Title :
Material system for high performance DRAM-CSP
Author :
Nomura, Yoshihiro ; Tomiyama, Takeo ; Tanaka, Toshiaki ; Inada, Tei-ichi ; Sumiya, Keiji
Author_Institution :
Hitachi Chem. Co. Ltd., Chiba, Japan
Abstract :
The μBGA(R) which Tessera Inc. developed is one of the most suitable chip scale packages (CSP) for high speed DRAMs. However, the larger the chip size, the harder it is to achieve high levels of package reliability. Based on the thermal stress analysis, we have determined the threshold values of elastic modulus and coefficient of thermal expansion (CTE) of both the adhesive film and the liquid encapsulant to achieve higher thermal cyclic properties. Through this study, we have developed new polymer alloys composed of a low modulus polymer and an epoxy resin. CSPs fabricated with the newly developed materials showed high reliability including thermal cyclic properties and solder reflow resistance at high temperature under Pb-free requirements
Keywords :
DRAM chips; assembling; chip scale packaging; elastic moduli; encapsulation; environmental factors; integrated circuit measurement; integrated circuit reliability; plastic packaging; polymer blends; reflow soldering; stress analysis; thermal expansion; thermal stresses; μBGA package; CSP; CTE; DRAM-CSP; Pb-free requirements; adhesive film; chip scale packages; chip size; coefficient of thermal expansion; elastic modulus; epoxy resin; high speed DRAMs; liquid encapsulant; low modulus polymer; material system; microBGA; package reliability; polymer alloys; reliability; solder reflow resistance; thermal cyclic properties; thermal stress analysis; threshold values; Capacitive sensors; Chip scale packaging; Curing; Electronic packaging thermal management; Flash memory; Lead; Polymers; Random access memory; Thermal expansion; Thermal stresses;
Conference_Titel :
Electronics Packaging Technology Conference, 2000. (EPTC 2000). Proceedings of 3rd
Print_ISBN :
0-7803-6644-1
DOI :
10.1109/EPTC.2000.906400
