Turnkey vs Consignment PCB Assembly: Which Model Fits?

Full turnkey means the assembler handles everything: purchasing every component on the bill of materials, fabricating or buying the bare boards, assembling, testing and shipping finished boards. You provide the design data and approve the build, and the assembler carries the sourcing work.

Consignment, also called kitted assembly, reverses that. You or your own buyers procure the parts and boards, send a kit to the assembler, and pay for the build labour. Partial turnkey sits between the two: the assembler buys most parts, while you supply selected items such as a scarce microcontroller, a costly module or customer-owned stock.

In turnkey, the assembler's purchasing team sources through distributors and, for hard-to-find parts, sometimes the open market. That is convenient, but state your sourcing rules in the quote request, such as authorised channels only, so that a shortage is not solved with a risky substitute.

In consignment you carry the inventory risk. If a kit is short of a part, the line waits, and you must plan extra quantity for small parts that are lost or damaged on the machine. Lead time shifts as well: turnkey lead time includes purchasing, while consignment lead time depends on how quickly you can assemble a complete kit.

Counterfeit and mislabelled parts are most likely in the open market during shortages. Whichever model you choose, insist on traceability, such as supplier invoices and lot or date codes, and avoid buying critical parts from unknown brokers. Consignment gives you direct control over provenance, but only if you exercise it.

Prototype runs are dominated by setup: stencils, programming, line changeover and engineering time. A turnkey assembler may be bound by minimum order quantities and reel or tube sizes, so a small build can require buying many more parts than you use. Consignment can avoid that waste if you can buy cut tape or small quantities yourself.

At volume, turnkey tends to benefit from the assembler's purchasing leverage, consolidated freight and managed buffer stock, and it saves your own team's time. Consignment can still win where you hold negotiated pricing on key parts or where customers supply parts by contract. Compare total landed cost, including your own purchasing effort, rather than the assembly line price alone.

The table below summarises the practical differences. Real quotes vary by assembler and by project, so treat it as a checklist of questions rather than a ranking.

A bill of materials is only buildable if each line identifies a part unambiguously. Give a manufacturer name and manufacturer part number, reference designators, quantity, value and package, and avoid generic lines such as a 10k resistor with no tolerance or footprint.

State approved alternates where substitution is acceptable, and mark lines where it is not. Check lifecycle status before release, because parts marked not recommended for new designs, last-time-buy or obsolete cause trouble in both turnkey purchasing and kit shortages. Cleaning up the BOM early prevents most quote delays and engineering queries.

Assemblers typically need a consistent data package. Mismatches between the BOM, the centroid file and the silkscreen are a common cause of queries and delays, so run a final cross-check before sending the pack.

Automated optical inspection (AOI) uses cameras to check part presence, polarity and solder joint appearance. X-ray inspection looks beneath components, which matters for BGAs and other packages with hidden joints that AOI cannot see. Neither one proves the board works.

For electrical test, in-circuit test (ICT) uses a bed-of-nails fixture for fast, thorough checks on volume runs, but the fixture takes time and money to build. Flying probe test moves probes to test points without a custom fixture, which suits prototypes and low volume, though it is slower per board. Functional test powers the board and exercises it like the product would, and it often needs a purpose-built jig and firmware, so define it early.

Box build extends assembly to the finished product: boards, cables, enclosure, labelling, packaging and final test. Decide early who sources the mechanical parts and harnesses, because box build adds more items to the bill of materials and more places for shortages.

The right model usually changes as the project matures. Use these as starting points rather than rules.

Hire PCB Designer provides turnkey manufacturing support: sourcing and coordination, test planning, global supply chain routing and functional testing. Because the same team designs the board, the BOM, alternates and test points can be prepared with assembly in mind.

We coordinate with our fabrication center in Bangladesh and the wider global supply chain, and we recommend the assembly model that suits your project stage and risk tolerance. Send your requirements through the contact form and we will review them with you.