Challenges Commonly Encountered in Flexible Printed Circuit Board
Flexible Printed Circuit Board
Printed circuit boards play a critical role in a wide range of applications from medical equipment to consumer electronics. They are often used in wearable technology, which has caused a surge in demand for flexible PCBs. They allow devices to be slimmer than they would otherwise be so that they can fit in a smaller, more portable space. But even with this advantage, a variety of challenges are commonly encountered when designing and producing flexible PCBs.
A primary challenge is balancing the flexibility needed in wearable products with rigidity required for mounting components. Balancing this conflict requires careful design that considers the physical shape and positioning of each component, allowing for reliable connection despite continual bending and flexing.
Another challenge is the need to keep the weight of the resulting product low enough for use. This can be difficult because many of the materials used in flexible printed circuit board are more expensive than their rigid counterparts. However, it is possible to find materials that are cost-efficient, which can help manufacturers meet the demands of the industry and their customers.
Challenges Commonly Encountered in Flexible Printed Circuit Board
Flex PCBs are also prone to damage from environmental factors such as power surges, lightning strikes and contamination from metallic dust. These environmental factors can damage the surface of the board or impact the traces on the inside of the PCB. Damage to the traces can cause shorts, which can cause a device to malfunction.
The flexibility of a flex circuit also creates challenges in the assembly process. Since the substrate is much thinner than with a rigid board, heat applied for soldering has nowhere to dissipate and can damage the circuit. Specially-designed fixtures called SMT process carriers are used to ensure that the circuit lies flat throughout the assembly. Additionally, local circuit fiducials are required in addition to panel fiducials so that the SMT pick-and-place machines can check for component alignment during placement.
Lastly, the flexible nature of a flex circuit makes it more susceptible to damage in secondary manufacturing operations. This requires a strong focus on DFX principles, storage and handling requirements, appropriate tooling and process modification, inline inspection at critical points in the process and employee training.
Another important challenge is ensuring that the etched and plated openings on the circuit board are large enough to prevent failure due to excessive contact between pads and conductive traces. These openings are also impacted by the proximity of the bending point and the solder joints, which should be positioned at the proper distance from the bending point to avoid delamination and solder pad breakage. In addition, it is important to ensure that the solder pad openings are large enough to accommodate the thickness of the copper circuit sheet. This can be accomplished through a combination of careful planning, etching and plating techniques.