prevent solder bridging during Rigid flex
Rigid flex is when a rigid section of the circuit board is combined with a flexible section. It is commonly used in PCBs with high-speed signals and long-life connectors. The flexible portion of the circuit is adhered temporarily to the rigid part by means of acrylic adhesives on both sides. This type of PCB is prone to solder bridges. The solder bridge is a conductive path between two or more adjacent pads, pins or conductors on the surface of the circuit. This defect is a major manufacturing problem that can cause serious electrical failures in the finished product.
Solder bridges can be caused by a number of issues in the manufacturing process. One of the main reasons is that the solder mask doesn’t cover all of the components. This is especially true in areas around the connectors. The gaps created by missing solder mask are ideal places for solder to bridging from one pad to another.
Another reason solder bridges occur is that the pads are too close together. This can be caused by either a misalignment in the placement of the components, or the pads being too large for the pins they are connected to. It can also be the result of excessive placement pressure or a dirty stencil with paste sticking to it. If there is too much paste applied, it may cause a “pasty slump” that results in the excess paste squeezing out between pads. Other causes of solder bridging include poor design, insufficient preheat temperature or the use of too much flux.
How do you prevent solder bridging during Rigid flex?
In addition to these factors, the PCB assembly house’s quality control procedures can play a big role in preventing solder bridges. It is important to choose a CM that has a good track record of eliminating this issue. They should have the tools and experience to properly inspect a board for defects and proactively take steps to prevent solder bridging.
Other common issues that can cause solder bridging are the use of incorrect lead lengths on through-hole components, pad widths and pitch sizes. These issues can be minimized by checking the data sheets for each component to make sure they meet IPC standards. It is also helpful to consult with the assembly house to discuss best practices for reducing these problems.
To help you avoid these issues, we offer rigid flex PCB training courses that teach a structured layout flow and address key DFM concerns for this unique fabrication method. The course covers topics like stackup creation, defining multiple board outlines, layer assignment, route borders and more. It is an excellent way to ensure that your flex designs are ready for production. If you are interested in learning more about our rigid-flex PCB training, please get in touch. We can arrange a live web conference with you and your team to demonstrate how to use the features of OrCAD PCB Editor to master rigid-flex PCB design. We can also provide a more in-depth look at advanced concepts such as bend areas, place and route techniques and 3D visualization.