JPH0550776A - Metal masking plate - Google Patents

Abstract

(57) [Summary] [PROBLEMS] The present invention relates to a metal mask plate having a taper in an opening portion, which improves the release property of cream solder from the metal mask plate, and has a high cream solder printing quality and a printed circuit board. The purpose is to ensure the quality of the joint. [Structure] An opening 9 of a metal mask plate 8 is tapered so that its diameter increases in the removing direction of cream solder. [Effect] Since the opening portion is tapered, the contact resistance when removing the cream solder is small, and the change in the amount of cream solder can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal mask plate used for cream solder printing.

[0002]

2. Description of the Related Art In recent years, with the progress of surface mounting technology, metal mask plates have been made compatible with narrow pitches. A conventional metal mask plate will be described below with reference to the drawings.

FIG. 4 is a block diagram of a conventional cream solder printing machine, and FIG. 5 is an enlarged sectional view of a metal mask plate in the conventional cream solder printing machine.

In FIG. 4, reference numeral 1 denotes a metal mask plate, which is provided with a straight opening 7 as shown in FIG. 5 (not shown in FIG. 4). Reference numeral 2 denotes a squeegee, which fills the straight opening 7 while moving the cream solder 6. A printed circuit board 3 is placed on the suction block 4 for solder printing. Further, 5 is a guide plate.

The operation of the cream solder printing machine configured as described above will be described below. First, the printed circuit board 3 is mounted on the suction block 4 and rises while being guided by the guide plate 5. Printed circuit board 3
When the metal mask plate 1 is superposed on the metal mask plate 1, the cream solder 6 supplied on the metal mask plate 1 is moved by the squeegee 2 and is buried in the straight opening portion 7 of the metal mask plate 1. The filled cream solder 6 descends together with the printed circuit board 3, the suction block 4 and the guide plate 5 and comes out of the metal mask plate 1. The cream solder 6 is printed on the printed circuit board 3.

[0006]

However, in the above structure, since the contact resistance when removing the cream solder is large between the cream solder and the inner surface of the straight opening portion of the metal mask plate, the metal having a narrow pitch interval is used. The mask plate has a problem that unless the contact resistance is further reduced and the releasing property is not improved, the amount of cream solder changes and it is impossible to prevent an open or a short circuit at the joint between the semiconductor and the printed circuit board. The present invention solves the above conventional problems, and an object thereof is to improve the detachability of cream solder from a metal mask plate and to improve the quality of cream solder printing.

[0007]

In order to achieve the above object, the means of the present invention is to provide a taper having a diameter increased in the opening direction of the cream solder in the opening portion of the metal mask plate.

[0008]

With the above structure, when the cream solder is removed from the opening of the metal mask plate, the contact resistance is smaller than in the conventional case, and therefore the change in the amount of cream solder can be minimized and removed.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is an enlarged block diagram of a metal mask plate according to the first embodiment of the present invention. In FIG. 1, 8 is a metal mask plate, and 9 is a tapered opening.

Since the apparatus of this embodiment shown in FIG. 2 has basically the same configuration as the conventional apparatus shown in FIG. 4, the same components are designated by the same reference numerals and detailed description thereof will be given. The description is omitted.

The difference from the prior art is that the opening 9 provided in the metal mask plate 8 has a taper whose diameter increases in the removing direction of the cream solder as shown in FIG.

The operation of the cream solder printing machine having the above-described structure and the metal mask plate incorporated therein will be described below.

First, the printed circuit board 3 is mounted on the suction block 4 and ascended while being guided by the guide plate 5. When the metal mask plate 8 is superposed on the printed circuit board 3, the cream solder 6 supplied on the metal mask plate 8 is moved by the squeegee 2 and is buried in the tapered opening 9 of the metal mask plate 8. Buried cream solder 6
Moves down together with the printed circuit board 3, the suction block 4 and the guide plate 5 and exits from the metal mask plate 8. The cream solder 6 is printed on the printed circuit board 3.

As described above, according to this embodiment, the taper is provided in the opening of the metal mask plate, so that when the cream solder is removed from the opening of the metal mask plate, the amount of cream solder is small with a small contact resistance. The change in can be minimized and eliminated. Therefore, the print quality of the cream solder can be improved, and the defective rate of the cream solder printing can be reduced as shown in FIG.

[0016]

As described above, according to the present invention, by providing a taper on the opening of the metal mask plate, the change in the amount of cream solder can be minimized and removed with a small contact resistance. It is possible to realize the excellent cream solder printing which can improve the quality of the joint portion of the printed circuit board.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view of a metal mask plate according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a cream solder printing machine according to the first embodiment of the present invention.

FIG. 3 is a defect rate curve diagram in the first embodiment of the present invention.

FIG. 4 is a block diagram of a conventional cream solder printing machine.

FIG. 5 is an enlarged sectional view of a conventional metal mask plate.

[Explanation of symbols]

 1,8 Metal mask plate 2 Squeegee 3 Printed circuit board 4 Suction block 5 Guide plate 6 Cream solder 7 Straight hole 9 Taper hole

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Aiichi Takei 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (1)

[Claims] 1. A metal mask printing plate for printing cream solder, wherein the opening has a taper having a diameter increased in accordance with a cream solder removing direction.