Donald C. Abbott

Palladium as a lead finish for surface mount integrated circuit packages

The authors discuss the use of a thin, preplated palladium lead finish as an alternative to solder. Tests and experiments designed to examine several key properties and behaviors of Pd as related to this application were performed. These tests included: wetting characteristics, solder joint metallurgy, wire bonding, interaction with molding compounds, and electrochemical characteristics. Following initial feasibility studies, an extensive set of reliability and performance tests were run on a wide range of packaged integrated circuits. These included: operating life, temperature/humidity, thermal cycle/shock, lead finish performance and visual/mechanical tests. >

Nickel/palladium finish for leadframes

The structure (and its rationale) of the palladium/nickel leadframe finish which Texas Instruments introduced in 1989 is reviewed and the reasons for its development, the advantages and features of this lead finish are discussed. Unique implications for the leadframe maker, the assembly test site and for the end user, result from using this finish, some of which were not anticipated at its inception. There are now more than 30 billion devices in the field with palladium/nickel plated leads. A synopsis of the performance of this finish with one of the lead-free pastes in the market is included. There is also a section on the observed shelf life of this finish under Battelle class 2 mixed flowing gas conditions.