Getting ten boards assembled without promising ten thousand

You need ten assembled circuit boards. The manufacturers you have approached want to discuss annual production volumes. Those volumes depend on testing the boards you are trying to order.

Separate the two jobs. Ask for the prototype batch to be priced on its own, including the setup and engineering work. Where that does not suit the manufacturer, use a service set up for small orders.

There are plenty of ways to get a small batch made. The less obvious part is choosing a supplier whose process fits the product. Two companies can both say they can build it while proposing quite different jobs.

There are companies that want your ten boards

PCBWay and JLCPCB offer both PCB fabrication and component assembly through online ordering. These are not just services for buying bare boards and soldering everything yourself. PCBWay lists an assembly minimum as low as five boards; JLCPCB lists quantities starting at two. Those are published capabilities, not a promise to accept every design.

Specialist prototype assemblers are another route. Screaming Circuits, for example, accepts single prototypes and offers a custom-quote route for more involved work. A small order does not always require persuading a production manufacturer to make an exception.

Ask the designer who they normally use, too. An established relationship is worth investigating when someone needs to answer questions during the build. Agree whether the designer will manage that work or simply supply the files.

Be clear about whether you are buying assembly of a checked design or paying for help getting the design ready. Compare an online assembly quote with a separately priced engineering service where necessary, rather than assuming either includes the other.

Please quote ten prototypes as a standalone job, including setup and the engineering work required. Production quantities are not established yet.

That is a perfectly reasonable enquiry. A manufacturer may decline or quote a price that makes the small job worthwhile. Neither outcome calls for a more imaginative sales forecast.

Find out what is normal work for that factory

A capability list tells you what a supplier can do. It does not fully explain how your order will run through the factory. Ask which operations are routine and which need a different machine, manual handling, special tooling or a subcontractor.

For an illustrative example, suppose one factory's economical line accepts assembly panels up to 200 x 200 mm and another's accepts 300 x 300 mm. A panel just beyond the first limit could require a different production route there while being routine at the second. Those dimensions are examples, not specifications for the suppliers named here.

Establish whether a quoted limit applies to an individual board or a panel containing several boards, and which stage of production it concerns. JLCPCB's published limits distinguish single boards from panels. Its Economic and Standard assembly services also differ in matters such as placement on one or both sides and supported layer stack-ups. They are not simply two prices for an identical process.

The production route can change before you reach an absolute machine limit. Eurocircuits distinguishes pooled orders, which share a production panel, from non-pooled jobs using a dedicated panel. Its ordering system flags options that take a design out of pooling. A specification that looks minor on the drawing can therefore change how the order is priced.

Which parts of this design take it outside your standard process? Would a small change bring it back?

Ask while the outline, component layout and enclosure can still be changed. Have the designer assess any proposed alteration, including the cost of checking it. Saving on manufacture is not worthwhile if the change compromises the product or costs more to validate than it saves.

Follow the job through the enclosure

If the order is for complete units, do not stop the discussion at the assembled board. Establish who supplies the enclosure, machines the openings, applies paint or printed overlays, and checks the result before the electronics are fitted.

Ask whether the assembler already works with your chosen enclosure manufacturer, and what that actually buys you: an existing purchasing arrangement, familiarity with the part, prepared machining instructions or experience assembling a similar product. A familiar brand name is not evidence that your modified enclosure has already been understood.

The enclosure manufacturer may be able to perform the modifications directly. OKW, for example, describes in-house machining, painting and printing, as well as printed adhesive decorative foils and their application. That is worth investigating before asking another company to organise the same operations.

Where work is outsourced, identify the handovers. Who sends the parts? Does the subcontractor have a minimum charge? Who handles rejected finishes? Whose delivery date includes the external work? Outsourcing can be entirely sensible. The problem is an unpriced or unowned step between the quote and the finished unit.

An equipment list is not a test plan

Ask what testing your batch needs and who will do it. Board inspection, checking electrical connections, loading firmware, functional testing and temperature cycling answer different questions. Do not treat a supplier's general testing capability as confirmation that your order includes all of them.

For temperature cycling, specify the product configuration, temperature range, rate of change, dwell time and measurements to record. Chamber specifications vary; ESPEC's published range, for example, distinguishes chamber performance and options for controlling a test from product temperature. Ask whether the supplier's equipment and available engineering support fit the test you need.

An external laboratory may be the appropriate route. For ten early prototypes, in-house power-up and investigation by your own engineer may also be appropriate. Make the division explicit, including who investigates a failed unit. Do not remove testing from the budget merely because it will happen after delivery.

You can split the component sourcing

You can supply parts, have the assembler buy them, or divide the responsibility. PCBWay explicitly offers mixed sourcing. If you already have a specialised sensor, ask whether you can supply it and leave the remaining components to the assembler.

Check packing requirements, extra quantities and unused-stock arrangements before sending components. PCBWay requests additional parts for handling and assembly losses, and says unused components are not returned by default. Arrange their return or retention explicitly.

List approved alternatives and require approval for anything else. Keep the designer involved through order approval. JLCPCB's component-matching instructions explain that parts not selected in the ordering interface can be left off the boards. Uploading a complete parts list does not establish that the final assembly order includes every component.

The same Gerbers still need a new-supplier check

Using one supplier for prototypes and another for production can make sense. Treat the move as a manufacturing handover, not simply a repeat purchase. The design may be unchanged while the supplier's data preparation, panelisation and assembly process change.

Internal-plane polarity is one example. Copper artwork can be represented positively or negatively; a mismatch in export or interpretation can invert the intended layer. OSH Park documents this problem and requires positive Gerbers for all copper layers. A ground plane coming back inverted is a data-preparation error to prevent, not a normal difference between factories to accept.

Have the designer confirm the new fabricator's accepted outputs, layer order and stack-up. Ask for processed layer plots or manufacturing data where available, rather than reviewing only the original export again. Eurocircuits provides access to the CAM-verified files used to produce and test its boards. Keep approved changes and resolved manufacturing questions with the design release.

Also supply an IPC-D-356A netlist exported from the PCB design, where the fabricator supports it. This gives an independent record of the intended connections to compare with the manufacturing artwork. Westak explains both the comparison and the limitation of testing against a netlist derived only from the Gerbers: an interpretation error can end up in the board and its test data. Ask what the bare-board electrical test is checked against.

Agree how the new supplier's first output will be validated before increasing volume. Keep the native design, released manufacturing files, parts list, placement data, assembly notes and test instructions together. If paid preparation work produces fixtures or revised files, agree ownership and access before commissioning it.

Compare the complete job

Give suppliers the same revision and ask them to separate one-off preparation, boards, components, assembly, programming, testing, enclosure work and delivery. Add the work left with your team, including any supplier-transfer checks. A cheaper board quote may still leave a more expensive product to finish.

Confirm when the clock starts. PCBWay states that assembly turnaround begins once the parts and required information are ready. Ask for the expected dispatch date, the unresolved items that could move it, and delivery time separately.

Whether on a factory visit or in a short technical call, ask the supplier to walk through your actual build. These are useful questions to send with the enquiry:

• What takes this job outside your normal process, and would a small change help?
• Which operations happen here and which go elsewhere?
• Who sources the parts and approves substitutions?
• Which programming and tests are included, and what happens to failures?
• What changes between this prototype batch and the next production quantity?

For a first engineering batch, a straightforward assembly service may be all that is needed. For complete units going into a customer trial, someone may need to coordinate considerably more. Buy that work explicitly.

Not all fabs, assemblers or full-product manufacturers are set up for the same job. The useful comparison is how each proposes to make your product, not just whether its capability list says it can. Find a process that fits the batch you need now, and understand what must change before ordering the next one.