Validation of Alternative RoHS Compliant Au-pastes for the DuPont LTCC 951 System

摘要

The restriction of the use of certain hazardous substances (RoHS) came into force on 1st July 2006. Equipment producers will need to obtain materials declarations or certificates of compliance from their suppliers. Certain exemptions from this regulation, e.g. RF-ports and certain medical applications, still allow to manufacture LTCC products with non RoHS compliant materials. However, there is a continuously growing demand for LTCC products without cadmium or lead. Since end of 2006 DuPont is offering Cd-free Au-pastes as possible replacements for established products. For cofiring internal and external conductors Au-paste type 5734 is frequently used by LTCC manufacturers. The alternative RoHS compliant paste is type CDF34. For pin, tab, and frame brazing a combination of Au-pastes 5062D (adhesion layer) and 5063D (barrier layer) are currently the first choice for according LTCC parts at MSE. The Cdfree versions are types 5062E and 5063E. MSE is currently validating all 3 new pastes according to a comprehensive test plan which includes 5 different test layouts for CDF34 and another 2 for 5062E, 5063E. Simultaneously, corresponding reference parts were started to have exact comparison possibilities. The validation of CDF34 includes the investigation of bondability, reliability of resistor terminations, vias, and adhesive bonded components. Furthermore, the lateral migration (insulation resistance) will be tested. The 5062E, 5063E validation includes reliability of soldered components, vias in soldered pads and soldering of frames and base plates. The different test cells include visual inspection and x-sections, initial measurements and results after thermal cycling, thermal storage, thermal shock, and humidity exposure.