Solder Joint Reliability of Double-Side Mounted DDR Modules for Consumer and Automotive Applications

This paper describes solder joint reliability studies for DDR memories using single side and double side mount modules in the application of consumer and automotive fields. The types of DDRs include LPDDR4 and GDDR5. The components are from well-known memory manufacturers. Both experimental work and numerical simulation are employed to understand the reliability and failure mechanisms. It is found the reliability of DDRs changes with different DDR types as well as suppliers. LPDDR4 has much lower reliability as compared to that of GDDR5. The reason is the low ball profile which has increased the thermal stress for LPDDR4. However, the most critical factor is the double side mount vs. single side mount configuration. Both experimental and FEA results show corner fill may be a better choice in handling both mechanical and thermal stresses. To enhance the solder joint reliability, one effective way is to employ corner fill, edge bond or underfill. However, in order to get better reliability, corner fill and underfill are normally recommended.