When you place a board with a China electronics manufacturing services (EMS) provider, one decision shapes cost, lead time and risk more than any other: who buys the components. In a turnkey model the EMS procures the entire bill of materials and delivers finished, tested boards. In a consignment model you supply some or all of the parts and the EMS only assembles them. Most real programs land somewhere in between — partial consignment, where you provide a handful of critical parts and the factory buys the rest. There is no universally cheaper option; the right model depends on your volume, how much of your BOM is price-sensitive or allocated, and whether you can source key parts as reliably as the factory can.
What is a turnkey component supply model?
Turnkey means the EMS owns the whole job end to end — it reads your bill of materials, buys every component, stocks the line, assembles, tests and ships. You hand over design files and a Gerber package; you get back working product. For most buyers this is the default, and for good reason: a single party is accountable for the result, you place one purchase order instead of dozens, and you avoid the customs, freight and warehousing overhead of moving parts to the factory yourself.
The trade-off is margin and visibility. The factory marks up the parts it buys, sometimes modestly on commodity passives and more noticeably on high-value ICs. You also see less of the supply chain: unless your contract requires it, you may not know which distributor a given chip came from. That matters most for the components where authenticity and allocation are real risks. A turnkey quote should always be broken out so you can see assembly cost separately from material cost, rather than a single bundled figure that hides where the money goes.
Turnkey also shifts inventory carrying onto the factory rather than your balance sheet. Because the EMS buys parts against your order, you are not the one financing reels of components that sit on a shelf waiting for a build slot — a real advantage for cash flow on longer programs. The flip side is that any price movement, shortage premium or minimum-order-quantity overhang on a specialised part flows back to you through the next quote, so on a turnkey relationship it pays to review the itemised material cost each run rather than assuming last quarter's pricing still holds.
What is consignment — and partial consignment?
Under full consignment, you buy every component yourself and ship it to the EMS as a kit; the factory charges only for assembly and test. You keep complete control of sourcing and pay no parts markup, but you also take on procurement, kitting, freight, import handling and — critically — the risk that a part you supplied is defective, counterfeit or short. If your kit arrives incomplete, the line stops and the delay is your problem, not the factory's.
In practice, partial consignment is far more common. Here you supply only the components you most need to control — typically long-lead MCUs, allocated power-management ICs, customer-specified or security parts — while the EMS buys everything else turnkey. This isolates your risk to a short list rather than the whole BOM, and it is the model most experienced buyers reach for. It does require tight coordination: the factory needs to know exactly which line items are consigned, when they will arrive, and who covers attrition if a reel runs short during placement.
Turnkey vs consignment: which one costs less?
The honest answer is that neither is automatically cheaper, and a quote that looks lower can cost more once hidden work is counted. Turnkey carries a parts markup but bundles in procurement labour, supplier management, customs handling and inventory carrying — real costs you would otherwise pay yourself. Consignment removes the markup but loads those costs back onto your team, plus the freight and import duty of shipping parts into China and the capital tied up in inventory you bought ahead of the run.
Consignment tends to win when you already buy a price-sensitive component in large volume and can secure pricing the factory cannot match, or when a part is on allocation and your existing supplier relationship gets you stock the EMS cannot. Turnkey tends to win on lower volumes, on builds where your BOM is mostly commodity parts, and whenever your own procurement overhead would swamp any markup you save. Before you assume consignment is the frugal choice, map every cost it adds — many of these are the same line items covered in our guide to the hidden costs of sourcing from China.
Who carries the risk in each model?
Risk follows ownership of the parts. Under turnkey, the EMS sourced the components, so component-level defects — wrong part, out-of-spec, counterfeit — are largely the factory's responsibility to resolve, and a good contract makes that explicit. Under consignment, you supplied the parts, so you generally own that risk: if a consigned IC turns out to be a remarked counterfeit, the factory assembled it in good faith and the loss is yours.
This is the strongest argument for buying consigned parts only through authorized channels with full traceability. Counterfeit and recycled components remain a genuine hazard in open-market electronics sourcing, and the protection is documentation: date and lot codes, certificates of conformance, and an unbroken paper trail back to the manufacturer or its franchised distributor. Industry counterfeit-mitigation standards such as SAE AS6081 exist precisely because independent-market parts carry this exposure. If you consign, treat traceability as non-negotiable rather than a nice-to-have.
How to de-risk either model
Whichever model you choose, the same discipline protects you. Get the quote itemised so material and assembly cost are visible separately. Specify approved manufacturer part numbers and name the distributors you will accept, so neither you nor the factory substitutes an unknown source under shortage pressure. Require traceability documentation on the components that matter, and align your payment milestones with delivery and acceptance rather than paying everything up front — the structures buyers use here are covered in our guide to payment terms with China factories.
Sourcing the parts themselves through an authorized distributor closes most of the gap between the two models. Working with an authorized IC distributor such as Huihexin Technology in Shenzhen gives you franchised-channel MCUs, power-management ICs, sensors and RF components with traceability and FAE support — which means whether you consign those parts or have your EMS buy them turnkey, they enter the build with a verifiable origin. For a wider view of how component supply, board assembly and final integration fit together in the region, our Shenzhen electronics manufacturing sourcing guide maps the full landscape.
Which model should you choose?
Start turnkey unless you have a specific reason not to. For a first production run, a low-to-moderate volume, or a BOM dominated by commodity parts, turnkey gives you one accountable partner and the least operational burden — and that simplicity is usually worth the markup. Move to partial consignment when one or two components dominate your cost or risk: a part you buy cheaper at volume, an allocated chip your relationship secures, or a security or customer-mandated component you must control. Reserve full consignment for high-volume, mature programs where your procurement function is strong enough to beat the factory on price across the whole BOM and absorb the logistics. The decision is rarely permanent — many programs start turnkey, then consign individual parts as volume and supply-chain knowledge grow. Whichever way you lean, write the model into the manufacturing agreement explicitly, line item by line item, so there is no ambiguity about who buys, who stocks attrition, and who answers for a part that fails incoming inspection.
Frequently asked questions
Is turnkey or consignment cheaper for a China EMS build? Neither automatically. Turnkey bundles a parts markup but saves procurement labour and customs handling; consignment removes the markup but adds your own buying cost, freight and inventory risk. The cheaper model depends on volume, how price-sensitive your BOM is, and whether you can buy key parts as well as the EMS can.
What is partial consignment? You supply a few specific components — usually long-lead, allocated or customer-specified parts — while the EMS buys everything else turnkey. It isolates the parts you most need to control without forcing you to procure the whole bill of materials, which is why it is the most common real-world model.
Who is responsible for component defects under consignment? Generally the buyer, because the EMS did not source the consigned parts. That is why buyers using consignment should procure through authorized channels and require traceability documentation on every critical line item.
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