JPH05131609A - Solder paste printing machine - Google Patents

Abstract

PURPOSE:To prevent generation of unevenness in supply quantity of solder paste or bridge, by a method wherein in a solder paste printing machine, an ultrasonic vibration is given to at least one of a mask and printed wiring board. CONSTITUTION:A conductive foil is formed on a fixed position corresponding to a lead of electronic parts possessing a large number of leads on a mounting surface of a printed wiring board 2. A metallic mask 1 is formed of a stainless steel mesh to obtain printing strength and accuracy of solder paste and an opening pattern 1a is formed on a position corresponding to the conductor foil of the printed wiring board 2. Then the title machine is constituted so that an ultrasonic vibrator 4 is joined to the metallic mask 1, an ultrasonic vibration is oscillated by a driving source and the ultrasonic vibration is given to the metallic mask 1.

Description

Detailed Description of the Invention

 [Object of the Invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solder paste printing machine for supplying solder paste to a predetermined conductor foil surface on a mounting surface of a printed wiring board by using a mask having openings.

[0002]

2. Description of the Related Art Generally, when mounting an electronic component having a large number of leads on a printed wiring board, the large number of leads are simultaneously thermocompression-bonded to the printed wiring board. In order to mount the electronic component in this manner, it is necessary to previously supply the solder paste to the predetermined conductor foil surface on the mounting surface of the printed wiring board by printing or the like.

Therefore, in the solder paste printing machine,
To the metal mask made of stainless steel rope mesh,
An opening pattern is formed on the mounting surface of the printed wiring board at a position corresponding to the predetermined conductor foil on which the solder paste is to be printed, and after positioning this metal mask and the printed wiring board, the metal mask is mounted on the mounting surface of the printed wiring board. And the solder paste is supplied from above the metal mask to print the solder paste on a predetermined conductor foil.

[0004]

However, the conventional solder paste printing machine as described above has the following problems.

The number of leads of electronic parts mounted on a printed wiring board is increasing more and more, and the pitch between the leads is becoming narrower accordingly. For example, when the pitch between leads is reduced to about 0.3 mm, it is necessary to use a metal mask in which the interval of each opening pattern of the metal mask is about 0.15 mm. Then, when separating the metal mask and the printed wiring board that are in close contact after printing the solder paste, due to the viscosity of the solder paste,
Part of the solder paste remains on the metal mask side, and the amount of solder paste supplied to the conductor foil on the printed wiring board becomes sparse. It had happened. In addition, the solder paste may drip and form a bridge between adjacent conductive foils, which causes a problem in reducing the reliability of the product. [Constitution of Invention]

[0006]

The present invention has been made to solve the above-mentioned technical problems, and a mask having an opening pattern is provided on a mounting surface of a printed wiring board on which electronic parts are mounted. In a solder paste printing machine that supplies solder paste via a solder paste printing machine, ultrasonic vibration is applied to at least one of the mask and the printed wiring board.

[0007]

As described above, according to the present invention, in the solder paste printing machine, ultrasonic vibration is applied to only the metal mask, only the printed wiring board, or both the metal mask and the printed wiring board. After the paste is supplied, when the metal mask is peeled off from the printed wiring board, the solder paste remains on the metal mask, which is caused by uneven supply of the solder paste or the solder paste dripping. It is possible to prevent a bridge and the like.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIG. Reference numeral 2 in the drawing denotes a printed wiring board, and a conductor foil is formed on a mounting surface (upper surface in the drawing) of the printed wiring board 2 at predetermined positions corresponding to leads of an electronic component having a large number of leads. ing. Reference numeral 1 denotes a metal mask. The metal mask 1 is formed of stainless steel mesh or the like in order to obtain the printing strength and accuracy of the solder paste, and is opened at a position corresponding to the conductor foil of the printed wiring board 2. The pattern 1a is formed. An ultrasonic vibration transmitter 4 is connected to the metal mask 1, and is configured to oscillate ultrasonic vibration by a drive source (not shown) to apply ultrasonic vibration to the metal mask 1.

Regarding the printing of the solder paste 3, first, the printed wiring board 2 is moved by a transfer device (not shown).
The solder paste printing machine is transported and arranged on a predetermined table (not shown) with the mounting surface facing upward. Next, the position of the conductor foil of the printed wiring board 2 to which the metal mask 1 has been conveyed and the opening pattern 1a formed in the metal mask 1 face each other, and the X of the solder paste printing machine is used.
Positioning is performed by a Y-direction drive mechanism (not shown).
After the metal mask 1 is positioned, the metal mask 1 is lowered by a predetermined amount by a vertical drive mechanism (not shown) of the solder paste printing machine and comes into contact with the printed wiring board 2 in a positioned state.

After the conductor foil of the printed wiring board 2 and the opening pattern 1a of the metal mask 1 are positioned, the solder paste is extruded from the tubular orifice by using pressurized air to supply a predetermined amount of solder paste. A device (not shown) supplies the solder paste onto the positioned metal mask 1, and the solder paste is poured into the opening pattern 1a of the metal mask 1. When a predetermined amount of solder paste is supplied to the opening pattern 1a of the metal mask 1, ultrasonic waves are transmitted to the metal mask 1 in the vertical direction (hereinafter simply referred to as Z direction) by the ultrasonic vibration transmitter 4. Vibration is applied, and the metal mask 1 is peeled off from the printed wiring board 2 while the ultrasonic vibration is applied. By doing so, the supplied solder paste that is in close contact with the metal mask 1 is peeled off without remaining on the back surface of the metal mask 1 or the like. Since the amplitude of ultrasonic vibration applied to the metal mask 1 is extremely small, the supplied solder paste 3 does not lose its shape and the solder paste 3 is applied onto a predetermined conductor foil of the printed wiring board 2. It is possible to accurately print a predetermined amount.

The ultrasonic vibration applied to the metal mask 1 is
It is configured to be changed depending on the type of solder paste to be printed, viscosity, or the like, and the frequency range is 28 KHz to 250 KHz, and an optimum frequency is selected and applied from this range.

FIG. 2 is a diagram showing a second embodiment, in which the ultrasonic vibration applied to the metal mask 1 is not in the Z direction but in the Z direction.
The configuration is such that it is given in the X direction or the Y direction as indicated by arrows X and Y. Since other configurations are similar to those of the first embodiment, the same reference numerals are given and the description thereof is omitted.

FIG. 3 shows a third embodiment having a structure for applying ultrasonic vibration to the printed wiring board 2. The configurations other than the ultrasonic vibration transmitter 4 in the first and second embodiments and the ultrasonic vibration transmitter 5 in this embodiment are the same as those in the first embodiment described above.
Since the second embodiment is the same as the second embodiment, the same reference numerals are given and the description thereof is omitted.

The ultrasonic vibration transmitter 5 is a printed wiring board 2
And is configured to apply ultrasonic vibration in the Z direction, the X direction, or the Y direction as in the first and second embodiments. The ultrasonic vibration applied at this time is 28 K as in the case of applying to the metal mask 1.
The ultrasonic vibration most suitable for the solder paste to be supplied is selected and applied from the frequency in the range of Hz to 250 KHz. Even with such a configuration, it is possible to obtain the same effects as those of the first and second embodiments.

In the first and second embodiments, the ultrasonic vibration is applied only to the metal mask 1, and in the third embodiment, the ultrasonic vibration is applied only to the printed wiring board 2. In the fourth embodiment, as shown in FIG. 4, ultrasonic vibration is applied parallel to both the metal mask 1 and the printed wiring board 2.

The ultrasonic vibration transmitter 4 is for applying ultrasonic vibration to the metal mask 1 as in the first and second embodiments, and the ultrasonic vibration transmitter 5 is for the third embodiment. This is a device configured to apply ultrasonic vibration to such a printed wiring board 2. The ultrasonic vibration transmitters 4 and 5 apply vibrations in the Z direction, the X direction, or the Y direction to the metal mask 1 and the printed wiring board 2, respectively, as described in the first to third embodiments. It is possible. Therefore, the metal mask 1 and the printed wiring board 2
There are many possible combinations of vibrations to be applied to. In particular, when the metal mask 1 is applied in the Z direction, the printed wiring board 2 has one of the three directions of X, Y, and Z directions.
Direction, the Z direction is applied to the printed wiring board 2 when the X direction is applied to the metal mask 1, or the Z direction is applied to the printed wiring board 2 when the Y direction is applied to the metal mask 1. Five cases are valid.

When the solder paste is printed by using the two ultrasonic vibration transmitters 4 and 5 in this manner, the ultrasonic vibrations to be applied have different frequencies or opposite phases. Of the above-mentioned five cases, in the case where the Z direction ultrasonic vibration is applied to the metal mask 1 and the Z direction ultrasonic vibration is also applied to the printed wiring board 2, especially the ultrasonic vibration is applied. If the frequencies of the ultrasonic vibrations transmitted from the transmitters 4 and 5 are given in opposite phases, a more uniform printing of the solder paste can be achieved, and a better effect can be obtained. is there. At this time, the vibration timing of the ultrasonic vibration applied to the metal mask 1 and the printed wiring board 2 can be arbitrarily set depending on the situation such as the opening pattern 1a of the metal mask 1.

As described above, since the vibration timing to the metal mask 1 and the printed wiring board 2 can be set arbitrarily, for example, the metal mask 1
In the case where there is a large variation in the size of the opening pattern 1a formed in, the ultrasonic vibration of low frequency corresponding to the relatively large opening pattern is first applied, and then the relatively small opening pattern is dealt with. It is also possible to set to apply ultrasonic vibration of high frequency.

1 to 4, which correspond to the above-described first to fourth embodiments, one ultrasonic vibration transmitter for applying ultrasonic vibration to the metal mask 1 or the printed wiring board 2 is provided. Although described, it is possible to apply the same frequency or different frequencies as a configuration for applying ultrasonic vibrations from a plurality of locations. At this time, the vibration timing of ultrasonic vibration applied to the metal mask 1 and the printed wiring board 2 at a plurality of positions can be arbitrarily set according to the printing condition of the solder paste. For example, in the case where the fine opening pattern and the relatively large opening pattern are biased toward both ends on the metal mask, ultrasonic vibration of high frequency is applied from the side where the fine opening patterns are gathered, and comparison is performed. A high effect can be obtained by applying ultrasonic vibration of a low frequency from the side where the large opening patterns are gathered. However, in the case where the ultrasonic vibration is applied from a plurality of places as described above, there is a risk that the ultrasonic vibrations interfere with each other and a part that does not transmit the vibration is left, but the ultrasonic vibration is applied. However, it is possible to eliminate such a problem easily by obtaining the position where such a problem does not occur in advance. Moreover, as described above, the vibration timing can be set arbitrarily. Since it is possible, it is possible to eliminate defects by adjusting these.

Further, as described in the fourth embodiment, the ultrasonic vibration applied to the plural places of the metal mask 1 and the printed wiring board 2 is compared with a low frequency corresponding to a relatively large opening pattern. It is also possible to set so that a high frequency corresponding to a fine opening pattern is applied at different timings.

In the first to fourth embodiments described above, the metal mask 1 formed by the stainless steel mesh is applied, but the present invention is not limited to this, and the metal mask 1 is made of a photographic emulsion. It is also possible to apply a silk screen or a metal screen.

Further, in the first to fourth embodiments, the dispenser device is applied to supply the solder paste. However, if the solder paste can be supplied in addition to this device, the dispenser device can be manually supplied. Of course, it is also possible to apply various methods.

[0023]

As described above, in the solder paste printing machine of the present invention, after the solder paste is supplied to the opening pattern of the metal mask, only the metal mask or only the printed wiring board, or the metal mask and the printed wiring board. Solder paste was printed by peeling the metal mask from the printed wiring board while applying ultrasonic vibration to both of them, so after supplying the solder paste, the metal mask can be maintained without breaking the supply form of the solder paste. Can be peeled off, so
Since the amount of solder paste supplied to the printed wiring board can be made uniform and the occurrence of bridges between the conductor foils having a narrow pitch can be reduced as much as possible, a multi-terminal electronic component having leads with a narrow pitch can be obtained. It becomes possible to easily and accurately mount the product, which contributes to the improvement of the reliability of the product.

Further, since the amount of the solder paste remaining on the metal mask can be reduced, the number of times of cleaning the metal mask can be reduced, which contributes to the improvement of the mobility of the solder paste printer.
Further, it is possible to reduce the mounting cost.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment.

FIG. 2 is a diagram showing a second embodiment.

FIG. 3 is a diagram showing a third embodiment.

FIG. 4 is a diagram showing a fourth embodiment.

[Explanation of symbols]

 1 Metal Mask 1a Opening Pattern 2 Printed Wiring Board 3 Solder Paste 4,5 Ultrasonic Vibration Transmitter

Claims (1)

[Claims] 1. A solder paste printing machine for supplying a solder paste through a mask having an opening pattern on a mounting surface of a printed wiring board on which electronic components are mounted, wherein at least one of the mask and the printed wiring board is superposed. A solder paste printing machine comprising an ultrasonic vibration applying mechanism for applying sonic vibration.