Micro zero-insertion-force (ZIF) connector for multi-substrate packages

In this project, we have designed, fabricated and tested a new micro zero-insertion-force (μ-ZIF) electrical connector capable of transferring power and signals among multiple electronic chips within a WIMS (wireless integrated microsystems) environmental monitor package with a volume of approximately one cubic-centimeter. The connector allows the chips to be inserted and removed with minimal force and the connector is physically, operationally, and environmentally compatible with the remainder of the package internals. The connector has high reliability, durability for multiple actuations, ease of fabrication, and ease of integration into the microsystem packages.; In this new connector, the contact pair was the chip-edge bond pad and a copper bus on the connector, connected with low temperature solder. The integrated circuit chips were inserted or withdrawn while the solder was molten, so little force was needed. Thin film heaters were deposited on a Macor (machinable glass ceramic) substrate in this connector for solder melting. The electrical bus, heaters, and solder were combined into two pieces of Macor substrates. This structure was simple without complex actuating mechanical components found in conventional ZIF connectors.; Low temperature lead free solder 42Sn/52Bi was chosen and tested. The required power supply, thermal response, and temperature range determined the performance of the heaters. A finite element model was attempted with the heaters on the bottom substrate. The thermal model guided the design of the heater response and temperature distribution. Based on the result of the thermal model, the heaters were fabricated, tested and improved. Oxidization, electrical migration and thermal stress were observed during heater testing. Oxidization was the primary cause of increase of resistance. A SiO₂ insulator layer with 1μm thickness was sputtered on the heaters in order to prevent the heaters from oxidization and corrosion. Because of pin-holes, the SiO₂ layer failed to protect the heaters from oxidization and corrosion. Epoxy replaced SiO₂ as the insulator layer on the heaters. The epoxy is a kind of polymer which can withstand high temperature and resist oxidization and corrosion. (Abstract shortened by UMI.)...