JPH0815191B2 - Method for manufacturing lead frame - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a lead frame using both press working and etching working.

(Prior Art) Current lead frame manufacturing methods include a method by etching and a method by pressing.

Among them, the method of manufacturing a lead frame by etching is a method of molding a predetermined resist pattern on a metal plate for manufacturing a lead frame at the same position on both sides, and then treating with an etching solution to simultaneously expose exposed portions of the metal plate from both sides. This is a method of performing etching. In this method, the etched portion has a lead interval.

On the other hand, in press working, a strip-shaped metal plate for manufacturing a lead frame is sequentially punched by a die.

Each of these processing methods has great advantages. For example, in press working, since feeding, positioning and the like at the time of working of the lead frame are carried out by the guide holes of the rail portion and the like, it is possible to carry out working with high accuracy.

In addition, normally, when resin molding,
To prevent the resin from leaking out through the gap between the leads,
A dam bar that connects the external leads is provided, and the dam bar is cut after resin molding. Such dam bar cutting can be easily performed by pressing.

Moreover, by press working, the formed lead side surface can be formed into a flat surface, and the mold flash does not remain attached to the side surface of the external lead portion near the resin mold portion after the dam bar is cut.

On the other hand, according to the etching process, the inner pattern part including the internal lead parts can be made finer in accordance with the demand for increasing the number of pins of the semiconductor device, more easily than the press process.

(Problems to be Solved by the Invention) As described above, in press processing and etching processing,
While each has its advantages, each also has its drawbacks.

For example, the pressing process has a drawback that it is difficult to make the inner pattern portion finer, and the etching process cannot form a flat surface on the side surface of the etched portion. It has a drawback that it adheres and cannot be subjected to surface treatment such as plating on the side surface of the external lead portion.

Therefore, an object of the present invention is to provide a method of manufacturing a lead frame that enables the inner pattern portion to be made finer and can prevent the mold flash from adhering to the side surface of the outer lead portion near the resin mold portion. .

(Means for Solving the Problem) The present inventor considers that in order to achieve the above-mentioned object, it is advantageous to use both of the workings in combination so that the advantages of the press working and the etching working can be utilized. As a result,
The present invention has been reached.

That is, the present invention prevents the resin from leaking outside through the gap between the leads outside the boundary between the inner lead portion inside the resin mold area and the outer lead portion outside the resin mold area during resin molding. When manufacturing a lead frame having a dam bar that connects between the external leads, the external lead part and the dam bar including the lead part between the boundary part and the dam bar, which is outside the resin mold region, are formed by pressing. After that, there is provided a method of manufacturing a lead frame, characterized in that an inner pattern portion including an inner lead portion to be in the resin mold region is formed by etching.

(Operation) According to the present invention, the outer lead portion and the dam bar, which are wider than the gap between the leads of the inner lead portion and are outside the resin mold region, are formed by press working. Therefore, the side surface of the external lead portion can be formed into a flat surface, and even if the dam bar is cut after the resin molding, the mold flash is not formed on the side surface of the external lead portion near the resin molded portion as in the case where the external lead portion is formed by etching. It can be prevented from adhering.

Further, since the inner pattern portion including the inner leads is formed by etching, it is possible to make the inner pattern portion finer, which was difficult by press working.

As described above, by forming the outer lead portion and the dam bar by pressing, and then forming the inner pattern portion including the inner lead portion by etching, it is possible to utilize the advantages of the pressing and etching. It is possible to make the pattern portion finer and prevent the mold flash from adhering to the side surface of the external lead portion near the resin mold portion.

(Examples) Hereinafter, preferred examples of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 shows a part of a lead frame 10 used in a resin-sealed semiconductor device. In FIG. 2, reference numeral 9 denotes a stage portion, which is plated with a noble metal such as gold or silver.
This is a part where a semiconductor element is fixed by a silicon eutectic alloy or the like.

Reference numeral 2 denotes an internal lead portion provided so as to surround the stage portion 9. The tips of these are also plated with a noble metal such as gold or silver, and are connected to the semiconductor element mounted on the stage portion 9 by a wire. Further, the portion surrounded by the broken line is the inner pattern portion 8 which is inside the resin mold region.

3 is an outer lead portion following the inner lead portion 2, 4 is a dam bar for connecting the leads of the outer lead 3,
Block the resin during resin molding.

The inner pattern portion 8 which is in this resin mold region
Then, the boundary with the external lead portion 3 outside the resin mold region (also the boundary with the resin mold region) is slightly inside the dam bar 4.

A rail portion 5 has a guide hole 6 formed at a predetermined position and is used for positioning the lead frame and the like.

In order to manufacture such a lead frame 10 shown in FIG. 2, first, as shown in FIG. 1 (a), a portion other than the inner pattern portion 8 in the resin mold region, that is, the dam bar 4, the rail. The outer lead portion 3 including the portion 5, the guide hole 6, and the lead portion 7 up to the boundary between the dam bar 4 and the resin mold is pressed.

Thereafter, the guide hole 6 formed by pressing is positioned and etched to form an inner pattern portion 8 having a predetermined shape as shown in FIG. 1 (b). After that, plating treatment, bending cutting and the like are performed.

There is a lead frame in which the pattern of the inner pattern portion 8 by etching is different, but the shape of the outer lead portion 3 is common. In the case of such a lead frame, it can be manufactured by processing a common portion by press working and etching the inner pattern portion into each pattern.

Further, the present embodiment can be applied to a lead frame used in a low melting point glass-sealed semiconductor device without a stage portion.

In this way, by forming the inner pattern portion 8 by etching, the fine inner pattern portion 8 can be formed.

Further, since the lead portion 7 included in the outer lead portion 3 between the dam bar 4 and the boundary portion of the resin mold region is also formed by press working, the side surface of the lead portion 7 has a flat surface as shown in FIG. Therefore, the mold flash 11 leaking between the lead portions 7 can be easily removed at the same time when the dam bar 4 is removed.

In this respect, when the entire area inside the dam bar 4 including the lead portion 7 is formed by etching, the side surface of the lead portion 7 has a recess and a protrusion as shown in FIG. There is an inconvenience that the side surface of the lead portion 7 is difficult to insert into the mold flash 11 when it is removed, and the mold flash remains between the lead portions 7.

The lead frame shown in FIG. 2 can be obtained by subjecting the lead frame obtained by pressing and etching to a predetermined surface treatment such as plating on the stage portion 9 and the like.

(Effect of the Invention) According to the present invention, the inner pattern portion can be formed finely, and the mold flash can be prevented from adhering to the side surface of the outer lead portion in the vicinity of the resin mold portion. In addition to being able to easily meet the request, it is possible to perform a uniform surface treatment such as plating over the entire surface of the external lead portion.

[Brief description of drawings]

1 (a) and 1 (b) are partial perspective views of the lead frame showing a process of processing the lead frame, and FIG. 2 is a partial front view of the lead frame. 3 and 4 are cross-sectional views of the mold flash leaking to the vicinity of the resin mold portion. In the figure, 2 ... internal lead part, 3 ... external lead part, 4 ... dam bar, 5 ... rail part, 6 ... guide hole, 7 ... between the boundary part of the resin mold region and the dam bar 4 Lead part, 8 ... Inner pattern part, 9 ... Stage part, 10 ... Lead frame.

Claims (1)

[Claims] 1. Outside the boundary between an inner lead portion inside the resin mold region and an outer lead portion outside the resin mold region, so as to prevent the resin from leaking outside through the gap between the leads during resin molding. After manufacturing the lead frame including the lead bar between the boundary and the dam bar, which is outside the resin mold region, when the lead frame having the dam bar connecting the leads is manufactured by press working. A method for manufacturing a lead frame, comprising forming an inner pattern portion including an inner lead portion in a resin mold region by etching.