JPH02177353A - Formation of lead of semiconductor device - Google Patents

Abstract

PURPOSE:To prevent failure of appearance of a lead, obtaining a lead bent part with improved seam part by bending a lead tip part of a semiconductor device in several steps, by setting the radius of curvature at the bent part to the same value, and by overlapping one part of the bent part. CONSTITUTION:A semiconductor device is placed on a bending die and a lead 4 is bent by a bending punch. Bending is performed in two steps. That is, a bent part 4a is formed at the tip of the lead 4 and then a bent part 4b is formed. Then, the radius of curvature of the bent parts 4a and 4b is set to the same value and then one part B of the neighboring two bent parts 4a and 4b is overlapped. Thus, a plurality of bent parts with the same radius of curvature at the lead tip part can be continuously formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for forming leads of a semiconductor device, which is used for forming leads of a semiconductor device such as a PLCC.

[Conventional technology]

Generally, in a lead forming method for a semiconductor device, the tip portion of a lead terminal is formed by bending it in multiple steps. This is because the surface of the lead terminal is subjected to, for example, a solder plating process, so if the tip of the lead terminal is bent all at once (120' to 130°), so-called solder whiskers will occur at the tip of the lead. This is because it is necessary to suppress the generation of solder whiskers.

Conventionally, the following method has been adopted for lead forming of this type of semiconductor device.The following method will be explained using FIG.
First, the semiconductor device 1 is placed on the bending die 2, and then the leads 4 are held between the bending die 2 and the stripper 3, and then bent by the bending bunch 5. At this time, lead 4
The bending is performed in two steps as shown in Figures 3 (a) and (b).
) is an enlarged view of part A in FIG.

[Problem to be solved by the invention]

By the way, in the conventional lead forming method for a semiconductor device, although the radius of curvature of each of the bent portions 4a and 4b of the lead 4 is set to the same radius of curvature, both of the bent portions 4a and 4b are
4b is not overlapped, and therefore both bent portions 4a
, 4b are not continuous, that is, both bent portions 4a,
A discontinuous portion occurred between 4b. As a result, there was a problem in that the joint between the two bent portions 4a and 4b was not good, and the lead 4 itself had a poor appearance.

The present invention has been made in view of the above circumstances, and provides a lead forming method for a semiconductor device that can obtain a lead bent portion with a good seam portion and thereby prevent appearance defects of the lead. It is something to do.

[Means to solve the problem]

A lead forming method for a semiconductor device according to the present invention is a lead forming method in which a lead end portion of a semiconductor device is formed by bending it in multiple steps, and the radius of curvature of each of these bending portions is set to the same radius, In addition, two adjacent bent portions partially overlap.

[For production]

In the present invention, a plurality of bent portions having the same radius of curvature can be continuously formed at each lead tip.

〔Example〕

Hereinafter, the method for forming semiconductor Ha leads according to the present invention will be explained in the first part.
This will be explained in detail with reference to the embodiments shown in FIGS. 2 and 3 (al and b).
, (The same members as bl are given the same reference numerals,
Detailed explanation will be omitted.

First, the semiconductor device 1 before lead forming is placed on the bending die 2 .Then, a press (not shown) is lowered and the leads 4 are sandwiched between the bending die 2 and the stripper 3 . After that, the leat '4 is bent by the bending bunch 5. Here, the lead 4 is bent in two steps as shown in FIG. 3 (δ) and (bl).
After the bent portion 4a is formed at the tip of the lead 4, the bent portion 4b is formed. At this time, the radius of curvature ρ of the bent portion 4a and the radius of curvature ρ2 of the bent portion 4b are set to the same radius (ρ1
=ρ2=ρ), and the portions B of the two adjacent bent portions 4a and 4b are overlapped.

In this way, the leads 4 of the semiconductor device I can be formed.

Therefore, in the present invention, the tip of each lead 4 has two bent portions 4a having the same radius of curvature ρ.

Since the lead bending parts 4b can be formed continuously, the lead bent parts 4a and 4b with good seam parts can be obtained.

In this embodiment, the bent portion 4a is formed by bending the tip of the lead 4 twice.

Although an example of forming the 4b is shown, the present invention is not limited to this. For example, it may be folded three times, four times, etc., and the number of folds may be changed as appropriate. can.

Further, in this embodiment, a case where the present invention is applied to a PLCC semiconductor device is shown, but the present invention can also be applied to other semiconductor devices such as an SOJ in the same manner as in the embodiment.

Incidentally, in the semiconductor device before lead forming according to the present invention, a semiconductor element is bonded onto a lead frame, the semiconductor element and the inner lead of the lead frame are connected by a wire, and then the wire is bonded.

It can be manufactured by sealing the inner lead and the semiconductor element with resin.

Thereafter, the lead forming process of the present invention is performed on the outer leads of the semiconductor device.

〔Effect of the invention〕

As explained above, according to the present invention, there is provided a lead forming method in which the lead end portion of a semiconductor device is formed by bending the lead end portion in multiple steps, the radius of curvature of each of these bending portions being set to the same radius, and Since two adjacent bent portions partially overlap, a plurality of bent portions having the same radius of curvature can be continuously formed at each lead tip. Therefore, it is possible to obtain a lead bent portion with a good seam portion, so that it is possible to prevent the occurrence of poor appearance of the lead.

[Brief explanation of the drawing]

FIG. 1 (Jl) and ~) are front views showing enlarged lead tips to explain the lead forming method for a semiconductor device according to the present invention, and FIG. 2 is a front view showing a lead used in the lead forming method for a semiconductor device. A sectional view showing a molding device, and FIGS. 3(a) and 3(b) are front views showing an enlarged lead tip portion to explain a conventional semiconductor device glue molding method. 1...Semiconductor Device, 4... Lead, 4a. 4h... Bent part, ρ, ρ1. ρ2... Radius of curvature, B... Overlapping part. Agent Oiwa 4, Reet". 4G , 4b: d'r' @press B: t-narrow leaf Figure 2 Figure 3 (Q) (b)

Claims (1)

[Claims] A lead forming method in which the tip of a lead of a semiconductor device is formed by bending it in multiple steps, the radius of curvature of each of these bending portions being set to the same radius, and a portion of two bending portions that are adjacent to each other. A method for forming leads for a semiconductor device, characterized by overlapping the leads.