Ekra, specialist for paste-printing technology, has joined the Semiconductor Equipment Consortium for Advanced Packaging (Secap), focused on bringing advanced packaging technology into manufacture. With Ekra’s participation, Secap is adding stencil printing to the process portfolio, as an alternative to electroplating and evaporation to deposit pastes of all kinds on substrates and wafers. Printing is used with solder bumping where the bump pitch is typically not smaller than 150 microns, done with stencils. Printing can be an economic way to deposit alloys for larger solder balls. For the deposition of under-bump metallization (UBM), sputtering and electroless processes are common while the bumps themselves are either printed or electroplated. Both methods have characteristic advantages and disadvantages. Also just recently, oven specialist firm BTU has joined Secap. The company will install a wafer-bump reflow system with integrated automated handling and flux coating in the 300mm Unitive-Secap line in Taiwan. With BTU’s participation, bump reflow is now at hand at the alliance. Reflow forms homogeneous solder spheres that create interconnects between under-bump metalization and solder. The process is critical for wafer bumping because of its influence on the reliability of solder joints. In the next 5 years, the number of wafers that require bumping or re-distribution processes is expected to increase by 500%. Wafer-level packaging will revolutionize packaging technology.
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