About the role
We're seeking experienced engineers to contribute to flip chip package development and assembly processes for advanced semiconductor devices (2.5D/3D/chiplet/fan-out/flip-chip).
This spans bump metallurgy, substrate integration, reflow and underfill processes, reliability, failure analysis, and cross-functional support through package and system productization.
Core Responsibilities
- Develop and optimize flip chip attach processes including bump formation,
placement, reflow, and underfill for high-performance semiconductor packages.
- Define and manage bump metallurgy stacks (e.g., Cu pillar, SnAg, micro-bumps)
and substrate pad finishes for robust interconnect performance.
- Drive package integration from die to substrate, ensuring alignment, coplanarity,
and yield optimization.
- Evaluate and mitigate assembly risks including warpage, non-wet opens, voiding,
head-in-pillow, and interconnect defects.
- Collaborate with substrate vendors, OSATs, and internal teams to define design
rules (pad pitch, bump pitch, keep-outs, stack-ups).
- Lead process development for reflow profiles, flux selection, cleaning, and underfill
dispense/cure.
- 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 flip chip packaging and assembly processes for
semiconductor devices.
- Deep understanding of bumping technologies (solder bumps, Cu pillar, micro-
bumps) and UBM/metallization systems.
- Experience with underfill materials, dispense techniques, flow behavior, and cure
processes.
- Understanding of thermo-mechanical behavior in flip chip assemblies (CTE
mismatch, warpage, solder fatigue, reliability risks).
- 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 bill of materials used in photonics packaging such as clear
adhesives and underfills as well as mold compounds and underfills for 2.5D
advanced packaging.
- 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 (PCB attach, second-level interconnect
reliability).