Development of Low-temperature Sintering Materials for Bare Cu lead-frame

This paper will discuss the fundamental study on nano-silver die attach newly developed with a unique approach using MO (Metallo-organic) technology.Nano-silver provides a low-temperature sintering capability. The nano-silver die attach shows high thermal performance and strong adhesion to Ag and Au plated dies and lead-frame with the metallic bond without pressure during the curing process.In addition, resin reinforcing technology and lowering modulus technology have been developed to improve the mechanical properties. By adding special epoxy resins to the die attach, the porous area is filled with the resin and the sintered structure is reinforced. Additionally, the reliability can be further improved by thermoplastic resin particles. The modulus and the stress caused by the CTE mismatch between the die and lead-frame can be lowered by adding the resin particles to the die attach.To meet the requirement for applications without Ag or Au plated Cu lead-frame, nano-silver die attach for bare Cu application have newly been developed. The addition of a special additive is effectively establish metallic bonding between the nano-silver particles and bare Cu lead-frame because the additive removes the oxide layer on the surface of Cu lead-frame. By adjusting the amount of epoxy and thermoplastic resin, adhesion strength on the bare Cu lead-frame can be more improved. The fundamental investigation for the mechanism and the reliability test results in the molded package will also be discussed in this study.