Examination of the Pore Structure of Copper Sintered Die Attach Layers by Local Thickness Analysis and Scratch Test

To capture the structure of die attach layers beyond porosity alone, more elaborate methods are required. Samples were sintered at 275 °C and 250 °C with 20 MPa pressure for 20 to 900 seconds. Cross-section SEM image analysis was conducted with pore classification by shape, using a circularity threshold, followed by size measurement by thickness distribution. Three fractions of pores with significant differences in size, spatial distribution and growth behavior were observed. The new approach improved the acquisition of quantitative data from cross-section images. Additionally, scratch testing revealed the distribution of relative strength in the layer. This test can be used when other methods, such as shear testing, are not feasible.