Monitoring of thermo-mechanical stress via CMOS sensor array: Effects of warpage and tilt in flip chip thermo-compression bonding

• Autores: Ari Laor, Depayne Athia, Alireza Rezvani, Horst Clauberg, Michael Mayer
• Localización: Microelectronics reliability, ISSN 0026-2714, Nº. 73, 2017, págs. 60-68
• Idioma: inglés
• Texto completo no disponible (Saber más ...)
• Resumen

  • Abstract Flip chip thermo-compression bonding (TCB) involves the use of heat and pressure to simultaneously form interconnections for microelectronic packaging. In-situ measurements of thermo-mechanical stresses that arise during this bonding process could provide unique insight to help better understand the TCB process. A 4 mm × 3 mm × 500 μm complementary metal-oxide-semiconductor (CMOS) sensor chip with an 8 × 8 array of Au-bumped sensor pads was developed for this purpose. It was designed to record XYZ force and temperature signals from bump locations, during a simulated flip chip process similar to TCB. In-situ measurements during simulated TCB events proved useful for tilt detection, thermal gradient characterization, and thermal expansion measurements. Further interpretation of the signals proved tilt and other thermo-mechanical effects were induced by thermal expansion mismatches. The most thermo-mechanically stressful stage of bonding was found to occur during thermal transients, specifically during bond head ramping. Further analysis concluded the actual time necessary to heat the bumps was less than 0.5 s. Finally, the lateral thermal gradient across the sensor chip was calculated to be smallest in the central bump locations, and largest in the bump array corners due to warpage, tilt, and heat sink effects of the digital logic region.