What Turnkey PCB Assembly Actually Includes

Turnkey PCB assembly is a contract manufacturing arrangement where the manufacturer handles all the procurement and production for printed circuit boards. The client supplies a design package that includes Gerber files, bill of materials (BOM), pick-and-place data, and assembly notes. The manufacturer is then responsible for sourcing the materials, assembling the circuit boards, inspecting them, and then shipping the finished product to the client.

Every supplier agrees on that definition. Where they stop agreeing is scope. Two quotes both labelled full turnkey can land thousands of dollars apart on the same BOM, because one covers the stencil, the first-article build, and the test fixture, and the other quotes those after you have committed. Turnkey tells you who buys the parts. It does not tell you how far the build goes.

So the question worth asking is not what turnkey PCB assembly means. It is which line items sit inside the number you were quoted, and which ones are still yours.

---

What a Turnkey PCB Assembly Quote Covers

Stage	What the supplier does	Included in the base quote?
Design data review	Checks Gerber files, BOM, and centroid data for buildability and flags DFM issues	Usually, free at RFQ
BOM scrub	Prices every line, flags EOL and single-source parts, proposes crosses	Yes
Bare board fabrication	Builds to your stackup in-house or through a managed fabrication partner	Yes
Component procurement	Buys all BOM lines, including overage	Yes
Incoming inspection and kitting	IQC, moisture-sensitive device handling, ESD control, reel prep	Yes
SMT	Stencil printing, pick and place, reflow	Yes
Through-hole	Wave, selective or hand soldering	Yes
Inspection	Visual and AOI as standard, X-ray where there are BGAs or bottom-terminated parts	Base level varies
Electrical test	Anything from continuity to full functional test	Varies, often quoted separately
Finishing	Depaneling, cleaning, conformal coating, potting, serialisation	Usually separate
Packing and export documentation	Anti-static packing, labeling, commercial invoice, certificate of conformance	Yes

---

Full Turnkey vs. Partial Turnkey vs. Consigned

These three manufacturing models differ based on who supplies the materials needed for the assembly.

Model	Components	Bare board	Material cash exposure	Best fit
Full turnkey	Supplier buys 100% of the BOM	Supplier	Supplier (recovered in unit price)	Most SMEs and startups without a procurement function
Partial turnkey	You supply named lines, supplier buys the rest	Usually the supplier	Split by line	Franchise pricing on specific parts, programmed or proprietary devices
Consigned (kitted)	You buy and ship a complete kit	You	You (upfront)	Established procurement teams with locked AVLs and existing stock

Full turnkey assembly is the right choice for most SME hardware programs, because the supplier (not the client) is liable for any issues with the materials or components. Let’s say a board fails because of a bad capacitor, the supplier will be the one responsible for replacing it. Under consignment, you supply the part and the assembler only guarantees their workmanship. So when a component fails, it can turn into an argument about which party is responsible for fixing the problem.

Partial turnkey assembly should only be an exception for certain lines on your BOM. It should not be the blanket model for the entire build. For example, you might choose to consign the FPGA you have a franchise agreement on or the microcontroller you pre-programmed. But consigning 400 passives to save on the markup could be a false economy if you end up spending more resources managing the kit than you save by outsourcing the assembly.

With consignment, you also take on all the costs related to attrition. Your assembler will end up consuming extra parts because of feeder leaders, mispicks, and rework. They’ll require some amount of overage to cover it. Cofactr puts the typical overage at around 10% of the part count listed on the BOM, with 10 to 20% added to parts cost on a prototype spin. So this can be a substantial amount. Small passives run even higher than that, while ICs and connectors run lower. But no matter what, if you only kit the exact quantities needed to put together each unit, the assembler will run out of parts before reaching the unit count you requested.

---

What the Turnkey Quote Does Not Include

The full expense of outsourcing to an assembler doesn’t always show up in the quote, because some line items are typically left off.

None of these costs are hidden, per se. But they usually won’t be listed in the price unless you specifically ask for them to be included.

Non-Recurring Engineering

At higher volumes, suppliers may absorb the non-recurring engineering (NRE) costs (e.g., stencils, programming, panel tooling, first-article build). But with a prototype or small order, these are more likely to be itemized as part of the quote.

Testing Procedures and Custom Fixtures

Running in-circuit testing requires a custom-built bed-of-nails fixture. This can be a fairly substantial expense. FixturFab puts the figure at $2,000 to $10,000+, depending on the complexity of the board.

Firmware and Programming

This includes loading images, provisioning keys, and end-of-line calibration. Each of these are labor steps that require a procedure and a golden unit.

Safety Certification

A supplier can help by building the boards according to the right standard or by providing you with submission support. But you’ll be ultimately responsible for the lab fees, sample builds, and the file. If you're considering UL, ETL, and CSA certification, budget that expense separately from the PCB assembly.

Post-Assembly Work

The steps that come after the board is built (e.g., enclosure tooling, cable harnesses, packaging design, and final assembly) are not typically included in the quote. Add these to the request for quotation (RFQ) as separate line items. That way, the supplier will have to either price them or write “N/A” so you’ll know exactly what will be included and what won’t.

---

What Is Still Your Liability Under a Full Turnkey Agreement?

Even with a turnkey arrangement, some decisions and responsibilities still fall in your court:

Approved Vendor List and Alternates

In the event of shortages, you will have the final say on which alternatives are acceptable. If your supplier has to wait for you to approve a new vendor or alternate parts, this can stretch out your timeline. To prevent this, specify which manufacturers are acceptable for each component ahead of production.

NCNR and MOQ Commitments

Some parts will have reel minimums, meaning you need to order a certain amount even if it exceeds what you actually need for your build. These minimums are considered non-cancellable and non-returnable (NCNR) lines and will get committed on your behalf. So ask whether these costs are included in the quoted unit price or if they will be added as a separate charge.

Excess and Obsolete Materials

Who owns and stores the extra materials left over at the end of production? Agree to this up front and specify what happens if the product is discontinued.

Engineering Changes

Changing your drawing is cheap at the design stage, but that changes once the materials have already been committed. If you issue an engineering change order (ECO) at that point, you’ll have to foot the cost for the inconvenience and the materials that were ordered but are no longer needed.

Production Volume

The pricing you get from a turnkey assembler is usually based on an assumed volume. If your production run is smaller than the supplier anticipated, your pricing will go up accordingly.

We recommend writing “no substitution of any BOM line without written approval” on your purchase order. This one sentence can help prevent the most common turnkey failures.

---

How Does the Assembler Source Your BOM?

Material Sourcing

Check whether your supplier sources materials through authorized distribution channels. It means the part came through a channel with a formal agreement with the component manufacturer. This comes with traceability and warranty. Otherwise, assume the material was sourced from the grey market or through a broker, and it won’t carry the same guarantees.

In a June 2026 position paper, the ECIA advised against procuring components from the grey market, especially for safety-critical applications.

A turnkey supplier should be able to tell you how they procured every material they use for your build. If they can’t, assume it’s not authorized distribution.

Material Availability

Availability is the other thing to consider, and it’s becoming tighter.

According to IBS Market Intelligence, in July 2026 the distribution inventory across 15 component categories dropped to 18% below their May 2025 levels. The average lead time for components also rose from 16.7 weeks in February 2026 to 20.6 weeks just a few months later, with semiconductors averaging 26.8 weeks. In total, 11 of the 15 categories were above the 12-week planning target.

The boards you ordered can only be shipped out to you after the assembler has received every single item on the BOM. So if your build includes a microcontroller with a long lead time, your PCBs can’t be assembled until that component arrives. This alone can set your entire schedule back, even if the assembler has a fast SMT line.

To minimize delays, give the assembler a list of pre-approved alternatives while you’re still at the RFQ stage. That way, you won’t have to scramble to get this done once a shortage hits. Treat any line item that comes back no-quote as a design decision you have to make.

---

What Does "Tested" Mean on a PCBA Quote?

On a PCB assembly quote, “tested” can refer to one of five testing methods:

Testing method	Catches	Doesn't catch	Typical application
Automated optical inspection (AOI)	Missing, skewed, tombstoned, or wrong-polarity parts, solder defects	Hidden joints, wrong component value	Every SMT build
X-ray	Voiding and opens under BGAs, QFNs, bottom-terminated parts	Functional faults	Boards with hidden joints
Flying probe	Shorts, opens, wrong values	System behavior	Prototypes, low volume, frequent revisions
In-circuit test	Same as flying probe, but far faster per board	System behavior	Stable designs at volume
Functional test	Whether the board does its job	Latent defects with no functional signature	Anything shipping to an end user

According to SPEA, the choice of test comes down to volume and stability: bed-of-nails fixtures suit mature designs at high volume, while flying probe testing is better suited for lower volumes and assemblies with frequent design changes. For most SME hardware, the testing method is a flying probe test (or no test) at the board level, with a functional test at the product level.

The acceptance class also determines which tests will be needed. The IPC-A-610 standard categorizes electronic assemblies into three classes:

Class 1 for general electronics where the product is mainly expected to function as intended.

Class 2 for dedicated service products that are expected to have extended life, but can fail occasionally without serious consequences (most industrial and commercial equipment falls under this class).

Class 3 for high-performance products where downtime can't be tolerated (Class 3 assemblies are costlier because they involve more inspection time and result in more scrap).

Name the acceptance class and the required testing in your RFQ. Otherwise, you’ll just end up with whatever the supplier’s default happens to be. Usually, it’s a Class 2 visual inspection plus AOI testing, but you won’t discover any testing gaps until a field return.

---

What Is the Difference Between Turnkey PCB Assembly and Box Build?

With a box build assembly, your supplier will handle more steps in the production. But with turnkey PCB assembly, you’ll need multiple vendors to complete your product unless you’re just commissioning a bare PCBA.

How different are these two manufacturing models? The best way to answer that is to count every step that still need to be done after you receive the boards. Obviously, there’s the enclosure and its tooling, cable harnesses, connectors, fasteners, and off-the-shelf hardware. Then the displays, seals, labels, and final assembly. Finally, product-level functional testing, certification samples, and packaging. Every single one of those steps might need to be outsourced to its own supplier, who each have their own individual lead times and quality systems.

Komaspec's project work follows this same box build pattern. For instance, we build mining IoT devices that integrate PCBAs, custom cables, and connectors into overmolded plastic housings that are rated to IPX7. The housing, cabling, and final assembly all run under one program, with the PCBA managed through our supply base.

A box build for an electromechanical product will include the PCBA as part of the overall program, so you won’t need a separate supplier to assemble it. And at the end of the day, if you're working with a turnkey supplier but are still managing five different vendors, you haven’t actually managed to consolidated your production.

---

Does Turnkey Assembly Change Your Country of Origin?

Sometimes. And this could be a bigger factor than it used to be.

US Customs and Border Protection (CBP) has ruled that populating and testing a PCBA can count as substantially transforming its components. So where the components were assembled could matter more than where they were sourced from. In their N324628 ruling, they found that components originating from China, including an LCD display, were substantially transformed by the PCBA manufacturing performed in Mexico.

The Office of the United States Trade Representative (USTR) extended 178 Section 301 exclusions on goods originating from China, but only until November 10, 2026. So if your PCBA is built is China and currently exempt, you should assume that the duty will be back in force by 2027.

There’s a chance the country where your PCB is built becomes its official country of origin. That’s why you should select your build location at the design stage. It’s also one of the benefits of working with a supplier that can build in more than one country.

For example, Komaspec operates six facilities across Guangzhou, Haiphong, and Ciudad Juárez. That gives us the flexibility to quote the same project against different tariff and transit profiles. This gives you a clear picture of the trade-offs of choosing to manufacture in China versus Vietnam and why it’s not just about picking the country with the cheapest labor.

But remember that the product’s origins are fact-specific, so confirm any real exposure with a customs broker or a binding CBP ruling rather than relying on the supplier's advice and assurances.

---

What to Put in the RFQ

Ask every supplier to price (or explicitly decline) each of these items:

1. The sourcing model used for each BOM line (turnkey, consigned, or partial).
2. Which sourcing channel was used for each line, with traceability documentation.
3. Non-recurring engineering costs (NRE), broken out into separate line items (i.e., stencil, programming, panel tooling, first article).
4. The IPC-A-610 acceptance class.
5. The testing scope (e.g., AOI, X-ray coverage), electrical test method, and who will be writing the functional test spec.
6. The attrition and overage rules by package size.
7. NCNR and MOQ exposures, and who owns the excess material at end of life.
8. A written substitution policy.
9. Country of origin and the HTS classification the supplier will declare.

The responses you get to these questions will vary, but any good supplier will provide you clear answers without hedging. Be wary of any vendor that doesn’t.

---

---

FAQs

What does turnkey PCB assembly cost?

It depends on your product design and how many units you order. Turnkey pricing includes the cost of components, board fabrication, machine and labor time, testing, along with any NRE. The price is mainly based on the number of components involved, package types, panel utilization, and test scope. Your desired production volume also makes a difference, because the NRE and setup costs amortize across the run. Because of that, the per-unit price drops sharply when you move from a prototype to production quantities.

Is there a minimum order quantity for turnkey PCB assembly?

There is, but it varies by supplier. The main constraint is usually the minimums for components (not for complete assemblies). Passives that are sold in full reels and non-cancellable line items can lead you to pay for a lot more material than are strictly needed for your PCBs. Ask about the minimum buy for each line on your BOM, because some components can have high minimums even if you’re only ordering a small quantity of boards.

What files does a turnkey PCBA quote need?

Supply the vendor with Gerber files or ODB++, a BOM with manufacturer part numbers and approved alternates, centroid or pick-and-place data, assembly drawings, and build notes with acceptance class and testing requirements. All the files you provide should be at the same revision. Submitting an incomplete package is the most common reason for quotes stalling.

Who owns the leftover components after a turnkey build?

This will be specified in the contract. Because of reel minimums and buffer stock, expect there to be residual materials after production is done. And make sure you know exactly who will be responsible for them. Reach a clear agreement with your vendor about ownership, storage, and disposition of excess materials before the first purchase order is sent out.

How long does turnkey PCB assembly take?

The assembly schedule is set around the component with the longest lead time. In mid-2026, the average component lead time was 20.6 weeks, with semiconductors nearing 27 weeks. The assembly itself typically only takes days or a few weeks once all the parts have been kitted.