What Are the Most Common Failure Modes for Flexible PCB Boards?
Most Common Failure Modes for Flexible PCB Boards
PCBs are designed with multiple layers of copper foil and resin. When they are subjected to mechanical stress, deformation or chemical degradation, the material can rupture and contaminate adjacent components or traces. This damage can result in electrical failure and short circuits that will cause the entire board to fail. Rigid-flex circuit boards are especially vulnerable to these types of problems. Whether your company uses these circuits in industrial systems or consumer electronics, understanding the most common failure modes can help you avoid costly production downtime and repairs.
Printed circuit board (PCB) manufacturing is an intricate process that involves many different processes and tolerances. If the fabricator fails to meet the exact tolerances laid out by a designer, it can lead to several issues that may compromise the function of the final product.
For example, a failed solder joint can allow metal to contact components that aren’t meant for it and cause shorts or even fires. This is particularly dangerous if the flexible pcb board is used in an industrial system. If a fire breaks out, it can interrupt the flow of electricity and cause other systems to stop working properly. Likewise, an electrical short can lead to damage such as burnt components and melted traces.
What Are the Most Common Failure Modes for Flexible PCB Boards?
Another common problem is the occurrence of broken tracks, which can be caused by any number of things. It could be that one of the conductive materials ripped off the track during assembly, or it could be that a component was soldered incorrectly. You can check for these problems using a continuity tester or multimeter.
Other types of PCB failures include chemical and environmental damage, delamination and mechanical failures. For example, if you’re using a rigid-flex board with surface mount (SMT) components, it’s important to make sure the adhesive is strong enough and that all of the components are clean before attaching them. Otherwise, the adhesive might not hold and the components may fall off.
Mechanical failures such as flex cracking and fatigue fracture initiation and propagation are also common for rigid-flex boards. These issues are caused by mechanical stresses and distortion that result from the location of stiffeners, via or PTH holes in the flex area, the shape of the flex area and coverlay layer configurations.
A further type of mechanical failure is delamination, which occurs when the lamination separates from the dielectric material. This can be caused by thermal excursions or electrostatic discharge, which can create a short between two layers of the circuit board. This will cause the layers to heat up and melt, resulting in a circuit that won’t work. This is a serious problem that can be extremely expensive to repair. Fortunately, it’s possible to prevent this kind of PCB failure by using appropriate design decisions during the fabrication process.