Alternative Compliant Interconnects: Thermo-Mechanical Reliability, Design and Testing

Abstract Two types of novel compliant interconnects are being proposed in this paper. The advantages of these two types of compliant interconnects are: accommodation of the mismatch due to different thermal expansions in electronic packages, integration with wafer-level fabrication process, low cost, fine pitch and high I/O density. The first type is a highly-compliant cantilevered spring interconnect for the next generation packaging and probing technology. To understand the reliability of the package with this novel compliant spring interconnect structure and the typical behavior of sliding contact, test vehicles with different orientations of the cantilevered springs (21 μm pitch) have been fabricated, assembled and subjected to thermal cycling test. In-situ resistance and temperature measurements have been conducted. The second type is a compliant free-standing interconnect, One-Turn Helix (OTH) structure. This structure is built as an one-turn strip helix in order to get good compliance in space. It can be fabricated through conventional photolithography-based IC fabrication process. Optimal design parameters have been identified for this structure taking into consideration the thermo-mechanical and electrical behavior of this unique structure.