Packaging Engineer- Bump Interconnect

We're seeking an experienced engineer to lead bump interconnect development for advanced semiconductor devices (2.5D/3D/chiplet/fan-out). This role spans ubump and C4 bump metallurgy, RDL design and plating, chip-side and interposer capture pad design rules, OSAT engagement, reliability, failure analysis, and cross-functional support through package and system productization. Core Responsibilities • Own end-to-end bump interconnect development for both ubump (micro-bump) and C4 processes, including bump formation, and reflow for use with mass reflow, TCB, and LAB chip attach for high-performance semiconductor packages. • Define and own bump metallurgy stacks for ubump (e.g., Cu pillar/SnAg) and C4 (e.g., SAC alloys) interconnects, including UBM selection and pad finish specifications for both chip-side and interposer capture pads. • Develop and own design rules for bump interconnects including pitch, bump diameter, standoff height, keep-outs, and land pad geometry for both the chip side and interposer or substrate capture pads. • Lead RDL (redistribution layer) process development including electroplating of Cu RDL traces, via fills, and pad finishes; define RDL design rules for line/space, via diameter, and layer stack-up to meet electrical and reliability requirements. • Collaborate with OSATs and bumping foundries to qualify ubump and C4 bumping processes, drive design rule alignment, and manage process transfers into production. • Evaluate and mitigate bump interconnect assembly risks including non-wet opens, voiding, head- in-pillow, intermetallic growth, and joint fatigue failures across both ubump and C4 interconnect types. • Perform root cause analysis of assembly and reliability failures using cross-sectioning, SEM, CSAM, and other failure analysis techniques. • Support reliability qualification including thermal cycling, drop, mechanical shock, and power cycling. • Work cross-functionally with design, reliability, thermal, and manufacturing teams to ensure robust package performance from concept through high-volume production. Required Technical Skills • Strong experience in bump interconnect processes including ubump (Cu pillar, micro-bump) and C4 bumping for semiconductor devices. • Deep understanding of bumping metallurgy including UBM stacks, solder alloy systems (SnAg), intermetallic compound (IMC) formation and growth kinetics, and their impact on joint reliability. • Experience with RDL plating processes including Cu electroplating, photoresist patterning, seed layer deposition, and associated design rules for line/space, via geometry, and pad stack. • Understanding of thermo-mechanical behavior in bump interconnect assemblies including CTE mismatch, warpage, solder joint fatigue, and IMC-driven reliability risks for both ubump and C4 configurations. • Hands-on experience with failure analysis and reliability testing (cross-sections, SEM, CSAM, thermal cycling). • Ability to work with OSATs and suppliers to develop and transfer assembly processes into production. • Strong problem-solving skills with ability to debug yield and reliability issues in manufacturing environments. Preferred / Differentiating Skills • Experience with III-V packaging, photonics packaging, and precision chip attach. • Experience with advanced packaging technologies including 2.5D interposers, 3D stacking, chiplets, and CoWoS-like architectures. • Familiarity with fine-pitch micro-bump and hybrid bonding approaches. • Experience integrating high-power or high-TDP devices with tight warpage and thermal constraints. • Exposure to thermo-mechanical modeling or collaboration with simulation teams for warpage and reliability prediction. • Understanding of system-level interactions (warpage, second-level interconnect reliability). • Deep expertise in bump metallurgy fundamentals including UBM stack design (Ti/Cu, etc.), solder alloy selection, wetting behavior, and the influence of plating chemistry and process conditions on bump morphology and composition. • Fundamental knowledge of intermetallic compound (IMC) formation, growth kinetics, and phase behavior in Cu/Sn, Ni/Sn, and Au/Sn systems; understanding of how IMC thickness, morphology, and composition affect joint strength, electromigration resistance, and long-term reliability. Education & Experience: Industry experience in semiconductor packaging with strong emphasis on bump interconnect processes, RDL development, and productization.