BUYER’S DECISION GUIDE
Seven criteria for choosing a US packaging partner.
Choose a US OSAT by working through seven gates in order: US-soil assembly and ITAR eligibility first — a legal hard gate for any defense or dual-use program — then quality posture (MIL-STD-883 workmanship methods and per-build traceability), technical process fit, prototype-to-low-volume continuity with a single partner, engineer-to-engineer access and DFM feedback, domestic supply-chain risk exposure, and finally an honest assessment of whether your program needs a US supplier or suits offshore volume economics.
A framework for engineers and program managers evaluating US OSAT suppliers — for RF, aerospace, defense, sensor, and hermetic packaging programs where the choice of partner is a program-risk decision, not just a vendor decision.
/ US-soil assembly / MIL-STD-883 workmanship / ITAR-aware / engineer-to-engineer
HOW TO USE THIS GUIDE
Seven gates. Work through them in order.
The criteria below are ordered by elimination power: earlier gates are hard constraints (legal, compliance, physical) that disqualify a supplier regardless of any later strength. Later gates are differentiation filters — they help you compare suppliers who have already cleared the first gates. Do not start at criterion 3 if criterion 1 has not been confirmed.
Work through gates 01–07 in order. Earlier gates eliminate; later gates differentiate.
CRITERION 01 — ITAR ELIGIBILITY
Is the work performed on US soil?
For any program that touches ITAR-controlled technical data — specifications, assembly drawings, process parameters — where the work is performed is a legal question, not a preference.
A foreign-owned facility, or one that performs assembly or process development offshore, cannot legally receive ITAR-controlled technical data without an export license from the US State Department. This is the first gate because it is absolute: no downstream quality posture or cost advantage compensates for it.
The relevant factors are ownership structure (not just incorporation location), where physical assembly occurs, where engineering and process development occurs, and whether the engineering team handling your data is domestic. A US entity with offshore subcontracting relationships may still carry exposure — confirm the full chain.
CRITERION 02 — QUALITY POSTURE
What workmanship standard does the line run to?
A quality claim without a reference standard is not a claim — it is a description. For defense, aerospace, and high-reliability programs, the relevant workmanship benchmark is MIL-STD-883.
The question is not whether a supplier mentions MIL-STD. It is whether their line is built to it: documented methods for die attach, wire bond, and hermetic seal; first-article inspection discipline; per-build process traveler data; and a defined nonconformance path. Traceability is the proof — a supplier who cannot produce a sample traveler from a prior build does not have the system to produce one from your build.
AS9100 certification is a strong signal of documented quality management, and worth asking about. It is not the only signal, and many programs do not formally require it at prototype or low-rate production stages. The right question is about what standard governs the line and how that standard is evidenced.
Note on framing: this guide describes what the standard means and what to ask — not which suppliers hold which certificates. Verify certification status directly with the supplier.
CRITERION 03 — TECHNICAL FIT
Does the supplier actually run the process your device needs?
“We do packaging” covers a range from simple epoxy die-in-package to flip-chip copper pillar on aluminum nitride with fluxless reflow. A supplier may be excellent at one and have never run the other.
Generic capability claims are not useful here. You need process-specific confirmation: the exact interconnect method your design calls for, demonstrated on a comparable substrate, at a comparable geometry, with yield data that proves the process window is understood.
The relevant process families include wire bonding, die attach and die bonding, flip-chip assembly, hermetic packaging, RF and mmWave packaging, and aerospace and defense packaging, plus upstream circuit and firmware design and process engineering. Each of these links to Heisler’s detailed capability pages — use them to understand what each process family requires and what to ask.
A supplier who has run a comparable process will answer the “comparable build” question specifically. A supplier who has not will describe their line generally.
CRITERION 04 — PROTOTYPE-TO-VOLUME PATH
Can one partner carry you from first article to low-rate production?
A re-qualification handoff between a prototype house and a volume supplier is not a formality. It is a re-proof of the process on different equipment, in a different environment, under a different quality system.
That handoff costs schedule, NRE, and yield risk. The process that worked at your prototype supplier may not behave identically on the production line — and the production supplier has no institutional memory of the development history. Every assumption made during prototype development has to be re-verified.
The alternative is a single partner who can take a first-article build through engineering iteration and into a locked, documented process that runs on the same line at low-rate production. That continuity is only possible if the supplier has the process range to run prototype complexity and the capacity to run production volumes — confirm both.
CRITERION 05 — NRE & ENGINEER ACCESS
Who in engineering will you actually talk to?
Design-for-manufacturability feedback at the start of a program is worth more than any amount of yield data at the end. A mistake caught in design review does not become a first-article failure.
The question is whether the person who takes your specification is a process engineer who has run the interconnect family your device requires, or a sales function that routes back to a floor operator you never meet. These are different engagements.
DFM review before NRE begins — the process engineer reviewing your pad layout, substrate selection, and bump geometry against the known process window — is where the best value in a prototype engagement is generated. How NRE and iteration are structured matters too: is a failed first article a cost overrun with undefined resolution, or a defined step in a documented development process with clear go/no-go gates?
Pricing and rates are not discussed in this guide. The model is what matters at the evaluation stage: does the engagement give you direct engineer access, and is iteration handled as engineering work or as rework?
CRITERION 06 — SUPPLY CHAIN RISK
What is your program’s single-point supply exposure?
Offshore packaging concentration creates program risk that shows up as schedule disruption from geopolitical events or logistics failures, and as technical opacity when you cannot audit a remote facility or protect design data in transit.
A domestic supplier that sources primary materials within the US, or from allied-nation suppliers with auditable supply chains, eliminates the first category and substantially reduces the second. The relevant questions are where primary substrates, die-attach materials, bond wire, and sealing materials are sourced; whether any single foreign-country dependency exists in that chain; and what the stated lead time is under normal and stressed logistics conditions.
This is not an argument that offshore supply chains are inherently unsafe — it is that, for programs where schedule predictability and data-security are requirements, the risk profile of the supply chain matters as much as the capability of the production line.
CRITERION 07 — PROGRAM FIT
When a US OSAT is the right choice — and when it isn’t.
Honest frameworks are more useful than promotional ones. A US OSAT is the right choice for some programs. Offshore packaging at scale is the right choice for others. Both statements are true.
A US OSAT is the right choice when your program has ITAR or defense-compliance gates; when you are in prototype-to-low-volume with active engineering iteration; when your device requires specialized RF, hermetic, sensor, or advanced packaging processes that offshore commodity lines do not run; or when design-data security and physical access for customer audit are requirements. These are not edge cases — they describe a large fraction of the US aerospace, defense, medical, and advanced-sensor market.
Offshore packaging at scale is the right choice when your program is mature and the design is locked; when volumes are high enough to drive unit economics; when there are no ITAR, compliance, or data-security constraints; and when the process your device needs is available on a commodity volume line. Forcing a program with those characteristics through a US low-volume OSAT does not serve the program.
The useful diagnostic is not “which is cheaper” — it is “what does my program actually require?” The criteria above answer that question.
US OSAT VS OFFSHORE — AN HONEST COMPARISON
An honest comparison.
These rows summarize how the two sourcing models behave across the seven criteria above. Neither column is universally correct — the right choice depends on what your program requires.
This comparison reflects general market patterns. Confirm specifics with each supplier you evaluate.
FAQ
Answers before you ask.
What does ITAR mean for semiconductor packaging, and why does it restrict offshore work?
ITAR — the International Traffic in Arms Regulations — controls the export of defense-related technical data, including packaging specifications, assembly drawings, and process parameters for regulated devices. When a packaging program involves ITAR-controlled data, that data cannot be transmitted to a foreign person or entity without a license from the US State Department. US-domiciled suppliers performing assembly on US soil with a domestic engineering team are not “foreign” under this definition. An offshore facility — regardless of its quality posture — cannot legally receive that data without a license, which makes it ineligible for the program regardless of any other capability.
Is AS9100 certification or MIL-STD-883 compliance required to choose a US packaging supplier?
AS9100 certification is a signal of documented quality management, and it is worth asking about. Whether it is required depends on what your program formally specifies. Many aerospace and defense prototype programs are executed by suppliers who build to MIL-STD-883 workmanship methods and maintain full process traceability without holding an AS9100 certificate. The right question for your supplier is not a binary “are you certified?” — it is: what standard governs your line, how is traceability maintained, and can you produce documentation for a prior build comparable to mine?
How do I evaluate a supplier's technical fit beyond their capability list?
Ask for a comparable build — same interconnect method, same substrate class, similar device geometry — and ask for the yield outcome and metrology summary from that build. A supplier who has run the process will answer specifically. A supplier who has not will describe their line generally. If no comparable build exists, ask how the first-article process would be structured: what is the development plan, what are the go/no-go gates, and how are iterations handled? The quality of that answer tells you whether the capability is theoretical or operational.
At what volume does offshore packaging become the better choice?
Volume alone is not the threshold. The triggers are: no ITAR or compliance constraints, a locked and mature design, no requirement for active engineering iteration, a process that a commodity volume line actually runs, and unit economics that dominate total program cost. A high-volume device with all of those characteristics is a reasonable candidate for offshore packaging. A prototype RF assembly on a specialized substrate at low volume — even if the device will eventually be produced at high volume — is not. The more useful diagnostic than “what volume?” is “what does this specific program require?” — and working through the seven criteria above.
What should I expect from an NRE engagement with a US packaging partner?
A well-structured NRE engagement starts with a design review — your packaging requirements presented to the supplier’s process engineer before a statement of work is written. DFM feedback at that stage identifies problems in the design that would otherwise become first-article failures. After the design review, expect a defined first-article build plan with specified inspection and metrology gates, and a clear documented path from first-article results to a locked process. The quality of the early engineering dialogue — whether it is specific, technical, and two-directional — is the best predictor of how the full program will go.
How do I assess a supplier's supply chain risk posture?
Ask two specific questions: where are your primary materials and substrates sourced, and what is your plan if that source is disrupted? A supplier who can name their primary material suppliers, confirm domestic or allied-nation sourcing for critical inputs, and describe a contingency path for supply disruption is managing this risk actively. A vague “we have multiple suppliers” answer without specifics is not sufficient for a high-reliability program. For programs where schedule predictability is a requirement, the supply chain risk posture of your packaging partner is a program variable, not a vendor detail.
Process More.
The process starts with a conversation.
Heisler’s scope runs from circuit design and firmware through wafer-level processing, packaging, and supply chain — for programs that need more than an assembly house. Bring us your program — process, geometry, substrate, and compliance requirements. We will tell you honestly whether we are the right fit, and what a first engagement would look like.
Request a Capability Brief →/ US-soil assembly / MIL-STD-883 workmanship / ITAR-aware / engineer-to-engineer access