Components on a Flexible PCB
The main functions of all printed circuit boards are to transmit electricity and signals from the components connected to it. But not all PCBs are created equal. There are three different types of printed circuit boards — rigid, flex, and rigid-flex. Rigid boards are those that don’t bend, whereas flex and rigid-flex can be shaped to fit into certain products or systems.
The most common type of flexible pcbs is the single-sided flex board. This is made from a flexible base layer called polyimide or a similar material, with copper foil on both sides of the substrate. The conductive layers are separated by an adhesive layer, which can be either a polyimide or an epoxy. The traces are then etched from both sides of the substrate, leaving behind the adhesive and copper layer on one side, and a dielectric layer with metalized holes on the other.
A flex PCB requires more complex etching than standard pcbs, so it’s important to make sure your layout design is optimized. For example, avoid placing components close to other components that could create electrical interference or noise. Also, it’s important to choose a suitable thickness for the flex board. This will determine how pliable it is and the number of flexing cycles it can handle.
How to Terminate Components on a Flexible PCB
In addition, if the board is going to be used in high-voltage applications, you should use a double-sided flex PCB. This type is more expensive than the single-sided version, but it offers better durability and reliability in high-voltage applications.
When it comes time to terminate the components on a flex PCB, you should use conventional soldering technology. This ensures mechanical robustness and process safety, especially when compared to automated soldering. Conventional soldering technology can also be used for bare copper and plated through hole connectors (PTH).
To terminate the connectors, insert them into through-plated holes in the PCB. This can be done automatically with a Pick&Place machine or manually by hand. Using the right connector termination method is crucial for your flex PCB’s performance. Once you’ve completed the soldering process, clean any residues from the PCB. This is important because any residual flux can cause corrosion in the connections. After cleaning, let the flex PCB cool before touching it.
The flex PCB is now ready to be assembled into the final product. The flex section can be joined to the rigid sections of the PCB with soldered connectors or vias. When bending the flex section, avoid sharp angles that may reduce its longevity. Instead, curved traces are preferable, since they produce less stress and will prevent damage to the copper traces. You should also make sure that the traces are spaced appropriately. This will reduce l-beaming, which can lead to stress and cracks in the copper traces. Finally, flex traces should be kept away from discontinuities like vias, cut-outs, and slits. This will help prevent abrasions and other problems during production.
