JPS6268636A - Lead forming method - Google Patents

Abstract

PURPOSE:To improve the reliability of a semiconductor device by forming the outer part lead with its bending in the back face direction of the package main body, first, then by applying pressure in the upper and lower direction by inserting a guide body between the outer lead curving part and package main body. CONSTITUTION:The lead 5 of the package main body 2 is preformed in the vertical direction via a lead presser and bending punch in advance. It is then bent in the vertical direction from the lead root part 5a with a bending punch 10 on a jig 9 and in succession the main body 2 is fixed to a fix jig 11 from the lower part with a pressing jig 12. A guide bar 14 is then inserted between the curving part 5c of the lead 5 and main body 2 and pressed from the upper and lower direction with lead position aligning dies 15a, 15b. With this pressing the dispersion in the height position of the lead is corrected, so the defective joining of a semiconductor device 1 can be prevented. The reliability in the semiconductor device is thus improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a technique that is effective when applied to lead forming, particularly to a lead forming technique for a semiconductor device in which leads are formed into a three-letter shape.

[Background Art] In a semiconductor device having a so-called plastic leaded chip carrier (PLCC) type package in which external leads protruding from the sides of the package body are formed into a 5-shape, for example, the tips of the external leads It is conceivable to first bend the external lead vertically, then bend the external lead in the vertical direction from the root, and finally form the tip into a curved shape to form a 5-shaped lead.

However, the inventors have found that when leads are formed through a plurality of forming steps as described above, the height of the formed leads with respect to the mounting surface of the mounting board may vary. That is, the semiconductor device described above is
When mounting by interposing a brazing material between the external leads and the electrodes on the mounting board, for example, the solder thickness on the electrodes of the mounting board is about 0.1 fi, whereas the height of each molded lead is The position shift is 0. The inventors have clarified that when variations occur in steps greater than IN, external leads that are not connected to the electrodes occur depending on the solder thickness.

An example of a detailed technical description of a semiconductor device in a PLCC type package is "Ultra LSI Device Handbook JP148-P159, published by Science Forum Co., Ltd., November 28, 1981.

[Object of the Invention] An object of the present invention is to provide a semiconductor device with high mounting reliability by preventing variations in the position of the leads with respect to the mounting surface.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Summary of the Invention] A brief overview of typical inventions disclosed in this application is as follows.

That is, a curve forming process in which the external lead is formed into a 5-shape, and a lead position where a pressing force is applied from above and below the semiconductor device with a guide body disposed between the inside of the curved part of the external lead and the pan cage body. By performing the alignment process, it is possible to prevent variations in the height position of the leads with respect to the mounting surface of the mounting board, so it is possible to maintain uniform bonding between each lead and the brazing metal, and prevent bonding defects. A semiconductor device with high mounting reliability can be provided.

[Example 1] Fig. 1 (al to fdl are schematic diagrams sequentially explaining a lead forming method according to an embodiment of the present invention, Fig. 2 shows a guide between the inside of the curved part of the external lead and the package body) It is a back view showing a state where the body is inserted.

The semiconductor device 1 on which lead forming is performed in this embodiment is a PLC.
This is a semiconductor device having a C-type package, and the package body 2 made of epoxy resin or the like is molded by, for example, a transfer molding method, and inside the package body 2 is a pellet 3 made of a silicon semiconductor.
The wire 4 and the like are buried therein.

The die 6 is placed with external leads 5 (hereinafter simply referred to as leads 5) extending horizontally from the side of the package body 2.
When placed on the top, the base portion 5a of the lead is fixed by the lead presser 7, the bending punch 8 is moved downward, and the lead 5 is held between the die 6 and the bending punch 8, and the tip portion of the lead is 5b is preformed vertically (FIG. 1(a)).

Next, the package body 2 is transferred onto another jig 9, and the leads 5 are bent vertically from their root portions 5a by a bending punch 10 (FIG. 1(bl)).

Next, the package main body 2 has a package holder part 11 on the bottom surface.
A pressing jig 12 is applied from below to the fixing jig 11 in which a is formed.
It is fixed at In this state, the J bunch 13 having the curved surface 13a formed on its upper surface moves upward, and the tip portion 5b of the lead 5 is curved into a 5-shape.

Next, guide bodies 14a to 14d having an elliptical cross section are inserted between the inner part of the curved portion 5c of the lead 5 and the package body 2. The guide body 14 is required to have such hardness that it does not substantially deform itself when pressed for lead position alignment. The guide body 14 is made of a metal material such as tool steel, for example. When the package body into which the guide body 14 is inserted in this manner is viewed from the back side, it becomes as shown in FIG. The pan cage main body 2 is connected to the lead position alignment type 15a together with this guide body 14.
and between 15b! 3! The package body 2 is pressed with a predetermined force from above and below by these lead position alignment molds 15a and 15b (FIG. 1(d)).

At this time, the curved portion 5C of the lead 5 is pressed by the bag body 2 and the guide rod 14 without any gap. Accordingly, variations in height position are corrected,
As a result, all the leads 5 are lined up on the same plane of the lead position alignment mold 15b, and the height positions of the leads 5 are aligned uniformly.

Embodiment 2 FIGS. 3A to 3 are schematic diagrams sequentially explaining a lead forming method according to another embodiment of the present invention.

The lead forming method of the second embodiment is almost the same as the lead forming method described in the first embodiment, except that the step of correcting the position of the lead 5 is performed at the same time as the step of forming the lead 5 into a curve.

That is, the tip portion 5b and the root portion 5a of the lead 5
When the package body 2, which is bent in the vertical direction, is fixed by the fixing jig 21 and the pressing jig 22,
A guide bar 23 having a semicircular cross section is attached along the peripheral edge of the back surface of the package body 2. When the guide rod 23 is fixed to the package body 2 by a fixing means (not shown), the J-punch 24 moves upward and the tip portion 5b of the lead 5 is formed along the guide rod 23 into a three-shape shape.

As described above, according to the second embodiment, the guide rod 23 having a semicircular cross section functions as a lead receiver when the lead 5 is curved.
4, they are held and molded without any gaps. Therefore, the height positions of the leads 5 are uniformly aligned with the curved molding without causing variations in the height positions of the leads 5 after molding.

[Effects] (1) A curve forming step in which the external lead is bent toward the back surface of the package body, and a guide jig is inserted between the inside of the curved portion of the external lead and the package body, and the top and bottom of the semiconductor device are By performing the lead position alignment step in which pressing force is applied from the direction, the height positions of the leads are aligned with respect to the mounting surface of the mounting board, making it possible to maintain good bonding properties between each lead and the brazing material. It is possible to prevent defects and the like and provide a semiconductor device with high packaging reliability.

(3) According to the above (11), even when the number of leads increases, the flatness of each lead can be maintained, so that the mounting sensitivity of the highly integrated semiconductor device can be improved.

(4) After the lead curve forming process, a lead position alignment process is performed in which pressing force is applied from above and below the semiconductor device with a guide jig inserted between the inside of the curved part of the external lead and the package body. As a result, the flatness of the leads can be improved by adding only a few steps.

(5) According to (4) above, it is possible to provide a semiconductor device with high packaging reliability at low cost.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the Examples and can be modified in various ways without departing from the gist thereof. Nor.

For example, in the embodiment, a case was described in which bending the lead in the vertical direction from the root part was performed in a single step using a bending punch as shown in FIG. In order to prevent stress from being applied to the package body, the package may be bent at an angle of about 45 degrees from the root portion for preforming, and then further bent in the vertical direction using a punch or the like.

Further, although the case where a bending punch is used for bending the lead has been described, the bending may be performed using a bending roller.

[Field of Application] The above description mainly applies to the field of application of the invention made by the present inventor, which is lead molding of a semiconductor device in a so-called PLCC type package in which leads protrude in all directions from each side of the package body. Although this has been described, the present invention is not limited thereto, and is an effective technique that can be applied, for example, to lead molding of a semiconductor device in which leads protrude in two directions.

[Brief explanation of drawings]

Figures 1 (5) to fdl are schematic diagrams sequentially explaining the lead forming method according to the first embodiment of the present invention, and Figure 2 is a guide between the inside of the curved part of the external lead and the package body according to the first embodiment. It is a schematic diagram sequentially explaining the state in which the rod is inserted.
・Pellet, 4...Wire, 5...Lead, 5a・
...Lead tip, 5b...Lead base, 5c
...Lead curved part, 6...Gui, 7...Lead holder, 8...Bending punch, 9...Jig, 1o...
・Bending punch, 11...Fixing jig, lla...Package holder is surface, 12...Press jig, 13...J punch, 13a...Curved surface, 14a-14d...Guide Dedicated 15a, 15b...Lead position alignment type, 21.
...Fixing jig, 22...Press jig, 23...Guide rod, 24...J punch. Figure 1

Claims (1)

[Scope of Claims] 1. A lead forming method for a semiconductor device in which external leads protruding from the side of a package body are bent and formed toward the rear surface of the package body, the external leads being bent toward the back side of the package body, and a lead position alignment step in which pressing force is applied from above and below the semiconductor device with a guide inserted between the inside of the curved portion of the external lead and the package body. A lead forming method characterized by: 2. The lead forming method according to claim 1, wherein the lead position alignment step is performed after the curve forming step. 3. The lead forming method according to claim 1, wherein the lead position alignment step is performed simultaneously with the curve forming step. 4. The lead forming method according to claim 1, wherein the guide body is a guide rod having an elliptical cross section. 5. The lead molding method according to claim 1, wherein the package body is formed by resin molding.