Lumen Maintenance of Ternary Ag-Alloy Wire Bonded LED Package after Reliability Tests

Abstract

In this investigation, ternary Ag-alloy wires were doped with different Pd and Au concentrations, and each wire was encapsulated in an LED package. The static and dynamic reliability were tested, and the lumen maintenance performance was examined. The static reliability tests included the sulfur test, LTSL, HTSL, and WHTSL. According to the sulfur test data, higher Pd and Au contents led to better lumen maintenance. Furthermore, the bonding wire of the LED with better lumen maintenance in the sulfur test had higher electrical resistance. The brightness decay rate of the white light LEDs was low in low-and high-temperature environments, but it was significantly higher after the WHTSL test. The dynamic reliability test after 1,000 hours of HTOL and WHTOL showed that the lumen maintenance improved with higher Pd and Au contents, indicating that doping Ag-alloy wires with sufficient amounts of Pd and Au can retard degradation due to thermal and humidity aging and oxidation reaction. Therefore, ternary Ag-Pd-Au alloy wires produced with specific drawing and annealing processes are suitable for application to mid-power white light LEDs.