JP2984082B2 - Resin sealing method - 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 sealing technique and a lead frame, and more particularly to a technique effective when applied to a resin sealing technique in an assembling process of a semiconductor device.

[0002]

2. Description of the Related Art For example, in the process of assembling a semiconductor device, semiconductor pellets mounted on a lead frame are
2. Description of the Related Art A resin package using a mold to protect a semiconductor pellet from an external environment has been used.

[0003] In the resin sealing technique using such a mold, the mold formed by pressing and filling a cavity formed of a concave portion formed on a mating surface of an upper mold and a lower mold is surely released. The ejector pins are placed at the positions of the cavities where the resin in which the semiconductor pellet is sealed is molded, and the upper and lower molds are separated from each other to take out the molding resin (at the time of mold release). An operation of extruding the molding resin from the cavity is performed.

[0004] As for resin sealing technology in assembling a semiconductor device, see, for example, “Industrial Research Institute Co., Ltd., published on November 18, 1986,“ Electronic Materials ”, November 1986.
It is described in literatures such as month names P160 to P165.

[0005]

Meanwhile, in response to the demand for further miniaturization of semiconductor devices, external dimensions such as the thickness of a package formed by resin sealing and the like are steadily decreasing. The thickness of the resin surrounding the pellet is small.

For this reason, in the mold having a structure in which the ejector pins are arranged at the positions of the cavities in which the semiconductor pellets are sealed as in the prior art, the molding resin is pressed by the stress of the extrusion operation by the ejector pins at the time of release. There is a problem that there is a great concern that cracks will occur.

The tip of the ejector pin is usually 50 μm in the cavity in order to suppress the generation of burrs and the like.
For example, when forming an extremely thin package having a thickness of 1.0 mm or less, even if the tip of the ejector pin slightly projects into the cavity as described above, There is a problem that it becomes a factor that hinders the smooth flow of the resin in the cavity, and a void (void) defect occurs due to insufficient filling of the resin.

In order to avoid the above-mentioned problems caused by the presence of the ejector pin, when the ejector pin is abolished, a part of the molding resin at the time of mold release is deteriorated due to deterioration of the mold releasability of the molding resin. There is a problem in that mold release failures such as chipping occur frequently and the yield in the resin sealing step is reduced.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a resin-sealing mold capable of both preventing the occurrence of molding defects caused by ejector pins and reliably releasing the mold by the ejector pins. is there.

Another object of the present invention is to provide a lead frame capable of reducing the occurrence of defects in a resin sealing step.

The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0012]

SUMMARY OF THE INVENTION Among the inventions disclosed in the present application, the outline of a representative one will be briefly described.
It is as follows.

That is, the present invention provides an upper mold and a lower mold,
A resin sealing metal provided with a cavity formed by a concave portion engraved on at least one of these opposing surfaces, and an ejector pin projecting from the opposing surface to release the resin filling the cavity. A resin sealing method using a mold, wherein a resin sealing mold communicates with a first cavity in which a desired object to be sealed is sealed with a resin, and the first cavity is connected to the first cavity. A plurality of second cavities arranged at opposing positions with the ejector pins interposed therebetween; an ejector pin being arranged at each of the plurality of second cavities; The release operation is performed by pressing with a pin.

According to the present invention, in the resin sealing method described above, the object to be sealed is a semiconductor pellet mounted on a lead frame including a plurality of leads and a frame portion located outside the leads. The two cavities and the ejector pins are provided at positions corresponding to the frame portion of the lead frame.

Further, according to the present invention, in the above-mentioned resin sealing method, a through hole is formed in a portion of the frame portion where the second cavity is arranged.

[0016]

According to the resin sealing method of the present invention described above, the first
The resin filled in the cavity and molded forms a package for sealing semiconductor pellets and the like, and the molding resin of the second cavity pressed by the ejector pins is discarded after molding, so that the product of the first cavity which becomes a product is formed. It is possible to realize a reliable mold release operation by pressing the molding resin in the second cavity by the ejector pin without causing molding failure due to damage of the molding resin or voids, and to eliminate the ejector pin. Therefore, it is possible to reliably prevent the occurrence of molding defects.

[0017]

[0018]

[0019]

Embodiment 1 Hereinafter, a resin sealing method and a lead frame according to one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic perspective view showing a part of a resin sealing mold used in a resin sealing method according to one embodiment of the present invention. FIG. 2 is a plan view and FIG. FIG. 3 is a schematic sectional view of a portion indicated by line III-III in FIG.

On the opposing surfaces of the lower mold 1 and the upper mold 2,
A concave portion 1a and a concave portion 2a are engraved, respectively, and the concave portion 1a and 2a form the main cavity 3 in a state where the opposing surfaces of the lower die 1 and the upper die 2 are brought into close contact (mold clamping state).

The lower die 1 is provided with a runner 1c communicating with the concave portion 1a (main cavity 3), and the pressurized resin 6 is filled into the main cavity 3 from outside through the runner 1c. Has become.

A lead frame 4 is held between the upper die 2 and the lower die 1. The lead frame 4 has a tab 4a on which a semiconductor pellet 5 is mounted and a tip 4a
And a frame portion 4c that supports the plurality of leads 4b in a continuous manner via tie bars 4e.

The semiconductor pellet 5 mounted on the lead frame 4 is electrically connected to each of the plurality of leads 4b by a bonding wire (not shown) or the like in a preceding wire bonding step.
The connection between the semiconductor pellet 5 and the lead 4b is not limited to the case of using the bonding wire, and the individual lead 4b and the bonding pad (not shown) provided on the semiconductor pellet 5 are directly connected by a known gang bonding technique. It is also conceivable that the connection is made in a specific manner, and it goes without saying that any connection method may be used in this embodiment.

Then, the semiconductor pellet 5 mounted on the lead frame 4 is positioned so as to be located in the main cavity 3 (between the concave portion 1a and the concave portion 2a). In this state, the main cavity 3 is filled with the resin 6 through the runner 1c to fix the semiconductor pellet 5 located at the center of the main cavity 3 inside the resin 6. Is performed.

In this case, in the lower mold 1 and the upper mold 2,
Concave portion 1a and concave portion 2a constituting main cavity 3
At the symmetrical position of the peripheral portion of the lead frame 4 corresponding to the position of the frame portion 4c of the lead frame 4,
A plurality of smaller concave portions 1b and concave portions 2b are provided.

The frame portion 4c of the lead frame 4
, Through holes 4d are respectively formed in portions corresponding to the concave portion 1b and the concave portion 2b, and when the lower die 1 and the upper die 2 are in close contact with each other, the concave portion 1b on the side of the lower die 1 and the upper die The recess 2b on the second side forms an integral space through the through hole 4d, and a plurality of sub-cavities 7 smaller than the main cavity 3 are formed.

Each of the sub-cavities 7 communicates with the main cavity 3 via a communication groove 1d formed on the side of the lower mold 1, and the resin 6 filled in the main cavity 3 is provided with the communication groove. By flowing through 1d, the sub-cavity 7 is also filled with the resin 6.

In the lower mold 1 and the upper mold 2, an ejector pin 8 is disposed in each of the concave portion 1 b and the concave portion 2 b constituting the sub-cavity 7. When the upper mold 2 and the upper mold 2 are separated from each other, an operation of projecting and extruding the resin filled in the subcavity 7 from both the lower mold 1 and the upper mold 2 is performed.

The resin sealing mold of this embodiment has a heating mechanism for heating the lower mold 1 and the upper mold 2 to a predetermined temperature, and a mechanism for pressurizing and filling the resin 6 as described above. Although they are provided, they are well-known mechanisms, and their illustration and description are omitted.

Hereinafter, an example of the operation of the resin sealing method and the lead frame 4 of this embodiment will be described.

First, the lower mold 1 heated to a predetermined temperature
The lead frame 4 is positioned so that the mounted semiconductor pellet 5 is positioned at the center of the concave portion 1a and the concave portion 2a (main cavity 3) in a state where the upper die 2 and the upper die 2 are separated from each other. The mold is closed so that the upper mold 1 and the upper mold 2 are in close contact with each other.

As a result, the semiconductor pellet 5 is located at the center of the space of the closed main cavity 3 composed of the concave portion 1a and the concave portion 2a, and the concave portion 1b and the concave portion 2b are provided around the main cavity 3. The sub-cavity 7 is constituted by the sub-cavity 7 and the ejector pins 8 arranged in the sub-cavity 7
Are drawn into the lower mold 1 and the upper mold 2.

Thereafter, the resin 6 is charged into the main cavity 3 through the runner 1c under pressure, and the semiconductor pellet 5 is
It is sealed inside a resin 6a molded into the shape of the main cavity 3. At this time, the plurality of sub-cavities 7 communicating with the main cavity 3 via the communication grooves 1d are simultaneously filled with the resin 6, and the resin 6b having the shape of the sub-cavities 7 is formed.

Then, while maintaining this state for a predetermined time, the resin 6 is heat-cured to obtain a sufficient strength.
The mold is opened to separate the lower mold 1 and the upper mold 2 from each other. At this time,
An ejector pin 8 provided at the position of the sub-cavity 7 protrudes into the sub-cavity 7 and pushes out the resin 6b filled and cured in the sub-cavity 7, and this force is applied to the lead frame 4, the main cavity 3 and the sub-cavity. The resin 6a filled in the main cavity 3 via the resin 6c filled and cured in the communication groove 1d communicating with the cavity 7 acts to release from both the lower mold 1 and the upper mold 2.

As a result, the resin 6a (package P) in which the semiconductor pellet 5 is sealed is released smoothly from the lower mold 1 and the upper mold 2. Further, since the package P in the main cavity 3 is not directly pressed by the ejector pins 8, there is no fear that the package P is damaged by the pressing operation of the ejector pins 8.

Further, since the ejector pins 8 do not exist in the main cavity 3 forming the package P, the flow of the resin 6 in the main cavity 3 is impeded by the presence of the ejector pins 8 during the pressurizing and filling operation. There is no fear of occurrence of defects such as harmful voids due to defective filling.

As a result, the smooth releasing operation by the action of the ejector pin 8 and the reduction of the product defect of the package P can be compatible with each other, and the yield in the resin sealing step is surely improved.

In the lead frame 4 on which the package P has been formed as described above, the tie bar 4e and the frame portion 4c are cut off, and the used resin 6b, 6c is removed in a later lead cutting step. Is cut off, and the product is obtained in a state in which the plurality of leads 4b protrude from the package P.

[0040]

Embodiment 2 FIG. 4 is a plan view of a mating surface of a resin sealing mold used in a resin sealing method according to another embodiment of the present invention, and FIG. FIG. 6 is a schematic cross-sectional view showing an example of the operation of the portion indicated by −V.

In the case of the second embodiment, the ejector pins 80 provided on the lower mold 10 and the upper mold 20 are connected to the outer side of the main cavity 30 constituted by the recess 10a of the lower mold 10 and the recess 20a of the upper mold 20. And abuts the frame portion 40c of the lead frame 40 at the time of release.

In this embodiment, the ejector pins 8
0 indicates that the lower mold 10 is in a mold-clamped state where the lower mold 10 and the upper mold 20 are in close contact with each other, as exemplified in FIG.
In order not to hinder the positioning of the lead frame 40 sandwiched between the upper mold 20 and the upper mold 20, the distal end is drawn in by a predetermined dimension from the mating surface of the lower mold 10 and the upper mold 20. Immediately before the lower mold 10 and the upper mold 20 are opened, as shown in FIG.
And presses the lead frame 40 when the mold is opened as shown in FIG.
An operation of reliably releasing the package P made of the resin 6a molded in the main cavity 30 from the main cavity 30 is performed.

As a result, the pressing force of the ejector pins 80 does not act on the package P in which the semiconductor pellet 5 is sealed in the resin 6a which fills and cures in the main cavity 30 when the mold is released. Damage to the package P and the internal semiconductor pellets 5 due to pressure is prevented.

Since the ejector pins 80 do not exist inside the main cavity 30, the flow of the resin 6 filled in the main cavity 30 is restricted by the ejector pins 80.
There is no fear of being hindered by the above, and a good sealing result can be obtained.

The position of the ejector pin 80 is as follows.
Not limited to the frame part 40c, it may be arranged at the position of the tie bar 40e connecting a plurality of leads 40b.

Although the invention made by the inventor has been specifically described based on the embodiments, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the invention. Needless to say.

[0047]

According to the resin sealing method of the present invention, it is possible to achieve both the prevention of molding defects caused by the ejector pins and the reliable releasing operation by the ejector pins.

According to the lead frame of the present invention,
The effect that the occurrence of defects in the resin sealing step can be reduced can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing a part of a resin sealing mold used in a resin sealing method according to one embodiment of the present invention.

FIG. 2 is a plan view thereof.

FIG. 3 is a schematic cross-sectional view of a portion indicated by line III-III in FIG.

FIG. 4 is a plan view of a mold matching surface of a resin sealing mold used in a resin sealing method according to another embodiment of the present invention.

FIG. 5 is a schematic sectional view of a portion shown by line VV in FIG. 4;

FIG. 6 is a schematic cross-sectional view illustrating an example of the operation of a resin sealing mold used in a resin sealing method according to another embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 lower die 1a concave portion 1b concave portion 1c runner 1d communication groove 2 upper die 2a concave portion 2b concave portion 3 main cavity 4 lead frame 4a tab 4b lead 4c frame portion 4d through hole 4e tie bar 5 semiconductor pellet 6 resin 6a resin 6b resin 6c resin 7c Cavity 8 Ejector pin 10 Lower die 10a Depression 20 Upper die 20a Depression 30 Main cavity 40 Lead frame 40b Lead 40c Frame portion 40e Tie bar 80 Ejector pin P package

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takafumi Nishida 5-22-1, Kamimizuhoncho, Kodaira-shi, Tokyo Inside Hitachi Microcomputer Systems Co., Ltd. (72) Inventor Hajime Sato 5-chome, Kamimizuhoncho, Kodaira-shi, Tokyo No. 1 Inside the Musashi Plant, Hitachi, Ltd. (72) Kunihiko Nishi, Inventor 5-20-1, Kamizu Honmachi, Kodaira City, Tokyo Inside the Musashi Plant, Hitachi, Ltd. (72) Katsuhiro Tabata, Kamizu, Kodaira City, Tokyo 5-20-1, Honcho, Musashi Plant, Hitachi, Ltd. (72) Koji Koizumi, Inventor Koji Koizumi, 5-20-1, Kamizu Honcho, Kodaira City, Tokyo Inside Musashi Plant, Hitachi, Ltd. (56) References JP-A Sho57 -7132 (JP, A) JP-A-2-271641 (JP, A) JP-A-63-162529 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01L 21/56 B29C 45/26 B29C 45/40 B29L 31:34

Claims (3)

(57) [Claims] 1. A cavity formed by an upper mold and a lower mold, a recess formed in at least one of these opposing surfaces, and a resin that fills the cavity by projecting from the opposing surface. A resin sealing method using a resin sealing mold having an ejector pin for performing a mold operation, wherein the resin sealing mold is configured to seal a desired object to be sealed with the resin. One cavity and a position communicating with the first cavity and facing the first cavity therebetween
And a plurality of second cavities disposed, the ejector pin is disposed at each position of the plurality of the second cavity, wherein the resin filled in each of the second cavity when the release ejector pin And performing a releasing operation by pressing the resin. 2. The resin sealing method according to claim 1, wherein
The object to be sealed is located outside the plurality of leads and the leads.
A semiconductor pellet mounted on a lead frame including a frame portion to be mounted, wherein the second cavity and the ejector pins are provided at positions corresponding to the frame portion of the lead frame. Sealing method. 3. The resin sealing method according to claim 2,
A portion of the frame portion where the second cavity is arranged
Resin sealing method characterized by having a through hole formed in
Law .