requirements for pcb assemblers

pcb assemblers face challenges with flexible and rigid-flex circuit boards. Whether a PCB needs to be bent during assembly or operation, careful design and rigorous testing are required to ensure the copper circuitry is not damaged. Rigid-flex PCBs also require careful handling during the manufacturing process and post-assembly, requiring attention to detail to prevent mechanical stress. With adapted assembly processes, cyclic fatigue testing, and shock and drop tests, flexible-rigid flex PCBs can be validated to meet the bending endurance requirements of their application.

a. Bend Radius: Creating the proper bending radius is crucial to avoid cracking or damage to traces and the substrate. This is especially important for dynamic bending scenarios where the board will be subjected to repeated flexing. A proper flex circuit design requires consideration of the material thickness, substrate type, and bending radius in order to achieve optimal performance.

Rigid-flex pcb assemblers require a careful balance between flexibility and rigidity in their design to ensure that both the rigid and flexible sections of the circuit can be manipulated without damage or failure. This can be accomplished by using a proper layer stack-up design, which consists of the appropriate copper weight and plating thickness to provide sufficient current-carrying capacity and signal integrity. The choice of materials for both the rigid and flexible sections is also important, as they must be compatible with each other to avoid warping or delamination.

What are the bending endurance requirements for pcb assemblers?

The aforementioned considerations are important in both the rigid and the flexible sections of a rigid-flex circuit board, but it is even more vital for dynamic bending applications. Dynamic flexing can cause strain on both the copper circuitry and the materials of the rigid portion of the circuit board, which must be tested to verify that they will be able to withstand the required stress levels.

This is where strain gauges come in, as they can accurately measure the mechanical deformation of a PCB during its test cycle, giving a more precise measurement than other methods, such as CT and X-rays. Bluehill Universal software can automatically calculate the required bending strain values for a given test condition and generate a graph showing the results, making it easy to understand the behavior of a PCB under load. The aforementioned software also supports 3 point bend testing, which is necessary for validating the bond strength of surface mount components to the adhesives that hold them in place on the PCB. The IPC/JEDEC 9704 standard defines the test method and procedures for this.