Laser focus depth adaptation for decapsulation of copper wirebonded devices

• Main Authors: Kor, Katherine Hwee Boon, Liu, Qing, Siah, Yu Wen, Gan, Chee Lip
• Other Authors: School of Materials Science & Engineering
• Format: Conference or Workshop Item
• Language: English
• Published: 2015
• Subjects: DRNTU::Engineering::Materials::Metallic materials
• Online Access: https://hdl.handle.net/10356/107318; http://hdl.handle.net/10220/25336; http://www.asminternational.org/web/edfas/technical?p_p_auth=ob3PcFz5&p_p_id=101&p_p_lifecycle=0&p_p_state=maximized&_101_struts_action=%2Fasset_publisher%2Fview_content&_101_assetEntryId=22674956&_101_type=content&_101_groupId=10192&_101_urlTitle=laser-focus-depth-adaptation-for-decapsulation-of-copper-wirebonded-devices
• Institution: Nanyang Technological University

Although pre-laser decapsulation reduces the time to acid exposure for subsequent chemical decapsulation of copper wirebonded devices, it can result in severely damaged or broken copper wirebonds if carried out at a focused depth followed by chemical decapsulation. Thin quad flat packages (TQFPs) of dimensions 22 mm × 22 mm, with copper wirebonds were pre-laser decapped (Nd:YAG laser, 1064 nm) at three depths of focus, at focus, (z-0.5) mm and (z-1) mm. Reducing the laser focus depth by 1 mm, followed by subsequent chemical decapsulation, resulted in the least damage to copper wirebonds. Average percentage reduction in copper wirebond diameter after complete (laser and chemical) decapsulation is about 2.30%.