What is actually being outsourced
An EMS partner does not just place components. It takes over four activities that are expensive to run in-house at low volume:
- Component sourcing. Purchasing, lead-time chasing, approved-manufacturer checks and incoming inspection.
- Process engineering. Stencils, paste, reflow profiles, AOI recipes, test fixtures.
- Capacity. Lines that can take a 50-piece prototype and a volume order without a new setup.
- Quality records. First article, in-process data, test logs and traceability.
For a company whose product is not electronics, all four are overhead. For a company whose product is electronics, the first two are core and only capacity is outsourced.
Where the cost actually comes from
Components. A plant that buys continuously has access to allocation and pricing a small buyer does not, and it can substitute an approved equivalent before the BOM is frozen.
Panel utilisation. Boards are priced as panel area, not board area. A supplier that fills panels across many customers pays less per board than one that runs a single design on a half-empty panel.
Process maturity. Yield is a cost line. A line that has run similar boards knows where the paste and profile need to be, which shows up as fewer reworks and fewer escapes.
Fixed cost. Four SMT lines and three DIP lines exist whether or not the customer's volume uses them. Outsourcing converts that fixed cost into a variable one.
Where the risk moves
Outsourcing does not remove risk; it relocates it. Three transfers matter:
- BOM ownership. On a turnkey order the supplier owns substitutions; on consignment the customer does. A "partial turnkey" line item without a written rule about who may substitute is where disputes start.
- Schedule coupling. A container, a customs hold or a Chinese New Year shutdown is now part of your lead time. Buffer stock, not urgency, is the mitigation.
- Change control. An engineering change after tooling has to be communicated and verified remotely. A written change procedure, with first-article approval per revision, is cheaper than a recall.
What to keep close
Final configuration, customer-specific firmware, JIT replenishment and service/repair stay near the customer. Products with export-control constraints need the classification checked before the data package leaves the company.
How to start without betting the product
- Send one board — ideally the hardest one — for a quotation and a DFM review.
- Build a small batch, review the first-article report and the test data, then release volume.
- Keep the second source qualified, even if it is never used.
Prototypes come back in 1–3 days and medium volume in 4–10 days, with a BOM quotation inside 24 hours, so the pilot does not have to wait for a volume decision. The order models are on the PCBA manufacturing page; the sourcing side is covered on the components sourcing page.
