A method for the measurement of chip to leadframe adhesion in LOCpackages

摘要

Adequate die-to-leadframe adhesion is necessary for LOC packageintegrity during and after manufacturing process. Poor adhesion mayresult in a variety of defects such as die adhesion failure, marginalwire bond, broken wire, exposed wire at the surface of the plasticencapsulated package, and bent leads, ultimately leading to electricalfailure [1,2]. In this paper, a technique to measure the adhesion ofleadframes to electronic chips in LOC type packages is described. Inthis method, the leads on opposite sides of the die are pulled using auniversal materials tester (e.g., Instron). We found that samplepreparation and measurement equipment set-up were critical to theconsistency and repeatability of the measurements. A comparison ofmeasurements on packages bonded with three different materials ispresented. Minimum bonding forces required for best yields weredetermined for these three types of chip-to-leadframe bonding materials.Using this information, we were able to rank materials with respect totheir relative adhesion characteristics