An innovative way to improve the reliability of gold wire in lighting emitting diodes (LEDs)

As the most promising candidate for the realization of high-efficiency light sources for general lighting, the high power lighting emitting diodes (LEDs) still have reliability issues that hinder the large scale application of LED devices. Nowadays, the reliability is becoming an essential barrier for LED devices to substitute the traditional light sources. Before it is applied into mass production, many kinds of experiments under harsh conditions should be done to predict its reliability. Among those factors affecting LED's reliability, fractures in the gold wire cannot be underestimated. Gold wire is often used for providing an electrical interconnection with outside power, while after some typical package reliability tests, such as the thermal cycling and thermal shock tests [3], there are fractures at two critical zones, the second bond and neck of the first bond. It is confirmed that the failure is mainly caused by the coefficient of thermal expansion (CTE) mismatch between gold and other materials and the large deformation of the silicone enclosing the gold wire.