JPS6132814B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a wire bonding method for connecting a semiconductor pellet and an external lead with a wire.

In the assembly process of semiconductor integrated circuits (IC, LSI), etc., a ball 3 is formed at the tip of a wire 2 inserted into a capillary 1, as shown in FIG.
As shown in Figure b, connect the ball 3 by pressing the capillary 1 to the pellet 6 welded to the tab 5 provided on the semiconductor substrate 4, then move the capillary 1 and connect it to the first pellet.
Connect the wire 2 to the external lead 7 as shown in Figure c. A heating element 8 heats the semiconductor substrate 4 and the external leads 7.

However, in the conventional wire bonding apparatus, the capillary 1 is bonded by feeding a certain length of the wire 2 from the pellet 6, which is the first bonding point, to the external lead 7, which is the second bonding point. The length of the second bonding point B is slightly different each time, and when the wire length is long, the wire is fed out for a long time and the wire loop is high, but when the wire length is short, the wire loop is high when bonding to the external lead 7. Because the wire loops are pulled, the connected wire loops are generally low, and as shown by the dotted line, the wires sometimes come into contact with the corners of the pellet 6 or the corners of the tabs 5, causing shoots. This phenomenon is particularly noticeable when the height of the pellet 6 is high and the height difference between it and the external lead 7 is large.

These shoots must be corrected one by one while looking through a microscope, which is a very difficult task. Furthermore, if the shape of the wire loop is low, shoots will occur even when molded (resin-sealed) in the next process, and since these are discovered in the inspection process after molding, the work loss during that time is a major drawback.

The present invention has been made in view of the above-mentioned conventional drawbacks, and an object of the present invention is to provide a wire bonding method that prevents the occurrence of shoots by increasing the shape of the wire loop.

The present invention will be explained below based on illustrated embodiments. FIG. 2 is an explanatory diagram showing an embodiment of the wire bonding method according to the present invention. Note that the same members as in FIG. 1 are designated by the same reference numerals and their explanations will be omitted. As shown in FIG. 2a, after the ball 3 is pressed and connected to the pellet 6 at the first bonding point A by the capillary 1, the capillary 1 is moved to the external lead 7 side at the second bonding point B. At this time, the capillary 1 is moved slightly beyond the second bonding point B, and then returned to the second bonding point B and bonded to the external lead 7. This extra movement amount of the capillary 1 is calculated in advance and the designated distance (length) is stored in a microcomputer (not shown).

The movement locus of the capillary 1 changes from the state shown by the two-dot chain line C in Fig. 2b to the second state as shown by the two-dot chain line D.
Capillary 1 returns to bonding point B and bonding is performed. At this time, when the capillary 1 returns to the second bonding point B position, the wire that has been once fed out due to the friction between the wire and the tip of the capillary 1 does not rise to the spool (not shown).

In addition, in order to return the capillary 1 that has been overrun from the second bonding point B to the second bonding point B, it is lowered as shown by the dotted line E in FIG. You can also move it directly above.

As is clear from the above description, according to the wire bonding method of the present invention, in order to overrun the capillary from the fixed bonding position of the external lead, the wire once fed out to the tip of the capillary rises in the direction of the spool. In order to push the wire back to the pellet side when the capillary moves back, the shape of the wire loop is formed high, and the occurrence of pellet shot and tab shot can be prevented.

[Brief explanation of the drawing]

FIGS. 1A, 1B, and 1C are explanatory diagrams showing a conventional wire bonding method, and FIGS. 2A and 2B are explanatory diagrams showing a wire bonding method according to the present invention. 1...Capillary, 2...Wire, 3...Ball, 4...Semiconductor substrate, 6...Pellet, 7...
External lead.

Claims (1)

[Claims] 1. In the wire bonding method of connecting a semiconductor pellet and an external lead with a wire, after connecting the wire to the semiconductor pellet, the capillary is moved slightly beyond the fixed bonding position of the external lead, and then the capillary is returned to the fixed position. A wire bonding method characterized by connecting a wire to an external lead.