JP2535358B2 - Manufacturing method of mold part in electronic parts - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a mold part in an electronic component by a synthetic resin mold.

[Conventional technology and its problems]

In electronic parts, for example, multi-pin type integrated circuit devices,
As shown in the figure, the lead frame 1 is formed by punching out a thin metal plate having a thickness (t).
Connect the connecting bars 3 on both the left and right sides with a dam bar 4 at unit width intervals forming each integrated circuit element, and install an island 6 on which the semiconductor chip 5 is mounted from the connecting bar 3 while A large number of inner lead portions 7 are formed so as to project toward the island 6.

Then, after wire bonding the semiconductor chip 5 die-bonded to the upper surface of the island 6 and each inner lead portion 7 with a gold wire 8 or the like, as shown in FIG. 7, a pair of upper and lower mold dies 10, 11 are formed. The island 6 and the inner lead portion 7 are located in the cavity 12 which is a molding space, and the base ends of the dam bar 4 and the inner lead portion 7 are sandwiched by the upper and lower mold dies 10 and 11, and the upper and lower molds Thermoplastic or thermosetting synthetic resin is injected into the cavities 12 of the molds 10 and 11, and the main body portion including the island 6 and the semiconductor chip 5 and the wire-bonded inner lead portion 7 is covered as a mold portion 13. After molding, the left and right connecting bars 3 and the dam bar 4 are cut so that the inner lead portions are electrically separated at the portions protruding from the mold portion 13. So that the production of integrated circuit devices by.

At this time, JP-A-60-92625 and JP-A-62-36834
As disclosed in the publication, etc., a minute gap for discharging the air in the cavity 12 to the outside is formed by the injected synthetic resin along the outer periphery of the inner lead portion, so that the gap is synthesized. When the resin enters and solidifies, a burr that connects the outer circumference of the inner lead portion and the adjacent inner lead portions is formed. Also, in order to prevent the synthetic resin in the cavity 12 from leaking out, the upper and lower mold dies 10 and 11 are sandwiched between the left and right connecting bars 3 and 3 and the dam bars 4 and 4, and a large number of inner lead portions 7 are formed. Since the upper and lower surfaces are also sandwiched between the upper and lower mold dies 10, 11, dust 14 such as deburred pieces of burrs during the molding process adheres to the sandwiching surface of either one of the mold dies. If so, the inner lead portion 7 may get on the rubber 14 during the sandwiching.

However, in the multi-pin type integrated circuit element, since the width of each inner lead portion 7 itself is small, the inner lead portion 7 on the dust 14 is easily bent vertically or horizontally, and the inner lead portion 7 is Since the adjacent pitches of are also narrow, the bent inner lead portions 7 may come into contact with the adjacent inner lead portions, or the wire bonding portion with the semiconductor chip 5 may be cut off, resulting in an extremely high product yield. There was a problem of getting worse.

The present invention aims to solve this problem.

[Means for solving problems]

Therefore, a method of manufacturing a mold part in an electronic component of the present invention includes a plurality of inner lead parts, and a lead frame for an electronic component having a base of each inner lead part connected to a dam bar is molded in a pair of upper and lower molds. When sandwiched between molds and molded by synthetic resin, the pair of upper and lower molds are extended along the upper and lower surfaces of the inner lead part connected to the dam bar from the cavity of the mold part that covers the main body of the electronic component. Form a recess with an appropriate gap, sandwich the upper and lower surfaces of the dam bar at the mating abutting parts of a pair of upper and lower molds, inject synthetic resin into the cavity, and secure the main body of the electronic component. A thin synthetic resin resin is placed in the recess along the upper and lower surfaces of the inner lead portion that is connected to the dam bar from the covering mold portion. Integrally to protrude, in which so as to then remove the thin film.

[Operation and effect of the invention]

As described above, in the present invention, when the lead frame of an electronic component having a large number of inner lead portions is sandwiched between a pair of upper and lower molding dies and synthetic resin molding is performed, the pair of upper and lower molding dies is provided with a main body of the electronic component. A cavity with an appropriate gap is formed along the upper and lower surfaces of the inner lead part that is connected to the dam bar from the cavity of the mold part that covers the dam bar, and the dam bar is formed at the mating contact part of a pair of upper and lower mold dies. Since the upper and lower surfaces are clamped, when the pair of upper and lower molding dies clamps the lead frame, both molding dies may directly contact the upper and lower surfaces of the inner lead portion over the entire length of each inner lead portion. Absent.

That is, even when dust adheres to the recesses of the molding die corresponding to the upper and lower surfaces of each inner lead portion during the molding operation, an accident such as bending each inner lead portion due to the dust does not occur. .

Therefore, according to the present invention, even if the cleaning of both molds is incomplete during the synthetic resin molding operation, the tip side of the inner lead portion bends vertically or horizontally in the cavity between the molds. This has the effect of eliminating electrical shorts and wire disconnection accidents at wire bonding locations.

Further, since the thin films of synthetic resin adhered to the upper and lower surfaces of each inner lead portion protruding from the side surface of the mold portion after the molding are similar to burrs generated during normal molding, it is necessary to perform the removal work. , A product with a beautiful appearance can be made.

Therefore, there is a remarkable effect that it is possible to contribute to the improvement of the quality of the electronic component and the reduction of the manufacturing cost by eliminating the occurrence of the defect of the electronic component due to the synthetic resin molding work.

〔Example〕

Next, an embodiment will be described with reference to the drawings. The lead frame 1 shown in FIG.
Is a connecting bar, 4 is a dam bar, 5 is a semiconductor chip, 6 is an island on which the semiconductor chip 5 is mounted by die bonding, 7 is an inner lead portion radially arranged so as to approach the side surface of the island 6, and 8 Is a wire such as a gold wire for wire-bonding the semiconductor chip 5 and the tip of the inner lead portion 7.

The first embodiment of the molding dies 20, 21 used in the present invention is as shown in FIG. 2 and FIG.
Has a cavity 22 that covers the semiconductor chip 5, the islands 6, the wires 8 and the inner lead portions 7, and mating contact portions 23, 23 that sandwich the upper and lower surfaces of the dam bars 4, 4 and all the inner lead portions 7 A recess 24 capable of forming a minute gap (h1) in the vertical direction is communicated with the cavity 22 on both the upper and lower surfaces of the base portion close to the connection portion with respect to the dam bar 4, and the tip of the recess 24 is aligned and contacted. It will be installed alongside our department 23.

Therefore, the vertical dimension of the recess 24 is equal to the thickness dimension (t) of the inner lead portion 7 plus twice the clearance dimension (h1), and the clearance dimension (h1) is equal to the air inside the cavity 22. The vertical dimension is approximately the same as a clearance (not shown) for pulling out to the outside, and is generally larger than the thickness of dust that adheres.

Further, the recess 24 in the embodiment of FIG. 2 has a wide fin shape which also communicates with a portion of the pitch gap 25 between the inner lead portions 7, 7 adjacent to each other.

Cavity 2 of mold dies 20, 21 in this embodiment
Inserting parts such as the island 6 in the lead frame 1 into 2 and sandwiching the upper and lower mold dies 20 and 21 between the dam bar 4 part and the connecting bar 3 part, the upper and lower parts of all inner lead parts 7 A gap having a vertical dimension (h1) can be formed on both sides with the recess 24, and a pitch gap 25 is also communicated between the inner lead portions 7, 7 adjacent to each other.

Next, when a liquid thermosetting epoxy synthetic resin, for example, is injected from a gate (not shown), the synthetic resin fills the inside of the cavity 22 and the recess 24 is formed so as to cover the peripheral surface of each inner lead portion 7. Flow into the mold die 20,21
By heating the mold for an appropriate time and then removing the molding dies 20 and 21, the mold part 27 can be formed according to the shape of the cavity 22, as shown in FIG. It is extremely thin as h1), and at the pitch gap 25 in the embodiment shown in FIG.
The fin-like thin film 28 that covers all the inner lead portions 7 to have a thickness of 2h1) is integrally formed by projecting from the side surface of the mold portion 27.

Next, after removing the thin film 28 with an appropriate tool or chemical, the connecting bars 3 and 3 and the dam bars 4 and 4 are cut off, and the sixth
As shown in the figure, an electronic component in which the inner lead portion 7 projects from the side surface of the mold portion 27 is manufactured.

Since the thin film 28 is similar to the burr in the synthetic resin mold, it can be easily peeled or removed from the inner lead portion 7.

FIG. 5, which is a cross-section taken along the same line as the line III-III in FIG. 2, shows an embodiment in which the thin film 28 projecting from the side surface of the mold portion 27 can be formed only on the upper and lower surfaces of each inner lead portion 7. At that time, the recess 29 in the molding die 20, 21 is the pitch gap 25 between the inner lead portions 7, 7.
It has a ridge-matching portion 30 that eliminates the problem.

In this embodiment, the synthetic resin does not protrude in a portion corresponding to the pitch gap 25 between the adjacent inner lead portions 7 and 7 after molding, and the thin film 28 is formed along the upper and lower surfaces of each inner lead portion. Since it has adhered, the removal work becomes easier.

In this way, when the lead frame of an electronic component having a large number of inner lead portions is sandwiched between a pair of upper and lower molding dies and synthetic resin molding is performed, the inner lead portion of each inner lead portion is removed from the mold portion that covers the main body portion of the electronic component. Since the thin film made of synthetic resin is integrally projected along both the upper and lower surfaces, even when the mold die for forming the mold portion sandwiches the lead frame, the both die molds are used for the inner lead portions. There is no direct contact with the upper and lower surfaces of.

Therefore, even if dust adheres to the mating surface portions of the molding die corresponding to the upper and lower surfaces of each inner lead portion, the dust does not cause an accident such as bending each inner lead portion. In the cavity between the molds, there is no possibility of causing an electric short circuit due to the tip side of the inner lead portion bending up or down or left and right, and a wire cutting accident at the wire bonding portion. Therefore, there is a remarkable effect that it is possible to contribute to the improvement of the quality of the electronic component and the reduction of the manufacturing cost by eliminating the occurrence of the defect of the electronic component due to the synthetic resin molding work.

The present invention includes a SIP type in which a large number of inner lead parts project from one side of a synthetic resin mold, a DIP type in which inner lead parts project from both sides of the mold part, and an inner lead part protruding from four sides of the mold part. It is needless to say that the present invention can also be applied to the injection type in which a molten thermoplastic synthetic resin is press-fitted into a mold during synthetic resin molding.

[Brief description of drawings]

1 to 6 show an embodiment of the present invention, FIG. 1 is a plan view of a lead frame, FIG. 2 is a sectional view showing a state in which the lead frame is sandwiched between upper and lower molds, and FIG. Is the second
FIG. 4 is an enlarged cross-sectional view taken along the line III-III in FIG. 4, FIG. 4 is a perspective view with both upper and lower molds removed, and FIG. 5 is a main part of the second embodiment shown in the same cross-section as FIG. FIG. 6 is an enlarged cross-sectional view, FIG. 6 is a perspective view of an electronic component, and FIG. 7 is a cross-sectional view for explaining a synthetic resin mold manufacturing method using a conventional molding die. 1 ... Lead frame, 3 ... Connection bar, 4 ... Dam bar, 5 ... Semiconductor chip, 6 ... Island, 7 ... Inner lead part, 8 ... Wire, 10, 11, 20, 21 ... Up and down Both molds, 12,22 …… cavity, 14 …… dust, 2
3 …… Mating contact part, 24,29 …… Recesses, 25 …… Pitch gap, 27 …… Mold part, 28 …… Thin film, 30 …… Bridge butting part.

Claims (1)

(57) [Claims] 1. A synthetic resin mold is formed by sandwiching a lead frame for an electronic component, which has a large number of inner lead parts and whose base parts are connected to a dam bar, between a pair of upper and lower mold dies. At this time, in the pair of upper and lower molding dies, a recess having an appropriate gap is formed along the upper and lower surfaces of the inner lead portion that is connected to the dam bar from the cavity of the mold portion that covers the main body of the electronic component, and The mating contact parts of a pair of upper and lower mold dies hold the upper and lower surfaces of the dam bar, inject synthetic resin into the cavity, and connect the dam bar from the mold part covering the main body of the electronic component. A synthetic resin thin film may be integrally projected in the recess along the upper and lower surfaces of the inner lead portion, and then the thin film may be removed. Method for producing a molded part in the electronic component according to claim.