ULTRASOUND MACHINE HIGH-LEVEL PCB CIRCUIT BOARD NO FURTHER A MYSTERY

Electroplated nickel gold is more frequently made use of on IC substrates (like PBGA), mostly for binding gold wires and copper wires; but when electroplating C substrates, more conductive wires must be designed within the gold finger binding place just before electroplating.---Exactly what are the color selections for PCB solder mask? Ine