JP3470265B2 - Stencil for resin printing and resin printing method using the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resin printing stencil used for resin-sealing an electric component such as a semiconductor element.
And a resin printing method using the same.

[0002]

2. Description of the Related Art Stencil printing has been widely used as a method of resin-sealing elements on a substrate. In this stencil printing, a squeegee slides on the stencil in which the through holes are formed, liquid resin is pushed out into the through holes, and resin printing is applied to the non-printed surface placed under the stencil. It is excellent in mass productivity, shape stability, and economical efficiency.

[0003]

While stencil printing has the above advantages, it also has the following problems. That is, when the resin is conveyed on the stencil by the squeegee, it is easy for air to be entrapped, and air bubbles are often mixed in the resin remaining on the stencil. After the printing is completed, the squeegee is pulled up above the stencil, but since the resin attached to the squeegee drops while entraining air, the liquid resin containing bubbles is also deposited on the stencil in this case.

When the next printing is started by the liquid resin containing the air bubbles as described above, the resin is not sufficiently filled into the stencil holes, so that there is a problem that the reliability of the resin sealing is significantly lowered. It was Therefore, JP-A-4-34623
Japanese Patent Publication No. 5 discloses that a scraping member is pressed against a squeegee and the squeegee is pulled up to scrape off excess resin adhering to the squeegee and discard the air bubble-containing resin.

However, the above publication does not show a concrete disposal means, and in order to remove the resin accumulated on the stencil, it is necessary to manually scoop out the liquid resin, resulting in poor work efficiency. There was a problem.

Further, Japanese Patent Publication No. 6-66350 discloses that
A method is disclosed in which the liquid resin is extruded and filled into the stencil through holes under vacuum to reduce the inclusion of bubbles in the sealing resin. However, even in the case of this method, air is mixed in the resin dripping from the squeegee because the pressure is returned to the normal pressure when the printed material is replaced after printing. When the amount of the resin dropped on such a stencil is large, sufficient defoaming is not performed even in the vacuum state during the next printing, and there is room for further improvement in terms of reliable resin sealing.

The present invention has been made to solve the above problems, and provides a stencil for resin printing and a resin printing method capable of easily and surely preventing air bubbles from being mixed into a resin to be printed. With the goal.

[0008]

The object of the present invention is to provide a printing area in which a through hole is formed in which a liquid resin is extruded and filled by a squeegee that slides on the surface, and the printed area is accommodated in the through hole. In a stencil capable of resin printing on a printed material, a discharge port is formed outside the printing area via a supply area capable of holding a liquid resin, and the resin accumulated on the upper surface can be removed from the discharge port. It is achieved by a stencil for resin printing. It is preferable that the discharge port is formed in a net shape.

Further, the above object of the present invention is a method of resin-printing on a material to be printed housed in the through hole using the above-mentioned stencil, which comprises a first step of supplying a liquid resin to the supply area. Secondly, the liquid resin in the supply area is conveyed to the printing area by the squeegee and is extruded and filled into the through hole to perform resin printing on the printing object.
And the third step of sliding the squeegee to the discharge port to remove the resin on the stencil from the discharge port, and positioning the squeegee above the discharge port and adhering to the squeegee. The dropped resin to the discharge port
And a resin printing method including the steps of. In this fourth step, it is preferable that the resin attached to the squeegee is scraped off by raising the squeegee while pressing the side surface of the squeegee against the scraping member provided above the discharge port. .

Further, it is preferable that both ends of the squeegee can hold a liquid resin when sliding on the stencil.

[0011]

DETAILED DESCRIPTION OF THE INVENTION Referring to the accompanying drawings,
A specific embodiment of the present invention will be described. Figure 1
FIG. 3 is a plan view showing a resin printing stencil according to an embodiment of the present invention. In the stencil 1, a through hole 2 is formed in the central printing area A. The through-hole 2 has a size capable of accommodating an object to be printed such as an element on a substrate to be resin-sealed, similar to that formed in a conventional stencil.
If the opening of the through hole 2 is too large and may hinder good extrusion filling, the upper portion of the through hole 2 may be covered with a porous film (not shown). Further, the number of the through holes 2 is not necessarily one, and a large number may be formed in the print area A.

On both the left and right sides of the through hole 2, the discharge ports 4 are provided via supply areas B and C capable of holding the supplied liquid resin.
6 are formed respectively. The shapes of the discharge ports 4 and 6 are not particularly limited, and may be rectangular, oval, or the like. Further, it is preferable that the sizes of the discharge ports 4 and 6 be such that a squeegee used in a resin printing method described later can be accommodated. The material and thickness of the stencil 1 are not particularly limited, but for example, a material having a thickness of about 1.0 to 5.0 mm made of copper, nickel, stainless steel or the like can be used.

Next, a method for resin printing using the stencil 1 will be described. As shown in FIG. 2, first, the stencil 1 is fixed to a supporting portion (not shown) of the resin printing apparatus, the substrate 20 on which the element 22 is mounted is fixed on the table 10, and then the table 10 is raised. The element 22 is stored in the through hole 2. Next, as shown in FIG. 4A, the squeegee 12 is moved to the print start position between the discharge port 4 and the supply area B, and the lower end is brought into contact with the upper surface of the stencil 2.

Then, a predetermined amount of liquid resin is supplied from the resin supply nozzle 14 and deposited on the supply area B. As the liquid resin, any liquid resin conventionally used for resin sealing work such as silicon resin, epoxy resin and urethane resin can be used.

Then, the squeegee 12 is actuated to slide on the printing area A in the direction of the arrow X, and the resin is extruded and filled in the void formed between the through hole 2 and the element 22.
The element 22 is resin-sealed. Thereafter, as shown in FIG. 3B, the squeegee 12 is further slid to the discharge port 6 on the other side, whereby the excess resin on the stencil 1 is conveyed and removed from the discharge port 6. It is preferable to allow the resin to be stored in a recovery container (not shown) through the resin recovery troughs 30 and 32 provided below the discharge ports 4 and 6, which facilitates the resin recovery operation. it can. The recovered resin may be discarded as it is, or may be reused after the defoaming treatment.

After the resin sealing work is completed in this way, the table 10 is lowered to replace the substrate 20 with a new one at the lowered position, and then the table 10 is raised again to pass a new element to be resin-sealed. Store in the hole 2. During this period, the squeegee 12 is kept stationary above the discharge port 6, so that the resin dripping from the squeegee 12 is discharged from the discharge port 6.
And is not deposited on the stencil 1.

Next, the squeegee 12 is moved to the printing start position between the discharge port 6 and the supply area C, liquid resin is supplied to the supply area C, and the squeegee 12 is operated to move the squeegee 12 over the print area A (see FIG. After sliding in the Y direction shown by a) and extruding and filling in the same manner as described above, excess resin is conveyed to the discharge port 4 and removed.

As described above, according to the resin sealing method of the present embodiment, the squeegee 12 sliding on the upper surface of the stencil 1 is reciprocally moved between the discharge ports 4 and 6, and the squeegee 12 is inserted into the through hole 2. Not only the resin filling but also the excess resin accumulated on the stencil 1 can be removed. Therefore, there is no possibility that the resin containing bubbles on the stencil plate 1 will be pushed into the through hole 2, and the reliability of resin sealing can be improved.

Although one embodiment of the present invention has been described above in detail, it goes without saying that the specific aspect of the present invention is not limited to this. For example, the outlets 4 and 6 are
A net-like material reinforced with a net material may be used, which reduces the risk of warping or waviness in the stencil, and allows more reliable resin sealing. As shown in FIG. 3, the shape of the mesh 42 formed by the mesh material 40 is
The shape may be (a) a diamond, (b) an ellipse, or any other shape such as a triangle, a rectangle, or a circle. In addition, in the same figure, the mesh portion is shown by hatching.

Further, in this embodiment, the discharge port 4,
The resin dripping from the squeegee 12 is collected from the discharge ports 4 and 6 by making the squeegee 12 stand still above the discharge port 6. The removing member 44 may be provided so as to extend horizontally, and the squeegee 12 may be lifted while pressing the side surface against the scraping member 44 to actively scrape off the adhered resin, thereby removing excess resin. Can be performed more efficiently.

Further, in the present embodiment, one squeegee 12 is slid back and forth to seal and remove the resin. However, instead of this, two different squeegees are provided, one for each. The above-described work may be performed by sliding only in the direction.

When the squeegee 12 slides on the stencil 1 and the resin may run off from both ends of the squeegee 12, as shown in FIG. 5, both ends of the squeegee 12 between the supply areas B and C are covered. Auxiliary discharge ports 46 and 48 are formed along the sliding direction of the squeegee 12.
You may make it collect | recover from 6,48.

Further, in this embodiment, the squeegee 1
Although the planar shape of 2 is linear, as shown in FIG. 6A, both ends of the squeegee 12 may be bent toward the advancing direction of the arrow to form the holding portion 12a. This allows
When the squeegee 12 slides on the stencil 1, the resin is held by the holding portions 12 a, so that the resin is prevented from protruding from both ends of the squeegee 12. When the squeegee 12 slides back and forth, as shown in FIG.
Holding portions 12b capable of holding the resin may be provided on both left and right sides of 2.

In the present embodiment, the supply areas B and C and the discharge ports 4 and 6 are provided on the left and right sides of the through hole 2, respectively. However, the supply areas B and C are supplied to only one of the through holes 2. A structure having an area and a discharge port may be provided.

[0025]

As is apparent from the above description, according to the resin printing stencil and the resin printing method of the present invention, the discharge port is formed outside the printing area of the stencil via the supply area. With a squeegee that slides on the stencil, the liquid resin can be extruded and filled into the through hole, and the residual resin on the stencil can be removed from the discharge port. Therefore, it is possible to easily and surely prevent the harmful effects caused by the inclusion of air bubbles in the printed resin.

[Brief description of drawings]

FIG. 1 is a plan view showing a resin printing stencil according to an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view showing an implementation state of a resin printing method according to an embodiment of the present invention.

FIG. 3 is an enlarged plan view showing another form of the discharge port shown in FIG.

FIG. 4 is an enlarged vertical cross-sectional view of an essential part showing a state of implementation of a resin printing method according to another embodiment of the present invention.

FIG. 5 is a plan view showing a resin printing stencil according to another embodiment of the present invention.

FIG. 6 is an enlarged plan view showing another form of the squeegee shown in FIG.

[Explanation of symbols]

1 stencil 2 through holes 4, 6 outlet 10 tables 12 squeegee 14 Resin supply nozzle A print area B, C supply area

Continuation of front page (56) Reference JP-A-61-234039 (JP, A) JP-A-10-175289 (JP, A) JP-A-10-172993 (JP, A) JP-A-4-346235 (JP , A) JP 2000-218763 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 21/56 B41F 15/08 303 B41F 15/40 B41M 1/12

Claims (5)

(57) [Claims] 1. A stencil that has a printing area in which a through hole is formed in which a liquid resin is extruded and filled by a squeegee that slides on the surface, and a resin printing can be performed on a printing material housed in the through hole. A resin printing stencil, characterized in that a discharge port is formed outside the area via a supply area capable of holding a liquid resin, and the resin deposited on the upper surface can be removed from the discharge port. 2. The stencil for resin printing according to claim 1, wherein the discharge port is formed in a mesh shape. 3. A method of performing resin printing on a material to be printed housed in the through hole using the stencil according to claim 1 or 2, comprising a first step of supplying a liquid resin to the supply area. A second step in which the liquid resin in the supply area is conveyed to the printing area by the squeegee and is extruded and filled into the through hole to perform resin printing on the material to be printed, and the squeegee is slid to the discharge port. A third step of moving the squeegee to remove the resin on the stencil from the discharge port; and a fourth step of locating the squeegee above the discharge port and dropping the resin attached to the squeegee to the discharge port. A resin printing method including a step. 4. In the fourth step, the resin attached to the squeegee is scraped off by raising the squeegee while pressing the side surface of the squeegee against a scraping member provided above the discharge port. The resin printing method according to claim 3, wherein: 5. The resin printing method according to claim 3, wherein both ends of the squeegee can hold a liquid resin when sliding on the stencil.