JPH0122981B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a semiconductor device using a multi-pellet mounting method for the purpose of improving productivity.

Generally, the manufacturing process for resin-sealed semiconductor devices such as transistors and ICs includes a pellet mounting process, a wire bonding process, and a resin molding process, and each of these processes requires multiple leads and covers for the purpose of mass production. A lead frame is used in which a series of pellet mount substrates are integrated. For example, a transistor is manufactured using a lead frame 1 as shown in FIGS. 1 and 2 in the following manner. However, in the lead frame 1, 2 is a plurality of leads, 3 is a plurality of pellet mounting substrates lined up in a series that are integrated with predetermined leads 2, 2, etc. by means such as caulking, for example, a heat sink, and 4 is a plurality of This is a tie bar portion that connects and integrates the leads 2, 2, . . .

First, the lead frame 1 is held horizontally and the heat sinks 3 are intermittently fed in the longitudinal direction at each array pitch, and each heat sink 3, 3, . When one heat sink 3 comes to the solder supply position, a certain amount of solder 5 is supplied onto this heat sink 3, and when the next pellet mount position is reached, the solder 5 that was previously supplied and melted is poured onto the heat sink 3. Semiconductor pellets (hereinafter simply referred to as pellets) 6 are supplied and pellet mounting is performed. When the pellet mounting is completed one by one in this way, the lead frame 1 is intermittently fed to the wire bonding position in the same posture, and each pellet 6, 6... and the corresponding lead 2,
2. Wires 7, 7, etc., such as gold wires, are bonded in order to the wires 7, 7, and so on. Then, the lead frame 1 on which all wire bonding has been completed is set in a mold, and exterior resin materials 8, 8, etc. are molded all at once at multiple key points.Finally, the lead frame 1 is removed from the mold.
The lead frame 1 is taken out and the tie bar portions 4 of the lead frame 1 are cut and removed all at once to obtain a plurality of individually divided semiconductor devices.

By the way, the above pellet mounting process involves taking out the externally positioned pellet 6 using a vacuum suction collet, etc., and supplying it to the fixed position of the heat dissipation plate 3 that has been fed into the fixed position, with respect to one lead frame 1. Because the process had to be repeated multiple times, the index of the pellet mounting process was poor, making it difficult to improve overall productivity. Also,
Due to misalignment of the pellets during mounting, it is difficult to accurately position and fix the pellets 6 on the heat sink 3, which tends to complicate the next wire bonding process, making it even more difficult to improve productivity. Ta.

The present invention has been made in view of the above problems, and particularly aims to develop and provide a multi-method manufacturing method in which the pellet mounting process is performed at a plurality of locations on a lead frame basis. Hereinafter, the present invention will be explained with reference to the drawings.

For example, when the present invention is applied to the manufacture of a semiconductor device using the lead frame 1 described above, the feature of the present invention is that the lead frame 1 has a strip-like shape as shown in FIGS. 3 and 4. metal disk 9
The pellet mounting process and subsequent steps are carried out using the following method. The disk 9 is a thin metal plate made of chromium copper or iron-nickel alloy, and has a length approximately equal to the length of the lead frame 1, and its width is set to be slightly larger than the length of one side of the pellet 6. Further, in the disk 9, recesses 10, 10, . . . are formed by pressing from the front surface to the back surface at a plurality of locations corresponding to the pellet mounting locations of the plurality of heat dissipating plates 3, 3, . . . of the lead frame 1. The bottom surfaces of the recesses 10, 10... have a rectangular shape that almost matches the pellet size.
The inner surface of 0... is formed into a tapered side surface facing outward from the bottom surface. Further, the depth to the bottom of the recesses 10, 10, . . . is slightly smaller than the height (thickness) of the pellet 6.

Next, a pellet mounting process using the lead frame 1 and disk 9 will be explained with reference to FIG. First, a fixed amount of solder 11, 11... is supplied all at once to the bottom surface of each recess 10, 10... of the disk 9 (FIG. 5A). This solder supply is carried out, for example, as shown in FIG. 6, by applying a fixed amount of solder pieces 11', 11', . What is necessary is to adsorb it and supply it to the recesses 10, 10, . . . . In addition, the disk 9 at this time is placed on the heating table 14 and heated, and when the solder pieces 11', 11'... are supplied, they are heated and melted on the bottom surfaces of the recesses 10, 10... . Next, the disk 9 is moved one pitch in the width direction, and the pellets 6,
6... are supplied all at once and soldered (Figure 5 B).
This pellet supply may also be performed using a plurality of integrated vacuum suction pens (not shown) in the same manner as the solder supply described above. In addition, this vacuum suction pen for supplying pellets, for example, sucks at once a plurality of pellets 6, 6, etc., which are arranged in a lattice shape by adhering them at a distance from each other on an adhesive sheet, takes them out from the adhesive sheet, and supplies them to the disk 9. A plurality of pellets 6, 6 placed at regular intervals on a flat tray.
. . are adsorbed at once, taken out from the tray, and supplied to the disk 9. Moreover, even if the pellet 6 is misaligned with respect to the recess 10 as shown by the chain line in FIG.
It is guided by the tapered inner surface of 0 and is automatically positioned and soldered. Also, when performing pellet soldering, it is possible to achieve more reliable soldering by applying a slight vibration to the pellet 6 using a vacuum suction nozzle.
and positioning.

On the other hand, as shown in FIG.
...is supplied in a fixed amount at once and deposited. The silver pastes 13, 13, . . . may be supplied by a pouring method using a plurality of nozzles, a doctor blade method using a mask having a plurality of through holes, or the like. Then, as shown in FIG. 5D, the silver paste 13 is pressed onto the silver paste 13, 13,... of each of the heat sinks 3, 3,... of the lead frame 1 by pressing the back side of each concave portion 10, 10,... of the disk 9. , 13... are spread to have the same thickness, and the disk 9 is positioned and glued. Then, the whole is sent to a heating furnace at a temperature lower than the melting point of solder 11 (about 250℃).
The silver pastes 13, 13, . . . are heated and dried to fix the disk 9 integrally to the lead frame 1.

In this way, each heat sink 3, 3 of the lead frame 1
...The pellet 6 is placed in the upper position via the disk 9,
6. When the pellet mounting is completed by fixing...
Next, the whole is sent to a wire bonding position, and as shown in FIG.
5. Bonding... It is possible to perform wire bonding at multiple locations at the same time by preparing multiple bonding tools (not shown), but with the recent increase in bonding speed, it is also possible to perform wire bonding at multiple locations sequentially using a single bonding tool. There is no big difference in time. Next, with the disk 9 fixed to the lead frame 1, a resin molding die is used to mold exterior resin materials 16, 16, . . . at a plurality of key points as shown in FIG. Then, when cutting the tie bar portion 4 of the lead frame 1, if the cutter is inserted along the side surface of the exterior resin material 16, 16... and the exposed portion of the disk 9 is cut, the 10th
A plurality of semiconductor devices shown in the figure can be obtained at once.

In addition, in the manufacturing method using the disk 9 described above, silver paste is applied to the back surface of the recesses 10, 10... of the disk 9, and the disk 9 is fixed onto the heat sinks 3, 3... of the lead frame 1. You may also do so. In addition, each recess 10, 10... of the disk 9.
Small holes for air venting are made on the bottom and sides of the solder to improve the fluidity of the solder 11, 11..., and the pellets 6, 6
It is also possible to make efforts to make the adhesion area uniform with the pellets 6, 6, etc., and to improve the heat dissipation of the pellets 6, 6, etc.

As explained above, according to the present invention, by using a disk, pellet mounting can be easily performed in a multi-mounting method for each lead frame, thereby greatly improving productivity and reducing manufacturing costs. In addition, since the pellets can be positioned by fitting them into the recesses of the disk, there is no need to accurately position the pellets before mounting the pellets, and there is no need to worry about the pellets being misaligned during the pellet mounting process. Wire bonding, etc. can be performed accurately and yields can be improved.

[Brief explanation of drawings]

1 and 2 are a partially sectional plan view and a sectional view taken along line A-A of a semiconductor device manufactured by a conventional manufacturing method, and FIGS. 3 and 4 are an example of a disk used in the present invention. FIG. 5 is an enlarged sectional view of the main parts of the disk and lead frame at each stage to explain the pellet mounting process according to the present invention, and FIG. FIG. 7 is a partially enlarged cross-sectional view of the disk during pellet supply in step B of FIG. 5, and FIGS. FIG. 6 is a plan view of a wire bonding process, a resin molding process, and a cutting separation process after the pellet mounting process shown in the figure. 1... Lead frame, 2, 2... Lead,
3, 3... Pellet mounting substrate (heat sink, etc.), 6, 6... Semiconductor pellet, 9... Disk, 10, 10... Recessed portion.

Claims (1)

[Claims] 1. Semiconductor pellets are inserted all at once into each recess using a strip-shaped disk with recesses formed at multiple locations corresponding to the pellet mounting locations of a lead frame on which multiple leads and pellet mounting substrates are formed. and a step of collectively fixing the back surfaces of the corresponding recesses of the disk onto each of the pellet-mounted substrates of the lead frame. Production method.