ROHM’s new compact high-output-lens LEDs eliminate light leakage countermeasures in vehicle instrument clusters

ROHM Semiconductor of Kyoto, Japan has announced the availability of compact high-output surface-mount LEDs equipped with a lens. The new lineup includes 18 devices, consisting of the CSL0901 series featuring standard brightness and the high-brightness CSL0902 series.

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 the 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 from these components, so they can better withstand the effects of aging caused by the extreme environments they are exposed to.

In response, ROHM has developed products targeting applications that require high reliability at the component level, such as developing the first high-brightness silver-free LEDs to prevent sulfuration (one of the leading causes of aging).

The new series consists of automotive-grade products that ensure high reliability in vehicle instrument clusters which operate under harsh environments. Raising the light source position from 0.18mm in standard products to 0.49mm allowed ROHM to significantly reduce light leakage. Meanwhile, size was reduced by about 18x compared with conventional reflector-type LEDs.

In addition, all devices are designed to prevent light degradation even under high-temperature environments (i.e. automotive). To achieve higher reliability, ROHM also developed a new type of resin for blue, green and white LEDs. As a result, during high-temperature testing with blue LEDs (85°C, IF=20mA, 1000hrs operation), ROHM improved the residual luminosity rate by about 80% over conventional products, contributing to greater application reliability. Furthermore, achieving higher precision during the manufacturing process (i.e. die bonding, molding) while maintaining the compact 1608 size (1.6mm x 0.8mm) made it possible to increase core brightness by 5-7 times over conventional LEDs.

Tags: Rohm

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