To order PCB assembly, prepare Gerber files, a complete BOM, a CPL or pick-and-place file, assembly drawings, quantity, delivery target and test requirements before asking for a final quote. The assembly supplier then reviews the files, confirms component sourcing, checks manufacturability, builds the boards, inspects solder quality and ships the accepted PCBAs.
The order goes more smoothly when the buyer treats PCB assembly as a file-controlled manufacturing process, not as a simple online purchase. Missing polarity notes, substitute rules or test requirements can delay quotation and create risk during production.
What Ordering PCB Assembly Means
Ordering PCB assembly means asking a supplier to fabricate or receive bare PCBs, source or accept components, place parts, solder them, inspect the board and deliver finished PCBAs.
This can be a consigned order, where you provide components, or turnkey PCB assembly, where the supplier helps source parts.
Step 1: Decide the Assembly Scope
The first step is to define what the supplier is responsible for. Do not ask for a quote until the assembly boundary is clear.
Step 1: Decide whether the order is bare PCB plus assembly or assembly only.
Step 2: Decide whether parts are turnkey, consigned or mixed.
Step 3: Decide whether testing, programming, coating or packing is included.
Step 2: Prepare Gerber and Drill Files
Gerber and drill files tell the supplier how the bare PCB is made. Even for assembly-only orders, the assembler often needs board files to check pad layout, polarity marks and panelization.
If fabrication is included, connect the assembly order with PCB manufacturing requirements before production starts.
Step 3: Prepare a Complete BOM
The BOM is the parts list for the assembly order. A good BOM should tell the supplier exactly what to buy or place.
| BOM Field | Why It Matters | Buyer Check |
| Reference designator | Links each part to the PCB | Match schematic and CPL |
| MPN | Defines exact component | Avoid vague descriptions |
| Quantity | Controls sourcing and placement | Check per-board and order total |
| Package | Affects assembly process | Verify footprint fit |
| Substitute rule | Controls alternate parts | Approve before purchase |
Step 4: Prepare the CPL or Pick-and-Place File
The CPL tells the machine where each component goes and how it is rotated. A wrong CPL can create a visually organized but electrically wrong board.
Check X/Y coordinates, rotation, board origin, top/bottom side and reference designators before sending the file.
Step 5: Add Assembly Drawings and Polarity Notes
Assembly drawings reduce mistakes on connectors, LEDs, diodes, ICs, electrolytic capacitors and other directional parts. They are especially useful when silkscreen marks are crowded or unclear.
Use arrows, pin-one marks and notes in the drawing. Do not rely on the BOM alone to explain orientation.
Step 6: Confirm SMT, THT and Mixed Assembly Needs
Different assembly methods need different process planning. SMT assembly uses solder paste, placement and reflow. Through-hole parts may need manual, wave or selective soldering.
If the board has both SMT and THT, confirm the sequence before production so tall parts, connectors and thermal parts do not block later steps.
Step 7: Confirm BGA, QFN and Fine-Pitch Risks
BGA, QFN and fine-pitch packages require extra care because defects may be hidden or difficult to repair. If the board includes these parts, tell the supplier before quotation.
For BGA assembly, ask whether X-ray inspection is recommended and whether rework limits should be defined.
Step 8: Define Testing Requirements
Testing requirements should be defined before the order is placed, not after the boards are assembled. The supplier cannot design a useful test plan from “test if possible.”
| Test | Checks | Best Use |
| AOI | Visible placement and solder defects | Most SMT boards |
| X-ray | Hidden solder joints | BGA and QFN boards |
| Flying probe | Opens and shorts | Prototype or low volume |
| Functional test | Real powered behavior | Product-level acceptance |
Step 9: Review the Quote Before Approval
Before approving the quote, check what is included. A low quote may exclude testing, programming, substitute control, detailed reporting or special packing.
Compare assembly scope, component sourcing, test scope, lead time, repair policy and shipment terms.
Step 10: Approve First Article or Sample Build
For new products, a first article or sample build helps catch BOM, CPL, polarity and test issues before the full batch is assembled.
This step is useful for prototype PCB assembly and low volume PCB assembly because small mistakes are easier to fix early.
Step 11: Check Inspection Reports Before Shipment
Do not approve shipment only because the assembly is finished. Check whether the agreed inspection records are complete.
- AOI result or defect summary.
- X-ray result for hidden joints if required.
- Test result for ICT, flying probe or functional testing.
- Repair or rework record.
- Final quantity and packing confirmation.
Common Mistakes When Ordering PCB Assembly
Most order mistakes come from unclear files or late decisions. The supplier can build faster when the buyer gives stable data.
- Sending BOM without MPNs.
- Sending CPL with wrong rotation.
- Not defining substitute approval.
- Forgetting test requirements.
- Changing quantity after sourcing begins.
- Approving shipment without checking records.
FAQs About Ordering PCB Assembly
What files do I need to order PCB assembly?
You usually need Gerber files, BOM, CPL, assembly drawing, quantity, test requirements and delivery target.
Can I order PCB assembly without a CPL file?
It may be possible for simple boards, but a CPL greatly reduces placement and rotation risk.
What is turnkey PCB assembly?
Turnkey means the supplier helps source components, assemble boards and often manage inspection or testing.
What is the difference between SMT and THT assembly?
SMT places surface-mount parts; THT uses leads through holes and may need a different soldering process.
Should I send approved substitutes?
Yes. Approved substitutes avoid delays when a component is out of stock.
Do I need functional testing?
Use functional testing when powered product behavior matters before shipment.
How long does PCB assembly take?
Lead time depends on board quantity, component availability, test scope and process difficulty.
Can a supplier review my BOM before I order?
Yes. BOM review is one of the best ways to find sourcing and package risks early.
What should I check before paying?
Check scope, files, substitutes, inspection, testing, delivery and shipment terms.
Can QFPCB support small PCB assembly orders?
Yes. QFPCB supports prototype and low-volume assembly as well as larger production orders.
Send Your PCB Assembly Order Files
If you are ready to order PCB assembly, send Gerber files, BOM, CPL, assembly drawings, quantity and test requirements to [email protected]. QFPCB can review the files, confirm the assembly scope and quote the project before production.
