JP2012066539A - Metal mask and solder paste printing method using the metal mask - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform printing of solder paste while easily performing alignment for a plurality of wiring boards without using an expensive device.SOLUTION: The printing of solder paste is performed using a metal mask 1 having a recessed part 2 provided at a position corresponding to the wiring board 12. In the metal mask 1, a plurality of the recessed parts 2 are provided on a surface of the metal mask 1 placed over the wiring board 12 to receive the wiring board 12 and position the wiring board 12. A hole part 3 is formed through at a position of the metal mask 1 corresponding to a pad 13 of the wiring board 12 received in the recessed part 2. When this metal mask 1 is used, dislocation of the wiring board 12 installed on a stage 10 can be corrected when the metal mask is lowered. Therefore, the printing of solder paste can be performed on a plurality of the wiring boards by a simple method and with high positional accuracy.

Description

  The present invention relates to a metal mask used when a solder paste is printed on a wiring board, and a solder paste printing method using the metal mask.

  Conventionally, solder paste printing by squeegee running is performed in the process of supplying solder paste to the pads of the wiring board. In solder paste printing, a metal mask provided with a hole at a position corresponding to a pad on a wiring board and a squeegee for running on the metal mask and filling the hole in the metal mask with the solder paste are used.

  Usually, a printing apparatus is used for printing solder paste. Image recognition is performed using a camera with alignment marks provided on the wiring board and the metal mask, and then alignment is performed by finely moving a printing stage or the like according to the alignment marks. Thereafter, the solder paste is printed with a squeegee.

  When printing a solder paste on a single wiring board, high-precision printing is possible by alignment using the camera as described above. However, when solder paste is printed on a plurality of wiring boards, the relative positions of the wiring boards vary, so that it is not possible to align all of the wiring boards in the same way as a single wiring board. Can not. When alignment between a certain wiring board and a metal mask is performed using a camera, there is a possibility that a positional deviation occurs between the other wiring board and the metal mask.

  On the other hand, in Non-Patent Document 1, each wiring board has an individual stage, a camera is used, and each wiring board is individually aligned using the pick-up and suction of the wiring board. A printing device is provided. Since the positioning is performed individually, it is possible to print the solder paste with high accuracy.

http://www.ho-minami.co.jp/tec/08.html Minami Co., Ltd. Technical Information Multi-alignment

However, the technique of Non-Patent Document 1 requires a complicated and expensive printing apparatus and requires a long time for the printing process because the alignment is performed one by one.
In the present invention, in view of the above circumstances, a metal mask capable of printing solder paste with high accuracy by a simple method by using a metal mask provided with a recess at a position corresponding to a wiring board, and the metal mask are used. An object of the present invention is to provide a method for printing a solder paste.

  The invention according to claim 1, which has been made to solve the above-described problems, is a metal mask that covers the wiring substrate in a step of printing a solder paste on the wiring substrate, on the surface of the metal mask that covers the wiring substrate. A plurality of recesses for accommodating the wiring substrate and positioning the wiring substrate, and a hole is formed through the metal mask corresponding to the pad of the wiring substrate received in the recess. Features.

  The invention according to claim 2 is the metal mask according to claim 1, wherein the depth of the recess is equal to the thickness of the wiring board.

According to a third aspect of the present invention, the recess is formed by a flat bottom surface and a side surface that surrounds the bottom surface and is connected to a surface of the metal mask that covers the wiring substrate, and the side surface includes the wiring substrate. The bottom surface is formed with an inclined surface that is inclined in the direction of decreasing the area of the bottom surface from the surface of the metal mask to be covered to the bottom surface. A metal mask according to any one of claims 1 and 2.
The invention according to claim 4 is characterized in that an angle θ formed by the inclined surface with respect to the bottom surface is 0 ° <θ ≦ 90 °, and preferably 30 ° ≦ θ ≦ 70 °. A metal mask according to any one of claims 1 to 3.
According to a fifth aspect of the present invention, the metal mask has a lower surface that covers the wiring board and an upper surface opposite to the metal substrate, and the concave portion is formed on the lower surface, from the lower surface to the bottom surface of the concave portion. Where T is the thickness of the metal mask 1 and t is the thickness of the metal mask from the bottom surface of the recess to the top surface, and the thickness t 5. The metal mask according to claim 1, wherein the metal mask part forming the part is the same member.
According to a sixth aspect of the present invention, the metal mask has a lower surface that covers the wiring board and an upper surface on the opposite side, and the concave portion is formed on the lower surface, from the lower surface to the bottom surface of the concave portion. Where T is the thickness of the metal mask, and t is the thickness of the metal mask from the bottom surface of the recess to the top surface, and the portion of the metal mask that forms the portion of thickness T The metal mask according to any one of claims 1 to 4, wherein the metal mask is a separate member from the metal mask portion forming the portion, and the members are joined.

  According to a seventh aspect of the invention, there is provided a solder paste printing method comprising printing a solder paste on a wiring board using the metal mask according to any one of the first to sixth aspects.

  By using a metal mask with a recess at a position corresponding to the wiring board, positioning becomes simple, and solder paste can be applied with high positional accuracy without causing problems such as short circuits on multiple wiring boards. Can be printed.

Sectional drawing which shows an example of the solder paste printing process of this invention Sectional drawing which shows one form of the manufacturing method of the metal mask of this invention Sectional view showing an example of a conventional solder paste printing process Sectional drawing which shows an example of the metal mask of this invention Sectional drawing which shows one Embodiment of the solder paste printing process of this invention Sectional drawing which shows one Embodiment of the conventional solder paste printing process

Embodiments of the present invention will be described below with reference to the drawings.
As shown in FIG. 1, the metal mask 1 of the present invention is provided with a recess 2 at a position corresponding to a wiring board 12. A hole 3 filled with solder paste is provided at a position corresponding to the pad 13 of the wiring board 12. Furthermore, the metal mask 1 has a plurality of recesses 2 and holes 3 and can simultaneously print solder paste on a plurality of wiring boards. In other words, a plurality of recesses 2 that accommodate the wiring board 12 and position the wiring board 12 are provided on the surface of the metal mask 1 that covers the wiring board 12. In addition, a hole 3 is formed through the position of the metal mask 1 corresponding to the pad 13 of the wiring board 12 accommodated in the recess 2.

A thin metal is used for the metal mask 1. SUS, Ni-based alloy, Cu-based alloy and the like can be used. Although not shown, these metal masks are fixed to a square bar-shaped aluminum alloy frame or the like. Any one of the recess 2 and the hole 3 provided in the metal mask 1 may be formed first. In other words, the metal mask 1 has a lower surface that covers the wiring substrate 12 and an upper surface on the opposite side, and the recess 2 is formed on the lower surface. Then, when the thickness of the metal mask 1 from the bottom surface to the bottom surface of the recess 2 is T, and the thickness of the metal mask 1 from the bottom surface of the recess 2 to the top surface is t, a portion having the thickness T is formed. The portion of the metal mask and the portion of the metal mask that forms the portion of thickness t are the same member.
The hole 3 is formed by a known method such as an etching method, a laser method, an electroforming method, a cutting method, or a pressing method. The recess 2 can be formed by a known method such as an etching method, an electroforming method, a cutting method, or a pressing method.
As shown in FIG. 2, the concave portion 2 is also formed by attaching a metal plate 6 from which metal or the like corresponding to the position of the wiring board is removed to the conventional metal mask 4 with an adhesive 5 or the like. be able to. At this time, instead of the conventional metal mask 4, the metal plate 6 from which the metal or the like corresponding to the position of the wiring board has been removed is attached to a metal plate that has not been processed with the hole with an adhesive 5 or the like. It is also possible to perform the processing. In other words, the metal mask 1 has a lower surface that covers the wiring substrate 12 and an upper surface on the opposite side, and the recess 2 is formed on the lower surface. Then, when the thickness of the metal mask 1 from the bottom surface to the bottom surface of the recess 2 is T, and the thickness of the metal mask 1 from the bottom surface of the recess 2 to the top surface is t, a portion having the thickness T is formed. The metal mask portion and the metal mask portion forming the thickness t are separate members, and these members are joined.

  The metal mask 1 has a lower surface that covers the wiring substrate 12 and an upper surface on the opposite side, and the recess 2 is formed on the lower surface. What is necessary is just to process so that the thickness t which subtracted the depth of the recessed part 2 from the thickness of the metal mask 1 may become the thickness of a metal mask required in order to become a desired solder paste printing amount. The thickness of t need not be particularly limited, but is generally about 0.02 to 0.5 mm, and the thickness is adjusted according to the components mounted on the wiring board. The thickness T corresponding to the depth of the recess 2 is preferably 0.05 mm to the thickness of the wiring board. In the case of 0.05 mm or less, the effect of alignment by unevenness cannot be obtained. More preferably, T is made equal to the thickness of the wiring board. At this time, when the metal mask 1 is brought into close contact with the wiring board 12, the portion of the metal mask not corresponding to the wiring board 12 comes into close contact with the stage 10, the upper surface of the metal mask 1 becomes flat, and solder paste printing is performed while suppressing variations. It becomes possible. In the conventional metal mask 4 shown in FIG. 3, there is a gap between the metal mask and the squeegee at a place other than the wiring board 12, and the metal mask 4 may be distorted when the squeegee is run.

The recess 2 is formed by a flat bottom surface and a side surface that surrounds the bottom surface and is connected to the surface (lower surface) of the metal mask 1 that covers the wiring substrate 12. The side surface is formed as an inclined surface that inclines in a direction to reduce the area of the bottom surface from the surface (lower surface) of the metal mask 1 that covers the wiring substrate 12 to the bottom surface. In the present embodiment, the bottom surface is formed with a contour having the same dimensions as the contour of the wiring board 12. In other words, it is preferable that the recess 2 of the metal mask 1 has a taper-like shape that becomes smaller in the depth direction from the surface of the metal mask 1 and has the same dimensions as the wiring board 12 at the bottom of the recess 2. Assuming that the position where the wiring board 12 is placed on the stage 10 is in a range that can be accommodated in the recess 2, the positioning function is exhibited by making the recess 2 tapered. As the pitch becomes narrower, the allowable value of the positional deviation becomes smaller, and the fine adjustment by the positioning function becomes effective. Furthermore, if the bottom of the recess 2 has the same dimensions as the wiring board 12, the alignment is completed when the metal mask 1 and the wiring board 12 are in close contact.
The angle θ of the taper-like shape of the recess 2 shown in FIG. 4 is set in a range of 0 ° <θ ≦ 90 ° and need not be particularly limited, but a more preferable range of θ is 30 ° ≦ θ ≦ 70 °. It is. If the angle θ is small, the effect of correcting misalignment cannot be obtained. On the other hand, if the angle θ is large, the wiring board 12 does not enter the recess 2 and the position cannot be corrected.

FIG. 5 shows an embodiment of a solder printing process using the metal mask 1 of the present invention. By providing a plurality of the recesses 2 of the metal mask 1, batch solder paste printing on a large number of wiring boards becomes possible.
First, the wiring board 12 is placed on the stage 10 (FIG. 5A). At this time, the relative positions of the plurality of wiring boards 12 placed on the stage 10 are various. Next, the metal mask is lowered (FIGS. 5B and 5C). By using the metal mask 1 having the recess 2, when the metal mask 1 is lowered, the wiring substrate 12 is accommodated in the recess 2 while the positional deviation is corrected. When the metal mask 1 and the wiring board 12 are in close contact, the alignment is completed. After the metal mask is lowered, air is sucked from the suction holes 11 provided in the stage 10, and the wiring board 12 is brought into close contact with the stage 10. Thereafter, the solder paste 22 is printed using the squeegee 21 (FIG. 5D), and the metal mask is raised (FIG. 5E). Finally, release the adsorption of the wiring board and remove the board from the stage.
On the other hand, when the conventional metal mask 4 is used, the positional displacement of the wiring board 12 due to the lowering of the metal mask 4 cannot be corrected, and solder paste printing is performed with the positional displacement occurring (FIG. 6).

  The present invention relates to a metal mask used when a solder paste is printed on a wiring board, and a solder paste printing method using the metal mask. According to the present invention, in a solder paste printing process on a plurality of wiring boards, positioning becomes simple, and solder paste can be printed with high positional accuracy without causing problems such as a short circuit.

DESCRIPTION OF SYMBOLS 1 ... Metal mask 2 of this invention ... Recess 3 ... Hole 4 ... Conventional metal mask 5 ... Adhesive 6 ... Metal plate 10 for recessed part formation ... Stage 11 ... Adsorption hole 12 ... Wiring board 13 ... Pad 21 ... Squeegee 22 ... Solder paste 23 ... Solder bump

Claims (7)

In the metal mask that covers the wiring board in the process of printing the solder paste on the wiring board,
A plurality of recesses for accommodating the wiring board and positioning the wiring board are provided on the surface of the metal mask that covers the wiring board,
A hole is formed through the metal mask corresponding to the pad of the wiring board housed in the recess,
A metal mask characterized by this.   The metal mask according to claim 1, wherein the depth of the recess is equal to the thickness of the wiring board. The recess is formed by a flat bottom surface and a side surface that surrounds the bottom surface and is connected to the surface of the metal mask that covers the wiring board.
The side surface is formed of an inclined surface that is inclined in a direction to reduce the area of the bottom surface from the surface of the metal mask that covers the wiring board to the bottom surface,
The metal mask according to claim 1, wherein the bottom surface is formed with a contour having the same dimensions as the contour of the wiring board.   The angle θ formed by the inclined surface with respect to the bottom surface is 0 ° <θ ≦ 90 °, and preferably 30 ° ≦ θ ≦ 70 °. The metal mask described.   The metal mask has a lower surface that covers the wiring board and an upper surface on the opposite side, the recess is formed on the lower surface, and the thickness of the metal mask from the lower surface to the bottom surface of the recess is T. When the thickness of the metal mask from the bottom surface of the recess to the top surface is t, the metal mask portion forming the thickness T portion and the metal mask portion forming the thickness t portion are: The metal mask according to claim 1, wherein the metal mask is the same member.   The metal mask has a lower surface that covers the wiring board and an upper surface on the opposite side, the recess is formed on the lower surface, and the thickness of the metal mask from the lower surface to the bottom surface of the recess is T. When the thickness of the metal mask from the bottom surface of the recess to the top surface is t, the metal mask portion forming the thickness T portion and the metal mask portion forming the thickness t portion are: The metal mask according to claim 1, wherein the metal mask is a separate member, and the members are joined.   A solder paste printing method, comprising: printing a solder paste on a wiring board using the metal mask according to claim 1.

Images