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Capillary Designs for Copper Wire Bonding

IP.com Disclosure Number: IPCOM000239020D
Publication Date: 2014-Oct-01
Document File: 3 page(s) / 487K

Publishing Venue

The IP.com Prior Art Database

Abstract

Cu bonding wire is being used in more and more products. Due to the properties of Cu metal and current bonder platform abilities, there are some quality concerns, such as Al squeeze-out and inconsistent stitch bond profiles, which can introduce electrical failures. In this paper we describe a capillary having tip dimensions developed to eliminate these concerns.

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Capillary Designs for Copper Wire Bonding

Abstract:

Cu bonding wire is being used in more and more products.  Due to the properties of Cu metal and current bonder platform abilities, there are some quality concerns, such as Al squeeze-out and inconsistent stitch bond profiles, which can introduce electrical failures.  In this paper we describe a capillary having tip dimensions developed to eliminate these concerns.

Body:

For Cu wire bonding, due to material properties and bonding parameter settings, there can be Al squeeze-out issues (i.e., the Al on the bonding pad).  The traditional wire bonder can only transfer ultrasonic vibrations in the Y direction so the Al squeeze-out in the Y direction is larger than that in the X direction.  In some cases, the Al squeeze-out was so serious that it caused electrical failures, such as bond pad shorts or wafer structure damaged opens, especially in fine pitch products.

Because of ultrasonic vibrations in Y direction, stitch bonds on east/west pins were wider than those on north/south pins; the stitch heels were also thinner, which may cause quality risks, such as low wire peel, heel crack and so on.

The proposed capillary design is meant to address these issues.  Some dimensions of the partition of capillary tip were changed to be elliptical; the dimensions of hole, inner chamfer and tip in Y direction were modified to be smaller than those in X direction.

This change can be achieved with specially designed capillary manufacturin...