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.