Packaging Engineer- Materials
SalaryNo pay range posted
LocationRemote, Hybrid Remote/SF Bay Area/Austin/Boston
Work modehybrid
Typefull-time
SenioritySenior
DepartmentAdvanced Packaging
Company size201–500 people
PostedJul 24, 2026 · 2mo ago
Verified live15h ago
At a glanceSummarised by Seekless from the posting.
Strong experience in wafer level molding and underfill processes for advanced semiconductor packages including FOWLP, 2.5D, and chiplet architectures
Deep understanding of mold compound and underfill material science including epoxy resin systems, filler particle size and loading, cure chemistry
Experience with underfill dispense techniques (capillary, no-flow, mold underfill), flow and void characterization, bleed-out control, and cure process optimization
Understanding of thermo-mechanical behavior driven by mold and underfill materials including CTE mismatch, warpage evolution, delamination driving forces
Hands-on experience with failure analysis of mold and underfill failures including cross-sections, SEM/EDS, CSAM, TGA, DSC, and DMA
Ability to work with OSATs and material suppliers to develop, qualify, and transfer mold and underfill processes into production
Strong problem-solving skills with ability to debug mold and underfill yield and reliability issues in manufacturing environments
Experience with underfill materials for III-V or photonics packaging including optically clear encapsulants and low-modulus underfills
Experience with mold and underfill integration in advanced packaging architectures including 2.5D interposers, 3D stacking, chiplet assemblies, and CoWoS-like structures
Familiarity with broad bill of materials for advanced packaging encapsulation including clear adhesives and underfills for photonics, high-filler, low-CTE mold compounds
Experience developing mold and underfill solutions for high-power or high-TDP devices where material thermal conductivity, warpage stability, and CTE are tightly constrained
Exposure to thermo-mechanical modeling or collaboration with simulation teams for warpage prediction, delamination risk assessment, and material property sensitivity analysis
Understanding of system-level interactions (TIM application and cold plate interaction with wafer level molded wafer)
Skills
FOWLP
2.5D
3D
chiplet
compression molding
transfer molding
mold underfill (MUF)
capillary underfill (CUF)
no-flow underfill
mold underfill
SEM/EDS
CSAM
TGA
DSC
DMA
thermal cycling
drop
mechanical shock
power cycling
About the role
We’re looking for a hands-on process and materials engineer to own wafer level molding and underfill processes, material qualification, and assembly integration across development and manufacturing.
Summary:
Seeking an experienced engineer to lead wafer level mold and underfill process development for advanced semiconductor packages (fan-out wafer level packaging, 2.5D/3D, chiplet). This role spans
mold compound and underfill material selection and qualification, wafer level molding and encapsulation processes, underfill dispense and cure, reliability, failure analysis, and cross-functional support through package and system productization.
Core Responsibilities:
•
Develop and optimize wafer level molding processes including compression molding, transfer
molding, and mold underfill (MUF) for fan-out and advanced heterogeneous packages.
•
Own mold compound and underfill material selection and qualification, including evaluation of
filler content, CTE, modulus, Tg, viscosity, and moisture uptake to meet thermo-mechanical and
reliability requirements.
•
Drive underfill process development including capillary underfill (CUF) dispense strategies, flow
and void optimization, and cure profile development for high-density flip chip and chiplet
assemblies.
•
Evaluate and mitigate assembly risks including warpage, delamination, void formation, bleed-out,
mold flash, and filler settling; define process windows and controls to ensure repeatable yield
across wafer and panel formats.
•
Collaborate with OSATs and material suppliers to qualify mold and underfill materials, define
dispense and cure equipment requirements, and manage process transfers into production.
•
Lead characterization of mold and underfill material properties (viscosity, gel time, cure kinetics,
adhesion, CTE, modulus) and correlate material behavior to process outcomes and package
reliability.
•
Work closely with thermal mechanical modeling teams to model solder joint reliability of bump
interconnects with various underfills and predict warpage with various mold compouds.
•
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 wafer level molding and underfill processes for advanced semiconductor
packages including fan-out wafer level packaging (FOWLP), 2.5D, and chiplet architectures.
•
Deep understanding of mold compound and underfill material science including epoxy resin
systems, filler particle size and loading, cure chemistry, and how material properties drive
thermo-mechanical package behavior.
•
Experience with underfill dispense techniques (capillary, no-flow, mold underfill), flow and void
characterization, bleed-out control, and cure process optimization including staged and snap
cure profiles.
•
Understanding of thermo-mechanical behavior driven by mold and underfill materials including
CTE mismatch, warpage evolution through cure and reflow, delamination driving forces, and
material-induced reliability risks.
•
Hands-on experience with failure analysis of mold and underfill failures including cross-sections,
SEM/EDS, CSAM, TGA, DSC, and DMA for material characterization and thermal cycling reliability
evaluation.
•
Ability to work with OSATs and material suppliers to develop, qualify, and transfer mold and
underfill processes into production, including equipment setup and process control plans.
•
Strong problem-solving skills with ability to debug mold and underfill yield and reliability issues in
manufacturing environments, including DOE-driven process optimization.
Preferred / Differentiating Skills:
•
Experience underfill materials for III-V or photonics packaging including optically clear
encapsulants and low-modulus underfills.
•
Experience with mold and underfill integration in advanced packaging architectures including
2.5D interposers, 3D stacking, chiplet assemblies, and CoWoS-like structures where material
interactions and warpage are critical constraints.
•
Familiarity with a broad bill of materials for advanced packaging encapsulation including clear
adhesives and underfills for photonics, high-filler, low-CTE mold compounds for 2.5D interposer
assemblies.
•
Experience developing mold and underfill solutions for high-power or high-TDP devices where
material thermal conductivity, warpage stability, and coefficient of thermal expansion are tightly
constrained.
•
Exposure to thermo-mechanical modeling or collaboration with simulation teams for warpage
prediction, delamination risk assessment, and material property sensitivity analysis for mold and
underfill optimization.
•
Understanding of system-level interactions (TIM application and cold plate interaction with wafer
level molded wafer).
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