REWORKABLE ENCAPSULANT-FREE FLIP CHIP ASSEMBLY
Original Publication Date: 1999-Jan-01
Included in the Prior Art Database: 2002-Jul-29
Current flip chip assemblies require encapsulant material for enhanced reliability performance. Encapsulant is used to couple the die mechanically to the substrate to constrain the board during ther- mal excursions and to reduce the stress transferred to the solder joints. Underfilling the die with encap- sulant requires additional equipment such as dis- pensing robots and curing ovens. In addition, typical encapsulant materials absorb approximately 0.6 wt% moisture which affects adhesion properties and can lead to "popcorn" type failures when a flip chip ball grid array package is attached to the mother board. Finally, the use of encapsulant precludes easy removal of the die (rework).