In order for us to properly execute an order, it needs a set of exact sizes and coordinates, trace widths, hole patterns and, of course, tolerances. Failure to comply with the given tolerances can cause a board to be rejected. Nowadays, as the switching speed of signals continues to increase, it is vital for a PCB designer to understand how to take into account the impedance of PCB traces. If a trace is defined as a PCB impedance control trace, it is not the width of the trace that has to be kept within certain values, dictated by the tolerances set by the board designer, but the PCB impedance value. In order to meet the PCB impedance requirements, the manufacturer can vary the trace width, height and other parameters. PCBs with impedance requirements will demand a level of precision higher than boards without such requirements.

Tongtai uses the industry standard Polar Impedance Calculator to calculate impedance. We provide an impedance report and serialized TDR coupons with each shipment free of charge. Typically, designers use published prepreg values from the data sheet to calculate impedance. We have done extensive research over the years to find out our "out or press" prepreg thickness, also known as the squeeze-out thickness. Using these values help us refine our impedance calculations so they are closer to actual values on the finished PCB. This is why we encourage you to work with our team and experienced Field Application Engineers at conceptual level so that we can help you refine your impedance calculations.