PCB Assembly
PCB assembly is the process of taking a newly manufactured circuit board and mounting components to it. This includes putting on resistors and other parts, which are what make the PCB function. It’s an important step in the manufacturing process and must be done correctly to ensure the finished product works as intended. There are a few things to keep in mind when working with a company that offers pcb assembly services, including the following:
Most companies specializing in pcb assembly will require you to provide them with a design file of your completed project before they begin the assembly process. This allows them to check the design for issues that may affect its functionality or manufacturability. This is known as a Design for Manufacturability (DFM) check.
Once a design file has been checked and the necessary components have been ordered, the next step in the assembly process is to mount them onto the circuit board itself. This is done with either surface mount technology (SMT) or through hole technology (THT). SMT is an automated process in which components are placed using a machine that can pick and place them. THT is a manual process in which the leads of components are inserted into holes that have been previously drilled into the PCB.
What is PCB Assembly?
After the components are placed, they must be soldered to the circuit board. This process involves heating the PCB and all of its components, liquifying the solder and ensuring that all of the connections are properly made. Once the solder has been melted and solidified, it can be inspected and cleaned as needed.
Before the components are soldered, the selected areas of the circuit board need to be coated with a solder paste. This is a thin, silver-colored liquid that functions as an adhesive for the individual parts. During this phase, a stencil is used that is similar to screen-printing a shirt, allowing assemblers to apply solder paste only in certain areas of the would-be circuit board. This is a key step in ensuring that the components are placed where they should be in the final PCB.
After a component has been reflow soldered, it must undergo a visual inspection to ensure that the fuses and other connection points have not been compromised. This is often performed by hand, although some manufacturers use x-ray inspection to catch internal issues that might not be visible to the human eye. X-ray inspection uses photons of different wavelengths to differentiate various materials, and is particularly useful for detecting solder quality issues like voids or pinholes.
The final step in the assembly process is testing the assembled circuit board to determine its electrical characteristics. This is a vital step that helps prevent field failures, accidents and malfunctions. If any of these characteristics show an unacceptable amount of fluctuation or hit peaks outside of the predetermined range, the PCB will fail testing and must be recycled or scrapped, depending on the manufacturer’s standards.