JPH1024551A - Squeegee of solder paste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize emitting quantity by providing two stirring rods rotated mutually contrarily toward an emitting orifice to a stirring part for kneading solder paste passing through the emitting orifice. SOLUTION: This squeegee openes a container lid 4 and, after solder paste is supplied into a metal container 1, the lid is closed to be fixed by setscrews 5 to hermetically close the container 1. By this constitution, deterioration such as the viscosity change or oxidation of solder paste can be minimized. Two stirring rods 2 are provided in the container 1 to be rotated by an external motor 3. Two stirring rods 2 are rotated in an inside direction toward an emitting orifice 6. By these stirring rods 2, the solder paste 7 is stirred and emitting pressure is generated toward the emitting orifice 6. The cross section of each stirring rod 2 may be circular but, by cutting grooves in the surface of the stirring rod to form a screw like cross section, stirring effect is generated still more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solder paste squeegee, and more particularly, to a squeegee at a predetermined position on a printed wiring board.
The present invention relates to a squeegee of a screen printing apparatus for supplying a predetermined amount of a printing agent such as a solder paste by printing.

[0002]

2. Description of the Related Art A squeegee is mounted on a screen printing machine used for printed wiring of a printed wiring board on which electronic components are mounted. Prior to a step of soldering a circuit pattern of the printed wiring board, a solder paste is screen-printed on a circuit pattern. Used in the step of applying to

Conventionally, a squeegee of this type has a closed container for storing solder paste, a discharge port provided at a lower portion of the container, and a stirring section for kneading the solder paste passing through the discharge port. It is composed of

[0004] The closed type container for storing the solder paste is for preventing the solder paste from being oxidized and preventing the solderability from being deteriorated. This is to keep the amount of the paste constant.

As a conventional example of this type of squeegee, there is one disclosed in Japanese Patent Application Laid-Open No. 4-284249. FIG.
FIG. 1 is a cross-sectional view showing a squeegee portion of this publication. In this example, the printing agent is cream solder, but the syringe 37 is used.
Creamy solder 3 shielded from the atmosphere
6 is a stirring roller 32 eccentric in a casing 35.
Is stirred to a viscosity suitable for printing, and the ejection port 31 is pressed by its own weight and the pushing force of the nitrogen gas supplied to the syringe 37.
And printed on a printed circuit board.

As described above, in the conventional example, the creamy solder is stirred by the eccentric stirring roller, and the stirred creamy solder is discharged from the discharge port by the pushing force of its own weight and nitrogen gas. It is supposed to.
Therefore, the discharge amount is determined by the viscosity of the cream solder, its own weight, and the nitrogen gas pressure.However, when the viscosity of the printing agent such as the cream solder or its own weight changes, it becomes troublesome to keep the discharge amount at an appropriate level. is there. Further, when supplying nitrogen gas, it is necessary to make the inside of the syringe a secret structure, and there is a problem that the structure becomes complicated.

[0006]

According to the present invention, there is provided a solder paste squeegee comprising a closed container for storing solder paste, a discharge port provided at a lower portion of the container, and the solder paste passing through the discharge port. A stirrer for kneading the solder paste, and a stirrer for kneading the solder paste. The stirrer is driven by a motor attached to the outside of the container to face each other. And two stirring rods rotating toward the discharge port.

[0007] The motor of the stirring unit may include a control unit for changing the number of rotations.

[0008]

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows the structure of a squeegee according to the present invention, wherein (a) is an external perspective view and (b) is a sectional view of (a).

In this squeegee, the inside of the metal container 1 is sealed by opening the container lid 4, supplying the solder paste, closing the lid, and fixing with the set screw 5. Thereby, deterioration such as change in viscosity and oxidation of the solder paste can be minimized.

Further, two stirring rods 2 are provided inside the container 1.
Are provided, and are rotated by an external motor 3. The two stirring rods 2 rotate inward toward the discharge ports 6 as indicated by arrows in FIG. This agitates the solder paste 7 and
The discharge pressure is generated toward the discharge port 6. In FIG. 1B, the cross section of the stirring rod 2 is a circle. However, a stirring effect is further generated when a groove is formed on the surface and the cross section is formed in a screw shape.

Next, the printing operation of the squeegee will be described with reference to FIG.
This will be described with reference to FIG. Usually, the squeegee is mounted on a screen printing machine (not shown) and performs the operation described below.
At first, the squeegee is separated from the surface of the metal mask 8 on the left side in the figure, and the stirring bar is not rotating. Next, the squeegee descends and adheres to the surface of the metal squeegee 8. At the same time as the squeegee starts sliding to the right, the stirring bar 2 starts rotating. If there is an opening of the circuit pattern in the metal mask 8 while the squeegee is sliding, the solder paste 7 fills the opening from the discharge port 6 of the squeegee due to the discharge pressure generated by the rotation of the stirring rod 2. (Center state in the figure).
When the sliding of the squeegee ends, the rotation of the stirring rod 2 stops,
The squeegee rises and the operation ends (the state on the right side in the figure). By performing the above operation reciprocally, the solder paste can be continuously supplied to the printed wiring board by printing.

That is, while the squeegee is sliding on the metal mask, the discharge pressure is applied to the discharge port by the rotation of the two stirring rods, the solder paste is injected into the opening of the metal mask, and the printing is completed. Occasionally, the rotation of the stir bar stops, so that the squeegee can be raised without leakage of the solder paste.

Further, an adjusting mechanism may be provided so that the rotational speed of the stirring rod is variable so that an appropriate discharge pressure can be obtained according to the viscosity of the solder paste.

[0015]

As described above, the solder paste squeegee of the present invention has two stirring rods in the stirring section and is rotated inward toward the discharge port to keep the viscosity of the solder paste constant. At the same time, the discharge pressure is obtained.
Therefore, by adjusting the number of rotations of the stirring rod, there is an effect that the discharge amount of the solder paste can be made constant and stabilized. Further, after the application of the solder paste is completed, if the rotation of the stirring bar is stopped, the discharge of the solder paste from the discharge port is stopped, so that there is an effect that the squeegee can be raised and moved to the next position without waste of the solder paste. Further, since the discharge pressure does not depend on the gas pressure of the container, there is an effect that the container does not need to be airtight and a simple structure is sufficient.

[Brief description of the drawings]

FIGS. 1A and 1B show an embodiment of the present invention, in which FIG. 1A is an external perspective view, and FIG. 1B is a cross-sectional view of FIG.

FIG. 2 is a sectional view showing the operation of the squeegee in FIG.

FIG. 3 is a sectional view showing a conventional squeegee.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Container 2 Stirrer stick 3 Motor 4 Container lid 5 Set screw 6 Discharge port 7 Solder paste 8 Metal mask 9 Printed wiring board

Claims (3)

[Claims] 1. A solder paste comprising a closed container for storing a solder paste, a discharge port provided at a lower portion of the container, and a stirring unit for kneading the solder paste passing through the discharge port. The squeegee according to any one of claims 1 to 3, wherein the stirring unit includes two stirring rods driven by a motor mounted outside the container and rotated toward the discharge port with respect to each other. 2. The squeegee for a solder paste according to claim 1, wherein the motor of the stirring unit includes a control unit for changing the number of rotations. 3. A squeegee for a solder paste according to claim 1, wherein said stirring rod has a cross section of a slush type.