JP2005343116A - Squeegee for soldering paste printer and soldering paste printing method for printed circuit board using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a squeegee for a soldering paste printer which reduces the rate of occurrence of scratching remnants of a soldering paste and stabilizes the amount of solder of the soldering paste being printed. <P>SOLUTION: In the squeegee 1 for the soldering paste printer used for applying the soldering paste to a printed circuit board, two or more squeegee blades 2 and 3 are fitted to a fixing implement 4, while angles α1 and α2 of the squeegee blades 2 and 3 with a plane F formed when the blades come into simultaneous contact with the plane F are made different from each other between the blades 2 and 3. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a squeegee for a solder paste printing machine for applying a solder paste to a printed wiring board, and a solder paste printing method on a printed wiring board using the squeegee.

  A general method for printing solder paste on a printed wiring board in which a solder paste is printed (applied) on a printed wiring board (printed board) by a solder paste printer (not shown) will be described.

  A printed board (generally, a surface-mounted printed wiring board) 51 as shown in FIG. 5 is prepared. In the substrate 51, the solder paste needs to be applied (printed) in a portion called a pad 52 that is usually exposed in a state where Cu or Cu is plated with solder.

  In order to print the solder paste only on the pad 52, a mask 61 as shown in FIG. 6 is used. The mask 61 includes a mask main body 63 in which a large number of openings 62 are provided in a portion where solder paste is printed, and a frame (fixed frame) 64 that maintains the tension of the mask main body 63 and facilitates attachment to and detachment from the printing press main body. Consists of. The mask body 63 is a plate having a thickness of about 0.15 mm (SUS and Ni are mainly used).

  First, as shown in FIGS. 7A to 7C, the position is adjusted so that the pad 52 of the substrate 51 and the opening 62 of the mask 61 coincide with each other by the alignment function of the printing machine. A mask 61 is overlaid on the surface of.

  After the mask 61 is overlaid, the solder paste p is supplied to the surface of the mask 61. After supplying the solder paste p, a squeegee blade 103 provided in the printing machine main body for sweeping the solder paste p on the surface of the mask 61 (printing the solder paste p into the opening 62 of the mask 61) is provided on the mask 61. The surface is brought into contact (FIG. 8 (a)).

  By using this squeegee blade 103 to press and move the surface of the mask 61 (in the direction of arrow A in FIG. 8) (FIG. 8B), the opening 62 of the mask 61 is filled with the solder paste p, and the mask The solder paste p is transferred to the pad 52 of the substrate 51 through the opening 62 of the 61 (FIG. 8C). When the mask 61 is separated from the substrate 51 after transferring the solder paste p (FIG. 8D), the solder paste p is printed only on the pads 52 of the substrate 51 as shown in FIG.

  Here, as shown in FIG. 10A and FIG. 10B, the squeegee 101 for a solder paste printing machine is configured by attaching one squeegee blade 103 to a fixing jig 102. The squeegee blade 103 is usually formed in a thin plate shape using a resin such as urethane or a metal. The squeegee blade 103 is attached to the fixing jig 102 so as to be at a predetermined angle with respect to the substrate 51 (see FIG. 8), and the fixing jig 102 is attached to the printing machine main body.

  The prior art document information related to the invention of this application includes the following.

Japanese Patent Laid-Open No. 9-174809 JP-A-9-205273

  However, since the squeegee 101 is configured by attaching a single squeegee blade 103 to the fixing jig 102, the squeegee 101 cannot cope with the unevenness of the substrate 51 and the mask 61, the wear of the squeegee blade 103, and the like. There is a problem that it is difficult to scrape off enough.

  For example, as shown in the Z part of FIG. 11, the solder paste p tends to remain on the surface of the mask 61 after the squeegee 101 is moved. This state is called insufficient solder scraping, which causes the printed amount of the solder paste p to become unstable.

  Due to the occurrence of insufficient solder scraping, the residual solder paste p left above the surface of the mask 61 (FIG. 12A) is transferred to the substrate 51 as it is, resulting in an excessive amount of solder (FIG. 12 ( b)) When the solder paste p filled in the opening 62 of the mask 61 remains on the mask 61 side, the amount of solder is insufficient. As a result, since it is not known whether the amount of solder is excessive or insufficient, it becomes very difficult to control the amount of solder.

  The variation in the amount of solder of the solder paste p to be printed appears as the variation in the amount of solder at the joint between the electronic component and the printed circuit board 51 as it is. When the amount of solder is large, solder bridges (defects where adjacent solder joints are electrically connected via solder) are likely to occur. When the amount of solder is small, there is no connection or lack of physical strength. It tends to occur. Therefore, the work which corrects them with hand solder will be needed.

  Accordingly, an object of the present invention is to reduce the occurrence rate of solder paste scraps and stabilize the amount of solder paste to be printed, and a squeegee for a solder paste printer, and a method for printing a solder paste on a printed wiring board using the squeegee Is to provide.

  The present invention was devised to achieve the above object, and the invention of claim 1 is a squeegee for a solder paste printer for applying a solder paste to a printed wiring board, and a squeegee blade as a fixing jig. And a squeegee for a solder paste printing machine in which the squeegee blades have different angles with the plane when they simultaneously contact the plane.

  According to a second aspect of the present invention, the squeegee blade is composed of a first squeegee blade and a second squeegee blade, and the first squeegee blade has an angle with the plane facing the moving direction. 2 is a squeegee for a solder paste printing machine according to claim 1, wherein the second squeegee blade is smaller in angle with the plane facing the moving direction than the angle of the first squeegee blade. .

  According to a third aspect of the invention, when the angle of the first squeegee blade is 60 °, the angle of the second squeegee blade is reduced by 1 to 15 °. It is a squeegee.

  The invention of claim 4 is the squeegee for a solder paste printer according to claim 2 or 3, wherein the thickness of the second squeegee blade is thinner than the thickness of the first squeegee blade.

  The invention according to claim 5 is the squeegee for a solder paste printer according to claim 2 or 3, wherein the hardness of the second squeegee blade is lower than the hardness of the first squeegee blade.

  A sixth aspect of the present invention is a method of stacking a mask on a printed wiring board, supplying a solder paste to the surface of the stacked mask, and using the squeegee for a solder paste printer according to any one of the first to fifth aspects, This is a method for printing a solder paste on a printed wiring board using a squeegee for a solder paste printer that presses and moves the surface and applies the solder paste supplied to the surface of the mask to the board.

  According to the present invention, an excellent effect of reducing the number of manual solder correction work man-hours caused by unscratched solder is exhibited.

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

  FIG. 1 is a cross-sectional view of a squeegee for a solder paste printer showing a preferred first embodiment of the present invention.

  As shown in FIG. 1, a squeegee 1 for a solder paste printer according to a first embodiment is provided in a solder paste printer main body (not shown) for applying a solder paste to a printed wiring board (printed board). Two squeegee blades 2 and 3 (two-stage configuration), and a fixing jig 4 for attaching and fixing the two squeegee blades 2 and 3.

  Each squeegee blade 2 and 3 is for sweeping the solder paste on the surface of the mask overlaid on the printed circuit board (imprinting the solder paste into the opening of the mask), and has the same thickness with resin such as urethane or metal They are formed in a thin plate shape so as to have the same shape. The first (stage) squeegee blade 2 is a blade preceding the moving direction A of the squeegee 1. The second (stage) squeegee blade 3 is arranged in parallel behind the squeegee blade 2 and follows the squeegee blade 2.

  The squeegee blades 2 and 3 are attached to the fixing jig 4 so that the heights of the blades (height from the bottom surface 4b of the fixing jig 4 to the tips 2s and 3s of the blades) h are equal to each other. To make the blade height h equal (no step on the blade tips 2s and 3s), maintainability when replacing the squeegee and conditions for actual use on the printing press (printing pressure, pushing amount, etc.) This is because the ease of operation is taken into consideration.

  Each squeegee blade 2, 3 has an angle with the plane F facing the moving (coating) direction A of the squeegee 1 when the tips 2 s, 3 s of both blades are simultaneously in contact with the plane (mask surface) F (the printed circuit board). The angle with the surface or the contact angle with the surface of the mask) α1, α2 is made different between the squeegee blades 2, 3.

  More specifically, the angle α1 of the first squeegee blade 2 is set to 60 ° or less, and the angle α2 of the second squeegee blade 3 is made smaller than the angle α1 (inclined toward the moving direction A). . For example, when the angle α1 of the first squeegee blade 2 is 60 °, the angle α2 of the second squeegee blade 3 is 59 to 45 ° smaller by 1 to 15 ° (preferably closer to 45 °). .

  The reason why the angle α2 of the second squeegee blade 3 is made smaller than the angle α1 is to improve the followability of the second squeegee blade 3 to the unevenness of the printed circuit board and the mask than the first squeegee blade 2. It is. Another reason is that the downward force applied to the mask by the second squeegee blade 3 is smaller than that of the first squeegee blade 2. As a result, the solder paste can be prevented from bleeding between the mask and the printed circuit board.

  A part of the upper part of each squeegee blade 2 or 3 is housed and attached to the bottom surface 4b of the fixing jig 4 so as to satisfy the height h and the angles α1 and α2 of the squeegee blades 2 and 3 described above. Mounting grooves 5 and 6 are formed, respectively.

  The printer main body to which the squeegee 1 is attached has at least a conveyor mechanism for transporting the printed circuit board, a chuck mechanism for fixing the printed circuit board, a mechanism for aligning and holding the mask, and a mechanism for controlling the pressing movement of the squeegee 1. Any conventional one may be used.

  Next, a solder paste printing method on a printed wiring board using the squeegee 1 will be described using an example using the printed board 51 described in FIG. 5 and the mask 61 described in FIG.

  First, by using a solder paste printing machine in which the squeegee 1 is attached to the printing machine main body, due to its positioning function, the pad 52 of the printed circuit board 51 and the opening 62 of the mask 61 coincide with each other as shown in FIG. The position is adjusted so that the mask 61 is overlaid on the surface of the substrate 51.

  After the mask 61 is overlaid, the solder paste p is supplied to the surface F of the mask 61, and the tips 2s and 3s of the squeegee blades 2 and 3 of the squeegee 1 are applied to the surface F of the mask 61 with a predetermined printing pressure and pushing amount. Contact at the same time.

  By using these squeegee blades 2 and 3 to press and move the surface F of the mask 61 (in the direction of arrow A in FIG. 2), the solder paste p is filled in the opening 62 of the mask 61 and the opening of the mask 61 is opened. The solder paste p supplied to the surface F of the mask 61 is transferred to the pads 52 of the substrate 51 through the part 62.

  At this time, as shown in part X of FIG. 2B, scrapes of the solder paste p are generated due to the unevenness of the substrate 51 and the mask 61 and the wear of the first squeegee blade 2. The remaining part of the paste p is scraped off by the second squeegee blade 3 as shown in FIG. When the mask 61 is separated from the substrate 51 after the solder paste p is transferred, an appropriate amount of the solder paste p is printed only on the pads 52 of the substrate 51.

  The operation of the present embodiment will be described.

  In the squeegee 1, when the two squeegee blades 2 and 3 attached to the fixing jig 4 are simultaneously in contact with the surface F of the mask 61, the angle α 2 of the second squeegee blade 3 is set to the angle of the first squeegee blade 2. By making it smaller than the angle α1, the followability of the second squeegee blade 3 with respect to the unevenness of the substrate 51 and the mask 61 is enhanced as compared with the first squeegee blade 2.

  For this reason, the squeegee 1 can cope with the unevenness of the substrate 51 and the mask 61 and the wear of the squeegee blades 2 and 3, and the excess solder paste p is scraped reliably and sufficiently by the second squeegee blade 3. be able to.

  Therefore, if the solder paste p is applied to the substrate 51 using the squeegee 1, an appropriate amount of the solder paste p is printed only on the pads 52 of the substrate 51, so that the rate of occurrence of solder paste scraping is reduced and the amount of solder is reduced. Excess and deficiency hardly occur, and the amount of solder of the printed solder paste p can be stabilized.

  As a result, solder bridges, no connection, insufficient physical strength, and the like due to solder residue are unlikely to occur, and there is no need to manually correct them, thereby reducing the number of manual solder correction operations.

  As described above, the characteristic required for the second squeegee blade is higher followability to the unevenness of the substrate 51 and the mask 61 than the first squeegee. Considering this, the second and third embodiments described below have been created.

  As shown in FIG. 3, in the squeegee 31 according to the second embodiment, the thickness of the second squeegee blade 32 is thinner than the thickness of the first squeegee blade 2. In the example of FIG. 3, the second squeegee blade 32 is attached to the fixing jig 33 so as to be parallel to the first squeegee blade 2.

  The second squeegee blade 32 has an angle with the plane F facing the moving direction A of the squeegee 31 smaller than the angle α1 of the first squeegee blade 2 when the squeegee blades 2 and 32 simultaneously contact the plane F. It may be made to become.

  In the squeegee 31, since the second squeegee blade 32 is thinner than the first squeegee blade 2, the followability of the second squeegee blade 32 to the unevenness of the substrate and the mask is greater than that of the first squeegee blade 2. Rise. For this reason, the effect similar to the squeegee 1 of FIG. 1 is acquired.

  As shown in FIG. 4, in the squeegee 41 according to the third embodiment, the hardness of the second squeegee blade 42 is lower than the hardness of the first squeegee blade 2. That is, the second blade 42 is softer than the first blade. For example, when the hardness of the first squeegee blade 2 is HS (Shore hardness) 90, the hardness of the second squeegee blade 41 is HS (Shore hardness) 70. In the example of FIG. 4, the second squeegee blade 42 is attached to the fixing jig 43 so as to be parallel to the first squeegee blade 2.

  The second squeegee blade 42 is smaller in angle with the plane F facing the moving direction A of the squeegee 41 than the angle α1 of the first squeegee blade 2 when the squeegee blades 2 and 42 are simultaneously in contact with the plane F. It may be made to become.

  In the squeegee 41, since the second squeegee blade 42 has a lower hardness than the first squeegee blade 2, the followability of the second squeegee blade 42 to the unevenness of the substrate and the mask is the first squeegee blade 2. More than. For this reason, the effect similar to the squeegee 1 of FIG. 1 is acquired.

  In the above embodiment, the example in which two squeegee blades are attached to the fixing jig has been described. However, three or more squeegee blades may be attached to the fixing jig. In this case, for example, the angle of the second and subsequent squeegee blades is set to the angle α1 of the first squeegee blade so that the squeegee blades have different angles with the plane when they simultaneously contact the plane. To gradually become smaller.

  In addition, the thickness of the second and subsequent squeegee blades may be made gradually thinner than the thickness of the first squeegee blade. You may make it become gradually lower than hardness.

1 is a cross-sectional view of a squeegee for a solder paste printer showing a preferred first embodiment of the present invention. FIG. 2A to FIG. 2C are cross-sectional views showing respective steps (printing steps) of a method for printing a solder paste onto a printed wiring board using a squeegee for a solder paste printing machine according to the present invention. It is a cross-sectional view which shows 2nd Embodiment. It is a cross-sectional view showing a third embodiment. It is a top view which shows an example of a printed wiring board. It is a top view which shows an example of a mask. 7A is a plan view showing the aligned mask and printed wiring board, FIG. 7B is a front view thereof, FIG. 7C is a cross-sectional view taken along line 7C-7C in FIG. It is an enlarged view of a part. FIGS. 8A to 8D are cross-sectional views showing respective steps of a solder paste printing method on a printed wiring board using a squeegee for a solder paste printer according to the background art. It is a top view of the printed wiring board after solder paste printing. FIG. 10A is a cross-sectional view of a squeegee for a solder paste printer according to the background art, and FIG. 10B is a front view thereof. It is a top view of the printed wiring board which shows the example of a solder printing malfunction. FIG. 12A to FIG. 12C are cross-sectional views showing an example of fluctuations in the amount of solder due to insufficient solder scraping.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Squeegee for solder paste printing machines 1st squeegee blade 3 2nd squeegee blade F Horizontal surface (mask surface)
α1 Angle with printed circuit board α2 Angle with printed circuit board

Claims (6)

  In a solder paste printing machine squeegee for applying solder paste to a printed wiring board, two or more squeegee blades are attached to a fixing jig, and the angle between each squeegee blade and the plane is simultaneously determined. A squeegee for a solder paste printer, wherein each squeegee blade is different from each other.   The squeegee blade is composed of a first squeegee blade and a second squeegee blade, and the first squeegee blade has an angle of 60 ° or less with respect to the plane facing the moving direction. 2. The squeegee for a solder paste printing machine according to claim 1, wherein an angle of the second squeegee blade and the plane facing the moving direction is smaller than the angle of the first squeegee blade.   3. The squeegee for a solder paste printer according to claim 2, wherein when the angle of the first squeegee blade is 60 °, the angle of the second squeegee blade is reduced by 1 to 15 °.   The squeegee for a solder paste printer according to claim 2 or 3, wherein a thickness of the second squeegee blade is thinner than a thickness of the first squeegee blade.   The squeegee for a solder paste printer according to claim 2 or 3, wherein the hardness of the second squeegee blade is lower than the hardness of the first squeegee blade. A mask is overlaid on a printed wiring board, a solder paste is supplied to the surface of the overlaid mask, and the surface of the mask is pressed and moved using the squeegee for a solder paste printer according to any one of claims 1 to 5, A method of printing a solder paste on a printed wiring board using a squeegee for a solder paste printer, wherein the solder paste supplied to the surface of the substrate is applied to the substrate.

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