Keunho Choi
2023-2024
Modification of Photo-resist Stripping Machine for High-thickness Photo-resist (6x the original thickness)
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Pioneered the introduction of a high-thickness photo-resist stripping process, capable of removing photo-resist up to six times thicker than the original, by implementing a Stop & Go conveyor system—marking its first application in industry mass production—saving $2.6M in dedicated equipment costs
2023-2024
Reliability and Yield Improvement of FC-BGA using FR4
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Identified moisture absorption as the root cause of delamination between the copper-dielectric surface and introduced a baking process along with circuit design optimization, reducing delamination rates from 50% to 0%
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Introduced a friction-minimizing system to reduce defect rates caused by damage during processing due to high thickness, improving the final yield from 5% to 30%
2024
Etching Process Development for Enhanced Removability of Copper Line Top Burr
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Developed a dedicated etching process by researching optimal etchants to remove copper burrs caused by substrate grinding, improving photo-resist stripping effectiveness
2022
Yield Improvement for Tape Type Substrates
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Developed a pre-treatment process to prevent unnecessary etching interference by researching the correlation between azole-based inhibitors and short defect rates, achieving a 30% improvement in defect rate