What a golden sample is, and why you sign it
Illuminious is a U.S. NPI engineering company. Engineered in San Francisco. Prototype builds, DFM and mass production in our own factory in Shenzhen. You sign one unit after PVT, the golden sample, and from then on every production batch has to match it.
What is a golden sample?
A golden sample is the reference unit you sign after DVT and PVT. It is built from production files, on production fixtures, and measured. Once you sign it, production is held to it: every batch in the Shenzhen factory is compared with that unit, and with its recorded values.
The sign-off record also sets cosmetic limits: which scratches, gaps and color shifts are acceptable, judged under set light at a set distance. Without a signed reference, "good" means whatever the line built last week, and disputes about color, fit, battery life or a rattle turn into opinions. With one, a dispute ends at the bench: put the batch unit next to the signed unit and compare the recorded values.
What is the difference between a demo build and a golden sample?
A demo build is your first working unit: the one you show investors, hand to a pilot user or film for Kickstarter. It proves the idea. A golden sample comes after DVT and PVT and proves the product and the process. You sign it, and production is held to it. A demo build is never the production reference.
| Demo build | Golden sample | |
|---|---|---|
| When | After the design and the DFM review | After DVT and PVT |
| Built from | Reviewed design files, with printed or machined parts | Production files, production tooling and fixtures |
| Proves | That the idea works | That the product and the process work |
| Who uses it | Investors, pilot users, a crowdfunding film | The factory, as the reference for every batch |
| What you do with it | Show it | Sign it |
Crowdfunding platforms expect a working prototype for hardware projects, so the demo build is the first unit with a deadline. We plan it so the same files carry on to EVT. If the golden sample and the demo build look alike, that is a good sign: the design carried through EVT, DVT and PVT with few surprises. For where the demo build sits in the stage path, see the demo build stage.
How a golden sample is made
| Step | What happens |
|---|---|
| PVT build | The line builds units from production files, on production tooling and fixtures, with the release firmware. |
| Measurement record | We measure the units against the test plan, started at EVT and finished at PVT: electrical values, function, fit and finish. |
| Your sign-off | You review a unit and its record, and you sign it as the golden sample. Both parties keep the record. |
| Reference unit kept | The signed unit stays in the Shenzhen factory as the reference. |
| Each batch compared | Production batches are checked against the signed unit and its recorded values. |
What does signing the golden sample commit me to?
Signing says this unit, with these measured values, is what you will accept from production. It fixes the design revision, the BOM, the firmware release and the cosmetic limits. Batches that match it pass. If you want something different later, that is a design change, and it needs a new golden sample.
Sign with the people who will judge the product later: the founder, the product lead, and whoever owns quality or the certification path. That is why the golden sample comes after DVT, not before. By then the design has met its specification and the certification path has started. Sign too early and you hold production to a unit that still needs changes.
How is production held to the golden sample?
Every production batch is compared with the signed unit. Boards go through automated optical inspection. Fixtures made for your product run in-circuit and functional tests. If a measured value moves away from the signed unit, an engineer reviews the drift before the next batch starts. The signed unit stays in the factory as the reference.
Where the product needs it, units also run burn-in or accelerated aging, with cycles of up to 168 hours. The checks follow the same test plan as the golden sample, so the signed unit and the line are measured the same way. Results are compared batch by batch, so a slow trend shows up before it becomes a failure. For the inspection methods, see testing and inspection and quality.
What happens when the design changes after sign-off?
A change to the design, the BOM, a key part or the firmware release means a new golden sample. We build units with the change, measure them against the old reference, and you sign the new one. Until then, production stays on the signed revision. An alternate part needs your approval first.
What you receive
The signed unit itself stays in the factory, because the line needs it next to the bench.
- The sign-off record: the design revision, the BOM, the firmware release, the measured values and the cosmetic limits.
- The PVT units and their test results.
- For each production batch, the inspection and test results compared with the reference.
- The PVT file set the golden sample was built from.
Order demo build parts online
Before the golden sample comes the demo build, and you can order its parts in the portal:
The EVT, DVT and PVT builds that lead to the golden sample are scoped with an engineer. See transfer to production and the NPI services page.
- Standard PCB & PCBA and Advanced PCB & PCBA: live supplier price, then a free engineering review within 24 hours on business days.
- Custom mechatronic parts & assemblies: mechanisms, housings and tested subassemblies, priced by a specialist within 24 hours on business days.
Recent work: holding every build to one reference
A startup building battery backup units for AI server racks moved through EVT, DVT and PVT with us. PVT fixed the golden sample as the production reference, and every later build was tested against it with charge and discharge tests and thermal checks. Read the case study.
Facts and questions
Can a demo build become the golden sample?
No. A demo build can be hand-tuned, built with printed parts or fixed with a jumper wire, and that is fine for a demo. The golden sample must come off the production line on production tooling and fixtures, because production is held to it. Only a unit built the way every later unit will be can serve.
Is a golden sample the same as a first article?
No. A first article inspection checks the first parts from a new tool or process against the drawing. A golden sample is the whole finished product, signed by you, that every batch is compared with. A product has many first articles, one per tool or part, and one golden sample per signed revision.
What happens if a batch does not match the golden sample?
The batch does not ship as a match. An engineer reviews the drift and finds the cause in the parts, the process or a fixture, then fixes it before the next batch runs. If the fix would change the product, it becomes a design change and needs your approval and a new golden sample.
Do I need a golden sample for a small production run?
Yes, if you want the run held to a standard you agreed. A small run still has batches, part lots and operators that change. Without a signed reference, nobody can say which unit is right. For a demo build or a pilot handed to a few users, a golden sample is not needed yet.
Tell us what you are building
- An engineer runs a free engineering review of your files, and nothing is charged when you submit.
- You see the findings first.
- We publish the official quote with an itemized total, lead time and validity window.
- You accept the official quote, and only then does payment open.