JPH01300589A - Printing machine - Google Patents

Abstract

PURPOSE:To accelerate rolling of printing paste for making it easy to obtain stable printing result with high precision by providing recesses on a part of a metal foil to be brought into contact with the printing paste, the metal foil having elasticity for stabilizing scraping pressure. CONSTITUTION:A printing machine comprises a metal mask plate 3 having through-hole patterns and an elastic metal foil squeegee 8 to be pressed against the metal mask plate 3 at a predetermined angle so as to scrape the printing paste 1 put on the metal mask plate for printing on a printed wiring board 2 disposed below the metal mask plate 3, The squeegee 8 further includes recesses of a predetermined depth formed on the side thereof to be brought into contact with the printing paste 1. Since the metal foil squeegee 8 for scraping the printing paste has elasticity, initial scraping pressure can be obtained always stably and hence it is possible to obtain printing result with high reproducibility easily. Further, since the surface of the metal foil to be in contact with the printing paste has recesses, it is possible to accelerate rolling of the printing paste that is an important factor for stabilizing the printing result.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a printing machine for printing printing paste cream solder or the like on printed wiring boards.

Conventional technology In recent years, in the technology for surface mounting semiconductor flat packages, chips, etc. onto printed wiring boards, there has been a remarkable trend toward finer pitch leads for semiconductor flat packages. Techniques for improving accuracy are becoming increasingly important.

Conventionally, this Keyaki printing press had the structure shown in Figure 6.

1 is cream solder of the printing paste to be printed on the printed wiring board 2; 3 is a metal mask plate with hole pattern parts 4 provided in the areas to be printed on the printed wiring board 2; 6 is located above the metal mask plate 3. This is a rubber squeegee. Reference numeral 6 denotes a holder for holding the rubber squeegee 5, and 7 is a printed wiring temporary holder for holding the printed wiring board.

The operation of this printing press will be explained below.

Press the rubber squeegee 6 onto the metal mask plate with a predetermined pressure F, and apply the cream solder 1 on the metal mask plate to the hole pattern portion 4 of the metal mask plate as shown in Fig. 6.
Push it in as shown in a, and scrape off the cream solder 1b that is not pushed in. After that, the printed wiring temporary holder is made by lowering the tool 7 in the direction of arrow B by the H dimension in FIG. As shown in the figure, it is printed on a printed wiring board separated from the metal mask plate.

Problems to be Solved by the Invention In such a conventional configuration, the scraping pressure F is largely dependent on the elasticity of the rubber squeegee, which is in pressure contact with the rubber squeegee during printing. No pressure can be obtained.

Therefore, as shown in FIG. 8, there is a drawback in that the print quality is likely to cause printing sag, in which the 01 of the print shape becomes large and the T2 becomes small.

For this reason, in recent years, in surface mounting technology for semiconductor packages, the S dimension of the printed pattern shown in Figure 9 has tended to become extremely small. This becomes a manufacturing bottleneck. Furthermore, as shown in Fig. 10, there is a degree of freedom in the elastic direction of the rubber of the rubber squeegee.
The central part of the cream solder pattern part printed by T1 in the figure has become smaller. Another problem is that printing with cream solder is better if the cream solder is rolled as fluidly as possible when scraped off with a squeegee, but the rolling properties are not good either.

The present invention solves the above-mentioned drawbacks of the conventional printing presses, and is capable of stably maintaining the initially set scraping pressure regardless of the number of printings, maintaining a highly reproducible printing condition, and printing. To provide a printing machine that activates the rolling of the paste during scraping and printing.

Means for Solving the Problems The printing machine of the present invention presses a metal mask plate having a hole pattern portion against the metal mask plate at a predetermined angle, scrapes off the printing paste on the metal mask plate, and prints the metal mask. It is equipped with a thin metal plate squeegee having spring properties and having unevenness of a predetermined depth on one side that contacts the printing paste to be printed on the printed wiring board located below the plate.

Due to the springiness of the thin metal sheet squeegee, the initial scraping pressure is always constant, making it easy to obtain highly reproducible printing conditions.

Furthermore, by providing irregularities on the surface of the thin metal plate that is in contact with the printing paste, it is possible to activate the rolling of the printing paste, which is an important factor in stabilizing the printing state.

Embodiment An embodiment of the printing press of the present invention will be described with reference to FIGS. 1 to 4.

In FIG. 1, 8 is a metal thin plate squeegee, and 9 is a metal thin plate squeegee holder for holding the metal thin plate squeegee.

Note that 1 is a cream solder which is a printing paste, 2 is a printed wiring board, 3 is a metal mask plate, 4 is a hole pattern part of the metal mask plate, and 7 is a printed wiring temporary holding tool, which is the same as the conventional structure. It's the same thing.

The operation of the printing machine of this embodiment configured as described above will be described below.

The metal thin plate squeegee 8 is brought into contact with the metal mask plate 3 at a predetermined angle α, and a predetermined pressure F is applied to apply the spring pressure of the metal thin plate, and the metal mask plate 3 is moved in the entry direction while maintaining the spring pressure. This causes the printing paste 1 on the metal mask plate 3 to be rolled in the direction shown by the arrow H.

As shown in FIG. 3, this O-ring becomes active when the printing paste is scraped by providing an uneven pattern with a depth L on the surface of the thin metal squeegee. Figure 4a,
Shown in b. Arrow E shows a state in which unevenness is provided on the surface of the thin metal plate squeegee to activate the rolling of the printing paste, and arrow G shows a state in which unevenness is not provided on the surface of the thin metal plate squeegee.

With this active rolling, the printing paste 1 on the metal mask plate 3 is pushed into the punch hole pattern portion 4 of the metal mask plate as in the conventional case.

The following operation is similar to the conventional example.

FIG. 2 shows the state printed in this manner.

T3 in Fig. 2 is smaller than T1 in Fig. 8 and can ensure a printing amount, and 02 in Fig. 2 is much smaller than 01 in Fig. 6. Therefore, T4 in Fig. 2 is smaller than T1 in Fig. 6. You can print both large and small prints.

Effects of the Invention As described above, according to the printing machine of the present invention, the scraping pressure is stabilized due to the springiness of the thin metal plate, and the unevenness is provided in the area where the thin metal plate contacts the printing paste. The rolling of the paper can be activated, and a stable and highly accurate printing condition can be obtained very easily. Therefore, it is possible to cope with finer pitch printing patterns in surface mounting technology, and is extremely useful in practice.

[Brief explanation of the drawing]

FIG. 1 is a side view of a printing press according to an embodiment of the present invention, FIG. 2 is a diagram of the printing state of the printing paste printed by the printing machine of the present invention, and FIG. 3 is a diagram of the surface state of P in FIG. 1. , Fig. 4a is a flow diagram of the printing paste when the surface condition shown in Fig. 3 is present, Fig. 4a is a flow diagram of the printing paste when the surface condition shown in Fig. 3 is not present, and Fig. 6 is a flow diagram of the printing paste when the surface condition shown in Fig. 3 is not present. 6 is a side view of a conventional printing press, FIGS. 6 and 7 are diagrams showing the process of printing the printing paste 1 on a printed wiring board 2 by operating the printing press of FIG. 6, and FIG. 8 is a side view of a conventional printing press. FIG. 9 is a printing pattern diagram of a printing paste printed by a conventional printing machine, and FIG. 10 is a diagram of a contact state between a rubber squeegee and a metal mask plate in a conventional printing machine. 1... Printing paste, 2... Printed wiring board, 3... Metal mask plate, 4... Hole pattern section, 5...・Rubber squeegee, 6...
...Holder, 7... Printed wiring temporary holder is a tool. Name of agent: Patent attorney Toshio Nakao and 1 other person! −
Printing paste No. 5rIl

Claims (1)

[Claims] A metal mask plate having a hole pattern portion, and a thin metal plate squeegee with spring properties that presses against the metal mask plate at a predetermined angle and has irregularities of a predetermined depth on one side in contact with the printing paste. A printing machine characterized in that the printing paste on the metal mask plate is scraped off and printed on a printed wiring board located below the metal mask plate.