JPH09162534A - Solder applying method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To separate surely solders with very small surface areas from a metallic mask plate and apply them in predetermined sizes to a printed board, using the conventional metallic mask plate and paste-like solders. SOLUTION: A solder applying device comprising a container 20 formed out of a recessed holder 7 stuck fixedly on a metallic mask plate 2; a pressure pump 8 for sending, e.g. air 10 to the container 20; an exhausting hole 11 for controlling the air pressure; an exhausting plate 5 with a spring 6 and for separating the metallic mask plate 2 from a printed board 3; an exhausting guide 4 for guiding the exhausting plate 5; and an updown cylinder 9 for pressing the metallic mask plate 2 of the container 20 against the printed board 3, in whose solder applying method, pressing the surfaces of paste-like solders 1 by the air pressure, the metallic mask plate 2 is separated from the printed board 3 to apply the solders 1 to the printed board 3 identically with patterns.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for applying solder to a substrate and a coating apparatus for manufacturing a product in which a surface mount device (SMD) is mounted.

[0002]

2. Description of the Related Art In recent years, in order to reduce the size and weight of products and increase the integration of mounted devices, surface mount devices have been used remarkably. In the process of soldering this surface mount device to a board such as a printed board, a metal mask board (or a screen mask board may be installed) on the printed board, and a paste-like (highly viscous liquid) is placed on the metal mask board. Solder, place the solder on the solder application area with a brush, mount the solder on the printed board (this process is called the coating and printing process), place the surface mount type device terminals on the solder, and remove the nitrogen atmosphere. The surface mounting type element is soldered to the printed board by melting and solidifying the solder in a reflow furnace or the like.

3A and 3B are views showing a conventional solder coating method. FIG. 3A shows a state in which a metal mask plate and a printed board are in contact with each other, and FIG. 3B shows a metal mask board and a printed board. The state figure which left | separated shows. The metal mask plate 2 having holes 13 corresponding to the solder application points on the printed board 3 is set on the printed board 3, and the paste-like solder 1 is applied to the metal mask board 2
Place it on top and insert the solder 1 into this hole with a brush or the like ((a) in the same figure). After that, only the metal mask plate 2 is moved upward, and the solder 1 is separated from the side surface of the hole 13 of the metal mask 2 by the weight of the solder 1 and the adhesive force between the solder 1 and the printed board 3.
The solder 1 was applied by being left on the printed board 3 (pointing to the solder 1 having a large area on the right side of FIG. 3B).

[0004]

However, recently, in order to reduce the size of the printed board and increase the degree of integration of components, it has become necessary to mount a downsized surface mount device on the printed board. Therefore, the soldered portion on the printed board has a very small area. Correspondingly, the holes on the metal mask where the solder is applied become smaller, and when the metal mask plate is separated from the printed circuit board after the solder is filled with the solder, the weight of the solder is small and it adheres to the printed circuit board. Since the force is also small, the adhesive force on the side surface of the hole of the metal mask plate is larger, and the solder adheres to the metal mask plate side, and the solder of a predetermined size does not remain on the printed board, and the solder is applied to the printed board. Not possible (Fig. 3
(B) Refers to the solder 1 having a small area on the left side). In order to prevent this, there is also a method of reducing the thickness of the metal mask plate in the area where the surface mount device is small, that is, in the area where the solder application area is small. , It is not realistic due to the wide variety of products,
Further, it is difficult to develop a solder having an increased adhesiveness with a printed board, because it requires a great deal of cost and development time.

The object of the present invention is to solve the above problems by
A coating method and a coating device capable of reliably peeling the solder from the metal mask plate using a conventional metal mask plate and a conventional paste-like solder, and coating a solder having a small area on a printed board with a predetermined size. To provide.

[0006]

In order to achieve the above object, in a method of applying paste-like solder to a substrate, a metal mask plate is placed on the substrate, and the paste placed on the mask plate. The solder paste is filled in the opening of the mask plate with solder-like solder, the surface of the solder is pressed with a gas at a pressure higher than atmospheric pressure, the solder is peeled off from the mask plate, and the solder is left on the substrate and applied. Good.

In order to realize the above-mentioned coating, a container is constituted by a mask plate made of metal and a concave holder fixed to the mask plate, and a pressure pump for sending gas into the container and the mask plate from the substrate. A device having a mechanism for attaching and detaching. The thickness of this mask plate is 0.1mm to 0.3mm
And the minimum width of the solder application point is 0.1mm to 0.3m
It is good to set m.

By utilizing the air pressure as described above, the adhesive force (including frictional resistance) between the side surface of the hole of the metal mask plate and the solder is overcome, the solder is peeled from the metal mask plate, and a predetermined size is achieved. The solder remains on the printed board, and solder is reliably applied to the printed board.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an embodiment of the present invention and is a cross-sectional view of an essential part of a solder coating apparatus. A container 20 composed of a concave holder 7 fixed on the metal mask plate 2,
For example, a pressure pump 8 for sending air 10 to the container 20, an exhaust hole 11 for adjusting the air pressure, an exhaust plate 4 with a spring 6 for separating the metal mask plate 2 from the printed board 3, and an exhaust guide for guiding the exhaust plate, A solder applicator is configured by the upper and lower cylinders 9 that press the metal mask plate 2 of the container 20 against the printed board 3. It should be noted that an inert gas such as nitrogen gas may be used instead of the air 10. Further, it is of course applicable to solder coating on a substrate other than the printed board 3 on which a surface mounting element such as a ceramic plate is mounted.

FIG. 2 is a state diagram in which the metal mask plate of the container is separated from the printed board. The solder 1 remains on the printed board 3, and the metal mask board 2 is pressed by the spring 6 to the printed board 3.
Move away from A solder coating method will be described with reference to FIGS. 1 and 2.
FIG. 1 shows a state in which the paste-like solder 1 is inserted into the holes 13 of the metal mask plate 2 at the solder application points by using a brush or the like. In this state, air pressure of about 1.2 to 1.5 atm is blown from the pressure pump 8 to pressurize the surface of the solder 1. When the upper and lower cylinders 9 are lifted upward, the exhaust plate 5 is pulled by the force of the contracted spring 6 as shown in FIG.
Pushes the printed board 3, and one end of the spring 6 holds the container 20.
The container 20 is lifted and the metal mask plate 2 is separated from the printed board 3 because it is fixed to the printed board 3. At this time, solder 1
Is pressed against the printed board 3 by air pressure and overcomes the adhesive force and frictional resistance between the side surface of the hole 13 of the metal mask plate 2 and the solder 1, the solder 1 remains on the printed board 3, and the solder 1 according to the pattern is printed. 3 coated. The air 10 in the container 20 is exhausted from the exhaust holes 11 and 12 so that excess air pressure is not applied to the solder 1 when the metal mask plate 2 separates from the printed board 3. The thickness of the metal mask plate 2 is about 0.1 mm to 0.15 mm, and the solder 1 can be reliably printed even in an extremely small area of about 0.3 mm in length and 1.2 mm in width at the solder application spot. It can be applied to the board 3, and small surface mount elements can be reliably soldered to the printed board 3. Since the process after solder application is the same as the conventional process, the description is omitted here. The material of the metal mask plate 2 is stainless steel, phosphor bronze, or the like.

[0011]

According to the present invention, by pressing the paste-like solder surface with air pressure, the solder is peeled off from the metal mask plate and the solder is surely left on the printed board in minute solder application, The area can be applied with solder, and a small surface-mounted element can be soldered to the printed board, so that the printed board can be downsized or mounted components can be highly integrated.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an essential part of a solder coating device according to an embodiment of the present invention.

FIG. 2 is a state diagram in which the metal mask plate is separated from the printed board.

FIG. 3 is a diagram showing a conventional solder application method, in which (a) is a state diagram in which a metal mask plate and a printed board are in contact with each other,
(B) is a state diagram in which the metal mask plate and the printed board are separated.

[Explanation of symbols]

 1 Solder (paste) 2 Metal mask plate 3 Printed board 4 Exhaust guide 5 Exhaust plate 6 Spring 7 Holder 8 Pressure pump 9 Upper and lower cylinders 10 Air 11 Exhaust hole 12 Exhaust hole 13 Hole 20 Container

Claims (3)

[Claims] 1. A method for applying a paste-like solder to a substrate, wherein a metal mask plate is placed on the substrate, and the paste-like solder placed on the mask plate is applied to a solder application point at an opening of the mask plate. A solder coating method, which comprises filling the solder surface with a gas having a pressure higher than the atmospheric pressure, peeling the solder from the mask plate, and leaving the solder on the substrate for coating. 2. A container comprising a metal mask plate and a concave holder fixed to the mask plate, comprising a pressure pump for feeding gas into the container, and a mechanism for attaching and detaching the mask plate to and from the substrate. Characteristic solder coating device. 3. A mask plate having a thickness of 0.1 mm to 0.3.
mm, the minimum width of the solder application spot is 0.1 mm to 0.
The solder applicator according to claim 2, wherein the solder applicator is 3 mm.