primary applications of pcb circuit board assembly
PCB circuit board assembly is the process of mounting components onto a printed circuit board (PCB) to create a working electronic device. PCBs typically use one of two primary techniques for component mounting: surface mount technology (SMT) or through-hole technology (THT).
The bare laminate base of a pcb circuit board assembly contains copper that carries electrical signals from the components to and from the motherboard, similar to how your nervous system carries messages between your brain and muscles. The base also contains other materials like fiberglass to provide structure and insulation. In addition to the conductors, PCBs may contain layers of insulation and other material to help prevent shorting and provide stability. The insulated material can be made from various materials, such as epoxy or polyimide.
Once the insulated layer is coated, a mask is placed over it that matches the design of the PCB. The bare laminate is then imaged with photosensitive film that is exposed to light and developed. The unexposed areas become sensitized and are bonded with metal ions to form copper in the imaged pattern. The copper is then plated over the entire board. The plated areas are soldered to the pads, pins, and other contacts.
What are the primary applications of pcb circuit board assembly?
The drilled holes are then made conductive by electroplating them with copper to form plated-through holes. Some plated-through holes are intended for the insertion of through-hole-component leads; others are used to connect different circuit board layers. Once a pcb has been drilled, soldered and tested, it is ready for assembly. During this step, the PCB is loaded into pick-and-place machines that add surface-mount components to the printed circuit board. These are smaller, more flexible components that can be positioned more easily than through-hole technology components. This type of assembly is usually faster than THT.
Solder paste is then applied to the PCB using a stencil or dispenser. The pcb is then sent to a reflow machine, which applies heat to the solder paste and melts it into place. Once the solder is melted, the components are then placed in their correct positions on the PCB and held in place with glue dots. A legend, or silkscreen or liquid photo imaging, is often printed on the top of the PCB to identify the location of the components and their function, switch settings, test points and other indicators that are helpful for assembling, testing, servicing and using the circuit board.
PCBs that have a lot of components with small lead pitch can cost more to assembly, as the tiny component placement requires more sophisticated machinery and trained operators. In addition, the rework and repair of such high-density devices can be more expensive. The best way to reduce assembly costs is to minimize the number of high-density components used on a PCB. It is also a good idea to choose a simpler PCB layout, or a single-layer board where possible. Finally, a careful review of component packaging and footprints can be beneficial in reducing assembly pricing.
