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US 6,746,896 B1Granted
Process and material for low-cost flip-chip solder interconnect structures
AssigneeGeorgia Tech Research Corporation
InventorsSong-Hua Shi, Ching-Ping Wong
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Abstract
The present invention provides a novel process and its required fluxable materials for building low-cost flip-chip interconnect structures. The novel process involves two fluxable materials, fluxable wafer-level compressive-flow underfill material (WLCFU) and fluxable tacky film, and applies these two materials on a wafer level. The two materials can provide sufficient fluxing capability during solder reflow and significant improvement of the fatigue life of the formed solder interconnects after fully cured.
Claims28
A wafer-level compressive-flow underfilling (WLCFU) process comprising the steps of:
- applying a WLCFU material onto a surface of a bumped wafer in an amount sufficient to ensure that the thickness of the solidified WLCFU layer is less than the height of the wafer bumps;
- solidifying the WLCFU material;
- separating the WLCFU material coated wafer into individual chips;
- covering the top of the bumps with a tacky film for promoting solder interconnects without intervening WLCFU material, wherein the tacky film and the WLCFU,material are not the same;
- mounting the WLCFU material and tacky film coated individual chips to substrates;
- and
- reflowing the solder bumps and curing the WLCFU material and tacky film simultaneously.
4 more elements
Dependencies are inferred from the claim text.