JPS63196067A - Method and device for molding lead of semiconductor device - Google Patents

Abstract

PURPOSE:To contrive the improvement of accuracy in molding and the reduction in the attrition of the leads of a semiconductor device and the device by a method wherein, after the leads are pressure welded by rollers on a bending die and bent, roller pressure welding for reducing the spring back due to the elasticity of the lead material is performed. CONSTITUTION:A primary molding process, wherein leads are pressure welded by rollers for bending them using a bending die, and a secondary molding process, wherein a roller provided at the end of one way of the inclined plane of a press top and another roller provided at the end on the side opposite to the above end are rotated for reducing the spring back generated by the bending to the maximum to give the function of a cam to a roller holder 11 mounted with these rollers, are provided. That is, a bending die 21 is formed the angle 21c of its shoulder part into a protruding curved surface, a roller 11B on the lower end is rolled down from above in a manner that the root part of a lead is fixed by pinching to bend the bending point 202a of the lead along the protruding curved surface and the part extending from the bending point of the lead to its terminal is housed in the part of relief of the bending die. As rollers are used for pressure welding elements to the lead, a semiconductor device, which is superior in dimentional accuracy and quality, can be obtained by molding.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Field of Application) This invention relates to a method and apparatus for forming leads of semiconductor devices, and particularly relates to a method and apparatus for forming leads of ICs, LEDs (light emitting devices), etc. Applies to equipment used in

(Prior Art) In the manufacture of semiconductor devices, for example, after performing chip bonding, wiring, etc. on a lead frame, an envelope is formed using a resin mold, and the leads are folded into the lead molded product with the lead frame removed. In some cases, bending is performed to obtain a molded article shown in a perspective view in FIG. In FIG. 3, 201 is an envelope formed by resin molding, 202.2
02... These leads are all bent at approximately 90 degrees at the bending point 202a, and their tips are slightly expanded outward with respect to the vertical plane.

A conventional lead forming method and an apparatus used therein are shown in cross-sectional view in FIG. 4 and will be described below. Note that the two-dot chain line in the figure indicates the fastening of both members. First, in FIG. 4 showing the device used for molding, 101 is a bending punch attached to the upper mold holder 103 via the punch side plate 102, Further, this bending punch 101 has a presser piece 104 slidably installed therein, and the presser piece 104 presses the unmolded semiconductor device with a hard carbine 106 pushed by a spring 105. Bending die 1
07 is attached to a lower mold holder 109 via a lower mold plate 108. This bending die 107 has a resin molded portion 201 of an unmolded semiconductor device envelope inserted into a recess 107a provided on the top surface, and an unprocessed portion of the semiconductor device glue 202 is placed on the shoulder portion of the top surface. And bending die 1
The lowering bending punch 101 pushes the lead portion that protrudes laterally from the bending die 107 and bends it approximately 90 degrees downward at the lead bending point at the shoulder of the bending die 107, and then the upper presser piece 104 is lowered, and its lower surface protrudes from the lead envelope and clamps and fixes the lead up to the bending point. Regarding this fixing, in order to prevent excessive pressure on the reed, a hard carbine 106 is attached to the upper part of the presser piece 104, which is pressed by a spring 105, and this mechanism allows the reed 202 to bend. It also has the function of attaching and detaching the lead from the bending punch, which tends to bite after being bent by the punch 101.

Note that a gap is provided between the side surface of the bending die 107 and the bending punch 101 to accommodate the bent portion of the lead.
In addition, the sides are provided with so-called "relief" that is slightly expanded inward to reduce springback of the reed.

(Problems to be Solved by the Invention) According to the above-mentioned conventional technology, the dimensional accuracy of the bending die and bending punch significantly affects the yield of the lead forming process, and the tip of the bending punch squeezes the lead surface, resulting in mass production. This increases the wear of the bending punch and further shortens the life of the mold.
There is a serious drawback that defects frequently occur due to excessive spacing between opposing leads.

Next, as a countermeasure against springback due to the elasticity of the lead, simply providing a "relief" in the bending die to reduce springback is not sufficient, and products with narrow tolerances in shape and dimensions often result in defects.

The present invention provides an improved lead forming method and apparatus in view of the problems of the prior art described above.

[Structure of the invention]

(Means for Solving the Problems) A method for forming leads of a semiconductor device according to the present invention includes pressing the leads of a semiconductor device against a bending die with a roller, bending the leads at a planned bending point, and then bending the leads. This device is characterized by applying roller pressure contact to the leads outward from the point in order to reduce return due to the elasticity of the lead material, and the device is attached to the upper die set via the upper die holder. A vertical roller holder is mounted on a bracket that moves up and down in unison with a vertical roller holder, which is pivoted by a rolling bearing in the center and has rollers attached to both ends by rolling bearings. A presser piece with a slope that pushes the roller against the roller holder and applies a rotational moment about its rolling bearing to the roller holder, and a bending point of the lead of the semiconductor device that is in contact with the lower end of the presser piece and is placed together with the lower end of the presser piece. After holding the envelope side and protruding the tip from the planned bending point, the bending die attached to the lower die set via the lower die holder and the lead part protruding from the bending die are bent. The present invention is further characterized in that it includes a roller at the lower end of the roller holder that presses the protruding portion against the side surface of the bending die.

(Function) The present invention uses a bending die attached to a lower die for bending and forming leads of semiconductor devices, and a roller whose center portion is vertically pivoted by a rolling bearing on the upper die and rollers are provided at both ends. Since the lower roller of the holder is rolled to perform the bending, and the upper roller is moved by a cam mechanism to form the lead, the precision of forming is significantly improved, and wear and tear on the lead and equipment is reduced.

(Example) An example of the present invention will be described below with reference to FIGS. 1 and 2. In the description, the same reference numerals are given to the same parts in the drawings and the description thereof will be omitted.

In FIG. 1, a roller holder 11 is vertically attached to a bracket 12 integrally attached to an upper die set 14 via an upper die holder 13 with a rolling bearing 11a in the center, and its upper end and At the lower end is a rolling bearing 11b coaxial with the rolling bearing 11a, and at the lie is a roller 11A.

11B is attached to the 0th order, 15 is a presser piece,
A slope that contacts the roller IIA at the upper end of the roller holder 11, pushes the roller IIA against the descent of the roller holder that moves up and down together with the bracket 12, etc., and applies a rotational moment to the roller holder around the rolling bearing 11a in the center thereof. 6 Next, 21 is a bending die, which is attached to the lower die set 23 via the lower die holder 22, has a recess 21a on the upper surface for housing the envelope 201 of the semiconductor device, and has a shoulder portion. 21b (FIG. 2), the root portion of the lead 202, that is, the portion from the bending point 202a to the envelope 201 is placed. When the presser piece 15 approaches, the shoulder portion 21b is adapted to clamp the root portion of the lead with its lower end. The lead is bent and formed as follows.

The semiconductor device is placed on the bending die 21 with the tip thereof protruding laterally from the bending point of the lead. This bending die 2
1 has a convexly curved shoulder corner 21C (Fig. 2), and with the root of the lead clamped and fixed, the roller IIB at the lower end moves down from above to bend the lead to the bending point 202.
A is bent along the convex curved surface. As a result, the portion of the lead from the bending point to the end fits within the "relief" portion of the bending die. Furthermore, the tip of the lead is pressed against the side surface of the bending die by the roller 11B, which is further moved down.

However, after this pressure contact presses slightly below the bending point, the roller IIA at the upper end of the roller holder is expanded outward by the slope 15a of the presser piece. Accordingly, the roller holder rotates around the rolling bearing 11a in the center, and a force is applied to the roller IIB at the lower end to push it inward.
The lead is strongly pressed against the side surface of the bending die 21 to prevent the lead material from rebounding due to its elasticity to the maximum extent, and is precisely fitted to the bending die. That is, highly accurate bending with reduced springback is achieved.

【Effect of the invention〕

This invention includes a first forming process in which a roller is used to press the lead to bend it using a bending die, and a roller is provided on the slope of the presser piece in order to minimize the springback caused by the bending. Another roller provided at the opposite end is rotated, and the roller holder to which these rollers are attached is subjected to a second molding process in which the roller holder has a cam function. This has the remarkable advantage that the manufacturing method is no different from the operation of conventional molding equipment, and can be performed at the same movement and speed.

Secondly, since this molding device uses a roller to press the leads onto the leads, it eliminates all the damage that occurs with conventional sliding contacts, such as plating peeling, short circuits between leads due to plating peeling, lead breaks, and ironing scratches. The problem was resolved.

Furthermore, it was possible to obtain a semiconductor device with excellent dimensional accuracy and quality by molding.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a lead forming apparatus according to an embodiment of the present invention, FIG. 2 is an enlarged cross-sectional view showing a bent part of a lead in an embodiment of the present invention, and FIG. 3 is a cross-sectional view of a semiconductor device. The perspective view and FIG. 4 are sectional views of a conventional lead forming apparatus. 11---m-Roller holder 11a---(center) rolling bearing 11A---
---Roller 11b at the upper end (of the roller holder) ---Rolling bearing 11B at the upper end ---Roller 11 at the lower end (of the roller holder)
cm - One lower end rolling bearing 12 ---- Bracket 13 ---- M1 type holder 14 ---- Type 1 die set 15 - 11 - Presser piece 15a - One presser piece slope 21 ---1--Bending die 21a --= Recessed portion 21b (of the bending die) -1--Shoulder section 21c (of the bending die) --- Corner 22 of the shoulder section (of the bending die)
- Lower die holder 23 - - Lower die set 106 ---- Kit carbine 201 ---- Envelope 202 (of the semiconductor device)
- Lead 202a (of the semiconductor device) --- lead bending point

Claims (2)

[Claims] (1) After pressing the lead of a semiconductor device against a bending die with a roller and bending the lead at the planned bending point, a roller is used to reduce the elastic return of the lead material to the lead outside the bending point. A lead forming method for semiconductor devices that uses pressure welding. (2) A vertical die that is attached to the upper die set via the upper die holder and moves up and down together with the bracket, which is pivoted by a rolling bearing in the center and has rollers attached to both ends by rolling bearings. a roller holder, a presser piece having an inclined surface that contacts the roller at the upper end of the roller holder and pushes the roller against the lowering of the roller holder and gives the roller holder a rotational moment around a rolling bearing in its center; A bending die that is in contact with the lower end, holds the envelope side from the planned bending point of the lead of the semiconductor device together with the lower end, has its tip protruding from the planned bending point, and is attached to the lower die set via the lower die holder. and a lead forming apparatus for a semiconductor device, comprising a roller at a lower end of a roller holder that bends a lead portion protruding from the bending die and then presses the protrusion portion against a side surface of the bending die.