Four layer BGA design optimization for improved thermal performance and lower cost

Optimization of 4 layer (4L) BGA thermal performance with best reliability and cost compromise is presented. Effects of design variables on thermal performance, reliability and cost are examined with both experiments and simulation. Long term thermal performance and solder joint reliability is also presented. It is found that removal of soldermask at DA are gives thermal improvement. With conventional DA, up to 20% soldermask opening can be used. It is demonstrated that by optimizing the die pad and solder mask pattern the thermal performance of a 4L BGA can be improved without degrade the reliability and addition cost.