JPH09331008A - Lead frame manufacturing method - Google Patents

Abstract

(57) [PROBLEMS] A lead frame which can easily manufacture a lead frame having a fine inner pattern portion and can prevent mold flash from adhering to a side surface of an outer lead portion near a resin mold portion. A method for manufacturing a frame is provided. SOLUTION: Resin is prevented from leaking to the outside through a gap between the leads outside the boundary between an inner lead portion 2 inside the resin mold area and an outer lead portion 3 outside the resin mold area during resin molding. When manufacturing a lead frame including a dam bar 4 connecting the external leads, the external lead portion 2 and the dam bar 4 including the lead portion 7 between the boundary portion and the dam bar, which is outside at least the resin mold region, are manufactured. After forming by pressing,
The inner pattern portion 8 including the inner lead portion 2 in the resin mold region is formed by etching, and then the inner pattern portion 8 and the like are subjected to required plating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead frame manufacturing method using both press working and etching working.

[0002]

2. Description of the Related Art Current methods of manufacturing lead frames include a method by etching and a method by pressing. Among these, a method of manufacturing a lead frame by etching is to form a predetermined resist pattern on a metal plate for manufacturing a lead frame at the same position on both surfaces, then treat with an etching solution, and simultaneously expose exposed portions of the metal plate from both surfaces. This is a method of performing etching. In the case of this method, the etched portion is the lead interval. On the other hand, in the press working, a strip-shaped metal plate for manufacturing a lead frame is punched out sequentially with a mold. Each of these processing methods has great advantages. For example, in press working,
Since feed, positioning, and the like during processing of the lead frame are performed by guide holes and the like in the rail portion, processing can be performed with high accuracy.

In general, the lead frame is provided with a dam bar for connecting the external leads so that the resin does not leak to the outside through the gap between the leads during resin molding, and the dam bar is cut after the resin molding. There is.
The cutting of the dam bar can be easily performed by press working. Moreover, by press working, the formed lead side surface can be formed into a flat surface, and the mold flash does not adhere 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 fineness of the inner pattern portion including the internal lead portion accompanying the request for increasing the number of pins of the semiconductor device can be more easily performed than the press process.

[0004]

As described above, although the press working and the etching working have their respective advantages, they also have their drawbacks. For example, in the press working, there is a drawback that it is difficult to make the inner pattern portion finer. It has a disadvantage that it adheres and surface treatment such as plating cannot be performed on the side surface of the external lead portion. Therefore, an object of the present invention is to provide a lead frame that can easily manufacture a lead frame with a fine inner pattern portion and that can prevent a mold flash from adhering to a side surface of an external lead portion near a resin mold portion. An object of the present invention is to provide a method for manufacturing a lead frame that can be manufactured.

[0005]

In order to solve the above problems, the present inventor considers that it is advantageous to use both of the workings so that the advantages of the press working and the etching working can be utilized. As a result, the present invention has been achieved. That is, the present invention is to prevent the resin from leaking to the outside through the gap between the leads during resin molding, outside the boundary between the internal lead portion inside the resin mold region and the external lead portion outside the resin mold region. When manufacturing a lead frame having a dam bar that communicates between external leads, at least outside the resin mold area, the external lead portion including the lead portion between the boundary portion and the dam bar and the dam bar are subjected to press working. After the formation, an inner pattern portion including an internal lead portion to be in the resin mold region is formed by etching, and then the inner pattern portion and the like are plated as required. .

According to the present invention, the external lead portion and the dam bar which are wider than the gap between the internal leads and are outside the resin mold region are formed by press working. For this reason, the side faces of the external lead portions can be formed flat, and even if the dam bar is cut after resin molding, the mold flash is applied to the side surfaces of the external lead portions near the resin mold portion as in the case where the external lead portions are formed by etching. Adherence can be prevented. Further, since the inner pattern portion including the internal lead is formed by etching, the inner pattern portion, which has been difficult by press working, can be made finer. As described above, since the outer lead portion and the dam bar are formed by pressing, and then the inner pattern portion including the inner lead portion is formed by etching, the advantages of the pressing and etching can be utilized. The pattern portion can be made finer, and the mold flash can be prevented from adhering to the side surface of the external lead portion near the resin mold portion. Further, after press working and etching, plating is performed on predetermined parts such as internal lead parts and external lead parts, so that an inner pattern part and an external lead part including uniformly densified internal lead parts can be easily formed. .

[0007]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 2 shows a part of a lead frame 10 used for a resin-sealed semiconductor device. In FIG. 2, reference numeral 9 denotes a stage, which is plated with a noble metal such as gold or silver, and is a portion to which the semiconductor element is fixed by a gold-silicon eutectic alloy or the like. Reference numeral 2 denotes an internal lead portion provided around the stage portion 9, the tip portions of which are similarly plated with a noble metal such as gold or silver and the semiconductor elements mounted on the stage portion 9 are connected by wires. . Further, the portion surrounded by the broken line is the inner pattern portion 8 including the inner lead portion 2 which is inside the resin mold region. Reference numeral 3 denotes an external lead portion following the internal lead portion 2, and reference numeral 4 denotes a dam bar for communicating between the leads of the external lead portion 3, which dams the resin at the time of resin molding. A boundary portion (also a boundary portion of the resin mold region) between the inner pattern portion 8 inside the resin mold region and the outer lead portion 3 outside the resin mold region is slightly inside the dam bar 4. Reference numeral 5 denotes a rail, which has a guide hole 6 formed at a predetermined position, and is used for positioning a lead frame.

Such a lead frame 1 shown in FIG.
In the manufacture of No. 0, first, as shown in FIG. 1A, a portion excluding the inner pattern portion 8 including the internal lead portion 2 to be in the resin mold region, that is, the dam bar 4, the rail portion 5, the guide hole 6, and The external lead 3 including the lead 7 extending from the dam bar 4 to the boundary of the resin mold is pressed. At the time of such press working, a portion including the vicinity of the resin mold boundary of the internal lead portion 2 which is within the resin mold area may be formed by press working. Next, by performing positioning and etching with reference to the guide hole 6 formed by press working, FIG.
As shown in (1), an inner pattern portion 8 having a predetermined shape is formed.

Thereafter, plating is applied to predetermined portions of the inner pattern portion 8 including the internal lead portions 2 and the like. For this reason, gold,
Noble metal plating such as silver can be applied, and external leads 3
Evenly over the entire surface of the substrate. Further, the lead frame 10 shown in FIG. 2 can be manufactured by subjecting the external lead portions 3 and the like to which the surface treatment such as plating has been performed to bending and cutting.

Here, when the order of pressing → etching → plating is the order of pressing → plating → etching, the plated portion and the non-plated portion coexist. The pressed metal plate is etched. As described above, when etching is performed on a pressed metal plate having different types of metals coexisting on the surface, it is generally very difficult to simultaneously perform different types of etching with a single type of etching solution on the different types of metals. Since it is necessary to sequentially perform etching using a plurality of types of etching solutions, the manufacturing process of the lead frame is complicated. In addition, since the etching rate and the like also differ depending on the type of metal, it is extremely difficult to perform uniform etching, and the formation of the inner pattern portion 8 and the like including the fine internal leads 2 requiring uniformity is required. Is inappropriate.

By the way, although the pattern shape of the inner pattern portion 8 formed by the etching process is different, there is a lead frame in which the shape and the like of the external lead portion 3 are common. In the case of such a lead frame, a common portion is processed by press working, and the inner pattern portion 8 is formed.
Can be manufactured by etching into the respective patterns. Further, the present invention can be applied to a lead frame without a stage portion used in a semiconductor device of a low melting point glass sealing type. As described above, by forming the inner pattern portion 8 by etching, a fine inner pattern portion 8 can be formed.

Further, a lead portion 7 included in the external lead portion 3 between the dam bar 4 and the boundary portion of the resin mold region.
3 is formed by pressing, the side surface of the lead portion 7 becomes a flat surface as shown in FIG. 3, and the mold flash 11 leaking between the lead portions 7 can be easily removed at the same time as the dam bar 4 is removed. In this regard, 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 shape having a concave portion and a protrusion as shown in FIG. When dropping, the side of the lead part 7
However, there is a disadvantage that the mold flash remains between the lead portions 7.

[0013]

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. It is possible to easily and easily meet the request, and 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]

FIG. 1 is an explanatory diagram of a lead frame illustrating an example of a lead frame processing step according to a lead frame manufacturing method of the present invention.

FIG. 2 is a partial front view of a lead frame obtained by a method for manufacturing a lead frame according to the present invention.

FIG. 3 is a cross-sectional view of a mold flash leaking to the vicinity of a resin mold portion.

FIG. 4 is a sectional view of a mold flash leaking to the vicinity of a resin mold portion.

[Explanation of symbols]

2 Inner lead part 3 External lead part 4 Dam bar 5 Rail part 6 Guide hole 7 Lead part between the boundary part of resin mold area and dam bar 4 8 Inner pattern part 9 Stage part 10 Lead frame

Claims (1)

[Claims] 1. A resin does not leak outside through a gap between the leads during resin molding outside a boundary portion between an inner lead portion inside the resin mold area and an outer lead portion outside the resin mold area. When manufacturing a lead frame including a dam bar that connects between the external leads, an external lead portion including the lead portion between the boundary portion and the dam bar, which is outside the resin mold region, and the dam bar are formed by pressing. After that, the inner pattern portion including the inner lead portion to be in the resin mold region is formed by etching, and then the required plating is applied to the inner pattern portion and the like.