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Browse Prior Art Database

DEVICE FOR SOLDER BOND ANALYSIS

IP.com Disclosure Number: IPCOM000005938D
Original Publication Date: 1990-Oct-01
Included in the Prior Art Database: 2001-Nov-16
Document File: 2 page(s) / 88K

Publishing Venue

Motorola

Related People

William O. Rogers: AUTHOR [+2]

Abstract

The quality of the solder bonds in power devices is of prime importance for both performance and reliability reasons. Detailed observation of the bond characteristics is difficult. Common methods include X-ray techniques, selective chemical etch to expose the joint and destroying the device with the hope of exposing some of the bond interface. Presented here is an easier and more effective method for:characterizing the quality of solder bonds.

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MOlYlROLA Technical Developments Volume 11 October 1990

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DEVICE FOR SOLDER BOND ANALYSIS

by William 0. Rogers and Donald L. Smith

Abstract

   The quality of the solder bonds in power devices is of prime importance for both performance and reliability reasons. Detailed observation of the bond characteristics is difficult. Common methods include X-ray techniques, selective chemical etch to expose the joint and destroying the device with the hope of exposing some of the bond interface. Presented here is an easier and more effective method for:characterizing the quality of solder bonds.

Previous Techniques

   Past analytical techniques to determine the chip or die bond quality of multi-layer rectifier devices have had limited success. Some methods are time consuming and the detection of solder bond abnormalities were often a matter of chance. A typical rectifier sandwich requiring analysis is shown below.

Some of the old methods of die bond analysis applied cutters to the die or pried the sandwich apart with a blade. Both methods cause the die to fracture with only an occasional small amount of the die bond exposed.

X-rays of the sandwich can reveal large voids, but no or minimal information on smaller voids, solder fatigue or peeling metallization is obtained.

A method to observe a selected die bond interface (anode or cathode) that exposes all, or most of, the entire inter- face region of interest in a rapid and effective manner is described here.

The die that is to be analyzed is placed into a specially designed machine that uses a combination of spring forces and selective heat to expose the bond interface of interest.

How It Works

   An adjustable force is applied to the die bond while rapidly heating the unit from one side. When the temperature approaches the melting point of the solder (about 290" C for PbllnlAg alloy) a ductile failure in the bottom (closest to the heater block) solder bond occurs. This perm...