Can flex PCB fabrication support
As you design your flexible PCB, it’s important to follow the engineering standards that dictate how your traces must be placed and their widths. These requirements ensure that the signals traveling down the traces don’t experience impedance discontinuities, which can cause delays and other problems during signal transmission.
Impedance control is essential in flex pcb fabrication due to the high-frequency signal propagation speeds, which can be disrupted by traces with uncontrolled impedance. When the characteristic impedance of a trace changes, it creates reflections that can slow the rise time of a signal or cause electromagnetic interference (EMI). Impedance discontinuities in flexible circuit boards typically occur due to variations in the thickness of the dielectric, the width of the copper, and the shape of the bend radius.
In order to maintain a consistent characteristic impedance and avoid these issues, you need to use PCB CAD software that’s optimized for flex circuits. The flex-friendly software will allow you to select the appropriate material thickness and design your traces with the required dimensions. You should also pay close attention to the bending radii and flex life of your design to ensure that your traces are durable enough.
Can flex PCB fabrication support controlled impedance traces?
Another factor that influences flex PCB fabrication is the number of layers in the design. The higher the layer count, the more complex and expensive your board will be to produce. To reduce the cost of your flex circuit, you can choose a lower-layer count and reduce the complexity of your design.
The base materials used for your flex circuits can affect the price, flexibility and availability. For example, choosing a thinner dielectric allows for higher-speed communication and better impedance control, but it may increase the manufacturing costs. Additionally, selecting a thicker dielectric limits the flexibility of your board.
A common method of establishing controlled impedance is by using reference plane layers and shielding. However, these features will increase the rigidity of the flex circuit and limit its bending capabilities. To keep the flex circuit thin and flexible, you should only utilize these techniques when necessary.
Another way to decrease your flex circuit cost is by using cost optimization techniques. This includes ordering in bulk and designing your circuit to meet minimum requirements. This will allow you to take advantage of fast-turn options, which are more affordable than standard turnaround times.
Finally, the choice of surface finish for your flex circuits can have an impact on cost. The most commonly used surface finish is ENIG, which provides a solderable surface for bond pads and conductive paths. However, other finishes may provide better performance and durability than ENIG, but at a higher cost. Therefore, it’s important to compare the tradeoffs between the different surfaces.
As a final tip, be sure to consult your flex PCB manufacturer’s calculator to determine how much your specific fab will cost. The calculator will help you find out how to optimize your fab and get the best results for your project.
