Elimination of ESD Events and Optimizing Waterjet Deflash Process for Reduction of Leakage Current Failures on QFN-mr Leadframe Devices

This technical paper presents the resolution of high leakage current failures on QFN-mr （Quad-Flat No-leads Multi-Row） LF （leadframe） devices by optimizing the waterjet deflash process and eliminating the ESD （electrostatic discharge） events. ESD damage to units can cause permanent or latent product failures which results in low final test yield, and worse, possible external customer complaints. The use of CO2 （carbon dioxide） bubbler was able to reduce the DI （deionized） water’s equivalent resistivity from 17 M？ to 0.30 M？, minimizing the tribocharging effect produced during the waterjet deflash process. Moreover, ESD events were eliminated by grounding the floating assembly equipment parts and installing appropriate ESD controls. It is of high importance to reduce or eliminate the leakage current failures to ensure the product quality, especially as the market becomes more demanding. After the optimization and implementation of the corrective and improvement actions, high leakage current occurrence was significantly reduced from baseline of 5,784 ppm to 20 ppm.