PCB Assembly FAQ

PCBATop is manufacturer specializing in PCB Assembly service under one roof.

We need Gerber files, Centroid data and BOM for your PCBA orders. If your PCB Gerber files are missing any of the above-mentioned three layers, please resend them, as this is the minimum request for PCBA. For the best possible result, please also send assembly drawings, instructions and photos to us to avoid any ambiguous and even mistaken placement of parts, though these are not required by most of the assemblers.

A centroid file is an essential component in the assembly process, specifically designed for quickly programming assembly machines. This file is also known as insertion data, pick-and-place data, or XY data. While some CAD tools automatically generate centroid files, others may require you to create or modify the file manually.

The centroid file plays a critical role as it details the position and orientation of all surface mount components. It includes vital information such as the reference designator, X and Y coordinates, rotation, and the side of the board (top or bottom) for each part. Notably, only surface-mounted components are included in the centroid file, ensuring precise assembly and efficient production.

We hope you can mark on any individual package or box with the corresponding line number on BOM, manufacturer’s part# or customer’s part#, quantities. A detailed packing list is preferred to enable us to count and check upon receipt of your parts.

By default, unused and excess parts supplied by you or purchased by us cannot be returned. If you wish for any excess parts to be sent back along with your assembled boards, please contact your service representative or make a note on your related order indicating which parts to return.

For SMT components not supplied on reels, please ensure they are provided on one continuous strip of tape. If you intend to assemble the same SMT part across different boards, avoid cutting them into separate strips—keeping them in a continuous strip of tape or on the reels is essential for efficiency.

Minimum Quantity Requirements:

• Resistors, Capacitors, Diodes (0603, 0805, 1206, 2225, SOT, SOD, MELF packages) : A minimum of 50 pieces is required, exceeding the required assembly quantity by 30 pieces. For instance, if the assembly quantity is 40 pieces, you should supply 70 pieces (50 minimum plus 30 extras).

• Resistors, Capacitors, Diodes (0201, 0402, miniMelf, miniature packages) : A minimum of 100 pieces is necessary, exceeding the required quantity by 50 pieces. For example, if the assembly quantity is 80 pieces, you should provide 130 pieces (100 minimum plus 50 extras).

For expensive components such as ICs, BGAs, QFPs, and connectors, we request a small number of excess parts (1–5 pieces based on the total quantity of assemblies) to ensure smooth assembly and timely shipping of your completed boards. If you have any questions or uncertainties, please feel free to send more extra parts or contact us for clarification.

Yes. This practice is called partial Turn-key. You can supply some parts, and we source the rest of the parts on your behalf. We will ask for your approval for anything that is not sure at our side. In case parts crossing or substitution is needed, we will again ask for your final approval.

Yes, We have the ability to handle BGA of 0.25mm pitch with X-ray testing. For BGAs, there are two designs with via on pad and via near pad connected by shorter trace. We need to tent and fill any vias near pad of the BGAs with solder mask to ensure the soldering quality. But for vias on pad, we need to fill via with resin to make sure good soldering quality.

Due to the complexity of how to determine the turn time of PCBA services, our policy is that turn-time begins immediately after all the parts and PCBs are ready and all the PCB files (Gerber files/other PCB files, etc.,) , Centroid (Pick & Place PNP file, or XY Data or files in other formats), BOM, and all other necessary data or documents/images/photos are complete for our assembly work.

Defects and issues may occasionally arise in the world of PCBA, given its intricate nature and attention to detail. If you encounter any defects or problems with your printed circuit board assembly, please inform us immediately. Our dedicated team will promptly evaluate and review the situation to determine the best course of action for remediation.

We offer solutions such as repairs, rework, or even remaking your boards if necessary. Should we need to assess the defective boards firsthand, we may request that you return them to us for analysis.

Rest assured, our commitment is to deliver fully functional boards to you, ensuring satisfaction with our high-quality PCBA services.

In our turn-key order process, timely sourcing of all components is crucial, as the overall turnaround time largely depends on how quickly we can acquire these parts. To keep you informed, we will provide regular updates through daily email communications regarding the status of your order.

While we await the arrival of all components, our team will proactively begin fabricating the printed circuit boards (PCBs) and creating the necessary stencils. This allows us to initiate the assembly process immediately upon receiving the parts, ensuring a seamless workflow and quicker project completion.