How much gold in a circuit board?
The Gold content of a circuit board depends on the application, if you are making a low speed circuit there will be no gold it will be mainly copper as they are very close to having the same conductance, if you where to start increasing the speed of a circuit you would want the tracks time constant to be as low as possible so a lot of emphasis will be put onto good layout disipline to reduce the tracks cross talk, you would then also reduce the tracks resistance, this is intially done by using gold plating as gold has a very low contact resistance much lower than either silver or copper, if you needed to reduce the resistance even further you would make the track out of silver as this has the lowest resistance
