Compliant Wafer Level Package

Abstract A high I/O density and high performance wafer level packaging technology called the Compliant Wafer Level Package (CWLP) is reported. The necessity for compliant interconnects in upcoming generations of electronic products is discussed by analyzing the technology requirements projected by the International Technology Roadmap for Semiconductors (ITRS). To be a true wafer level package, the technology should have following three characteristics11: I) package all Integrated Circuits (ICs) intact on wafer at once, II) perform wafer level test and burn-in, and III) assemble the WLP on the system board without using an underfill. Compliant interconnects are essential to accomplishing wafer level test and assembly without underfill. These topics are discussed in the paper followed by fabrication and performance analysis of the CWLP technology.