JP2010260293A - Method and equipment for printing paste material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem in which, with an increased moving speed of a squeegee, the squeegee passes over an opening before a paste material such as a solder paste is fully packed in the opening of a mask. <P>SOLUTION: With a mask 2 arranged on a circuit board 1, and with solder paste 5 supplied onto the mask 2, a squeegee 3 is moved on the mask 2 in the direction of the arrow A. As a result, rolling in the direction of the arrow B is generated on the solder paste 5, making printing of the solder paste materialized on the opening 2a of the mask 2. In the solder paste 5, a columnar roller 6 is arranged and moved in the same direction and at the same speed as the squeegee 3. Also, the roller 6 is rotated in the same direction (the direction of the arrow C) as the rolling direction of the solder paste 5 and at the speed of revolution equal to or greater than the rolling of the solder paste 5. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a paste material printing method and a paste material printing apparatus, and in particular, a paste material screen printing method for filling a predetermined mask opening pattern with a paste material such as a solder paste on a circuit board, and screen printing used in the paste material screen printing method. It relates to the device.

  For example, to mount surface-mount electronic components such as QFP, BGA, and chip components on a circuit board, solder paste is applied to the pad on the circuit board by screen printing, and the electronic components are mounted on the circuit board. Then, solder reflow is performed for mounting. Here, in the conventional solder paste printing apparatus, the solder paste on the mask is filled into the opening hole of the mask by moving the squeegee and pushing the squeegee and rolling generated in the solder paste. In recent years, in order to improve the productivity of the printing process, there is an increasing need to increase the moving speed of the squeegee. However, in the conventional squeegee configuration, when the squeegee is moved at a high speed, the squeegee passes through the opening hole before the opening hole is completely filled, and the opening hole cannot be sufficiently filled. As a countermeasure, it is possible to ensure the filling property by reciprocating the squeegee, but this coping method cannot reduce the time required for printing.

  By the way, the technique which arrange | positions a roller in a paste material and tries to improve the rolling property of a paste material is proposed (for example, refer patent document 1, 2). FIG. 5 is a cross-sectional view of the printing apparatus disclosed in Patent Document 1. In FIG. 5, 11 is a circuit board having a pad 11a, 12 is a mask provided with an opening 12a, 13 is a squeegee that moves in the direction of arrow A while pressing the mask 12, 15 is a solder paste, and 16 is a squeegee. 13 is a roller that is disposed in front of 13 moving directions (arrow A direction) and moves in the arrow A direction together with the squeegee 13. Then, the roller 16 is rotated in the arrow C direction opposite to the rolling direction of the solder paste 15 (arrow B direction). In this conventional example, the rolling of the solder paste is reinforced by the rotation of the roller, and the pushing force of the solder paste into the mask opening is increased.

  Further, in Patent Document 2, a roller that rotates in the same direction as the original rolling direction of the conductive paste and a roller that rotates in the opposite direction are provided in the conductive paste to increase the pushing force of the conductive paste onto the circuit board. Techniques for increasing are disclosed. FIG. 6 is a cross-sectional view of the printing apparatus disclosed in Patent Document 2. As shown in FIG. In FIG. 6, 21 is a circuit board, 22 is a mask provided with an opening 22a, 23 is a squeegee that moves in the direction of arrow F while pressing the mask 22, 25 is a conductive paste, and 26a and 26b are conductive. First and second rollers 27 arranged in the paste 25 and moving in the direction of arrow F together with the squeegee 23 are stages on which the circuit board 21 is placed. The first roller 26a is rotated in the direction opposite to the arrow F direction, and the second roller 26b is rotated in the arrow F direction. With this configuration, in the region sandwiched between the first roller 26a and the second roller 26b, a downward flow of the conductive paste 25 with a high pressure occurs, and an opening pattern with a high aspect ratio is obtained. The conductive paste can be sufficiently filled.

JP 09-239955 A JP 2008-221541 A

In the prior art disclosed in Patent Document 1, although rolling is strengthened locally, the solder paste moves in the direction opposite to the rolling direction at the tip of the solder paste in the printing direction. Poor pressure to fill. Therefore, in this prior art, if the squeegee is moved at a high speed, the mask opening is likely to be insufficiently filled. Further, in the device described in Patent Document 1, since the roller is provided at the tip position of the solder paste, the amount of solder paste supplied in advance increases, or the solder paste attached to the outer surface of the roller dries. Problems arise.
Moreover, in the printing apparatus described in Patent Documents 1 and 2, the flow of the paste material is divided into two directions, the rolling direction and the anti-rolling direction, the paste material in each direction flows independently, and the two flow paste materials are The opportunity to stir is impaired, and there is a concern that the uniformity of the paste material viscosity will deteriorate. In particular, in the one described in Patent Document 2, a conductive paste pool is easily generated in the paste material, and the uniformity of the paste material viscosity is further hindered. Furthermore, in what is described in Patent Document 2, since the amount of paste material to be supplied increases, the drying of the paste material also increases, so that the deterioration of paste material quality becomes a problem. In addition, a pair of opposed rollers is essential and has a complicated configuration.

  An object of the present invention is to solve the above-mentioned problems of the prior art. The purpose of the present invention is, firstly, to enable a mask material to be sufficiently filled with a paste material even when high-speed printing is performed. Secondly, it is possible to prevent drying of the paste material and non-uniformity of its viscosity.

In order to achieve the above object, according to the present invention, there is provided a paste material printing method for printing a paste material on a print mask by moving a squeegee on a circuit board, the paste material occurring along with the movement of the squeegee There is provided a paste material printing method characterized in that printing is performed while increasing the rotation speed of the entire rolling.
Preferably, a roller that moves together with the squeegee is provided in the paste material, and the rotation speed of the rolling of the paste material is increased by the rotation of the roller.

In order to achieve the above object, according to the present invention, there is provided a paste material printing apparatus for moving a squeegee and printing a paste material on a print mask on a circuit board, wherein the squeegee has the same speed in the same direction as the squeegee. A paste material printing apparatus is provided, which is provided with a roller that is moved and rolled in the paste material to be rolled and rotated in the rolling direction of the paste material.
Preferably, the roller is disposed at a substantially central portion of the paste material rolling.

According to the present invention configured as described above, rolling generated in the paste material by squeegee movement is enhanced as a whole by the roller rotating in the same direction as the rolling direction. That is, the rotational speed of the paste material is increased as a whole. As a result, even if the speed of the paste material fed into the mask opening increases, the filling pressure into the mask opening increases, and the squeegee moves faster, the paste material fills the mask opening with sufficient pressure. Will be.
In addition, since the rolling of the paste material is only in one direction and the paste material is less likely to stay, the stirring of the paste material can be performed efficiently, and uneven viscosity and increase in viscosity are suppressed. In addition, since only one roller is provided at the substantially central portion of the rolling of the paste material, it is possible to reduce the diameter of the roller and to increase the printing speed without increasing the size of the apparatus and relatively simple. This can be realized by the configuration.

Sectional drawing which shows the structure of one embodiment of this invention. Sectional drawing which shows the structure of Example 1 of this invention. Sectional drawing which shows the structure of Example 2 of this invention. Sectional drawing which shows the structure of Example 3 of this invention. Sectional drawing which shows the structure of a 1st prior art example. Sectional drawing which shows the structure of a 2nd prior art example.

Next, an embodiment of the paste material printing apparatus of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a sectional view showing an embodiment of a paste material printing apparatus of the present invention. In this embodiment, a solder paste (also called cream solder) is used as the paste material. As shown in FIG. 1, a circuit board 1 is placed on a stage (not shown) of a printing apparatus, and then a mask 2 is placed on the circuit board. A predetermined circuit and necessary pads (both not shown) are formed on the circuit board 1. The mask 2 is formed of a metal plate, and an opening 2a is opened at a necessary portion. The opening 2a is located on a pad of the circuit board 1. A solder paste 5 is supplied on the mask 2, and this solder paste 5 is screen-printed on the circuit board 1 by the squeegee 3 held by the holder 4. That is, when the squeegee 3 is moved in the direction of arrow A while pressing the mask surface with the holder 4, rolling of the solder paste 5 in the direction of arrow B occurs, and filling of the solder paste into the opening 2a of the mask 2 is promoted. And printing is realized. The squeegee 3 is made of an elastic material such as rubber. Here, according to the present invention, the cylindrical roller 6 is disposed in the solder paste 5 so that the rotation center thereof substantially coincides with the rolling center portion of the solder paste. The roller 6 is disposed so that its central axis is parallel to the plate surface of the squeegee 3 and is moved at the same speed in the same direction as the squeegee 3 (direction of arrow A). Further, the roller 6 is rotated in the same direction as the rolling direction (arrow B direction) of the solder paste 5, that is, in the arrow C direction, at a rotational speed equal to or higher than the rolling of the solder paste 5.
The movement of the squeegee 3 and the roller 6 and the rotation of the roller 6 are controlled by the operation of the movement drive source and the rotation drive source, which are not shown. The material of at least the surface of the roller 6 is desirably a material having a large friction against a solder paste such as rubber. Alternatively, the viscosity may be physically increased by providing irregularities or fins on the outer periphery of the roller 6.

Next, the operation of the printing apparatus of the present invention shown in FIG. 1 will be described in more detail.
First, the circuit board 1 is placed on the stage (not shown) of the printing apparatus, and then the mask up / down driving mechanism (not shown) is operated to lower the mask 2, as shown in FIG. 1 is brought into contact with the mask 2. Next, the squeegee 3 and the roller 6 are moved horizontally in the direction of movement A by operating a moving drive source (not shown), and at the same time, the rotating drive source (not shown) is operated to rotate the roller 6 in the direction of rotation. Rotate in the direction of C at a predetermined rotation speed. Further, the movement of the squeegee 3 and the roller 6 is continued, and after the squeegee 3 passes above the opening 2a of the mask 2, the movement of the squeegee 3 and the roller 6 is stopped and the rotation of the roller 6 is stopped.

In the above process, as the squeegee 3 moves, the solder paste 5 rolls in the direction of arrow B due to the interaction between the mask 2 and the squeegee 3 with which the solder paste 5 contacts. Further, since the rolling is accelerated by the rotational force generated by the roller 6 and is sent out in the direction of the squeegee 3, the solder paste 5 existing in the vicinity of the contact area between the mask 2 and the squeegee 3 has a speed to the opening 2a. The filling pressure is increased. Therefore, the solder paste 5 is pushed into the opening 2 a at a high speed, and the opening 2 a is sufficiently filled with the solder paste 5.
Thereafter, the mask vertical drive mechanism (not shown) is operated to separate the mask 2 from the circuit board 1, and then the circuit board 1 is unloaded.

  FIG. 2 is a cross-sectional view showing Example 1 of the present invention. In FIG. 2, the same components as those shown in FIG. In this embodiment, the surface of the metal roller 6 is provided with irregularities 6a. The unevenness is provided with peaks and valleys parallel to the axis of the roller 6.

  FIG. 3 is a cross-sectional view showing a second embodiment of the present invention. In FIG. 3, the same components as those shown in FIG. In this embodiment, the cross-sectional shape of the roller 6 is a polygon (a regular octagon in the illustrated example).

  FIG. 4 is a sectional view showing Example 3 of the present invention. In FIG. 4, the same members as those shown in FIG. In this embodiment, plate-like fins 6 a that are parallel to the axis of the roller 6 are provided on the outer periphery of the roller 6.

  Although preferred embodiments and examples have been described above, the present invention is not limited to these embodiments, and appropriate modifications can be made without departing from the scope of the present invention. For example, a metal mask is used as the mask, but other masks may be used, and the squeegee may be made of metal other than rubber, for example. The present invention is also applicable to printing materials other than solder paste, for example, conductive paste or insulating paste.

DESCRIPTION OF SYMBOLS 1, 11, 21 Circuit board 11a Pad 2, 12, 22 Mask 2a, 12a, 22a Opening part 3, 13, 23 Squeegee 4 Holder 5, 15 Solder paste 6, 16 Roller 6a Concavity and convexity 6b Fin 25 Conductive paste 26a 1st Roller 26b Second Roller 27 Stage

Claims (8)

  A paste material printing method in which a paste material on a print mask is printed on a circuit board by moving a squeegee, wherein printing is performed while increasing the rotational speed of rolling of the paste material that occurs with the movement of the squeegee. Characteristic paste material printing method.   The paste material printing method according to claim 1, wherein a roller that moves together with the squeegee is provided in the paste material, and the rotation speed of the rolling of the paste material is increased by the rotation of the roller.   The paste material printing method according to claim 1, wherein the paste material is a solder paste.   A paste material printing apparatus that moves a squeegee and prints a paste material on a print mask on a circuit board, is moved in the same direction as the squeegee at the same speed, is placed in a rolling paste material, A paste material printing apparatus comprising a roller rotated in a rolling direction.   The paste material printing apparatus according to claim 4, wherein the roller is arranged so that a rotation center thereof substantially coincides with a substantially central portion of the rolling of the paste material.   The paste material printing apparatus according to claim 4, wherein fine irregularities are formed on a surface of the roller.   The paste material printing apparatus according to claim 4, wherein the roller has a polygonal cross-sectional shape.   The paste material printing apparatus according to claim 4, wherein the roller includes a plurality of fins.

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