Browse Prior Art Database

Automatic Wire Bonding and Wire Removal

IP.com Disclosure Number: IPCOM000087358D
Original Publication Date: 1977-Jan-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 3 page(s) / 53K

Publishing Venue

IBM

Related People

Ho, HK: AUTHOR

Abstract

This article describes a mathematical model for the spacing of wires on bonding pads for automatic wire handling.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 58% of the total text.

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Automatic Wire Bonding and Wire Removal

This article describes a mathematical model for the spacing of wires on bonding pads for automatic wire handling.

The figure illustrates a pad with two wires bonded on it.

Other dimensions are also shown, and they are defined as follows: P(w) = size of pad

d = diameter of wire S(o) = outside spacing

S(i) = inside spacing

S(1) = spacing between wire center and the edge of

pad on the same side of the wire

S(min) = required minimum spacing between centers of

wires (limited by the requirement of wire-removal

tool)

S(cc) = center to center spacing between the two wires

on a pad.

Some of the terms not indicated in Fig. 1 are defined below:

T(3sigma) = total 3sigma statistical tolerance of the bonding

machine and the product

(T(1))(3 sigma) = resultant 3sigma bonding machine tolerance

T(a) = total fixed tolerance in the system.

In the process of wire-bonding, two factors must be considered, namely: (1) to make a good bond, and (2) to be able to remove the wire, if necessary. The distance between the center of the wire and the edge of the pad on the same side of the wire (i.e., S(1) shown in Fig. 1), is a very important factor. If P(w) is given, the sum of S(o) and S(i) is a fixed value. Increasing S(o) will increase the probability of making a good bond, and increase the probability of encountering bad removals. (A bad removal means that the spacing between two wires is so small that the wire-removal tool cannot be used to remove the unwanted wire.) In order to minimize the sum of bad bonds and bad removals, the standard deviations of bad bonds and bad removals must be equal. The model presented in this disclosure is base...