JPS6130749B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lead frame used in a resin-sealed semiconductor device.

A method for manufacturing a resin-sealed semiconductor device using a conventional lead frame is as follows. A lead frame is prepared, a die is fixed to the semiconductor die mounting part, the external lead electrode part of the die and the stitch part of the internal lead are connected with a thin metal wire, and the semiconductor die is molded by transfer molding or the like. After sealing with resin, the external leads are tin-plated, and then molded into a dual-in-line type or the like and assembled.

According to this conventional manufacturing method, the manufacturing process from transfer molding to the tin plating process is long.
To describe the process in detail, the molding,
As a pretreatment for resin curing and plating, the resin protruding from the external leads is removed and tin plating is performed.
During these steps, the removal of the protruding resin is particularly difficult. In other words, in the case of chemical removal,
The chemicals cause pollution problems, have an adverse effect on the surface of the sealing resin, and if the chemicals are weak, they may not be able to be removed, resulting in poor quality. Furthermore, in the case of mechanical removal, i.e. brushing, filing,
Scraping it off with a knife is not suitable for mass production, and mass production would require a large capital investment, and there were problems such as damaging the surface of the external lead and impairing the quality of the tin plating. Therefore, it has been considered to use a lead frame whose external lead portions are tin-plated in advance. However, in order to securely attach the semiconductor die to the die mounting part, a process is required in which the lead frame is placed on a heater block and a gold-silicon alloy is formed between the semiconductor die and gold or a gold alloy. Since the temperature of the block is around 450°C, the tin on the tin-plated lead frame will melt, and in the next process of thermocompression wire bonding, the lead frame will also be placed on a heater block at around 300°C, so the tin will melt. Metsuki melts. Previously, therefore, pre-tinned lead frames could not be used.

An object of the present invention is to eliminate the above-described problems in the manufacturing process and provide a lead frame suitable for manufacturing high-quality semiconductor devices.

The present invention relates to a lead frame used in a resin-sealed semiconductor device, in which the stitching part and the die mounting part of the inner lead to be resin-sealed are plated with gold or silver, and the outer part is not resin-sealed. There is a part where the lead part is tin-plated and the width of the internal lead and die support part on the way from the stitch part and die mounting part to the resin-sealed end is significantly narrower than other parts. The lead frame is characterized in that the back side of the lead at this narrow portion is integrally reinforced with a material that is an electrically poor conductor and has poor thermal conductivity.

Next, one embodiment of the lead frame of the present invention will be described with reference to the drawings.

FIG. 2 is a perspective view showing the embodiment, and FIG. 3 is a perspective view showing the internal structure of a resin-sealed semiconductor device assembled using the lead frame. A part of the inner lead of the lead frame 1 from the gold- or silver-plated stitching part 5 to the resin-sealed end, the gold- or silver-plated die mounting part 2, and the frame body part 12 of the lead frame. A notch is made in a part of the support part connecting the parts, and a part 9 is provided in which the internal lead width of that part is significantly narrowed.
In order to reinforce the stitching part and die mounting part beyond this part, the narrowed part 9 of these internal leads and the support part is integrally reinforced from the back side with a thermally strong resin tape 10 such as Kapton tape. be. (Kapton is a product name) The drawing shows a case where the stitched portion is reinforced. Kapton resin tape has a heat resistance of about 350°C for a short period of time, and can withstand temperatures as long as required for die bonding and wire bonding. Also, since this tape is attached to the lead frame by thermocompression bonding, it will not peel off even when heated. The reinforcing material is not limited to Kapton resin, but any material that has heat resistance, is an electrically poor conductor, and has poor thermal conductivity can be used. Normally, when a lead frame is subjected to die bonding or wire bonding in the next process, the former heats only the die mounting part locally, and the latter heats only the die mounting part and the stitching part locally. In this case, even in the case of the above-mentioned local heating due to the influence of heat conduction or radiant heat, if the narrow portion 9 is not provided as in the present invention, the tin plating 8 will not be formed in a lead frame where the external leads are pre-plated with tin. There is a risk of melting. However, in the lead frame of the present invention, there is a portion 9 in the middle of the internal lead that is significantly narrower than other portions, which impedes heat conduction, and the resin tape 10 used for reinforcement has the effect of blocking radiant heat. . In addition, the tin plating on the external leads is plated slightly deeper into the inner lead side than the resin-sealed end, so when the lead frame of the present invention is used, the tin plating is applied when the lead frame is sandwiched between the upper and lower molds during resin sealing. As a result, the surface thereof is soft, and therefore the gap between the upper and lower molds is almost eliminated, and the protruding resin 11 can be almost ignored.

In the lead frame of the present invention, the external leads are tin-plated in advance, so the quality of the tin plating is better than in a manufacturing method in which plating is performed after resin sealing, and the manufacturing process of a semiconductor device using this lead frame is , die bonding, wire bonding, resin sealing, and lead molding, eliminating the conventional tin plating process after resin sealing, which has the effect of shortening the manufacturing process.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a conventionally used lead frame, Fig. 2 is a perspective view showing an embodiment of the lead frame of the present invention, and Fig. 3 is a resin seal assembled using the lead frame of the present invention. FIG. 2 is a perspective view showing the internal structure of a stop-type semiconductor device. 1...Lead frame, 2...Die mounting section, 3
...Die, 4...External extraction electrode part, 5...Stitch part, 6...Metal thin wire, 7...Sealing resin, 8...
Tin plating, 9...Narrowed width part, 10...Resin tape, 11...Protruding resin, 12...Lead frame frame body part.

Claims (1)

[Claims] 1. In a lead frame used for a resin-sealed semiconductor device, the stitching part of the inner lead and the die mounting part are plated with gold or silver, and the outer lead part which is not sealed with resin is plated with tin, and the inner lead is plated with gold or silver. A portion of the resin-sealed portion of the lead and die mounting portion support lead is formed into a narrow width, and this narrow portion is integrally reinforced with a material that is an electrically poor conductor and has poor thermal conductivity. A lead frame for resin-sealed semiconductor devices characterized by the following.