Recently, most vehicle instrument cluster designs have adopted shields to prevent light leakage from the LEDs to surrounding areas. However, light leakage remains a challenge due to a small amount of space that is required between the shield and the PCB to account for expansion caused by temperature changes. Additionally, some applications using LEDs, such as automotive and industrial systems where electrical components are exposed to severe conditions, require high reliability. Taking these issues into account, Rohm has developed what the company claims to be the first high-brightness silver-free lens LEDs to prevent sulfuration, one of the leading causes of ageing. Raising the light source position from 0.18mm in standard products to 0.49mm allowed Rohm to significantly reduce light leakage. Meanwhile, the 1.6×0.8mm devices are approximately 18x smaller than conventional reflector-type LEDs. In addition, all devices are designed to prevent light degradation even under high temperature environments. The company developed a new type of resin for blue, green and white LEDs to achieve higher reliability, improving the residual luminosity rate by approximately 80% over conventional products.
Rohm Semiconductor – www.rohm.com