JPH0535273U - Squeegee for stencil printing - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a stencil for stencil printing having good quality and performance, which can secure a predetermined exudation pressure and a rolling diameter and can keep the upper surface of a transfer resin layer smooth. [Structure and Effect] A hard squeegee main body that is supported perpendicularly to the stencil surface is provided, and a line contact portion for the stencil surface is formed at the lower end of the main body, and a front side of the line contact portion is provided. A first inclined surface that is formed above the line contact portion and has a relatively small inclination angle, and a second inclined surface that is formed above the upper end of the inclined surface and that has a relatively large inclination angle. .

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a stencil for stencil printing.

[0002]

[Prior art and its problems]

 It is becoming widespread to perform resin encapsulation of electric components in surface mounting of electric wiring boards by applying stencil printing means. According to the resin encapsulation method using the stencil printing means, a stencil having the same through hole pattern as the mounting pattern of the electrical component is used, and the through hole of the stencil and the electrical component aligned with the through hole are used. The liquid resin as the printing ink is pushed into and filled in the voids by operating the squeegee to perform resin sealing of the electric component.

It is considered that stencil printing is based on three elements of stencil, squeegee and ink (liquid resin). Generally, the mechanism of stencil printing seen from the squeegee is that the squeegee a is slid at a constant angle α in the direction of the force F ₀ as shown in FIG. 3, thereby rolling the resin b and pushing the resin b into the stencil. An internal pressure (exudation pressure F) is generated, and the resin on the plate surface is cut off and transferred to the printing material. At this time, the exudation pressure F is expressed as F = F ₀ tan α, and the smaller α is, the larger F is. The amount of resin pushed into the stencil is determined by the angle α and the rolling diameter formed by the squeegee wall surface.

A rubber elastic body is most often used as a material for the currently provided squeegee. In the case of the flat squeegee shown in FIG. 4, even if printing is performed at the tip angle α, the friction resistance with the stencil surface is increased. Since the tip of the squeegee a bends, the exudation pressure is caused by the angle α ₀ formed by the bending of the squeegee a, so that a force larger than that at the apparent angle α is obtained. Moreover, since the rolling diameter is caused by the angle α, it is possible to secure a sufficient amount of resin pushed into the stencil.

However, when stencil printing is performed using a flat squeegee, as shown in FIG. 5, the tip curve of the squeegee a is released when passing through the through hole c ₁ of the stencil c, and is transferred to the resin. There is a problem in that a depression d is formed on the upper surface of the layer b ₁ , and this phenomenon becomes remarkable as the area of the through hole increases. Moreover, since the flat squeegee is in contact with the plate surface at an angle, the squeegee stroke is longer than that of the vertical type, and a large stencil and printing machine are required.

In order to solve the above problems, a square squeegee a'as shown in FIG. 6 has been proposed. However, since the angle α of the square squeegee a ′ is constant at 45 °, the exudation pressure is limited and the rolling diameter is small, so that the thickness of the stencil c and the opening area of the through hole c ₁ are large as shown in FIG. However, there is a problem that the amount of the resin b pushed into the through hole c ₁ becomes insufficient.

The present invention has been made for the purpose of eliminating such conventional problems.

[0008]

[Means for solving problems]

 The present invention comprises a hard squeegee body that is supported perpendicularly to the stencil surface, the main body having a line contact portion for the stencil surface at the lower end and a front side of the line contact portion. And a first inclined surface having a relatively small inclination angle formed above the line contact portion and a second inclined surface having a relatively large inclination angle formed above the upper end of the inclined surface. And a squeegee for stencil printing.

[0009]

【Example】

 An embodiment of the present invention will be described below with reference to the accompanying drawings.

As shown in FIGS. 1 and 2, the squeegee of the present invention comprises a squeegee body 2 supported by a holder 1 so as to be perpendicular to the stencil surface a ₁ .

The main body 2 is required to be rigid, and is made of hard rubber or other hard plastic into a long plate shape in the width direction of the stencil a and usually has a wall thickness of about 9 mm. ..

At the lower end of the main body 2, a line contact portion 3 with respect to the stencil surface a ₁ is formed at a center position in the thickness direction, preferably slightly offset to the rear side as shown in the drawing.

Further, the main body 2 is provided with a rear inclined surface 4 on the rear side and first and second inclined surfaces 5, 6 on the front side with respect to the line contact portion 3. There is.

The rear inclined surface 4 is for maintaining a space between the lower end of the squeegee body 2 and the stencil surface a _1, and extends from the line contact portion 3 toward the rear vertical wall surface 21 at an arbitrary angle, for example, 45. It is formed at an angle of °.

On the other hand, among the first and second inclined surfaces 5 and 6 on the front side, the first inclined surface 5 is formed from the line contact portion 3 toward the front and obliquely upward. The first inclined surface 5 is a portion mainly for obtaining the exudation pressure necessary for pushing the resin into the stencil through hole, and the inclination angle thereof is relatively small. For example, from the range of 5 to 30 ° And the shape of the through hole are taken into consideration. If the tilt angle does not reach the above range, it is apparently close to a single tilt angle, and the effect of the two-step tilt becomes difficult to obtain. If the tilt angle exceeds the above range, it is difficult to obtain a predetermined exudation pressure. Therefore, it is not preferable.

On the other hand, the second inclined surface 6 is formed from the upper end of the inclined surface 5 toward the front vertical wall surface 22. The second inclined surface 6 is a portion mainly for obtaining a predetermined rolling diameter required for filling the resin into the stencil through hole, and the inclination angle thereof is relatively large, for example, from the angle range of 25 to 70 °. The thickness is selected and the shape of the through hole is taken into consideration. If the inclination angle does not reach the above range, it tends to be difficult to obtain a predetermined rolling diameter, and if it exceeds the above range, the rolling diameter unnecessarily increases, making it difficult to obtain the desired rolling state. Both of them are not preferable because they tend to occur.

The inclination angle d ₂ of the second inclined surface 6 needs to be larger than the inclination angle d ₁ of the first inclined surface 5, and the angle difference d ₂ −d ₁ between the _two is usually 15 to 40. It is appropriately selected and determined within the range of °. When the angle difference does not reach the above range, it is apparently close to a single inclination angle, while when it exceeds the above range, it tends to be controlled by only one of the angles, which is not preferable.

The width L of the first inclined surface 5 and the second inclined surface 6 in the thickness direction.₁, L₂The ratio of L₁: L ₂ = 1/4 to 1: 1 is appropriate. Generally speaking, the width L of the first slope 5₁If the above ratio does not reach the above-mentioned ratio, it becomes difficult to secure a predetermined exudation pressure, and if it exceeds the above ratio, the rolling diameter may be adversely affected.

FIG. 2 shows a state of stencil printing by the squeegee of the present invention in an enlarged manner only for the portion of the stencil a.

Since the squeegee body 2 is supported by the holder 1 so as to be perpendicular to the stencil surface a ₁ , the squeegee stroke is shorter than that of the conventional inclined type shown in FIG. The smaller it is, the better.

Further, since the squeegee body 1 has the first inclined surface 5 having a relatively small inclination angle at the lower part of the front surface, like the rubber elastic flat squeegee shown in FIG. 4 in which the apparent inclination angle is reduced by bending the tip. A sufficiently large exudation pressure can be secured.

Further, since the second inclined surface 6 having a relatively large inclination angle is provided on the upper part of the front surface, the rolling diameter becomes sufficiently large as shown by the broken line in FIG. 1, and as shown in FIG. A sufficient amount of resin to be pushed into the stencil through hole c can be secured.

Further, since the squeegee body 2 is hard, there is no risk of causing a tip curve as seen in the conventional type shown in FIG. 4 and hence a recess on the upper surface of the transfer resin layer, and as shown in FIG. The upper surface of the transfer resin layer b ₁ can be kept smooth.

[0024]

【effect】

 According to the squeegee of the present invention, the first inclined surface having a relatively small inclination angle is provided at the lower portion of the front surface and the second inclined surface having a relatively large inclination angle is provided at the upper portion. The squeegee for stencil printing with good quality and performance can be maintained because the sloped surface ensures a predetermined exudation pressure and rolling diameter, and because it is hard, the upper surface of the transfer resin layer can be kept smooth at all times. Can be provided.

[Brief description of drawings]

FIG. 1 is a side view of an essential part showing one embodiment of the present invention.

FIG. 2 is an explanatory diagram showing the first usage status.

FIG. 3 is an explanatory diagram of basic elements of a squeegee.

FIG. 4 is an explanatory diagram showing an example of a conventional squeegee.

FIG. 5 is an explanatory diagram showing a first usage situation.

FIG. 6 is an explanatory view showing another example of a conventional squeegee.

FIG. 7 is an explanatory diagram showing the first usage status.

[Explanation of symbols]

 1 Squeegee body 2 Wire contact part 3 First inclined surface 4 Second inclined surface

Claims (1)

[Scope of utility model registration request] 1. A hard squeegee body supported perpendicularly to the stencil surface, wherein a line contact portion for the stencil surface is formed at a lower end of the main body, and a front side of the line contact portion is provided. , A first inclined surface having a relatively small inclination angle formed above the line contact portion and a second inclined surface having a relatively large inclination angle formed above the upper end of the inclined surface. A squeegee for stencil printing, which is characterized in that