range of the wiring area 110 is about 200 mm × 200 mm.

On the other hand, in the dummy area 120, a dummy pattern 121 which is not used as a circuit is formed. The size of the dummy area 120 is about 80 mm in width. In this embodiment, a solid dummy pattern 121 is used as the dummy pattern.

The size of the frame 220 is 450 mm × 440 m
It is about m. The frame 220 is controlled to move up and down by a braking mechanism (not shown). The vertical movement of the frame 220 is shown in FIG.
Can be independently controlled on the A side and the B side.

The screen held by the frame 220 is a stainless steel 325 mesh, and the emulsion thickness is 75.
It is a micrometer. A pattern corresponding to the wiring pattern 111 is formed in advance on a portion of the screen 210 where the wiring area 110 is printed. This part is similar to a normal off-contact printing screen. Further, in the area of the screen 210 where the dummy area 120 is printed, a pattern for printing the solid dummy pattern 121 is formed in advance.

A vacuum suction mechanism (not shown) is provided on the stage 300 so that the object 100 to be printed can be fixed. The stage 300 is vertically moved and controlled by a braking mechanism (not shown).

Next, each step of this embodiment will be described with reference to FIG.

Referring to FIG. 2A, first, by operating the vacuum suction mechanism of the stage 300, the print substrate 1 is printed.
00 is fixed to the stage 300. After the substrate 100 is fixed, the frame 220 is lowered and the screen 210
Is brought into close contact with the object 100 to be printed. After this, the substrate 1
The horizontal position between 00 and the screen 210 is adjusted. At this time, if a mark for alignment is provided at a corresponding position on the printing material 100 and the screen 210, the position can be easily adjusted.

Referring to FIG. 2B, the printing substrate 100
After adjusting the horizontal position of the screen 210, the paste 240 is supplied onto the screen 210. In this example, a silver-paradium paste with a viscosity of 35 kps is used. After the paste 240 is supplied onto the screen 210, the squeegee 230 is moved from the A direction to the B direction in the drawing. By moving the squeegee 230, paste 240
Is pressed against the screen 210 and is printed on the substrate 100. As a result, the wiring pattern 111 is formed in the wiring area 110 of the printing target 100, and the dummy area 1 is formed.
A dummy pattern 121 is printed on each of 20. At this time, since the screen 210 is in close contact with the printing object 100, the screen 210 is not deformed. When the movement of the squeegee 230 is completed, the pattern printing is completed. At this point, the material to be printed 100 and the screen 210 are in a state of being bonded by the paste 240.

Referring to FIG. 2C, after the printing of the pattern is completed, the A-direction side of the frame 220 is lifted upward by 2 mm. As a result, the screen 210 is peeled off at the 410 portion, which is the end portion in the A direction of the printing target 100.

Referring to FIG. 2D, after the frame 220 moves, the stage 300 is braked downward. As a result, the peeling of the screen 210 is
From direction B to direction B. Then, the final plate separation occurs at the right end portion 420 of the printing material 100. 420 where the final plate separation occurs is in the dummy area 120 of the substrate 100. Therefore, the wiring pattern 1 which is a pattern actually used as a circuit
The print defect 114 does not occur in No. 11.

Next, another embodiment of this embodiment will be described. In this embodiment, the wiring region 110 and the dummy region 12
Although the dimensions and materials of the screen 210, the screen 210 and the paste 240 are specified, the scope of the present invention is not limited to this. In addition, in this embodiment, after moving the frame 220 upward, the stage 300 is moved downward. However, instead of moving the stage 300 downward, the same effect can be obtained by moving the A side and B side of the screen 210 simultaneously upward. Further, in the present embodiment, the dummy area 120 is provided on the entire peripheral portion of the substrate 100, but the desired effect can be achieved by providing the dummy area 120 only on the portion where plate separation finally occurs. You can

Next, the effect of this embodiment will be described.

In this embodiment, a dummy pattern 121, which is not used as a wiring, is formed in the dummy area 120 at the peripheral portion of the printed material 100, and when the screen 210 is peeled off, one side of the printed material 100 is used. Since the plates are gradually peeled off to cause the plate separation on the dummy region 120, print defects do not occur in the wiring pattern 111. Further, in this embodiment, since the wiring pattern 111 is printed by contact printing, the wear of the screen 210 is suppressed and the life of the screen 210 is extended.

Next, a second embodiment of the present invention will be described. First, the purpose of this embodiment will be described. When manufacturing a multilayer ceramic wiring board, the green sheet serves as the printing object 100. Then, a plurality of these green sheets are laminated to form a multilayer ceramic wiring board. At this time, if the paste amount of the wiring layer is large, the adhesion between the green sheets may not be sufficiently performed. Therefore, in this embodiment, the paste 240 printed on the dummy area 120 is used.
The purpose of this is to reduce the amount of the wiring and to form the wiring layer with the paste of the smallest possible amount.

The feature of the present embodiment is that the dummy patterns 122 printed in the dummy area 120 are in the form of a grid, and other structures and the printing method are the first.
There is no difference from the case of the embodiment. Referring to FIG. 3, in the present embodiment, a dummy pattern 122 having a grid pattern is provided in the dummy area 120. Dummy pattern 12
The amount of the paste 240 that forms 2 is the dummy pattern 1
It can be adjusted by changing the lattice spacing of 22. Specifically, the screen 210 is set to the minimum width necessary for adhering and holding the screen 210 and causing plate separation in the dummy area 120. The same adjustment can be performed by changing the width of the straight line forming the dummy pattern 122.

Next, the effect of this embodiment will be described. In this embodiment, since the dummy patterns 120 are provided in the dummy area 120 in a grid pattern, the amount of the paste 240 printed on the dummy area 120 can be reduced. Therefore, even when a plurality of print-objects having patterns formed by printing are laminated, such as a multilayer ceramic wiring board, the respective print-objects can be sufficiently bonded.

Next, a third embodiment of the present invention will be described.

The feature of this embodiment is that the dummy pattern 123 printed in the dummy area 120 is in the shape of a dot, and other structures and printing methods are different from those of the second embodiment. There is no. With reference to FIG. 4, in the present embodiment, the dummy pattern 120 is provided in the dummy area 120. The size of the dots is set to the minimum size necessary to hold the screen 210 in an adhesive state and hold the plate separation in the dummy area 120. The effect achieved by this embodiment is similar to that of the second embodiment.

Next, a fourth embodiment of the present invention will be described. The feature of this embodiment is that the thick film forming method of the present invention is executed by diverting the frame-orientation printing machine 510 that has been conventionally used, and the other points are the same as those of the first embodiment. Does not change.

Referring to FIG. 5, in the present embodiment, a frame tilt type printing machine 510 is used. The frame tilt-type printing machine 510 itself is the same as that used conventionally. Screen 21 of the frame tilting press 510
0 rotates around the fulcrum 521.

Among the steps of this embodiment, the steps up to printing the paste 240 on the wiring area 110 are the same as those of the first embodiment. On the other hand, in the step of peeling off the screen 210, unlike the first embodiment, the special braking of the frame 220 and the stage 300 is not performed. All that is required is to raise the frame 220 at an appropriate speed. Frame 220 is fulcrum 5
Since the screen 210 rotates around 11, the peeling of the screen 210 starts from the end portion in the F direction in the drawing and proceeds in the E direction. The final plate separation is the dummy area 120 at the end in the E direction.
Occurs in. Therefore, as in the case of the first embodiment,
The printing defect 114 of the wiring pattern 111 can be prevented.

Next, the effect of this embodiment will be described.

According to this embodiment, since the conventional frame tilt-type printing machine 510 is diverted, it is not necessary to add a special mechanism.

Next, a fifth embodiment of the present invention will be described. The feature of this embodiment is that the conventional table-orientation type printing machine 520 is diverted to execute the thick film forming method of the present invention, and other points are the same as those of the first embodiment. Does not change.

Referring to FIG. 6, in this embodiment, a table tilt type printing machine 520 is used. The table tilt type printing machine 520 is the same as the one generally used conventionally. The stage 300 of the table tilt-type printing machine 520 rotates about a fulcrum 521 in the vertical direction.

Among the steps of this embodiment, the steps up to printing the paste 240 on the wiring area 110 are the same as those of the first embodiment. On the other hand, in the stripping process of the screen 210, unlike the first embodiment, special braking of the frame 220 and the stage 300 is not performed. Stage 300
Need only be lowered at an appropriate speed. Stage 300
Is rotated around the fulcrum 521, the screen 210
The peeling off starts from the H direction in the figure and proceeds in the G direction.
The final plate separation is the dummy area 12 at the end in the G direction.
It occurs at 0. Therefore, as in the case of the first embodiment,
The printing defect 114 of the wiring pattern 111 can be prevented.

Next, the effect of this embodiment will be described.

According to this embodiment, since the conventional table tilt type printing machine 520 is diverted, it is not necessary to add a special mechanism.

[0046]

As described above, according to the thick film forming method of the present invention, the dummy pattern 121 is formed in the dummy area 120 at the end portion of the substrate 100, and the screen 210 is formed.
At the time of peeling, the screen 210 is peeled from one end of the printing target 100 to cause plate separation in the dummy area 120. Thereby, the print defect 114 in the wiring pattern 111 can be prevented. Due to this effect, it has become possible to form the wiring layer by using the contact printing method. Therefore, the effect of extending the life of the screen 210 can also be achieved.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram showing a first embodiment of the present invention.

FIG. 3 is a diagram showing a second embodiment of the present invention.

FIG. 4 is a diagram showing a third embodiment of the present invention.

FIG. 5 is a diagram showing a fourth embodiment of the present invention.

FIG. 6 is a diagram showing a fifth embodiment of the present invention.

FIG. 7 is a diagram showing a conventional technique.

FIG. 8 is a diagram showing a conventional technique.

FIG. 9 is a diagram showing a conventional technique.

[Explanation of symbols]

 100 Printed Material 110 Wiring Area 111 Wiring Pattern 112 Signal Wiring 113 Land 114 Printing Defect 120 Dummy Area 121 Dummy Pattern 122 Dummy Pattern 123 Dummy Pattern 210 Screen 220 Frame 230 Squeegee 240 Paste 300 Stage 510 Frame Aori Printing Machine 511 Support Point 520 Table Aori Type printing machine 521 fulcrum

Claims (7)

[Claims] 1. A first step of bringing a screen mask into close contact with an object to be printed, and forming a wiring pattern used as a circuit on the object to be printed by passing a paste through an opening of the screen mask. A second step of forming a dummy pattern that is not used as a circuit at an end of the printed material, and the screen mask so that a peeling portion progresses toward the dummy pattern of the printed material. And a third step of peeling from the material to be printed. 2. The third step comprises a fourth step of separating one end portion of the screen mask from the object to be printed,
The thick film forming method according to claim 1, further comprising: a fifth step of separating a stage holding the object to be printed from the screen mask. 3. The thick film forming method according to claim 1, wherein the dummy pattern is a solid pattern. 4. The thick film forming method according to claim 1, wherein the dummy pattern is a grid pattern. 5. The thick film forming method according to claim 1, wherein the dummy pattern is a dot pattern. 6. The method for forming a thick film according to claim 1, wherein the first step, the second step and the third step are performed by a frame tilt type printing machine. 7. The thick film forming method according to claim 1, wherein the first step, the second step and the third step are performed by a table tilt type printing machine.