PCB assembly (PCBA) is the process of attaching electronic components—such as resistors, capacitors, ICs, and connectors—onto a bare PCB. This process transforms a blank board into a fully functioning electronic circuit.
PCB assembly uses two main technologies:
Depending on the application, your board may require SMT, THT, or a hybrid assembly process.
Before any physical work begins, the assembly team reviews all supplied documentation to ensure clarity and manufacturability. Key files include:
Sample PCBA BOM
At OnBoard Circuits, we offer free DFM (Design for Manufacturing) checks to catch issues like:
Pro Tip: PCBs can be designed using an array of PCB design software such as KiCad, Altium or CircuitMaker, among many other options.Submit your files early. Pre-production review can prevent delays and costly board respins.
For SMT assembly, a metal stencil is used to apply solder paste (a mix of solder alloy and flux) onto each pad where a component will be mounted.
Common solder paste types include:
Pro Tip: Ensure your stencil is designed with the right thickness (usually 4–6 mils) and aperture reduction to prevent paste smearing.
Once the solder paste is applied, the PCB moves to a pick-and-place machine. These high-speed automated machines do the following:
Modern machines place up to 60,000 components per hour with incredible precision (±0.05 mm).
Pro Tip: Clearly define your part orientations in the BOM and centroid files. Include fiducial marks on the board for optical alignment.
Once components are placed, the board goes through a reflow oven. The oven has multiple temperature zones that:
The melted solder forms solid, reliable joints between pads and component leads. The thermal profile depends on:
Pro Tip: Sensitive components like Ball Grid Arrays (BGAs) or Quad Flat No-lead (QFNs) require tight temperature control. Always share reflow profiles with your contract manufacturer for validation.
Your board may include through-hole parts that are inserted manually or via automated insertion machines. These components include:
After insertion, they are soldered using:
Pro Tip: Group through-hole parts in board design to simplify wave soldering and reduce the need for masking.
At this stage, every board goes through rigorous inspection to ensure it meets IPC standards and customer expectations.
Inspection methods include:
OnBoard Circuits adheres to IPC-A-610 Class II or Class III standards depending on customer needs.
Pro Tip: If you require test services, provide test points, instructions, and custom fixtures during the design stage.
Post-inspection, the board goes through final prep:
Pro Tip: Specify any special labeling or packaging requirements when requesting a quote.
If your product is sold in Europe or California, you may require lead-free (RoHS-compliant) assembly. Be sure to:
Pro Tip: OnBoard Circuits supports all three models.
Typical PCBA turnaround times vary:
We offer quick-turn PCB assembly with no Minimum Order Quantity (MOQ), perfect for R&D and low-volume builds.
Pro Tip: Prevent delays by getting a DFM consultation early in the process.
Yes! We offer full turnkey service, component sourcing, and part substitutions if needed.
Yes—include test procedures and fixtures if required.
Pro Tip: At OnBoard Circuits, we specialize in high-quality PCB manufacturing and assembly, offering fast turnaround and DFM support at every stage.
When precision, speed, and support matter, OnBoard Circuits delivers. With decades of experience, we support everything from one-off prototypes to production-level builds with equal attention and care.
We’re proud to offer:
Or call us at 888-648-5071to talk to an expert about your next build.
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