Design Guideline of 2.5D Package with Emphasis on Warpage Control and Thermal Management

A 2.5D Package is composed of many material sets and in general its size is larger than conventional single chip packages. Warpage control and thermal management are critical issues in both manufacturing yield and reliability. The CTE of substrate is a well-known factor to control warpage in a single die packages. However, the existence of another layer (interposer) makes the problem more complicated. Optimization of the material sets, which include lid, EMC, chip, Interposer and geometric factors, are essential. Geometric factors such as chip-to-chip distance, lid thickness, and interposer area ratio with respect to substrate are the prime interest. Upon completion of the parametric study, the affecting factors for warpage control and thermal management are identified and documented quantitively. Area ratio of lid attach, lid thickness, CTE of EMC and CTE of substrate are major factors that affect warpage control. For thermal management, EMC coverage on top of the chip, fan speed, and conductivity of TIM are the major factors that affect on thermal resistance. The Design guideline is drafted with the importance and tendency of design factors in mind: for example, the larger, the better characteristics or the smaller, the better characteristics.