JPH08107172A - Lead frame manufacturing method - Google Patents

Abstract

PURPOSE: To improve the adhesion to a molding resin with a good workability. CONSTITUTION: A press die for press-working a lead frame has lead forming faces 17 having very small protrusions and recesses 15. The faces 17 include the surfaces of a punch 15 and die 14 or stripper 13 which are to contact with the lead faces of resin molded parts. The protrusions and recesses 15 are, prior to the pressing, made by roughening the surface by the etching method or may be made by the electric discharge, grinding or filing. The protrusions and recesses 15 formed on the press die are transferred to the lead faces of the resin molded parts in the pressing step.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead frame used for ICs and transistors, and more particularly to a method for manufacturing a lead frame manufactured by press working.

[0002]

2. Description of the Related Art In an IC or a transistor, it is very important to improve the adhesion between the lead frame and the molding resin in order to prevent moisture from entering from the outside and improve the reliability.

Conventionally, in order to prevent the invasion of water,
The lead route in the molding resin is lengthened to lengthen the intrusion route, and as shown in FIG.
A groove (groove processing) 10 and a lock hole (or anchor hole) 3 were provided.

[0004]

However, in the press working, if the lead routing is complicated, finer working is required, and the lead inclination or shift is likely to occur.

Also, a V groove is formed in the inner lead portion,
Inserting a lock hole may cause the lead to float or sink, or lead to tilt or shift.

Further, such processing is usually performed by a fine punch, which easily causes chipping or breaking of the punch, and is likely to cause defective lead frame shape (incomplete punching, etc.).

An object of the present invention is to provide a method for manufacturing a lead frame which solves the above-mentioned problems of the prior art and is easy to process and can improve the adhesion with the mold resin.

[0008]

SUMMARY OF THE INVENTION The present invention is a method of manufacturing a lead frame manufactured by press working, in which lead molding of a press die, which comes into contact with a lead surface of a mold resin sealing portion, is performed prior to the press working. The surface is provided with irregularities, and the irregularities are transferred to the leads of the mold resin sealing portion during press working.

In this case, in order to make the lead forming surface uneven, it is preferable to roughen the surface by etching, electric discharge machining, a grindstone or a file.

[0010]

In order to improve the adhesion between the mold resin and the lead frame, the contact area should be increased. This makes it possible to prevent or delay entry of moisture.
Therefore, the entire lead is processed, not the partial processing of the lead such as the V groove. In other words, it is to make unevenness on the entire lead surface of the mold resin sealing portion. To prevent partial processing, make irregularities on the punch, die, and stripper surfaces, which are the lead forming surfaces of the press die.

Particularly, the punching surface has a punching surface for punching the lead frame material and a surface adjacent to this punching material for the material which remains without being punched. Regarding the punched surface, the surface on which the material is hit is uneven.

When a raw material is pressed for manufacturing a lead frame, the mold resin sealing portion of the raw material is struck by the punch, die, and stripper having the irregularities, so that these irregularities are transferred. It is preferable that the transferred concavo-convex region is provided on the entire surface of the lead of the mold resin sealing portion that is in contact with the mold resin. However, the die pad on which the chip is mounted and the tip of the inner lead that performs wire bonding must have some flatness, so it should be treated exceptionally as a flat surface without irregularities or even with irregularities. Only the part of is made fine.

When the unevenness is thus transferred to the lead surface of the mold resin sealing portion, the adhesion between the lead frame and the mold resin is improved and the moisture resistance is improved.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a main part of a press die manufactured by press working the IC lead frame of this embodiment. Minute irregularities 15 are formed on the lead molding surface 17 of the press die that is in contact with the lead surface of the mold resin sealing portion, that is, each surface of the punch 12, the die 14 or the stripper 13. In particular,
The surface of the punch 12 is not a punching surface for punching a lead frame material, but an uneven surface 15 is formed adjacent to the punching surface for hitting the material which remains without being punched. This unevenness 15
Can be attached by roughening the surface by etching prior to press working, roughening the surface by electric discharge machining, or roughening the surface by a grindstone or a file.

When a lead frame material 11 is punched out using a press die having an uneven surface as described above to manufacture a lead frame, the unevenness 15 is formed in the molding resin sealing portion on the surface of the lead frame during press working. Transcribed. This is shown in FIG. Concavities and convexities 7 are transferred to the front and back surfaces of the inner leads 6 and the suspension leads 4 in the mold resin sealing portion 16 surrounded by the mold line 5. However, the island 8 on which the IC chip is mounted,
The wire bonding portion (coining portion) 9 at the tip of the inner lead is not provided with these irregularities. In the figure, 1
Is an outer frame, and 2 is an outer lead.

As described above, according to this embodiment, since the entire surface of the lead surface in the mold line of the IC lead frame is made uneven by the press die during the press working, a part of the inner lead is finely divided. Such as when inserting a V-shaped groove or a lock hole,
No sinking or tilting of the lead or shift occurs, and the unevenness processing is not done with a fine punch, but with the press die itself that forms the lead frame, so punching and chipping of the punch occur In addition, the lead frame does not have a defective shape.

Further, in the press-processed lead frame, since the minute unevenness is transferred to the mold resin sealing portion in the mold line, the adhesion between the mold resin and the lead frame can be improved, and the semiconductor The reliability of the device can be improved.

Although the IC lead frame has been described in the above embodiment, the same applies to the transistor lead frame.

[0019]

According to the present invention, since the lead molding surface of the press die for manufacturing the lead frame is made uneven, and it is transferred to the lead surface, it is possible to prevent the V groove and the anchor hole as in the conventional case. Unlike the case where a very limited partial area is processed, the processing is easy, and lead shift, lead floating, lead twisting, etc. do not occur, and the processing accuracy of lead frame manufacturing is not impaired.

Further, by transferring the unevenness, the adhesion between the mold resin and the lead frame is improved, so that the invasion of water from the outside into the mold resin can be effectively suppressed,
The reliability of the semiconductor device can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part of a press die for explaining an embodiment of a method for manufacturing a lead frame of the present invention.

FIG. 2 is a plan view of a lead frame manufactured according to this embodiment.

FIG. 3 is a plan view of a conventional lead frame.

[Explanation of symbols]

 11 Lead Frame Material 12 Punch 13 Stripper 14 Die 15 Unevenness 16 Mold Resin Sealing Part 17 Lead Molding Surface

Claims (3)

[Claims] 1. A method for manufacturing a lead frame manufactured by press working, wherein, prior to press working, a lead mold surface of a press die which comes into contact with a lead surface of a mold resin sealing portion is made uneven, and press working is performed. At the time of, the unevenness is transferred to the lead surface of the mold resin sealing portion, and the method for manufacturing a lead frame. 2. The method for manufacturing a lead frame according to claim 1, wherein the unevenness is formed by etching. 3. The method of manufacturing a lead frame according to claim 1, wherein the unevenness is formed by electric discharge machining.