The evolution of build-up package technology and its design challenges

This paper reviews sequential build-up (SBU) laminate substrate development from its beginning in 1988. It reports on developments in this technology for IBM applications since its adoption in 2000. These laminated substrates are nonuniform structures composed of three elements: a core, build-up layers, and finishing layers. Each element has evolved to meet the demands of packaging applications. Thin-film processing has greatly enhanced the wiring capability of SBU laminate substrates and has made this technology very suitable for high-performance designs. This paper focuses on the challenges encountered by IBM during the design, manufacture, and reliability testing phases of development of SBU substrates as solutions for application-specific integrated circuit (ASIC) and microprocessor packaging applications. © 2005 IBM.