Flat-Packs Under Thermal Shock: A Simplified Analysis of Flexural Stress in the Lid-to-Wall Seal.

Abstract : On the basis of a simplified one-dimensional transient heat-flow analysis, formulas are developed for the maximum flexural stresses developed in the lid-to-wall seals of microelectronic flat-packs during thermal-shock screening by Method 1011 of MIL-STD-883. A numerical example is presented to illustrate the use of the formulas. Application of the formulas to package design and to the selection of a screening level for an already designed package is briefly discussed.