What Makes A Good PCB Stack-Up?
PCB stack-up is an important factor in determining the electro magnetic compatibility performance of a product. A good stack-up can be very effective in reducing radiation from the loops on the PCB, as well as the cables attached to the board, while a poor stack-up can largely increase the radiation.
To make a good PCB stack-up, 4 factors are really important. They are the number of layers, the number and types of planes used, the ordering or sequence of the layers, and the spacing between the layers.
Usually the number of layers is concerned a lot. Though in many cases the other three factors are of equal importance, the spacing between the layers is sometimes the least important in PCB designers’ mind.
When decide the number of layers, the following should be considered. They are the number of signals to be routed and cost, frequency, emission requirements, and whether the PCB is in a shielded or unshielded enclosure or not. Among them, the cost really matters. In reality all considerations are of critical importance and should be considered equally.