PCB Assembly

The bare printed circuit board (PCB) is populated—or “stuffed” with electronic components to create a functional PCA, or printed circuit assembly. This process is the final step of the PCB manufacturing and assembly cycle, transforming a bare board into a complete, functioning circuit. The most common methods for adding components are through-hole and surface mount technology. The latter, referred to as SMT, is the dominant method used in contemporary electronic devices. Through-hole components are inserted into holes surrounded by conductive pads or lands on the surfaces of the board; solder paste is used to hold the components in place. The component leads are joined to the board using wave or manual soldering.

For SMT assembly, the bare board is first coated with a layer of soldering paste, followed by a layer of SMT components. The specialized SMT pick and place machine then “picks up” the components with its vacuum grip and places them on top of the soldering paste in preprogrammed locations. Once the SMT components have been placed, the PCB is sent through reflow soldering. The reflow process heats the solder, melting and liquifying it to form the necessary connections before passing through a series of coolers, which cool down and solidify the melted solder.

During the reflow process, a visual inspection takes place to ensure the proper placement of components. If any problems are found, the board can be reprocessed.

Once the soldering and inspection are complete, the final assembly can begin. In addition to soldering through-hole components and reflow soldering the surface mount parts, the PCA can also go through manual hand soldering for delicate components. If there are any sensitive through-hole components on the PCA, the assembler should be provided with instructions about how to handle them properly; for example, if the board will undergo wave soldering, it’s important to communicate that THT parts may be damaged by the process and should be manually soldered in a different manner.

What is PCB Assembly?

To avoid time to market delays, a customer should choose a domestic pcb assembly us service provider if possible. Domestic assemblers offer faster turnaround times than offshore assemblers, as well as certification transparency and a shared legal system for intellectual property protection.

THT and SMT assembly can require several procedures, including printing with solder paste, placing SMD parts, reflow soldering, and carrying out AOI or AXI. Sierra Circuits is a highly experienced supplier of both THT and SMT PCBs, and adheres to the industry-recognized IPC-2581 standard. This open, vendor-neutral XML format streamlines communication and improves the accuracy of data transfer across the supply chain, from design to production.

To ensure a successful PCB Assembly, it’s vital to provide the assembler with a clean Bill of Materials (BOM) and clear assembly notes. The BOM should include part numbers and manufacturers’ references, as well as the recommended thermal management profile. The assembly notes should clearly specify the desired soldering method for each component, and include information on how to properly apply the solder paste. In addition, the notes should include instructions for removing non-washable components and handling through-hole components that will be subjected to the wave or manual soldering processes.

Related Post

Leave a Reply

Your email address will not be published. Required fields are marked *