Characteristic of the Wire-Penetration Films for Stack-Die CSP Application

For the current advanced packages, Bismaleimide Triazine (BT) substrates are widely used for making Multi-chip package (MCP) because of its high-density I/O applications. Stack-die CSP (Chip Scale Package) is developed under the concept not only for the above advantages but also for the multifunctional applications. For the purpose of mass product, the designs of stack die-attached process should be simplified and wire-penetrated. In this paper, we focus on the characteristics of the wire-penetration films, and then designing the process to stack dies. We performed the JEDEC level 3 precondition conditions, pressure cook test (PCT) and thermal cycle test (TCT). Our results revealed that the WPF-L system is more stable than WPF-H system for the ambit storage and whole assembly process. Rheology and penetration test results also indicate the WPF-L with relative wider working window in dies mounts process than WPL-H system. Noteworthy, WPF-H exhibit higher the viscosity at ambit temperature will induce die broken issues during die pick up process. WPF-L system with a few special big filler has a concern about die surface damage during the die mount process.