How Are Components Mounted onto a Board Assembly?
Components Mounted onto a Board Assembly
A jiggling component or dangling coil can have serious consequences for the functionality of your device, so it’s essential that all components are properly mounted onto a board assembly. The process of affixing electronic components to a circuit board is called PCB mounting, and it requires a precise combination of skills, tools, and equipment to ensure that all connections are secure and in the right place.
In the past, many steps in this process were manual but are now almost exclusively automated for more efficient and reliable results. Before assembly can begin, the circuit board must be etched to remove copper from its surface and expose the areas where the components will be placed. Then, a solder mask is applied to protect the underlying layers and provide places for attachment of the surface mount components. Finally, the board is silkscreened with labels that indicate what each component does on the finished product.
There are several different methods that can be used to mount the components on a Board, but there are two primary technologies: Surface Mount Technology (SMT) and Through-Hole Insertion Technology (THT). SMT is ideal for smaller, more sensitive parts like resistors and diodes, and it can be done manually or with robotic machinery. Through-hole technology works well for larger leads and wires that need to be plugged through holes in the board, and it can also be either manually or automated.
How Are Components Mounted onto a Board Assembly?
The first step in a typical PCB assembly process is applying solder paste, which is a greyish substance that contains tiny metal balls, or solder, mixed with a flux to help the solder melt and bond to the copper on the board. This is typically done using a stainless-steel stencil, which allows assemblers to apply the solder paste evenly to the locations where the components will sit on the finished product.
Once the solder paste has been applied, the board is sent to a robotic pick and place machine that adds the surface-mount components. Manufacturers supply these components in reels, tapes, trays, or tubes, and the pick-and-place machines use mechanical or vacuum-based movements to take each one from its packaging and put it into position on the board. This method helps to reduce human error and speeds up production.
After the components have been placed, the board goes through a reflow oven. This is a special type of heated environment that has different zones with specific temperature profiles. The preheat, soak, and reflow zones all have their own temperatures and durations, which can be customized for each individual product.
This is a critical step in the process that ensures all of the solder points on the board are hot enough to melt and adhere the components. Once the boards have been reflow-soldered, they are removed from the reflow oven and allowed to cool down, which helps to prevent any potential issues with thermal stress. Once the boards have cooled, they’re ready for inspection and testing. Depending on the requirements of your project, additional processes can be added, including conformal coating, which is a protective layer that safeguards the boards against environmental factors like moisture and heat.
