JPH06104364A - Lead frame, method of molding semiconductor chip using the same, and mold for molding - Google Patents

Abstract

(57) [Summary] (Correction) [Purpose] To make the flow of the molding resin of the resin-sealed semiconductor device uniform. [Constitution] A dummy lead 6 is formed between each inner lead 5 of a conventional lead frame, and each dummy lead 6 is bent upward or downward, or alternately bent upward and downward,
When the molding resin 18 is injected using the molding die 17 and the IC chip 8 is resin-sealed, a resistance is given to the molding resin 18 flowing through the inner leads 5 by the dummy leads, and the speed of the molding resin 18 is increased. And the speed of the molding resin 18 flowing over the IC chip 8 and under the die pad 3 are made substantially equal. [Effect] It is possible to prevent the generation of voids due to the wraparound of the mold resin flowing through the inner leads.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead frame which allows a sealing resin to flow in a preferable state in a molding die when molding a semiconductor chip with a resin, a method of molding a semiconductor chip using the same, and a molding method therefor. It is related to the mold.

[0002]

2. Description of the Related Art A conventional lead frame and a semiconductor chip molding method using the same will be described with reference to FIGS. FIG. 9 is a plan view showing a conventional lead frame, FIG. 10 is a cross-sectional side view of a conventional resin-sealed semiconductor device, and FIG. 11 is a semiconductor using the lead frame shown in FIG. FIG. 6 is a plan view showing a state in which a chip is transfer-molded with resin.

A conventional lead frame L shown in FIG.
d is two frame frames 29 that are spaced apart and extend in parallel.
A die pad 31 connected by both frame frames 29 and suspension leads 30; a tip portion of the die pad 31 which is close to the peripheral portion of the die pad 31 and surrounds the die pad 31 with a predetermined gap width; 9 is shown as a single unit. A portion 30a is a portion bent downward, and therefore the die pad 31 is in a depressed state.

The lead frame Ld having such a structure is
Metal plate, eg, 42% N with a thickness of 0.1 to 0.3 mm
It is manufactured by stamping or etching a metal strip of i-Fe alloy.

The resin-sealed semiconductor device Sb shown in FIG.
Is a die-bonding of the semiconductor chip 34 on the die pad 31 of the lead frame Ld, and a bonding pad (not shown) on the surface of the semiconductor chip 34.
And the tip of the inner lead 33 are connected by a wire 35, and the semiconductor chip 34, the wire 35, the tip of the inner lead 33 and the like are sealed with a resin 36 by a transfer molding method.

When this resin molding is performed, in order to make the flow of the molding resin uniform, the resin thickness 37 on the semiconductor chip 34 and the resin thickness 38 under the die pad 31 are often designed to be equal. .

[0007]

However, in the structure of such a conventional lead frame Ld and the semiconductor device using the same, as shown in FIG. 9, the semiconductor chip 34 is used.
Compared with the resin thickness 37 above and the resin thickness 38 below the die pad 31, resin thicknesses 39, 40 above and below the inner lead 33
11A, when the mold resin 36 is injected from the direction of the arrow Y, as shown in FIG. 11A, the flow of the mold resin flowing through the inner lead 33 portion having a small flow resistance precedes, so that the semiconductor chip 34 and the die pad 31 are exposed. There is a problem that voids (air bubbles) 41 remain below and so-called void defects occur. It is an object of the present invention to provide a lead frame having a structure that prevents the flow of resin that promotes the generation of such voids 41, a method of molding a semiconductor chip, and the like.

[0008]

Therefore, in the lead frame of the present invention, the tip portions are arranged at a predetermined interval width along the peripheral portion of the die pad on which the semiconductor chip is mounted and the tie bar is provided. In a lead frame surrounded by a plurality of supported leads, a tip portion is present between the tip portions of the leads, and the other end is arranged with dummy leads held by the tie bar, and a groove is formed in each of the dummy leads. The dummy leads were sandwiched between molding dies, bent at the groove portions, and the molding resin was injected.

[0009]

Therefore, since the dummy leads exist in the resin flow paths above and below the inner lead, a flow resistance is formed in that portion, and when the mold resin is injected, the flow resistance is received in that portion. The speed of resin flow is suppressed,
The speed can be almost the same as that of the resin on the semiconductor chip and under the die pad, which originally flow slowly.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 8, a lead frame of the present invention, a method of molding a semiconductor chip using the same, and a molding die will be described. 1 shows a first embodiment of a lead frame of the present invention, FIG. 1A is a plan view thereof, and FIG.
Is a sectional view of the dummy lead taken along the line AA of FIG.
FIG. 2C is a cross-sectional view of the dummy lead taken along the line BB in FIG. 1A, and FIG. 2 shows a state in which the semiconductor chip is fixed to the lead frame in FIG. 1 and mounted on a molding die for resin molding. FIG. 3 is a sectional side view showing FIG. 3, FIG. 3 shows a state where mold resin is injected in the state of FIG. 2, FIG. 3A is a plan view showing a state in the middle of molding, and FIG. FIG. 4 is a view showing a second embodiment of the lead frame of the present invention, FIG. 4A is a plan view thereof, and FIG. 4B is a sectional view of the dummy lead taken along the line AA of FIG. 5 is a sectional side view showing a state in which a semiconductor chip is fixed to the lead frame of FIG. 4 and mounted on a molding die for resin molding, and FIG. 6 is a third embodiment of the lead frame of the present invention. FIG. A shows a plan view of FIG. FIG. 7 is a cross-sectional view of the dummy lead taken along the line AA in FIG. 7A, and FIG. 7 is a cross-sectional side view showing a state in which the semiconductor chip is fixed to the lead frame of FIG. 6 and mounted on a molding die for resin molding. FIG. 8 is a partial sectional view of the mold for molding which is one of the present invention.

The lead frame La shown in FIG. 1 is an SOP.
Which is used in a semiconductor device of the type, and as shown in FIG.
A die pad 3 connected by both frame frames 1 and suspension leads 2; a tip portion thereof is provided in the vicinity of the peripheral portion of the die pad 3 so as to surround the die pad 3 with a predetermined gap width, and is supported by a tie bar 4; It is composed of a plurality of inner leads 5 and the like, and FIG. 1 shows only one unit. A portion 2a is a portion bent downward, and therefore the die pad 3 is in a depressed state.

In the present invention, the dummy leads 6A and 6B, which have a tip portion between the tip portions of the inner leads 5 and the other end of which is held by the tie bar 4, are arranged alternately. As shown in FIG. 2B, the dummy lead 6A has a concave groove 7 on the surface of the dummy lead 6A.
(Hereinafter, simply referred to as “groove 7”) was formed, and groove 7 was formed on the back surface of the dummy lead 6B. The lead frame La having such a structure has a thickness of 0.125 mm and is 42%.
It was manufactured by punching out a Ni-Fe alloy.

The IC chip 8 is placed on the die pad 3 of the lead frame La, and a plurality of electrode pads formed on the surface of the IC chip 8 are connected to the tips of the inner leads 5 by wires (see the figure for simplicity. 2 is omitted), as shown in FIG. 2, so that the groove 7 of each dummy lead 6A is located at the edge 12 where the abutting surface 10 of the upper die 9 and the cavity 11 abut. Then, the lead frame La is separated from the upper mold 9 and the lower mold 13 so that the groove 7 of each dummy lead 6B is located at the edge 16 where the abutting surface 14 of the lower mold 13 and the cavity 15 meet. It is placed in the molding die 17 and is fastened.

When the lead frame La is placed in the molding die 17 and tightened as described above, the dummy lead 6 is centered on the groove 7 by the fastening force of the molding die 17.
The tips of A and 6B are bent. That is, the tip of the dummy lead 6A is bent toward the upper mold 9, and the tip of the dummy lead 6B is bent toward the lower mold 13. This is the upper and lower molds 9,1
This is because the fastening force of No. 3 causes the metal surface of the surface where the groove 7 is not formed to expand more than the metal surface of the surface of the dummy lead where the groove 7 is formed.

When the 42% Ni--Fe alloy having the above thickness was used for fastening, the bending height H of the tip of the dummy lead was about 0.15 mm. In this case, the distance between the bottom surfaces of the cavities 11 and 15 of the molding die 17, that is, the total resin thickness T of the semiconductor device was set to 1 mm.

When the molding resin 18 is injected from the direction of the arrow Y as shown in FIG. 3A with the lead frame La clamped by the molding die 17 as described above,
Mold resin 1 flowing through each inner lead 5 on both sides
8 receives the resistance due to the bent dummy leads 6A and 6B, and the speed is almost the same as the flow of the mold resin 18 on the IC chip 8 and under the die pad 3 which originally has a large resistance, so that the void-free resin sealing The type semiconductor device S can be manufactured (FIG. 3B).

FIG. 4 shows a second embodiment of the present invention.
The lead frame Lb is composed only of the dummy leads 6A having the groove 7 formed only on the upper surface, and is mounted on the molding die 17A as shown in FIG. All the tips of the dummy leads 6A are bent upward. The lead frame Lb
The other structure is similar to that of the lead frame La. Such a lead frame Lb is useful when a resin-sealed semiconductor device having a structure in which the resin wall thickness Ta on the inner lead 5 is thicker than the resin wall thickness Tb under the inner lead 5 is manufactured.

FIG. 6 shows a third embodiment of the present invention.
The lead frame Lc is composed only of the dummy leads 6B having the groove 7 formed only on the lower surface, and is mounted on the molding die 17B as shown in FIG. 7 and tightened by the molding die 17B. All the tips of the dummy leads 6B are bent downward. The lead frame L
The other structure of c is the same as that of the lead frame La. Such a lead frame Lc is useful when a resin-sealed semiconductor device having a structure in which the resin thickness Tb under the inner lead 5 is thicker than the resin thickness Ta on the inner lead 5 is manufactured.

In each of the above-mentioned embodiments, the case where the dummy lead is bent by the fastening force of the molding die is given. But,
When it is necessary to bend the tip portion of the dummy lead more largely, for example, the bending height H in FIG. 2 is 0.2 mm.
When it is desired to fold it to a certain extent, it is no longer possible to bend it with the fastening force of the molding die. When it is necessary to bend the dummy lead 6A in such a manner as shown in FIG. 8, when the dummy lead 6A is bent to the upper side, the lower mold 13 is used.
At the edge 16 of the abutting surface 14 of the groove 7 of the dummy lead 6A.
By forming the minute protrusions 19 corresponding to the above, and sandwiching and clamping the lead frame Lb with such a molding die 17A, all the dummy leads 6A can be surely bent relatively upward to a relatively large extent.

When it is necessary to bend all of the dummy leads 6B downward relatively relatively, it is sufficient to form the minute projections 19 on the edge 16 of the abutting surface 10 of the upper die 9 and bend them. When it is necessary to alternately bend the leads 6A and 6B to the upper side and the lower side by a relatively large amount, the minute protrusions 19 are formed on the edges of the abutting surfaces of the upper and lower molds in correspondence with the grooves 7 of the dummy leads. It can be formed and bent. The height L of such minute protrusions 19 is 0.01 to
About 0.05 mm is desirable, and this degree is sufficient.

Even if the bending of the dummy lead is performed with a relatively small amount of bending as described in the first embodiment, if it is desired to positively and surely bend the minute lead 19 as described above. It may be performed using an upper mold and / or a lower mold provided with.

Although the groove 7 in each of the above-described embodiments is expressed as a concave groove, this groove may not be a concave groove but may be a V-shaped groove. The concave groove can be formed by half etching, and the V-shaped groove can be formed by V notch processing.
Therefore, the lead frame of the present invention can be manufactured without changing the manufacturing process of the conventional lead frame.

Since the dummy lead is on the same plane as the inner lead until it is fastened by the molding die,
The die bonding process, the wire bonding process, and the transfer process therebetween can be handled by the conventional technique for handling a lead frame.

Although the SOP type semiconductor device lead frame has been described as an example in the above embodiment, the present invention is not limited to the SOP type semiconductor device lead frame, and it is not limited to the QFP type lead frame.
It goes without saying that the present invention can also be applied to a lead frame used in a type semiconductor device.

[0025]

As described above, according to the lead frame of the present invention and the method of manufacturing a semiconductor device using the same, dummy leads are formed, and the tips of these dummy leads are bent to form the inner leads. Since resistance is given to the mold resin flowing in the part, the speed of the mold resin flowing in that part becomes almost equal to the speed of the mold resin flowing in the semiconductor chip and under the die pad, preventing the occurrence of voids (air bubbles). can do. Further, the lead frame of the present invention can be manufactured without changing the manufacturing process of the conventional lead frame. Furthermore, since the dummy lead is on the same plane as the inner lead until it is fastened with the molding die, the conventional lead frame handling technology must be used for the die bonding process, wire bonding process, and transfer process between them. It is possible to obtain excellent effects.

[Brief description of drawings]

1 shows a first embodiment of a lead frame of the present invention, FIG. 1A is a plan view thereof, FIG. 1B is a sectional view of a dummy lead taken along the line AA in FIG. 1A, and FIG. FIG. 4B is a cross-sectional view of the dummy lead on the line BB of FIG.

FIG. 2 is a sectional side view showing a state in which a semiconductor chip is fixed to the lead frame of FIG. 1 and mounted on a molding die for resin molding.

3 is a plan view showing a state where a molding resin is injected in the state of FIG. 2, FIG. A is a plan view showing a state in the middle of molding, and FIG. 3B is a plan view showing a state in which molding is completed.

FIG. 4 shows a second embodiment of the lead frame of the present invention, FIG. 4A is a plan view thereof, and FIG. 4B is a sectional view of the dummy lead taken along the line AA of FIG.

5 is a cross-sectional side view showing a state in which a semiconductor chip is fixed to the lead frame of FIG. 4 and mounted on a molding die for resin molding.

FIG. 6 shows a third embodiment of the lead frame of the present invention, FIG. 6A is a plan view thereof, and FIG. 6B is a sectional view of the dummy lead taken along the line AA of FIG.

7 is a cross-sectional side view showing a state in which a semiconductor chip is fixed to the lead frame of FIG. 6 and is mounted on a molding die for resin molding.

FIG. 8 is a partial cross-sectional view of a molding die that is one of the present invention.

FIG. 9 is a plan view showing a conventional lead frame.

FIG. 10 is a cross-sectional side view of a conventional resin-encapsulated semiconductor device.

11 is a plan view showing a state where a semiconductor chip is transfer-molded with resin using the lead frame shown in FIG. 9.

[Explanation of symbols]

 La lead frame Lb lead frame Lc lead frame S resin-sealed semiconductor device 1 frame frame 2 suspension lead 3 die pad 4 tie bar 5 inner lead 6 dummy lead 6A dummy lead 6B dummy lead 7 groove 8 IC chip 9 upper die 10 collision Surface 11 Cavity 12 Edge 13 Lower mold 13A Lower mold 14 Abutting surface 15 Cavity 16 Edge 17 Mold for mold 17A Mold for mold 18 Mold resin 19 Minute protrusion

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Claims (3)

[Claims] 1. A lead frame, in which a peripheral portion of a die pad on which a semiconductor chip is mounted is surrounded by a plurality of leads supported by tie bars, the distal end portions being arranged at a predetermined interval width along the peripheral portion. A lead frame in which a tip portion is present between the tip portions of the leads, dummy leads having the other end held by the tie bar are arranged, and grooves are formed in each of the dummy leads. 2. The lead frame according to claim 1, wherein a semiconductor chip is fixed to the die pad of the lead frame, and the semiconductor chip and the like are molded by using a mold including upper and lower molds. It is sandwiched by upper and lower molds, each dummy lead is bent at the portion where the groove is formed, resin is injected in a state where the resin flow path has resistance, and the semiconductor chip or the like is transfer molded. And a method of molding a semiconductor chip. 3. A transfer mold comprising upper and lower molds each having a cavity,
A mold for transfer molding, characterized in that minute protrusions are formed with a predetermined interval width in the vicinity of the mold line on the pressing surface of the upper mold or the lower mold.