Short answer: Under turnkey PCB assembly your EMS buys every component on the BOM and delivers finished boards; under consignment you buy and ship the parts and the factory only assembles them. Turnkey moves shortage, counterfeit and cash-flow risk onto the supplier; consignment keeps control — and the cost of being wrong — with you.
Most buyers pick a model by reflex: startups go turnkey because they have no purchasing team, established OEMs go consignment because they already have distributor contracts. Both reflexes are defensible and both are frequently wrong for a specific build. This article goes past the headline definitions into the operational detail that actually decides which model works: how a BOM gets split under partial turnkey, what happens to your parts when they land at the factory, who eats the cost when a reel comes up short, and where the leftovers go when the run finishes. Our PCBA cost breakdown for China manufacturing compares the two models from the pricing side; this one is written from the shop floor.
What is turnkey PCB assembly?
Turnkey means the manufacturer takes the whole job: bare board fabrication, component procurement, assembly, inspection and test, and often box-build. You supply design data — Gerber or ODB++, a structured BOM, pick-and-place data — and receive tested assemblies. One purchase order, one supplier, one line of accountability.
The commercial consequence people miss is that turnkey converts a procurement problem into a schedule commitment. When the EMS owns the BOM, it also owns every lead-time surprise in it. At BELI Technologies, component sourcing runs through authorized distributors and original manufacturers, with standard parts typically available in 3 to 7 days and spot-market reach for hard-to-find or end-of-life items. A turnkey order including sourcing typically takes 2 to 3 weeks in total — that figure exists because procurement, not placement, is the long pole.
What is consignment PCB assembly?
Consignment — sometimes called "customer-supplied material" or CSM — means you buy the components yourself and ship them to the factory, which quotes and invoices assembly labour only. The factory receives, verifies, kits and places your parts.
Consignment is not simply "turnkey minus the parts cost". It changes what the factory can promise. Quick-turn assembly becomes possible — quick-turn prototype assembly at BELI takes 48 hours once boards and components are on site, with no MOQ — but the clock only starts when the last reel arrives. Any date you are given is conditional on your own kit being complete and correct.
Turnkey vs consignment across five dimensions
| Dimension | Turnkey (EMS buys) | Consignment (you buy) |
|---|---|---|
| Who buys the material | EMS purchasing team, against your approved BOM and any locked AVL | You, through your own distributor accounts or existing contracts |
| Who carries shortage risk | EMS. A part on allocation is the supplier's problem to solve, by alternate sourcing or spot market, before it becomes your delay | You. A single missing line item holds the whole kit; the line is scheduled around your delivery, not the other way round |
| Who carries counterfeit risk | EMS, through channel choice — authorized distributors and original manufacturers, with traceability and original packaging preserved | You. Factory receiving checks can screen part of it, but the sourcing decision and its consequences were yours |
| Cash flow | One invoice, later in the cycle; material cost is bundled into the build | You fund components up front, sometimes months before the boards are built, and hold that inventory on your balance sheet |
| Lead time | Typically 2–3 weeks including sourcing; the EMS absorbs procurement variance | 48-hour quick-turn assembly once parts and boards are on site — but total time is your procurement time plus freight plus 48 hours |
The last row is where most schedule disputes originate. A consignment quote showing "48 hours" and a turnkey quote showing "2–3 weeks" describe different clocks, not different factory speeds. Compare door-to-door dates, measured from the day you issue the PO, or you will conclude that consignment is five times faster than it is.
Partial turnkey: how a BOM actually gets split
In practice, most mature programmes run neither pure model. They run partial turnkey, where the BOM is divided line by line. BELI supports turnkey and consignment with no fixed ratio between them, which means the split can follow engineering logic rather than a contractual minimum.
The split that works is usually by risk class, not by cost:
- Customer-supplied: parts you already hold stock of; parts under a negotiated corporate contract you cannot beat locally; qualified single-source ICs where the vendor relationship carries firmware, NDA or allocation privileges; anything safety- or certification-critical where you refuse to delegate the sourcing decision.
- Factory-supplied: passives, connectors, discretes and commodity logic where the local supply chain is faster and cheaper than air-freighting reels from your side of the world; parts with volatile availability where you want the EMS chasing alternates; anything where the reel minimum buy vastly exceeds your build quantity.
Two administrative points make or break a split BOM. First, the split must be a column in the BOM file itself — a "supplied by" field on every line, agreed before quoting, not an email thread. Our guide to the files required for a PCBA quotation covers the rest of the BOM structure that a factory needs. Second, the shortage rule must be written down for both halves: what happens if a customer-supplied line is late, and what happens if a factory-supplied line goes on allocation. A split BOM without an agreed shortage rule is the single most common source of blame arguments in contract manufacturing.
What happens to your parts when they arrive at the factory
Consigned material should not bypass receiving control, and the receiving process is worth settling in writing before your kit ships rather than after a discrepancy appears. For the material BELI buys under turnkey, incoming components go through 100% visual inspection plus X-ray sampling, with traceability records maintained through the supply chain and original packaging preserved. If you are consigning, ask which of those checks will be applied to your kit, who signs off the count, and what happens when something fails — and get the answer attached to the quote, not to a later email.
The checklist below is what to agree with any assembler before a consignment kit leaves your building. Treat the right-hand column as what to ask for in writing rather than as a default that comes with every order:
| Check | What it catches | What you should receive |
|---|---|---|
| Quantity count against the kit list | Short shipments, miscounted cut tape, missing line items | A discrepancy report before the line is scheduled, not after |
| Part number and marking verification | Wrong package variant, wrong tolerance or temperature grade, mislabelled bags | Confirmation against the MPN on your BOM line, not just the description |
| Visual inspection | Damaged leads, resurfaced or re-marked parts, bent tape, contaminated reels | Photographs of anything rejected |
| X-ray sampling | Internal die and bond-wire anomalies in suspect ICs — the classic counterfeit signature | Sample images on request for high-value or broker-sourced lines |
| Moisture-sensitive device handling | Broken dry-pack seals, missing or expired humidity indicator cards, unbaked MSL 3+ parts | Confirmation of baking before reflow, or a documented exception |
| Packaging format for the line | Loose parts and cut strips that cannot be machine-fed and force hand placement | A note on which lines will be placed manually, and the cost implication |
Packaging deserves emphasis because it silently destroys consignment savings. Reels and full tape feed a pick-and-place head. Loose parts in a bag do not. If you save on unit price by buying cut tape and tubes, some of that saving comes back as manual placement labour and slower throughput — and hand-placed fine-pitch parts do not carry the same process confidence as machine placement.
Attrition: why your kit needs more parts than your build quantity
Every SMT process loses a small number of parts to feeder setup, first-article verification, misplacements caught by inspection, and rework. That loss is called attrition, and under turnkey the factory absorbs it inside its own material planning. Under consignment it is your problem, and it is the most common reason a consignment run stops one board short of the order quantity.
Agree an attrition allowance per line before you ship, and expect it to be higher in percentage terms on tiny quantities and on small passives — a 0201 chip capacitor has a far higher setup loss rate than a 64-pin QFP, and a 20-board prototype run cannot amortise feeder setup over anything. High-value single-source ICs are usually treated separately, with a small fixed spare count rather than a percentage. Whatever numbers you land on, put them in the kit list so the incoming count either passes or generates a shortage notice on day one.
Who is responsible when a part is missing or defective?
This is the clause that matters and the one most often left vague. The workable principle is that responsibility follows the sourcing decision.
| Scenario | Turnkey | Consignment |
|---|---|---|
| Part goes on allocation before the build | EMS sources an alternate or spot-market supply and reports the schedule impact | Your problem; the build slot is held or released per the agreed rule |
| Kit arrives short of the build quantity | Not applicable — the EMS planned the quantity | Partial build, or hold, at your instruction; both usually carry a re-setup cost |
| Part is counterfeit or out of spec | EMS liability; channel choice and incoming inspection were the supplier's controls | Your liability, unless factory inspection should reasonably have caught it and did not |
| Part damaged in factory handling | EMS replaces it | EMS replaces or reimburses at your documented purchase cost — agree the basis in advance |
| Board fails because of a soldering defect | The assembler's to correct — soldering is its process; put the rework terms in the contract | Same — process defects belong to the factory regardless of who bought the part |
| Board fails because the specified part was wrong | Depends on who chose the alternate; a written approval trail settles it | Yours — the factory placed what your BOM specified |
Note the asymmetry in the counterfeit row. Consignment does not transfer the inspection duty away from the factory, but it does transfer the sourcing judgement to you. If you buy from a broker to beat a 40-week lead time, factory inspection is a safety net, not an indemnity.
Where does the leftover material go?
Excess is guaranteed under consignment, because reels and MPQs rarely divide neatly into build quantities. Decide the disposition before the run, and put it in the purchase order:
- Return with the shipment. Cleanest for prototype and one-off builds. Ask for excess to be returned in original packaging with a reconciliation sheet showing issued, consumed, scrapped and returned quantities per line.
- Hold as bonded stock for the next run. Sensible for repeat programmes. Agree in writing that the material remains your property, how long it will be held, and under what storage conditions — MSD parts in particular have a shelf life once the dry pack is opened.
- Scrap on your authority. For cheap passives where return freight exceeds the value. It should still appear on the reconciliation, never disappear quietly.
The document to insist on either way is that material reconciliation. It is the only thing that lets you close the loop between what you paid for, what went onto boards, and what you still own. Without it, consignment inventory quietly leaks and the loss surfaces two builds later as an unexplained shortage.
Which model should you choose?
| Your situation | Better model | Why |
|---|---|---|
| First prototype build, no purchasing function | Turnkey | Nobody on a three-person hardware team should be spending a week reconciling distributor stock levels |
| You already hold stock bought for a cancelled run | Consignment | The material is sunk cost; paying twice for it makes no sense |
| Corporate contract pricing on key ICs | Partial turnkey | Consign the contracted lines, let the factory buy the commodity passives locally |
| Schedule is the binding constraint | Turnkey | One party owns the critical path and can act on allocation news the day it breaks |
| Certification-critical BOM under strict change control | Partial turnkey with a locked AVL | Keeps sourcing authority over safety- and EMC-relevant parts with you, without hand-managing every resistor |
| Long-lead or allocated parts on the BOM | Turnkey, or consign only that line | Whoever has the better channel access for that specific part should buy it — decide line by line, not globally |
| Cash is tight and revenue comes after shipment | Turnkey | Avoids funding a full BOM months before the boards exist |
| Repeat volume production, mature stable BOM | Either — model the total cost | At volume the deciding factors are working capital, inventory carrying cost and who genuinely buys better |
One more consideration for scaling teams: whichever model you start with, staying with a factory that supports both means you can change your mind without changing supplier. Moving a programme between factories to switch commercial models means requalifying the process — a bad trade, as our guide to EVT, DVT and PVT build stages explains.
Does turnkey really cost more?
Turnkey quotes look higher because they contain the BOM. Whether they are more expensive is a different question, and one you can only answer by comparing like with like: your landed component cost plus your procurement labour plus inbound freight plus inventory carrying cost, against the factory's material line.
The honest generalisation is that a well-connected Shenzhen EMS often buys commodity passives, connectors and standard logic more cheaply than an overseas customer buying in prototype quantities, while a large OEM with corporate contracts usually buys its key ICs more cheaply than any factory can. That is precisely why partial turnkey exists. A BOM review that flags availability, lifecycle status and qualified alternates before the quote is the tool for this decision — our guide to cutting BOM costs without cutting corners shows what that kind of review can surface.
What to send for a quote under each model
The design package is the same either way — Gerber or ODB++, structured BOM, pick-and-place data. What differs is the commercial detail attached to it:
- Turnkey: BOM with manufacturer part numbers on every line, approved alternates flagged, no-substitute lines marked explicitly, and target build quantity plus any forecast that would change price tiers.
- Consignment: the same BOM plus a kit list stating packaging format per line, the attrition allowance you are supplying, expected arrival date, and the disposition rule for excess.
- Partial turnkey: both, with a "supplied by" column filled in on every single line — no blanks, because a blank is where an assumption grows.
Under either model, expect AOI and X-ray inspection with ICT or functional test as the quality baseline; BELI keeps first-pass yield at or above 99.5%, and its manufacturing is certified to ISO 9001:2015, ISO 14001 and ISO 13485:2016. Quality process does not change with who bought the parts, and it should not.
Work with a factory that supports both
BELI Technologies runs turnkey and consignment PCB assembly with no fixed ratio between them, so you can hand over the full BOM, ship us a complete kit, or split it line by line and change the split between builds. There is no MOQ for prototypes, quick-turn prototype assembly takes 48 hours once boards and parts are on site, and turnkey orders including sourcing typically run 2 to 3 weeks. If you are not sure which model suits your build, send us your BOM and design files — we quote from them and review the BOM for availability, lifecycle and alternates, which is usually enough to show which lines are worth consigning and which are quicker to buy here. Small-batch work is covered in more detail in our low-MOQ and small-batch PCB assembly guide.
Related reading: How Much Does PCBA Cost in China · What Files Are Required for PCBA Quotation · Key Questions to Ask Before Outsourcing PCBA