JPH02114539A - Assembly of resin-sealed semiconductor device - Google Patents

Abstract

PURPOSE:To restrain a wiring lead from being deformed during its formation process and to reduce a formation cost by a method wherein an island part and the wiring lead are connected collectively in a lead frame and a tip part of each wiring lead is supported by the island part. CONSTITUTION:The tip on the side of an island part at individual wiring leads 3 is connected collectively to the island part 2 and is held by the island part 2. A support lead 11b connecting a plularity of wiring leads 3 mutually at individual frames is formed so as to surround the island part 2. On the other hand, the individual frames are partitioned by support leads 11a formed so as to connect one pair of external leads 10 by crossing one part of the wiring leads 3. Since tip parts of the individual wiring leads 3 are supported by the island part 2, it is possible to restrain the wiring leads from being deformed even when an unneccesary force acts during formation of a lead frame 1 and to enhance a yield; accordingly, it is possible to reduce a formation cost of the lead frame 1.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a method for assembling a resin-sealed semiconductor device.

[Prior Art] FIG. 4 is a partial plan view showing one pattern of a lead frame used in a conventional method for assembling a resin-sealed semiconductor device.

The island portion 22 provided at the center in the width direction of the tape-shaped lead frame has a square shape, for example, and its four corners are held by hanging leads 21 to frame portions at the ends of the lead frame in the width direction. In addition, the island section 22
For example, five wiring leads 23 are arranged extending toward each of the four sides. This wiring lead 23 is arranged in a state separated from the island portion 22.

In addition, in the case of a multi-pin lead frame, the wiring lead 2
3 has a width of 0.1 mu, a length of 20+nn, and a thickness of 0.
It has a long, thin shape with a diameter of 1 mm.

A conventional method for assembling a resin-sealed semiconductor device includes the following steps using the above-mentioned lead frame.

(1) Die Bonding Step Each pellet (not shown) that has been bonded is bonded onto the island portion 22 with a resin such as silver paste, and then heat-treated and fixed.

(2) Wire bonding process The electrodes on the pellet and the wiring leads 23 are wired by wire bonding.

(3) Sealing process The tips of the pellet, bonding wire, and wiring lead 23 on the island portion 22 are sealed with resin, and these are fixed to each other.

(4) External lead cutting/processing process The wiring lead 23 is cut so as to protrude from the resin sealing portion by an appropriate length, and is further bent.

[Problems to be Solved by the Invention] However, in the conventional method for assembling a resin-sealed semiconductor device, the wiring leads 23 of the lead frame used
Moreover, especially in the case of a multi-pin lead frame, since each wiring lead 23 is thin, long, and thin, lead deformation is likely to occur. For this reason, the manufacturing yield of lead frames is low, and the lead frames used in the conventional method are disadvantageous in that they are expensive.

In addition, in the die bonding process, the wiring leads 22 may be damaged due to heat treatment for fixing the pellets to the island portion 22 or due to careless handling of the lead frame.
is easily deformed.

For this reason, there is a problem that the position of the wiring lead 23 to be bonded changes in the wire bonding process, which reduces the yield.

The present invention has been made in view of such problems, and includes:
Assembly of a resin-sealed semiconductor device that is resistant to lead deformation, allows the use of a lead frame with low manufacturing costs, significantly improves the yield of the wire bonding process, and reduces processing costs. The purpose is to provide a method.

[Means for Solving the Problems] A method for assembling a resin-sealed semiconductor device according to the present invention includes a step of mounting a pellet on the island portion of a lead frame in which the island portion and wiring leads are integrally connected. The method is characterized by comprising the steps of wire bonding between the pellet and the wiring lead, cutting and separating the wiring lead and the island, and sealing the pellet with resin.

[Function] The lead frame used in the present invention integrally connects the island portion and the wiring lead, and each wiring lead is supported by its tip or the island portion.
Deformation of the wiring lead during manufacturing is suppressed. Therefore, the manufacturing cost of the lead frame is low. Furthermore, since deformation of each wiring lead is suppressed during handling of the lead frame or mounting of pellets, the yield of wiring leads is significantly improved even during wire bonding because only the positions of the wiring leads are corrected.

Then, after this wire bonding or after pellet mounting and before wire bonding, the wiring lead and the island portion are cut and separated. Thereafter, by resin-sealing the pellets, a resin-sealed semiconductor device can be assembled using the same steps as in the prior art. In this way, according to the present invention, a resin-sealed semiconductor device can be assembled at low cost and with high yield.

[Example] Next, an example of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a plan view showing one pattern of a lead frame 1 used in the method of assembling a resin-sealed semiconductor device according to an embodiment of the present invention.

The two band-shaped external frames 10 extend parallel to each other, and a plurality of island parts 2 are arranged in the center of the two external frames 10 at predetermined widths. Further, each island portion 2 has a square shape, for example, and two sides thereof are parallel to the external frame 10. Two sides parallel to the external frame 10 of each island section 2 are external frames 10
It is connected to the external frame 10 by a plurality of wiring leads 3 (five in the illustrated example) extending perpendicularly to the external frame 10 .

On the other hand, the other two sides of each island part 2 are connected to the opposite sides of the adjacent island parts 2 by wiring leads 3 (five in the illustrated example) extending parallel to the external frames 10 at the center between a pair of external frames 10. is connected to.

In this way, each wiring lead 3 has its tip on the island portion 2 side integrally connected to the island portion 2 and is held by the island portion 2.

Further, in each frame, support leads llb for interconnecting a plurality of wiring leads 3 are provided so as to surround the island portion 2. On the other hand, the support lead lla
intersects with a part of the wiring lead 3 to form a pair of external frames 1
Each frame is partitioned by this support lead lla.

In this way, the lead frame 1 used in the embodiment of the present invention integrally connects the island portion 2 and the wiring leads 3, and the tip of each wiring lead 3 is connected to the island portion 2.
Therefore, even if unnecessary force is applied during manufacturing of the lead frame 1, deformation thereof is suppressed. This improves the manufacturing yield, so the manufacturing cost of the lead frame 1 is low.

In the first embodiment of the present invention, first, a pellet 4 is bonded onto the island portion 2 of the lead frame 1 with silver paste 5 (see FIG. 2), and then the pellet 4 is attached to the island portion by heat treatment. Fix it to 2.

Next, the wiring portion 3 is cut using the cutting device shown in FIG. This cutting device is composed of a lower mold 7 and an upper mold 6. This lower mold 7 is formed of a metal block, and is provided with a groove 7a passing through it in the thickness direction.

The upper mold 6 has an inverted U shape, and both ends thereof have grooves 7.
It is provided at a position aligned with a. And upper mold 6
is lowered and both tips thereof penetrate into the groove 7a of the lower mold 7, thereby removing the lead frame 1 placed on the lower mold 7.
The wiring leads 3 of are sheared.

The lead frame 1, which has undergone the tie bonding process, is positioned and placed on the upper surface of the lower mold 7 so that the groove 7a and the planned cutting position of the wiring lead 3 are aligned.

After that, the upper mold 6 is lowered, and the tip of the upper mold 6 is
a to cut and separate the wiring lead 3 and the island portion 2 by shearing.

Next, after wiring the electrodes of the pellet 4 and the wiring lead 3 by wire bonding, the pellet 4 on the island portion 2, the bonding wire (not shown), and a part of the wiring lead 3 are sealed with resin. Fasten to each other.

Thereafter, the leads 3 are separated from the external frame 10 and the portions of the leads 33 protruding from the resin-sealed portion are bent, thereby assembling a resin-sealed semiconductor device.

In this example, in the die bonding process,
Since the lead frame 1 in which the island portion 2 and the wiring leads 3 are integrally connected is used, each wiring lead 3
Since its tip is supported by the island part 2,
During the heat treatment for fixing the pellet 4 to the island portion 2 or when handling the lead frame 1, the wiring lead 3
deformation is suppressed. Therefore, during wire bonding, the position of the wiring lead 3 to be bonded can be prevented from changing. Thereby, the yield in the wire bonding process can be significantly improved.

On the other hand, even if the same lead frame 1 is used, the cutting position can be changed by replacing the upper mold 6 and lower mold 7 with ones of the respective sizes, and the pellet 4
Since the wiring leads 3 are cut after die bonding, it becomes possible to mount a pellet 4 larger than the island portion 2. This makes the lead frame 1 highly versatile, and eliminates the need to prepare many types of lead frames 1 depending on the size of the pellet 4.

Next, a second embodiment of the present invention will be described.

First, as shown in FIG. 3, after the pellet 4 is mounted on the island portion 2 of the lead frame 1, the electrode on the pellet 4 and the wiring lead 3 are wired with the bonding wire 12.

Next, the wiring lead 3 is cut by a cutting device to separate the wiring lead 3 and the island portion 2.

As shown in FIG. 3, this cutting device includes a laser oscillator 9,
A mirror 8 is provided to direct the laser beam 13 from the oscillator 9 to a predetermined cutting position of the wiring lead 3. This mirror 8
is rotationally driven by a motor (not shown), and scans the lower surface of the lead frame 1 by continuously changing its angle with respect to the laser beam 13. Note that the focus of the laser beam 13 is set on the lower surface of the wiring lead 3 so that only the wiring lead 3 is cut.

In this cutting process, first, the wire-bonded lead frame 1 is placed above the mirror 8, and the laser beam 13 emitted from the laser oscillator 9 is directed by the mirror 8 to a predetermined cutting position of the wiring lead 3.

Then, the mirror 8 is rotated to scan the lower surface of the lead frame 1 with the I/- laser beam 13 to cut the wiring cord 3. Thereby, the wiring lead 3 and the island portion 2 are cut and separated.

Next, the pellet 4, bonding wire 12, and wiring lead 3 are fixed to each other by a resin sealing process. Thereafter, the portion of the lead 3 protruding from the resin-sealed portion is cut leaving only a predetermined length, and this portion is bent to assemble the resin-sealed semiconductor device.

In this embodiment, since the wiring lead 3 is cut by the laser beam 13 after wire bonding, the cutting position can be easily changed and corrected, so the cutting process is more flexible than the first embodiment. It has the advantage of being superior in properties.

[Effects of the Invention] According to the present invention, since the lead frame in which the island portion and the wiring lead are integrally connected is used, the tip of each wiring lead is supported by the island portion, so that manufacturing of the lead frame is simplified. Even if unnecessary force is sometimes applied, deformation of the wiring lead is suppressed. This significantly improves the manufacturing yield, thereby reducing the manufacturing cost of the lead frame.

Further, since deformation of each wiring lead is suppressed during die bonding or handling of the lead frame, variations in the position of the wiring leads to be bonded during wire bonding can be prevented. Therefore, wire bonding between the electrode on the pellet and the wiring lead can be performed with high yield.

In this way, according to the present invention, processing costs in the assembly process of a resin-sealed semiconductor device can be significantly reduced.

[Brief explanation of drawings]

FIG. 1 is a plan view showing one pattern of a lead frame used in the method of assembling a resin-sealed semiconductor device according to an embodiment of the present invention, and FIG. 2 is a cutting diagram used in the first embodiment of the present invention. FIG. 3 is a cross-sectional view showing the cutting device used in the second embodiment of the present invention, and 4UA is a cross-sectional view showing the cutting device used in the second embodiment of the present invention. FIG. 3 is a partial plan view showing a pattern. 1; Lead frame, 2, 22; Island part, 3.2
3; wiring lead, 4; pellet, 5; silver paste, 6;
Upper mold, 7; Lower mold, 8; Mirror 9; Laser oscillator, 1
0; external frame, 11a. 11b; Support lead, 12; Bonding wire, 13
;Laser light, 21;Hanging lead 1st figure 2

Claims (1)

[Claims] (1) A step of mounting a pellet on the island portion of a lead frame that integrally connects the island portion and the wiring lead, and performing wire bonding between the pellet and the wiring lead, and performing wire bonding between the pellet and the wiring lead. A method for assembling a resin-sealed semiconductor device, comprising the steps of cutting and separating the pellet from the island portion, and sealing the pellet with a resin.