The Study of LED Silver Plated Lead Frame Discoloration Mechanism

Light emitting diodes (LEDs) are increasingly widely used as a new generation of environmentally friendly green light source. However, during the use of LED especially white LED, influenced by corrosive substances, high temperature and so on, silver plated lead frame will be resulted in a discoloration problem which will adversely affect the light efficiency and color temperature of LED. In this paper, through analyzing several failure cases it is concluded that there are two main reasons for discoloration of silver plated lead frame. One is that corrosive substances such as sulfur, chlorine and so on cause the silver plated lead frame to discolor. The other is that the silver plated lead frame is oxidized to blacken. At the same time, the comparative verification test is designed to verify the mechanism of oxidation blackening. The fundamental reason for the oxidation blackening of the silver plated lead frame is that the anti-tarnish process used by good and failure silver plated lead frame is different and the effect of anti-tarnish process used by failure silver plated lead frame is poor.