Reliability and Durability Enhancement of Large-area Mullite-cordierite Composite Substrates for Semiconductor Probe Card

Abstract

Spherical mullite (M)-cordierite (C) composite granules were prepared by spray drying the fine starting powders obtained from attrition milling to produce sintered mullite-cordierite composite pellets with a dense structure. The effects of attrition milling on the morphology, size and size distribution of the formed composite granules were investigated. The results showed that the milled starting powders formed the spherical granules with homogeneous size distribution. The composition ratio (M:C = 100:0, M:C = 90:10, M:C = 70:30, M:C = 50:50, M:C = 30:70, M:C = 0:100) and sintering temperature (1300–1450℃) were optimized to fabricate the sintered mullite-cordierite composite pellets with low thermal expansion coefficients (TECs) and excellent mechanical properties. Samples of 70 wt% mullite-30 wt% cordierite sintered at 1350℃ exhibited excellent bulk density, porosity, TEC, and flexural strength. Based on these results, a large-area mullite-cordierite composite substrate was fabricated for application in semiconductor probe card. The changes in sheet resistance and flexural strength were measured to study the influence of the environmental tests, including high temperature storage test, damp heat test, and thermal shock test, on the large-area substrate. A low rate of change in sheet resistance and flexural strength was observed. After the environmental tests, the sheet resistance and flexural strength were confirmed to be within 10% of their values prior to the tests. These results show that the fabricated mullite-cordierite composite exhibits high reliability and durability and is a suitable for semiconductor probe cards.