JP2979686B2 - Transfer molding dies and semiconductor devices - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer mold and a semiconductor device, and more particularly, to a runner for flowing a resin into a cavity for sealing a semiconductor element or the like between a resin pressing pot and a cavity block. The present invention relates to a transfer molding die having:

[0002]

2. Description of the Related Art Conventionally, transfer molds for molding a semiconductor element by resin sealing are shown in FIGS. 4 and 5. FIG. FIG. 4 is a sectional view of a general mold common to the embodiments, and FIG. 5 is a conventional example, and is a bird's-eye view in which a part of the cavities and runners of FIG.
Is a bird's-eye view of the semiconductor device. In the figure, an upper mold 1 and a lower mold 2 are combined with a pot 11, cavity blocks 4a and 4b having cavities, runner blocks 3a and 3b for supplying resin to each cavity block, and the like. When the mold 12 is supplied from the upper mold, the cavity 5 is sealed and filled with resin.

[0003] The molding method is to preheat the tablet-like resin 12 in another facility to warm the resin to a certain temperature,
The resin whose viscosity has been reduced so that it can easily flow into each cavity is inserted into the pot 11, and the resin is pressed from the upper portion by a force of several tons from the upper portion of the plunger body 10 and pushed out to each part. At this time, since there is only a gap of several microns between the pot 11 and the plunger ring 10a attached to the plunger body 10, the resin does not leak upward through the plunger ring 10a. Further, the resin extruded by the plunger body 10 proceeds along the runner 6 engraved on the runner blocks 3a and 3b. The runner 6 is designed so that the resin flows uniformly in each of the cavity blocks 4a and 4b. Therefore, the shape of the runner 6 is bent and complicated. The resin is extruded from the pot 11 and passes through the runner 6, and is injected into each cavity 5 through the gate 7. Since the cavity 5 is substantially sealed, the pressure applied from the plunger body 10 is applied to the cavity 5 at substantially the same pressure, and the void in the resin is compressed. The cavity 5 has a gate 7 serving as an injection port.
There is an air vent 8 provided for the purpose of air blowing in the opposite direction, and voids in the resin are pushed out from the cavity 5.

[0004]

In the above prior art, a gap 13 between the tablet-like resin 12 and the pot 11 is provided.
Or tablet-like resin 12 and plunger body 10,
There is also air in the gap 13 with the lower runner block 3b.
In addition, many of the tablet-like resins 12 also contain a large amount of air. Further, as shown in FIG. 5, the runner 6 through which the resin flows is engraved, so that it is naturally filled with air.

As described above, while the molten resin containing a large amount of air is extruded from the pot 11 and proceeds through the runner 6, a void-like resin is gradually generated by the air, and , As if it were in a foamed state. In particular, since the runner 6 is designed so that the resin flows uniformly in each of the cavity blocks 4a and 4b, the shape is bent and complicated. As a result, the void-like air 15 entrained in the resin further foams and is injected into the cavity 5 through the gate 7. As described above, since the cavity 5 is sealed and pressed by the plunger main body 10, the void-like air 15 in the resin is compressed, and the air vent 8 for exposing the air is used to reduce the air in the resin. Void is to be extruded. However, since there is too much air in the foaming state, as shown in FIG.
Of the semiconductor device 18, and the quality of the semiconductor device is remarkably deteriorated.

Further, when the voids 16 are generated on the surface of the semiconductor device 18, the voids 16 become pocked, resulting in a poor product appearance. In addition, a large amount of voids are concentrated in a part and unfilled 17
In this case, not only the appearance of the product is poor, but also fatal defects such as insulation and water resistance due to resin even if the semiconductor element is exposed or not exposed. This disadvantage is slightly different depending on the resin, but in the case of the transparent resin, the void 16 is remarkable and the inside can be grasped from the external appearance, so that the product becomes even more fatal.

The present invention has been made in view of the above-mentioned drawbacks, and an object of the present invention is to minimize the generation of resin in a foamed state in the course of the runner advancement, and to prevent voids or unfilled resin in the sealing resin. An object of the present invention is to provide a transfer mold that can prevent the occurrence of filling.

[0008]

In order to solve the above-mentioned problems, a means according to the present invention is to arrange a runner block between a resin pressing pot portion and a cavity block, and to form an upper mold and a lower mold of the runner block. In a transfer mold having a runner engraved on a parting surface of the runner , a tree is formed on the parting surface of a bent portion of the runner.
Extends linearly the upstream of the grease flow to create
Is shall provide a Abend.

At this time, the resin flow in the bent portion of the runner is
The upstream of the runner is extended linearly and cut almost the same as the runner.
A resin pool having an area is formed, and the par of the resin pool is formed.
A thin air vent communicating with the outside is provided on the parting surface, and a fine air vent communicating with the outside is provided on the parting surface of the straight portion of the runner. The air vent has a width substantially equal to the width of the runner and a thickness that does not allow the resin to flow out, and is preferably about 0.03 mm. And Invention 4
Is for sealing a semiconductor element with a resin using the transfer mold.

[0010]

[Function] When the pre-heated tablet-like resin is pressed with a plunger, the tablet-like resin and the air existing around it are entrained, and the tip of the molten resin becomes a foamed state and proceeds along the runner, and the flow stage Since no pressure is applied, the foaming state is not reduced. The bent part of the present invention
There is no grease and it leads directly to the air vent,
Some air vents are installed in the straight section of the runner.
Only air in fat is pushed out. Further, the resin reservoir portion of the run-<br/> toner the same cross-sectional area of the present invention, since the extended straight upstream flow of resin bent part, is likely to enter the distal end resin foam state. The air is pressurized here for closing, and only the air in the resin is pushed out to the outside by the thin air vent installed in that portion, and the low-void resin is injected into the cavity through the gate.

[0011]

Next, an embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a bird's-eye view of Embodiment 1 according to the present invention.
FIG. 2 schematically shows only a lower mold, FIG. 2 is a plan view of a runner block showing a second embodiment, and FIG. 3 is a sectional view of FIG. In each figure, the air vent 9 and the like are spaces and are shown by cross-hatching to emphasize them. Each of the embodiments is applied to the mold shown in FIG. 4 described above, and the overall structure and molding method of the mold are as described in the section of the prior art, and thus the description thereof will not be repeated.

In the first embodiment shown in FIG.
Is fixed to the lower mold 2, and the cavity block 4 b having the cavity 5 is aligned with the runner block 3 b and fixed to the lower mold 2. As a characteristic structure of the first embodiment, the upstream of the flow of the resin at the bent portion of the runner 6 connected to the cull portion 11a immediately below the pot (11) is linearly extended so that the resin having substantially the same cross-sectional area as the runner 6 is formed. A reservoir 14 is formed, and a thin air vent 9 communicating with the outside is provided on the parting surface of the resin reservoir 14. Air vent 9
The width is approximately the same as the width of the runner 6 and the thickness is such that the resin does not flow out.

In the embodiment 2 shown in FIGS. 2 and 3, in addition to the air vent 9 having the resin pool 14, the resin flow is directly provided on the parting surface of the bent portion of the runner 6 without providing the resin pool 14. Are extended linearly to provide a thin air vent 9a communicating to the outside, and a linear portion of the runner 6 is also provided with a thin air vent 9b communicating to the outside on the parting surface.

In each embodiment, the preheated tablet-like resin 12 is pressed by the pot 11 and the plunger 10, so that the molten resin 15 foamed from the cull portion 11a is moved along the arrow F into the runner 6. Proceed to the bent part. The resin is pushed out of the mold from the thin air vents 9, 9a, 9b installed in each part to the outside of the mold at the flow conversion point and the straight part, and sent to each cavity. become. in this way,
Air vents 9, 9 a, 9 b are provided on the bent portion or straight portion of the runner block of the lower mold or the upper mold so that only air can escape to the outside of the mold. The air vent 9 is provided at the tip of the resin reservoir 14.

[0015]

As described above, according to the present invention, it is as if foaming was caused by the resin pool at the bent portion of the runner and the thin air vent or the thin air vent installed at the bent portion or the straight portion. The air in the molten resin can be pushed out to the outside, and the low-void resin that has passed through the runner is sent to each cavity block. As a result, a resin having a low void is injected into each cavity from the runner, so that a defective product appearance of the semiconductor device and an unfilled defect in which a large amount of voids are partially concentrated are extremely reduced. In addition, there is an effect that the product quality of the transfer-molded semiconductor device is significantly improved.

[Brief description of the drawings]

FIG. 1 is a bird's-eye view of a first embodiment according to the present invention, showing only a lower mold simply.

FIG. 2 is a plan view of a runner block according to a second embodiment.

FIG. 3 is a sectional view of FIG. 2;

FIG. 4 is a sectional view of a general mold common to the embodiments.

5 is a bird's-eye view of a conventional example in which a part of the cavities and runners of FIG. 4 is enlarged.

FIG. 6 is a bird's-eye view of a semiconductor device;

[Explanation of symbols]

 2 Lower mold 3a Runner block 3b Runner block 4a Cavity block 4b Cavity block 5 Cavity 6 Runner 9 Air vent 9a Air vent 9b Air vent 14 Resin pool F Resin flow

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ Identification code FIB29L 31:34 (56) References JP-A-61-85829 (JP, A) JP-A-1-205432 (JP, A) JP-A-4-29334 (JP, A) JP-A-60-127127 (JP, A) JP-A-58-192020 (JP, U) JP-A-4-52021 (JP, U) JP-A-1-119318 ( (JP, U) JIKA 1-67010 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) B29C 45/02 B29C 45/26 B29C 45/34 H01L 21/56

Claims (4)

(57) [Claims] 1. A transfer molding die comprising a runner block disposed between a resin pressing pot portion and a cavity block, and a runner engraved on a parting surface of an upper die and a lower die of the runner block. Said la
Resin flow on the parting surface of the bent part of the inner
A thin air vent that extends the flow linearly and leads to the outside
Transfer molding die and providing a. 2. The transfer molding die according to claim 1, wherein an upstream portion of the resin flow at a bent portion of the runner is straightened.
A resin reservoir that extends linearly and has approximately the same cross-sectional area as the runner
A pool is formed on the parting surface of the resin pool.
A transfer mold having a thin air vent communicating with the outside . 3. The transfer molding die according to claim 1, wherein a thin air vent communicating with the outside is provided on the parting surface of the linear portion of the runner. 4. A semiconductor device, wherein a semiconductor element is sealed with a resin using the transfer molding die according to claim 1.