Impedance Control in Rigid Flex Circuits
The primary function of any circuit board, including rigid-flex PCBs, is to allow signals to pass from different parts of the device. Those signals must travel through the traces on the board, and signal impedance is one of the key factors that affects how well those signals work. Controlling the impedance of these traces is crucial for ensuring that your product’s components operate as intended. In this article, we’ll discuss how to handle impedance control in rigid-flex circuits and some of the important design considerations you need to make.
The first thing you need to understand is how impedance works in a rigid flex circuits. Impedance is a measure of a circuit’s resistance to the flow of current, and it’s measured in ohms. A rigid-flex circuit with good impedance will have low resistance and will not cause any signal degradation. To achieve this, you’ll need to ensure that your circuit’s traces have the right width and spacing, as well as the right thickness of copper.
Rigid-flex circuits typically use a combination of rigid and flexible sections, and the stack-up that you choose will have a big impact on your final design. If you choose a high-layer count, you can expect your flex to have less pliability than if you used fewer layers. This is because more layers can increase the amount of stress and strain placed on your flex.
How to Handle Impedance Control in Rigid Flex Circuits
Another factor that can impact impedance is the dielectric layer. A thin dielectric layer will have a lower dielectric constant than a thicker one, and this will reduce your rigid-flex’s impedance. You’ll also want to make sure that your flex has the right amount of copper, as it will affect the characteristic impedance of the conductive layer.
A final factor that can influence the impedance of a rigid-flex circuit is the layer transition zone. This is the area that transitions from the flex core to the rigid layer and solder mask. This zone should be smooth and free from splices or other areas of discontinuity. The transition should also be a uniform thickness to avoid any variations in the characteristic impedance of your signal line.
As you can see, there are many factors that impact the performance of a rigid-flex circuit, and you’ll need to address each one to create a reliable product. This is why it’s so important to partner with a reliable PCB manufacturer that has experience with rigid-flex circuits. They will be able to provide you with the best-quality products, and they will have the expertise necessary to help you get your products to market faster.