JP6003134B2 - Screen printing apparatus and screen printing method - Google Patents

Description

  The present invention relates to a screen printing apparatus and a screen printing method for printing a solder paste on a substrate through a screen mask.

  As a method for supplying a solder paste (hereinafter simply referred to as “paste”) to a printed wiring board, a method by screen printing is widely used. Screen printing is performed by overlaying a screen mask with openings on the printed wiring board corresponding to the electrodes on the printed wiring board, embedding the paste on the screen mask in the openings with a squeegee, and then printing the screen mask on the printed wiring. In this method, the paste is transferred onto the printed wiring board by being separated from the board. In recent years, miniaturization of printed circuit boards for electronic components has been promoted, and it is necessary to stabilize the quality of paste and screen-print on printed circuit boards efficiently.

  For this reason, a heating mechanism is provided in the squeegee to heat the paste so that the paste does not harden due to the ambient temperature or the like (for example, see Patent Document 1).

  Here, when the paste is embedded in the openings of the screen mask, it is preferable that the temperature of the paste is slightly high and the viscosity is low. On the contrary, when the paste is embedded in the openings of the screen mask and then released from the screen mask, the temperature of the paste should be slightly lower and the viscosity should be higher. However, in the above-described system in which the paste is directly heated, it is difficult to make both the ease of embedding and the ease of mold release the best conditions.

  Therefore, by setting the temperature of the squeegee slightly higher and setting the temperature of the surrounding atmosphere low, the filling property of the paste to the screen mask and the release property of the paste after printing from the screen mask can be satisfied at the same time. (For example, refer to Patent Document 2).

JP 08-332714 A JP 2010-076285 A1

  However, even in such a configuration, a configuration in which the heated squeegee always touches the paste is employed. For this reason, the whole paste was easy to be heated, and the volatile component contained in the paste volatilized, resulting in a problem that the paste quality deteriorated early. In addition, when the paste quality deteriorates, it is necessary to frequently replace the paste, which causes problems such as an increase in waste paste.

  Accordingly, an object of the present invention is not only to efficiently embed solder paste with reduced viscosity in the openings of the screen mask, but also to suppress quality deterioration due to an increase in the overall temperature of the solder paste. A printing apparatus and a screen printing method are provided.

  In order to solve the above problems, the screen printing apparatus of the present invention moves the squeegee along the surface of the screen mask, embeds the solder paste in the opening formed in the screen mask, and prints the solder paste on the substrate. In the screen printing apparatus, a heating unit that heats the screen mask immediately before the squeegee is provided in front of the movement direction of the squeegee.

  The screen printing apparatus of the present invention not only can efficiently embed solder paste with reduced viscosity in the openings of the screen mask, but also can suppress quality deterioration due to an increase in the overall temperature of the solder paste, Ease of release from the screen mask can be improved.

The screen printing apparatus which concerns on one Embodiment of this invention is shown, (A) is a side view of the principal part, (B) is a front view of the principal part. It is a side view of the principal part which shows the modification 1 of the screen printing apparatus of one Embodiment of this invention. It is a side view of the principal part which shows the modification 2 of the screen printing apparatus of one Embodiment of this invention. It is a side view of the principal part which shows the modification 3 of the screen printing apparatus of one Embodiment of this invention. It is a side view of the principal part which shows the modification 4 of the screen printing apparatus of one Embodiment of this invention. It is a side view of the principal part which shows the modification 5 of the screen printing apparatus of one Embodiment of this invention. It is a side view of the principal part which shows the modification 6 of the screen printing apparatus of one Embodiment of this invention.

  Next, a screen printing apparatus according to an embodiment of the present invention will be described with reference to the drawings. The embodiments described below are preferred specific examples of the screen printing apparatus of the present invention, and may have various technically preferred limitations. However, the technical scope of the present invention particularly includes the present invention. As long as there is no description which limits, it is not limited to these aspects. In addition, the constituent elements in the embodiments shown below can be appropriately replaced with existing constituent elements and the like, and various variations including combinations with other existing constituent elements are possible. Therefore, the description of the embodiment described below does not limit the contents of the invention described in the claims.

  FIG. 1 shows a screen printing apparatus according to an embodiment of the present invention, FIG. 1 (A) is a side view of the main part, FIG. 1 (B) is a front view of the main part, and FIG. 2 is an embodiment of the present invention. The side view of the principal part which shows the modification 1 of the screen printing apparatus of FIG. 3, FIG. 3 is the side view of the principal part which shows the modification 2 of the screen printing apparatus of one Embodiment of this invention, FIG. 4 is one Embodiment of this invention The side view of the principal part which shows the modification 3 of the screen printing apparatus of FIG. 5, FIG. 5 is the side view of the principal part which shows the modification 4 of the screen printing apparatus of one Embodiment of this invention, FIG. 6 is one Embodiment of this invention The side view of the principal part which shows the modification 5 of this screen printing apparatus, FIG. 7 is the side view of the principal part which shows the modification 6 of the screen printing apparatus of one Embodiment of this invention.

  In FIG. 1, 11 is a printed wiring board, and 12 is a screen mask superimposed on the printed wiring board 11. In the screen mask 12, one or more apertures 13 are formed corresponding to the electrodes of the printed wiring board 11. A solder paste (hereinafter simply referred to as “paste”) 15 that is moved by the squeegee 14 on the surface of the screen mask 12 is embedded in the opening 13. The paste 15 embedded in the opening 13 is transferred onto the surface of the printed wiring board 11 by releasing the screen mask 12 from the printed wiring board 11 (release). Here, when the paste 15 is embedded in the opening 13, for example, the temperature is increased by about 10 ° C. to reduce the viscosity by about 10 to 20% (10 to 20 Pa · s).

  The squeegee 14 is heated by a temperature adjustment mechanism (not shown) that can be set in the range of 0 ° C to 99 ° C. The temperature adjustment mechanism is performed by transmitting temperature from the upper part to the lower end of the squeegee 14, and for example, a heating hot water circulation provided with a cooling cold water circulation route is used. Independent of the temperature control of the screen masks 12 before and after the opening 13 for performing paste printing on the front and rear sides of the moving direction of the squeegee 14 moving along the surface of the screen mask 12 (see arrows in FIG. 1A). The temperature control units 16 and 17 for heating or cooling are arranged.

  Each of the temperature adjusting units 16 and 17 includes a temperature control unit 18 and a blade 19 in which a lower end 19a as a contact unit is brought into contact with the surface of the screen mask 12 from the temperature control unit 18.

  As long as the temperature controller 18 can heat or cool the blade 19, the heat source and the like are not particularly limited. At this time, as long as the moving direction of the squeegee 14 reciprocates between the temperature adjusting units 16 and 17, the front side in the moving direction can be used as a heating unit, and the rear side in the moving direction can be used as a cooling unit. Simultaneously with the reversal of direction, the heating part and the cooling part can be functionally (non-mechanically) reversed, that is, can be converted relative to each other. Therefore, the temperature control unit 18 can also use a heat converter (such as a Peltier element) to switch the temperature of the blade 19 between the heating temperature and the cooling temperature in a short time simultaneously with the reversal of the moving direction.

  In addition, the temperature control unit 18 specifically considers the moving speed of the squeegee 14 in consideration of the material and amount of the paste 15, and the temperature of the squeegee 14 by the temperature adjustment mechanism as a direct heating unit is 20 ° C. to 99 ° C. The temperature of the aperture 13 and its surrounding screen mask 12 is heated by the blade 19 in front of the aperture 13 corresponding to the range before the screen printing (before embedding), and the aperture 13 and its surrounding screen mask are set. The temperature of 12 is raised by about 20 ° C. When the paste 15 is embedded in the opening 13, the temperature of the paste 15 embedded in the opening 13 can be increased by about 10 ° C. due to the temperature around the heated screen mask 12, and the viscosity of the paste 15 is increased by 10-20. By reducing it by about% (10 to 20 pa · s), the embedding property (filling property) into the opening 13 can be easily ensured.

  Further, the temperature control unit 18 cools the opening 13 after printing and the surrounding screen mask 12 with the blade 19 from the rear of the opening 13 after the paste 15 is embedded behind the paste 15 in the moving direction. At this time, the temperature of the blade 19 is set to about 0 ° C. to 10 ° C., the screen mask 12 is cooled, and the paste 15 embedded in the opening 13 and the surrounding temperature are cooled to about room temperature.

  As shown in FIG. 1B, the blade 19 is divided into a plurality of parts in the width direction of the screen mask 12 orthogonal to the moving direction, and temperature control is possible for each of them. Thereby, if only the blade 19 corresponding to the opening 13 in which the paste 15 is actually embedded is heated, the entire paste 15 conveyed by the squeegee 14 is prevented from being heated excessively. The divided (zoned) blades 19 can limit the blades 19 that are heated and cooled when passing through a portion where the fine holes 13 that are difficult to embed and release the paste 15 are formed, for example. The deterioration of the paste 15 can be suppressed, and at the same time, the power required for heating and cooling can be reduced.

  When the blade 19 used for heating is of a type that directly contacts the surface of the screen mask 12 and transfers heat, the screen mask 12 and the printed wiring board are embedded before the paste 15 is embedded in the opening 13 by pressing. 11 can be improved. The blade 19 at this time is preferably arranged in an inclined range of 40 ° to 60 ° in order to make use of the spring property, although it depends on the material to be applied. Other angles may be used as long as heat transfer to the screen mask 12 is possible. For the blade 19, a material having high thermal conductivity, such as copper, is suitable.

  As described above, according to the present invention, the entire paste 15 is not excessively heated by the squeegee 14 to be printed, but the opening 13 at the embedding position and the screen mask 12 in the vicinity thereof are imprinted immediately before printing with the blade 19 in front of the squeegee 14. Is heated to increase the temperature of only the paste 15 embedded in the aperture 13 and reduce only the viscosity of the paste 15 in that portion, thereby suppressing the temperature increase to the paste 15 not directly involved in printing. it can. Therefore, volatilization of volatile components contained in the paste 15 can be suppressed, and deterioration of the paste 15 can be suppressed. Moreover, since the viscosity of the filled paste 15 that is in contact with the screen mask 12 is lowered by cooling after embedding, the releasability can be improved. In addition, since the embedded paste 15 is locally cooled, the cooling efficiency is high, and it is possible to contribute to downsizing and power saving of the entire apparatus.

  By the way, in the above-described embodiment, the direct contact heat transfer type using elastic copper or the like for the blade 19 is disclosed, but other types of contact with the surface of the screen mask 12 or non-contact type are also available. good.

  FIG. 2 shows an example of temperature control units 26 and 27 that perform contact heating and cooling. The temperature control units 26 and 27 shown in FIG. 2 include a temperature control unit 28 and a heat transfer unit 29 in which a roller 21 as a contact unit that comes into contact with the surface of the screen mask 12 from the temperature control unit 28 is rotatably disposed at the lower end. And.

  The roller 21 is heated or cooled by the heat transfer section 29, and can improve the adhesion between the screen mask 12 and the printed wiring board 11 before the paste 15 is embedded in the opening 13 by the pressing force. Heating and cooling can be performed without damaging the mask 12.

  FIG. 3 shows an example of temperature control units 36 and 37 that perform contact-type heating and cooling. 3 includes a temperature control unit 38 and a blade 39 formed with a substantially U-shaped contact portion 39a that contacts the surface of the screen mask 12 from the temperature control unit 38 at the lower end. I have.

  The contact portion 39a is heated or cooled by the blade 39, and can improve the adhesion between the screen mask 12 and the printed wiring board 11 before the paste 15 is embedded in the opening 13 by the pressing force. Heating / cooling can be performed without damaging 12, and heating / cooling can be performed while mitigating the influence of warping of the printed wiring board 11 and the screen mask 12.

  FIG. 4 shows an example of temperature control units 46 and 47 that perform non-contact heating and cooling. 4 includes a temperature control unit 48 and a nozzle 49 that injects heating air or cooling air from the temperature control unit 48 toward the surface of the screen mask 12.

  For example, a known blower or the like is used for the temperature adjustment units 46 and 47, and heating air or cooling air whose temperature is controlled by the temperature control unit 48 is blown from the nozzle 49. The heating air and the cooling air are basically not limited as long as a gas such as air or nitrogen is blown.

  FIG. 5 shows an example of temperature adjusting units 56 and 57 that perform non-contact heating. 5 includes a temperature control unit 58 and a heater member 59 that heats the surface of the screen mask 12 from the temperature control unit 58.

  For the heater member 59, for example, a known heat transfer coil or the like is used, and the temperature is controlled by the temperature control unit 58.

  FIG. 6 shows an example of temperature control units 66 and 67 that perform non-contact heating. 6 includes a temperature control unit 68 and a heater member 69 that heats the surface of the screen mask 12 from the temperature control unit 68.

  For example, an infrared lamp or a halogen lamp is used as the heater member 69, and the temperature is controlled by the temperature control unit 68.

  FIG. 7 shows an example of the temperature adjusting units 76 and 77 in the case where a combination of non-contact type heating and contact type cooling is combined. 7 includes a temperature control unit 78, a heater member 79a that heats the surface of the screen mask 12 from the temperature control unit 78, and a cooling squeegee 79b that cools the surface of the screen mask 12. It has.

  For example, an infrared lamp or a halogen lamp is used as the heater member 79a, and the heating temperature is controlled by the temperature control unit 68. The cooling temperature of the cooling squeegee 79 b is managed by the temperature control unit 68. A partition wall 71 having a heat insulating material is provided between the heater member 79a and the cooling squeegee 79b, and is insulated between the heater member 79a and the cooling squeegee 79b.

  It should be noted that the present invention is not limited to the combination of heating and cooling methods shown in FIG. 7, and those shown in the embodiments shown in FIGS. 2 to 6 can be used in appropriate combinations for heating and cooling. In addition, a mechanism for cooling the screen mask behind the squeegee 14 in the moving direction may be omitted if necessary.

DESCRIPTION OF SYMBOLS 11 Printed wiring board 12 Screen mask 13 Opening 14 Squeegee 15 Solder paste 16 Temperature control part (heating part / cooling part)
17 Temperature control part (cooling part / heating part)
18 Temperature control part 19 Blade 19a Lower end (contact part)

Claims (8)

In a screen printing apparatus that moves a squeegee along the surface of a screen mask, embeds a solder paste in an opening formed in the screen mask, and prints the solder paste on a substrate.
A heating unit that heats the screen mask immediately before the squeegee in front of the squeegee in the moving direction ;
A cooling unit that cools the screen mask behind the squeegee in the moving direction;
It said heating unit and said cooling unit, a screen printing apparatus characterized by Ru relative convertible der according to the moving direction of the squeegee. The screen printing apparatus according to claim 1 ,
The said printing part heats at least one part of the width direction of the said screen mask orthogonal to the moving direction of the said squeegee. The screen printing apparatus characterized by the above-mentioned. The screen printing apparatus according to claim 1 or 2 ,
The said heating part is provided with the contact part which contacts and heats the said screen mask. The screen printing apparatus characterized by the above-mentioned.   In a screen printing apparatus that moves a squeegee along the surface of a screen mask, embeds a solder paste in an opening formed in the screen mask, and prints the solder paste on a substrate.
  A heating unit that heats the screen mask immediately before the squeegee is provided in front of the squeegee in the moving direction, and the heating unit includes a contact unit that contacts and heats the screen mask.
  A screen printing apparatus characterized by that. The screen printing apparatus according to claim 3 or 4 ,
The screen printing apparatus, wherein the contact portion is slidably provided on the screen mask. The screen printing apparatus according to claim 3 or 4 ,
The screen printing apparatus, wherein the contact portion is provided to be able to roll on the screen mask. In a screen printing method of printing by embedding a solder paste on a substrate through an opening formed in the screen mask while moving a squeegee to the surface of the screen mask,
A screen printing method comprising heating the screen mask ahead of the opening in the moving direction of the squeegee by contact with the screen mask . The screen printing method according to claim 7 .
The screen printing method characterized by cooling the screen mask behind the squeegee in the moving direction of the squeegee.

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