OSAT Supplier Qualification Assessment for Fabless and IDM Teams
Choosing or re-evaluating an outsourced assembly and test (OSAT) partner means looking past price and capacity. This ten-question assessment scores the controls that most often decide whether a subcontractor protects your yield, traceability and delivery.
1. What quality system certifications and customer audits does the OSAT hold?
Examples: ISO 9001, IATF 16949 for automotive, AS9100 for aerospace, ISO 13485 for medical.
2. How does the OSAT control key assembly processes (wire bond, die attach, mold, plating)?
3. How good is lot traceability from wafer to finished unit?
4. How does the OSAT handle test, including program control and correlation?
5. How mature is the OSAT's change control and notification process?
6. How are failure analysis and corrective actions managed?
7. Is capacity committed and visible?
8. How is ESD, contamination and moisture sensitivity handled on the line?
9. What supply chain and continuity risks have been assessed?
Consider substrate, lead frame, mold compound and single-site dependency.
10. How well does the commercial and data relationship support you?
How to use the assessment
Answer each question based on evidence from audits, quality agreements, shared data and past performance, not on sales presentations. Run it per OSAT site, since a company with several factories can differ widely between them. The score places the supplier in one of four bands and returns suggested actions you can place in the quality agreement.
- Use audit findings and records as evidence
- Assess each site separately
- Reassess after major changes or incidents
What the questions test
The questions cover quality system maturity, process control, traceability, test control, change management, corrective action, capacity commitment, ESD and moisture handling, continuity and data exchange. These are the areas where subcontracted semiconductor operations most commonly fail customers, for instance through undetected process drift or unannounced changes to materials.
How to read the score
The score is a percentage of the maximum, and the bands guide the level of oversight. A high score with a low result on traceability still deserves action, because a single weak area can dominate a field return investigation. Look at the lowest answers, not only the total.
Common mistakes
Do not rely on a certificate alone, since it shows a system exists, not that it works for your product. Do not skip the quality agreement, which is where change notification and data sharing obligations belong. Avoid single-site dependency without a documented fallback.
Frequently Asked Questions
Is this a replacement for an on-site audit?
No. It structures the evidence you collect and highlights gaps. Critical or automotive, medical and defense products usually require an on-site audit as well.
What does OSAT stand for?
Outsourced semiconductor assembly and test. These companies package wafers into finished devices and test them for fabless companies and integrated device manufacturers.
How often should an OSAT be reassessed?
At least annually for critical suppliers, and after any significant change such as a site move, ownership change, process change or quality escape.
Which score is good enough?
It depends on product risk. Consumer parts may tolerate the conditional band with oversight, while safety critical parts should aim for the upper bands plus an on-site audit.
If you want OSAT lot status, yield and delivery data flowing into your ERP automatically, Netray can help design that integration with your team.
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