Influence of Joining Conditions on Bonding Strength of Joints: Efficacy of Low-Temperature Bonding Using Cu Nanoparticle Paste

• Published in: Journal of electronic materials 2013-06, Vol.42 (6), p.1260-1267
• Main Authors: Yamakawa, Tomohiro, Takemoto, Tadashi, Shimoda, Masayoshi, Nishikawa, Hiroshi, Shiokawa, Kunio, Terada, Nobuto
• Format: Article
• Language: English
• Subjects: Applied sciences; Bond strength; Characterization and Evaluation of Materials; Chemistry and Materials Science; Electronics; Electronics and Microelectronics; Exact sciences and technology; Instrumentation; Joints; Lead free solders; Materials; Materials Science; Microelectronic fabrication (materials and surfaces technology); Nanoparticles; Optical and Electronic Materials; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Sintering; Solid State Physics
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-013-2583-2

We investigated a new low-temperature bonding process utilizing Cu nanoparticle paste without addition of sintering promoter. Joint bonding strengths above 30 MPa were achieved even at a low bonding temperature of 250ºC. We attribute the higher bonding strengths of joints fabricated using the vacuum preheating process to the rapid progression of Cu nanoparticle sintering due to the activated nanoparticle surface at lower temperatures. The increase in bonding strength depended on the applied pressure, in addition to the bonding temperature. The formation of a dimple-like morphology was confirmed in the ductile fracture area. This indicated that the joint bonded strongly with the bonding layer, in agreement with the results of bonding tests carried out on strongly bonded joints. The bonding ability of the joints obtained using Cu nanoparticle paste could be improved by controlling the joint fabrication conditions.