JP3113974B2 - Stencil for resin printing and sealing of electrical components - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stencil for resin printing and sealing of electric parts, and more particularly, to a resin printing and sealing method for sealing an electric part mounted on an electric wiring board with a stencil printing means. Regarding stencils.

[0002]

2. Description of the Related Art The present applicant has previously disclosed Japanese Patent Application Laid-Open No. 64-82639.
In Japanese Unexamined Patent Publication (Kokai) No. 6-95594, a method of applying a stencil printing means to seal an electric component with a resin was proposed.

According to the above invention, the following effects can be obtained. (A) The thickness of the sealing resin layer is uniform, and a stable and reliable resin sealing effect can be obtained. (B) Resin sealing with the smallest resin sealing area becomes possible,
It can deal with high density of component mounting. (C) Since the thickness of the sealing resin layer is determined by the effective height of the through hole of the stencil, the thickness can be easily controlled. (D) Even a large device such as an LSI can be sealed with a resin in one operation, and stable resin sealing can be performed regardless of whether the device is large or small. (E) One printed circuit board can be processed in one operation, and the productivity is excellent.

[0004]

However, the above-mentioned prior invention has a slight problem in that the supply amount of the sealing resin tends to be excessive, and in particular, it has become impossible to meet the recent demands for thinning and lightening. . That is, according to the prior invention, the squeegee c is actuated by operating the squeegee c in a state where the electric component b mounted on the electric wiring board a is stored in the through hole 2 'of the stencil 1' as shown in FIG. When the liquid sealing resin d is pressed and filled into the portion 2 ', as shown in FIG.
Is the bulge d at the movement end point p1 side.
As shown in FIG. 6 , when the stencil 1 'is released, a large amount of stringing occurs on the movement end point p1 side where the filling amount is large. As a result, at the after stencil release, FIG
As shown in FIG. 7 , the thickness of the sealing resin layer d2 increases on the side of the movement end point p1 where the amount of stringing is large, and the thickness becomes uneven. appear. The uneven thickness causes an excessive supply of the sealing resin, which is incompatible with the reduction in thickness and weight.

An object of the present invention is to provide a stencil having a novel structure capable of eliminating the above-mentioned problems of the prior invention.

[0006]

The present inventors have conducted intensive studies to eliminate the problems of the above-mentioned invention, and as a result, at least the resin bulge d1 (see FIG. 15) when the sealing resin is pushed and filled by the squeegee operation. ) Is found to be effective in improving the tendency of the sealing resin layer to be biased in thickness when the projecting edge projects inward from the upper end of the peripheral wall of the through-hole in the region where the through-hole occurs. It has been reached.

That is, the present invention provides a method of mounting on an electric wiring board.
In a state where the electric parts are stored,
Apply liquid encapsulation resin to the surrounding area and the top using stencil printing means.
Equipped with a through-hole for actuation of the keyage and transfer supply
In the stencil, the peripheral wall forming the through hole is perpendicular to a plane.
2 which has a quadrilateral shape and is orthogonal to the moving direction of the squeegee
Over the entire length of the side of the squeegee on the end side in the moving direction of the squeegee
A protruding edge is formed at the upper end of the peripheral wall.
And

[0008] Further , the present invention provides a method of mounting a semiconductor device on an electric wiring board.
In a state where the electric parts are stored,
Apply liquid encapsulation resin to the surrounding area and the top using stencil printing means.
Equipped with a through-hole for actuation of the keyage and transfer supply
In the stencil, the peripheral wall forming the through-hole portion has a flat circular shape.
The squeegee moves in a shape or a similar shape.
30 ° to 90 ° on both sides from the end point of the direction
A protruding edge is formed at the upper end of the peripheral wall over the angle.
It is characterized by having.

[0009]

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

FIG. 1 is an enlarged plan view and a longitudinal sectional view showing one of the first type through-holes 2 provided in the stencil 1 of the present invention. It has a shape, and an inner end is formed at an upper end portion of the through hole peripheral wall portion 2A forming the through hole portion 2 .
A protruding edge 3 protruding in the direction is formed.

The protruding edge portion 3 is a portion near the periphery of the upper end opening of the through-hole portion 2, and the sealing resin bulges d1 when the sealing resin is pushed and filled by the squeegee c operation (see FIG. 15).
Is required to be formed in the region where

FIG . 1 shows a first tie having a protruding edge 3 only on the side 2a on the end point side in the moving direction with respect to the moving direction Y of the squeegee c .
Is shown.

The through-hole 2 may have a flat circular shape or a similar shape, for example, an elliptical shape .
The keyge is formed over an area on the movement end point side, for example, over a range of 180 ° on the movement end point side as shown in the second type of FIG.
You. In the case where the protruding edge portion 3 is formed in an arc shape as in the second type , it is necessary that the protruding edge portion 3 be formed at least by 30 ° with reference to the movement end point p1 over an angle range of 60 °.

The protruding edge portion 3 is usually formed to have the same width over the entire length . However, when the protruding edge portion 3 is formed in an arc shape as in the third type shown in FIG. The projection width may be gradually reduced as the distance from the projection increases.

The cross-sectional shape of the protruding edge portion 3 is suitably a rectangular shape as shown in FIGS. 1 to 3 in terms of ease of molding, but may be a substantially inverted right-angled triangular shape in some cases. In this case, the protruding edge 3 is formed over substantially the entire height of the through-hole peripheral wall 2A.

If the protruding width of the protruding edge portion 3 is too large, the sealing resin may be prevented from being pushed into the through-hole portion 2 by the squeegee operation, whereas if it is too small, the thickness of the sealing resin layer may be reduced. Since there is a possibility that the effect of reducing the bias may not be so much reduced, the diameter of the through-hole 2 in the squeegee moving direction is usually 5 to 35%, preferably 10 to 3% of the diameter.
0%, more preferably within the range of 15 to 25%.

The total volume of the protruding portion 3 occupying the entire volume of the through-hole portion 2 (the protruding portion forming portion is also regarded as a part of the volume) is as follows:
If this is too large, there is a possibility that the filling amount of the sealing resin is insufficient.
Usually, it is appropriately selected from the range of about 10 to 50%, preferably about 15 to 45%, more preferably about 20 to 40%.

On the back surface of the stencil 1, an annular recess 4 having a slightly larger outer diameter than the through hole 2 is formed concentrically with the through hole 2.
Between the annular recess 4 and the through-hole 2, a thin-walled through-hole edge 2B is formed. The through-hole edge 2B has a shape such that the lower end can linearly contact the surface of the electric wiring board a.
With this shape, it is possible to prevent the liquid sealing resin from wrapping around the back surface of the stencil 1 as in the prior invention (Japanese Patent Application Laid-Open No. 64-82639).

When the electric component b having the maximum height among the various electric components mounted on the electric wiring board is accommodated in the through hole 2 of the stencil 1 of the present invention configured as described above, Electrical department
A gap for filling the liquid sealing resin is formed between the stencil and the stencil 1 so that the top of the wire does not come into contact with the squeegee when the sealing resin is pushed and filled. It is slightly immersed in the part 2.

Then, operate the squeegee according to the usual method.
When the liquid sealing resin is pushed and filled into the hole portion , after the pushing and filling, the sealing resin rises at the movement end point p1 side of the squeegee and tends to be oversupplied . Sealing resin with less uneven thickness
A layer is obtained.

As described above, the resin layer formed by applying the stencil of the present invention has a small thickness unevenness, and can contribute to the reduction in thickness and weight of the resin layer .

Although the reason for this is not clear, the protruding edge 3 provided in the area of the squeegee movement end point p1 side in the periphery of the through-hole 2 has the raised height d1 of the sealing resin by the protruding width as compared with the conventional product. In addition, the resin in the raised portion is more easily flowed toward the central region as the thread is drawn at the time of die-cutting. It is presumed that the volume and thus the filling amount of the resin are reduced, and the reduction in the filling amount can slightly absorb the excess supply due to the swelling . By the way, immediately after forming the encapsulating resin layer , the resin still has fluidity, so even if the thickness is uneven in the central region, it flows toward the periphery, and the thickness naturally becomes uniform before curing. Will be done. In particular, when the projecting edge 3 is formed on the entire circumference of the hole 2, as shown in FIG. 12, at least on the lower surface side of the projecting edge 3, the sealing resin is uniformly filled over the entire circumference. As a result, after die cutting,
Since the thickness of the peripheral portion of the sealing resin layer is substantially uniform over the entire circumference, a further effect can be expected by reducing the bias tendency of the thickness of the resin layer.

In the present invention, for example, the following can be exemplified as electric components to be sealed with resin. Electrical components: IC card package, QFP, PLCC
Such as COB, T-BGA, P-BGA, C-BGA, etc.
GA, TAB, LED module, flip-chip underfill, CSP, sensor and other resin-sealed packages, passive components, active components, coil components, capacitors, resistors, diodes, transistors, etc.

In the present invention, the thickness of the stencil 1 is determined based on the largest electric component among various electric components mounted on the electric wiring board. What is necessary is just to have the thickness which can be accommodated in the immersion state of the degree which can prevent the contact with.

The inner diameter of the through hole 2 may be large enough to form a gap required for resin sealing around the electric components housed inside. It is set to be 10 μm or more larger than the outside position, for example, the connection position of the wire b1 on the substrate circuit.

In the present invention, the material of the stencil is not particularly limited, and may be any metal, such as stainless steel, aluminum, copper, etc., plastics, and inorganics, such as glass and ceramic.

In processing the through-holes, the protruding edges, and the like, various known processing means can be applied depending on the material. For example, cutting, physical processing such as laser, and chemical processing such as etching are applied to metal, and cutting,
Physical processing such as laser and molding means such as casting injection are applied. For glass and the like, physical processing such as cutting laser and sintering using cast molding and the like are applied.

[0028]

According to the stencil of the present invention, the tendency of excessive supply of the sealing resin liquid and the tendency of unevenness in the thickness of the resin layer can be reduced, and it is possible to cope with a thinner and lighter resin layer.

[Brief description of the drawings]

FIG. 1 is an enlarged plan view and an enlarged vertical cross-sectional view of a first type through hole showing an embodiment of the present invention.

FIGS. 2A and 2B are an enlarged plan view and an enlarged vertical sectional view of a second type through hole;

3A and 3B are an enlarged plan view and an enlarged vertical sectional view of a third type of through-hole portion.

FIG. 4 is a longitudinal sectional view showing a state before a conventional squeegee is operated.
FIG.

FIG. 5 is a longitudinal sectional view showing a state after the operation of the conventional squeegee .
FIG.

FIG. 6 is a longitudinal sectional view showing a state of stringing when releasing a conventional product.
is there.

FIG. 7 is a longitudinal sectional view showing a state of forming a resin layer.

[Explanation of symbols]

 Reference Signs List 1 stencil 2 through-hole 2A through-hole peripheral wall 2B through-hole rim 3 protruding edge 4 recess

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Koichi Nagai 12-16 Koyanagicho, Ibaraki-shi, Osaka Precious Mansion 302 (72) Inventor Tsuneichi Hashimoto 1-24-2 Kitano Yasu-cho, Yasu-gun, Shiga Prefecture (56) References JP-A-11-40588 (JP, A) JP-A-55-141733 (JP, A) JP-A-11-40590 (JP, A) (58) Fields investigated (Int. ⁷ , DB name) H01L 21/56

Claims (6)

(57) [Claims] 1. A stencil printer is used to transfer and supply a liquid sealing resin to a periphery of an electric component and an upper part of the electric component by applying a stencil printing means in a state where the electric component to be mounted on the electric wiring board is stored. In a stencil provided with a through hole for the, the peripheral wall forming the through hole has a quadrilateral shape in a plane right angle,
Of the two sides orthogonal to the moving direction of the squeegee,
The upper end of the peripheral wall over the entire length of the side on the end side in the moving direction of
A stencil for resin printing and sealing of electrical components, characterized in that a ridge is formed on the stencil. 2. An electric component to be mounted on an electric wiring board.
In this condition, the electric parts are placed around and above the electric parts.
Apply stencil printing means to the stencil
In a stencil provided with a through hole for transferring and supplying
The peripheral wall forming the through hole is a circular plane or similar
From the end point of the squeegee moving direction.
On each side at any angle between 30 ° and 90 °
A protruding edge is formed at the upper end of the peripheral wall.
Stencil for resin printing and sealing of electrical parts. 3. The end of the squeegee in the direction of movement of the squeegee.
With the maximum width,
3. The method according to claim 2, wherein the width of the protrusion is reduced.
Stencil for resin printing and sealing of electrical parts. 4. The diameter of the through-hole portion in the squeegee moving direction of the through-hole portion.
Has a maximum projection width equivalent to 5 to 35% of the diameter based on
The stencil according to any one of claims 1 to 3 , wherein the stencil is formed. 5. The total volume of the protruding edge portion is equal to the total volume of the through-hole portion.
2. The method according to claim 1, wherein the occupancy is 10 to 50%.
5. The stencil according to any one of to 4 ). 6. A stencil stamping of an electric component mounted on an electric wiring board.
When applying squeegee and applying resin
And applying the stencil according to any one of claims 1 to 5,
Operate the squeegee into the through hole of the stencil and press the liquid sealing resin.
After filling and filling, the stencil is released to release the electric parts.
Is sealed with a resin layer transferred from a stencil.
Resin sealing method for electrical parts.