Operate under   insufficient vacuum.

Adjust the   equipment to increase the vacuum of the electroplating furnace

The distance   between the substrate and the tungsten wire is too close.

Control the   distance between substrate and tungsten wire.

The luminous   time of evaporation is too long.

Control the   evaporation time.

The voltage and   current are too high during evaporation.

Adjust to   appropriate evaporation voltage and current.

The plating materials   are oxidized

Change the plating   materials.