JPH0878844A - Thick film printing equipment - Google Patents

Abstract

PURPOSE: To effectively prevent warp and crack at the time of through hole printing of a board, and effectively prevent contamination of the board back which is to be caused by paste. CONSTITUTION: Through hole printing for forming conductor paste 28 in through holes 23 of a board 21 by screen 27 printing is performed while sucking the conductor paste 28 from the side of a work holder 22 on which the board 21 is mounted. A cushioning sheet 26 is arranged which retains the board 21 elastically and provided with penetrating holes 26a corresponding with through holes 23.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thick film printing apparatus suitable for through-hole printing on a double-sided printed board, and more particularly to a thick film printing apparatus having an improved substrate supporting structure.

[0002]

2. Description of the Related Art Conventionally, as an example of a thick film printing apparatus suitable for through-hole printing on a substrate of this type, there is an apparatus configured as shown in FIG. This has a work holder 2 which is a base for supporting a substrate 1 made of an insulating substrate such as alumina so as to be vacuum-suckable.

The substrate 1 has a plurality of through holes 3 penetrating therethrough in the plate thickness direction. The outer peripheral edge of the substrate 1 has a bottomed cylindrical work holder 2 having an upper end opened in the drawing. Is airtightly fixed and supported.

A vacuum pump is connected to the center of the bottom of the work holder 2 via a pipe 4, and a vacuum gauge for detecting the degree of vacuum and an opening / closing valve are interposed in the middle of the pipe 4, and the work is operated by the vacuum pump. The inside of the holder 2 is evacuated.

When the through holes of the substrate 1 are printed by this vacuum suction, first, the substrate 1 is placed and fixed on the work holder 2 so that the upper end opening thereof is closed,
The printing screen 5 is stretched on the substrate 1, a required amount of the conductive paste 6 such as solder is placed on the printing screen 5, and the conductive paste 6 is spread on the printing screen 5 with a spatula-shaped squeegee 7. Spread to a substantially uniform thickness.

As a result, as shown in FIG. 4, the circular conductor paste 6 having a diameter larger than that of each through hole 3 is transferred onto each through hole 3 on the upper surface of the substrate 1 in the drawing, and each through hole is formed. The upper end opening in the figure of 3 is closed by the conductor paste 6.

At this time, the inside of the work holder 2 is evacuated by the operation of the vacuum pump, and the central portion of each conductor paste 6 on each through hole 3 is sucked toward the inside of the work holder 2 through each through hole 3. Conductor paste 6
Part of each of the through holes 3 is sucked downward in the drawing, and as shown in FIG. 5, a part of the conductor base 6 is sucked and guided and attached to each bottom surface of each through hole 3 in the drawing. As a result, each through hole 3 is opened and the through hole 3 is formed.

As shown in FIG. 5, these through holes 3 are for electrically connecting, for example, the conductor patterns 11a and 11b formed on the front surface 1a and the back surface 1b of the substrate 1 in the front-back direction, respectively.

In such a through-hole printing method, in order to keep the viscosity of the conductor paste 6 constant and to keep the vacuum suction force of the vacuum pump 5 at an optimum value corresponding to the viscosity of the conductor paste 6, the opening / closing valve is used. The opening is adjusted manually or automatically.

[0010]

However, in such a conventional thick film printing apparatus, since the substrate 1 made of alumina or the like is thin (for example, 0.2 mm), the substrate 1 may be warped due to vacuum suction. Since it breaks, it is conceivable to interpose a base plate 12 such as a metal plate having rigidity between the substrate 1 and the work holder 2 in order to prevent this. Through-holes 13 corresponding to the through-holes 3 of the substrate 1 are formed in the floor plate 12, respectively.

However, this substrate 1 has both front and back surfaces 1
Since the conductor patterns 11a, 11b and the like are printed on a and 1b, the conductor pattern 11b on the back surface 1b side contacts the upper surface in the figure of the base plate 12 made of a metal plate or the like.

For this reason, the back surface 1b of the substrate 1 and the floor plate 12 are
Since a minute gap is formed between the upper surface of the work holder 2 and the upper surface of the substrate 1 and they do not adhere to each other, a part of the vacuum suction exhaust gas on the side of the work holder 2 leaks into the minute gap, and the conductor paste 9 is transferred to the rear surface 1b side of the substrate 1. There is also a problem in that the conductor pattern 11b on the back surface 1b side is also soiled by being sucked in.

Therefore, the present invention has been made in consideration of such circumstances, and an object thereof is to effectively prevent warpage and cracks during through-hole printing of a substrate, and
It is an object of the present invention to provide a thick film printing apparatus capable of effectively preventing the back surface of the substrate from being contaminated by the paste.

[0014]

The present invention is configured as follows in order to solve the above-mentioned problems.

The invention according to claim 1 of the present application (hereinafter, referred to as the first
In the thick film printing apparatus, the through-hole printing for forming the paste in the through-hole of the substrate by screen printing is performed while sucking the paste from the base side on which the substrate is placed. Is elastically supported, and an elastic material is provided which has a through hole corresponding to the through hole.

Further, the invention according to claim 2 of the present application (hereinafter referred to as the second invention) is characterized in that the through hole of the elastic material is formed to have a trapezoidal diameter rather than the through hole of the substrate. To do.

Further, in the invention according to claim 3 of the present application (hereinafter referred to as the third invention), the elastic material is placed on the base and has through holes corresponding to the through holes of the substrate. It is characterized by being sandwiched between a rigid base plate and a substrate.

Furthermore, the invention according to claim 4 of the present application (hereinafter referred to as the fourth invention) is characterized in that the elastic material is formed such that both front and back surfaces thereof are parallel to each other.

The invention according to claim 5 of the present application (hereinafter referred to as the fifth invention) is characterized in that the substrate has conductor patterns printed on both front and back surfaces thereof.

[0020]

[Action]

<First to Fifth Inventions> Since a thin substrate made of alumina or the like is supported by the elastic material, even if the substrate is vacuum-sucked through the through hole of the elastic material, the substrate can be prevented from warping or cracking. Even when the circuit pattern is formed on the back surface of the substrate, the unevenness due to the circuit pattern is elastically absorbed by the elastic material, so that the elastic material adheres to the back surface of the substrate and no gap is formed between the two. Therefore, even if the paste is vacuumed from the base side through the through hole of the elastic material, it is possible to prevent the paste from flowing around to the back surface of the substrate and being contaminated due to the exhaust leak.

<Second Invention> At the time of through-hole printing of this substrate, a pressing force of a squeegee or the like is applied to the elastic material via the substrate, and the through hole of this elastic material is elastically deformed so as to be reduced in diameter. Since the through-hole is formed in advance to have a larger diameter than the through-hole, the through-hole of the elastic material has a smaller diameter than the through-hole of the substrate, and the paste does not adhere to the through-hole and become dirty or blocked. It can be effectively prevented.

<Third invention> Since the elastic material is sandwiched between the substrate and the rigid base plate, the elastic material can be securely fixed. Therefore, it is possible to prevent the through hole of the substrate and the through holes of the elastic member and the floor plate from being displaced from each other and narrowing or closing the openings of these through holes to reduce or disable the vacuum suction efficiency.

<Fourth Invention> Since the front and back surfaces of the elastic member are parallel to each other, the elastic member can hold the substrate substantially horizontally. Therefore, it is possible to prevent the paste transferred to the substrate from flowing due to the inclination of the substrate.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is an enlarged longitudinal sectional view of an essential part of an embodiment of the present invention. In the figure, a thick film printing apparatus 20 is a substrate for supporting a substrate 21 made of an insulating substrate such as alumina so as to be vacuum-suckable. It has a work holder 22 which is a table.

The substrate 21 has a front surface 21a and a back surface 21b on both sides of which a circuit pattern shown by a black semicircle is printed, and a plurality of front and back surfaces 21a and 21b are electrically connected to each other. The through hole 23 is penetrated in the plate thickness direction, and the outer peripheral edge portion of the substrate 21 is airtightly fixed and supported by the upper end portion in the figure of a bottomed cylindrical work holder 22 having an open upper end in the figure. ing.

The pipe 2 is provided at the center of the bottom of the work holder 22.
A vacuum pump or the like (not shown) is connected via 4, and the inside of the work holder 22 is evacuated by the operation of the vacuum pump during screen printing of the through holes 23.

A base plate 24 having rigidity such as a metal plate is placed and fixed on the work holder 22 as a base, and the base plate 25 has a through hole 25a penetrating in the thickness direction thereof.
Are substantially the same diameter as the through holes 23 of the substrate 21, and are concentrically formed at corresponding positions.

A cushion sheet 26, which is an elastic material, is placed and fixed on the floor plate 25 by sticking or the like.
The cushion sheet 26 is formed of a synthetic rubber such as silicone rubber, natural rubber, or a resin material having elasticity such as urethane into a sheet having a predetermined thickness such that the front and back surfaces thereof are substantially parallel to each other. A through hole 26a is formed at a position corresponding to each through hole 23 of the substrate 21. However, as shown in FIG. 2, these through holes 26a are formed concentrically with a diameter slightly larger than that of each through hole 23.

In FIG. 1, the substrate 2 is shown for convenience of explanation.
1, the cushion sheet 26 and the floor plate 25 are exaggeratedly thicker than the work holder 22, but the cushion sheet 26 is formed thinner than the substrate 21. , The error of the suction force of the vacuum exhaust by the vacuum pump is reduced.

On the other hand, a printing screen 27 is provided on the substrate 21.
The conductive paste 28 such as solder is placed on the printing screen 27 in a required amount, and the conductive paste 28 is spread on the printing screen 27 with a spatula-shaped squeegee 29 to spread the conductive paste 28 to a substantially uniform thickness. The conductor paste 28 is transferred to each through hole 23 by
It is designed to print through holes.

When the through-hole printing is performed by the thick film printing apparatus 20 configured as above, first, the floor plate 25, the cushion sheet 26, and the substrate 21 are placed on the work holder 22.
And stack them in this order one by one, and fix them.
The upper conductor paste 28 is spread with a spatula-shaped squeegee 29 to spread the conductor paste 28 almost uniformly.

As a result, the circular conductor paste 28 having a diameter larger than that of the through hole 23 is transferred onto each through hole 23 on the upper surface of the substrate 21 in the drawing, and the upper end opening of each through hole 23 in the drawing is formed. It is closed by the conductor paste 28.

At this time, the inside of the work holder 22 is evacuated by the operation of the vacuum pump, and the central portion of each conductor paste 28 on each through hole forms the floor plate 25 and each through hole 25a, 26a of the cushion sheet 26. , Is sucked inward through the through holes 23. As a result, a part of the conductor paste 28 is sucked downward in the drawing through each through hole 23, and a part of the conductor paste 28 is sucked and guided to each peripheral edge of the lower surface opening of each through hole 23 in the drawing. Then, each through hole 23 opens.

Therefore, according to this embodiment, since the cushion sheet 26 is laid on the lower surface of the substrate 21, the substrate 2
The cushion sheet 26 can elastically absorb the unevenness due to the circuit pattern shown by the black semicircle on the back surface 21b of FIG. For this reason, the back surface of the substrate 21 and the top surface of the cushion sheet 26 are in close contact with each other, and a minute gap is hardly formed between both surfaces. Therefore, unlike the conventional example shown in FIG. 6, the conductor paste 28 is applied to the back surface 21b of the substrate 21. It is possible to effectively prevent the dust from flowing around and being polluted by the leak of the vacuum exhaust.

Moreover, since the cushion sheet 26 is sandwiched between the base plate 25 having rigidity and the substrate 21, warping and cracking of the substrate 21 due to vacuum exhaust can be effectively prevented, and the back surface 21b of the substrate 21 can be prevented. Since the degree of close contact with the upper surface of the cushion sheet 26 is further increased, it is possible to more reliably prevent the conductive paste 28 from being contaminated due to the leak of vacuum exhaust to the back surface 21b of the substrate.

Also, as shown in FIG. 2, since the through holes 26a of the cushion sheet 26 are formed to have a larger diameter than the through holes 23, the cushion sheet 26 is sandwiched between the substrate 21 and the floor plate 25. Even if the pressing force of the squeegee 29 is applied to the cushion sheet 26 and the cushion sheet 26 is elastically compressed, the through holes 26a are formed in the through holes 2 as shown by broken lines in FIG.
The diameter is smaller than 3, and the conductor paste 28 is elastically deformed so as to project to the inner peripheral surface side, so that the conductor paste 28 passes through the through holes 26a.
It is possible to effectively prevent the stains from being attached to the inner peripheral surface of the.

Further, since the front and back surfaces of the cushion sheet 26 are formed substantially parallel to each other, the substrate 21 supported by the cushion sheet 26 can be held substantially horizontally. Therefore, it is possible to prevent the flow of the conductor paste 28 when the substrate 21 is inclined, and thus it is possible to improve the accuracy of the printing position of the conductor paste 28.

In the above embodiment, the case where through-hole printing is performed on the substrate 21 has been described, but the cushion sheet 26 is laid on the lower surface of the substrate 21 in the printing process other than this through-hole printing. Warping and cracking can be effectively prevented. However, in this case, the through hole 26a is not provided at all in the cushion sheet 26, or the diameter thereof is formed to be a small diameter of, for example, 1/5 or less.

[0040]

As described above, in the first to fifth inventions of the present application, since a thin substrate made of alumina or the like is supported by the elastic material, even if the substrate is vacuum sucked through the through hole of the elastic material, the substrate It is possible to prevent warping and cracking. Also,
Even when a circuit pattern is printed on the back surface of the substrate, the unevenness due to this circuit pattern is elastically absorbed by the elastic material, so the elastic material adheres to the back surface of the substrate and no gap is formed between the two. Even if the paste is vacuum-sucked from the base through the through hole of the elastic material, it is possible to prevent the paste from flowing around to the back surface of the substrate and being contaminated by the exhaust leak.

Further, in the second invention of the present application, a pressing force of a squeegee or the like is applied to the elastic material via the substrate during the through-hole printing of the substrate, and the through hole of the elastic material is elastically deformed so as to reduce its diameter. However, since the through-hole is formed in advance to have a larger diameter than the through-hole, the through-hole of the elastic material has a smaller diameter than the through-hole of the substrate, and the paste adheres to the through-hole to be soiled or blocked. Can be effectively prevented.

In the third invention of the present application, the elastic material is sandwiched between the substrate and the rigid base plate, so that the elastic material can be securely fixed. Therefore, it is possible to prevent the through hole of the substrate and the through holes of the elastic member and the floor plate from being displaced from each other and narrowing or closing the openings of these through holes to reduce or disable the vacuum suction efficiency.

In the fourth invention of the present application, since the front and back surfaces of the elastic material are parallel, the elastic material can hold the substrate substantially horizontally. Therefore, the paste transferred to the substrate can be prevented from flowing due to the inclination of the substrate, and the accuracy of the paste printing position can be improved.

[Brief description of drawings]

FIG. 1 is an enlarged longitudinal sectional view of an essential part of an embodiment of a thick film printing apparatus according to the present invention.

FIG. 2 is a partially enlarged view of FIG.

FIG. 3 is an overall configuration diagram of a conventional thick film printing apparatus.

FIG. 4 is a partial plan view of the substrate shown in FIG.

5 is an end view of the VV line cutting portion of FIG. 4. FIG.

FIG. 6 is a partially enlarged view of another conventional example.

[Explanation of symbols]

 20 Thick Film Printer 21 Substrate 21a Substrate Front 21b Substrate Back 22 Work Holder (Base) 23 Through Hole 25 Floor Board 25a Floor Through Hole 26 Cushion Sheet (Elastic Material) 26a Cushion Sheet Through Hole 27 Screen 28 Conductor Paste 29 Squeegee

Claims (5)

[Claims] 1. A thick film printing apparatus for performing through-hole printing for forming a paste in a through-hole of a substrate by screen printing while sucking the paste from a base side on which the substrate is placed. A thick film printing apparatus comprising an elastic material elastically supported and having a through hole corresponding to the through hole. 2. The thick film printing apparatus according to claim 1, wherein the elastic material has a through hole formed to have a diameter larger than that of the through hole of the substrate. 3. The elastic material is placed on a base and sandwiched between a rigid base plate having a through hole corresponding to a through hole of the substrate and a substrate. The thick film printing apparatus described. 4. The thick film printing apparatus according to claim 1, wherein the elastic material is formed such that both front and back surfaces thereof are parallel to each other. 5. The thick film printing apparatus according to claim 1, wherein the substrate has conductor patterns printed on both front and back surfaces thereof.