Note: The job is a remote job and is open to candidates in USA. Onyx is a venture-backed silicon photonics startup focused on building high-performance systems for next-generation AI infrastructure. They are seeking a hands-on advanced packaging engineer to lead the multi-die flip chip assembly and chip attach bring-up for heterogeneous compute modules, emphasizing prototype development and OSAT transfer.
Responsibilities
- Lead development of flip chip assembly processes including die attach, bumping, reflow, and underfill for multi-die systems
- Own chip attach bring-up on wafer-level and prototype substrates (200mm+ platforms)
- Define and optimize Cu pillar, micro-bump, and solder interconnect stacks for high-density integration
- Develop and tune TCB / LAB / fluxless bonding processes for fine-pitch multi-die assemblies
- Drive integration of multi-die chiplet packages (3–4 die stacks / heterogeneous integration)
- Debug and resolve assembly failures including warpage, non-wet opens, voiding, delamination, and alignment issues
- Perform root cause analysis using CSAM, SEM cross-sectioning, and reliability test data
- Collaborate closely with OSATs, substrate vendors, and internal design teams to define package design rules and process windows
- Support reliability qualification (thermal cycling, mechanical shock, power cycling)
- Work across design, process, and manufacturing teams to transition from prototype → scalable production
Skills
- MS/PhD in Materials Science, Mechanical Engineering, Chemical Engineering, or related field, with significant industry experience in semiconductor advanced packaging, flip chip assembly, or OSAT/foundry environments
- Lead development of flip chip assembly processes including die attach, bumping, reflow, and underfill for multi-die systems
- Own chip attach bring-up on wafer-level and prototype substrates (200mm+ platforms)
- Define and optimize Cu pillar, micro-bump, and solder interconnect stacks for high-density integration
- Develop and tune TCB / LAB / fluxless bonding processes for fine-pitch multi-die assemblies
- Drive integration of multi-die chiplet packages (3–4 die stacks / heterogeneous integration)
- Debug and resolve assembly failures including warpage, non-wet opens, voiding, delamination, and alignment issues
- Perform root cause analysis using CSAM, SEM cross-sectioning, and reliability test data
- Collaborate closely with OSATs, substrate vendors, and internal design teams to define package design rules and process windows
- Support reliability qualification (thermal cycling, mechanical shock, power cycling)
- Work across design, process, and manufacturing teams to transition from prototype → scalable production
- Experience with HBM, DRAM stacking, or memory-centric advanced packaging
- Exposure to chiplet-based or heterogeneous integration systems
- Familiarity with CoWoS-like 2.5D architectures or interposer-based integration
- Experience in high-TDP or thermally constrained packaging environments
- Exposure to fluxless bonding processes or fine-pitch micro-bump scaling challenges
- Familiarity with thermo-mechanical modeling (warpage / stress simulation)
- Experience bridging design intent ↔ manufacturing constraints in advanced packaging flows
Company Overview