Mount Technology SMT Be Used in Assembling Flexible Printed Circuit Boards
Despite the fact that surface mount technology SMT is now used in many electronic products, there are still many myths and misconceptions about this assembly process. Some of the biggest ones relate to whether SMT can be used in assembling flexible printed ciruit board (FPCB) or not. As a result, we have put together this FAQs page to help clarify the most commonly asked questions about surface mount technology. We hope that you find it useful!
SMT stands for surface mount technology and is an automated assemblage process that is faster and more efficient than the older through-hole technology. It also allows for higher component density and smaller footprints. The process can be single- or double-sided, and does not require drilling holes through the PCB — which saves on costs and time in manufacturing.
The main steps of SMT are solder paste printing, component placement and reflow soldering. A solder paste printer applies a thin layer of tin and copper to the pad surfaces on the flexible printed circuit board, where the components will be placed. After the solder paste is applied, a machine then places the individual component on the board using its specialized nozzles. Finally, the board goes through a reflow oven where the solder melts and bonds the component to the pad, completing the circuit.
Can Surface Mount Technology SMT Be Used in Assembling Flexible Printed Circuit Boards?
Yes, with the right design parameters SMT can be used in assembling FPCBs. The main challenge is ensuring that the flex circuit is robust enough to handle repeated bending and movement. For this, the flex circuit should be made from higher-grade Rolled Annealed (RA) copper foil instead of regular unannealed copper. RA copper is much more resilient and can be stretched far longer before fatigue cracking occurs. It is also more springy in the Z deflection direction – exactly what you want for a flex circuit that will be bending and moving all the time.
Another factor to consider is the SMD component size. Compared to through-hole components, SMDs are typically much smaller, which can lead to interference coupling. However, this can be overcome by using a multilayer board construction with ground plane, and the overall effect is still less than through-hole components.
X-ray testing can be a useful tool in the inspection of SMT components and solder joints on a PCB. It can help identify any shorts or defects that may not be easily visible to the naked eye. Alternatively, in-circuit testing (ICT) can be performed to check the functionality of the circuit board, including any shorts or intermittent connections. These tests can be carried out by a professional, independent test house (ITH) that uses an ICT platform and custom fixturing designed for the specific flex circuit being tested. This is a great way to check that the final product will work correctly as intended and that it meets all necessary specifications after it has been assembled using SMT.
