Nondestructive evaluation of TAB bonds by acoustic microscopy

A matrix of TAB (tape automated bonding) inner and outer lead devices with a built-in range of quality was investigated. Each bond interface was documented acoustically and then pull-tested to develop a database upon which to formulate a specific test method. Data demonstrate excellent correlation between the degree of bonding and correlative pull tests (destructive) when artifacts of the pull test were compensated. A series of probability curves was generated to predict pull strength from SLAM data alone. In particular, the scanning laser acoustic microscope (SLAM) produces real-time images (30 fields of view per second) at ultrasonic frequencies from 10 to 200 MHz. The speed of scan and the practicality of acoustic microscopy make the method potentially viable for nondestructive evaluation of microelectronic packaging. A standard is proposed for inclusion in MIL-STD 883.<<ETX>>