High Output Lens LEDs That Eliminate Light Leakage Countermeasures


Improves reliability and reduces size of various applications

ROHM announces the availability of compact high output surface mount LEDs equipped with lens. This new lineup includes 18 devices, comprising of the CSL0901 series featuring standard brightness and the high brightness CSL0902 series.

Most vehicle instrument cluster designs have 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 from these components, to better withstand the effects of aging caused by the extreme environments they are exposed to.

Product with high reliability

In response, ROHM has taken a step ahead in the industry to develop products targeting applications that require high reliability at the component level, such as developing the first high-brightness silver-free LEDs to prevent sulfuration, which is one of the leading causes of aging.

This newest series consists of automotive-grade products that ensure high reliability in vehicle instrument clusters which operate under harsh environments.

In addition, all devices are designed to prevent light degradation even under high temperature environments (automotive). ROHM also developed a new type of resin for blue, green and white LEDs to achieve higher reliability. Furthermore, achieving higher precision during the manufacturing process (i.e. die bonding, molding) while maintaining the compact 1608 size (1.6×0.8mm) made it possible to increase core brightness by 5 to 7 times over conventional LEDs.

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Key Features

1. Optimised light source position prevents light leakage, achieving greater space savings
Reflector-type LEDs are typically used as light sources for instrument clusters. However, the increased need for space savings is causing many manufacturers to consider smaller LEDs. General compact molded LEDs are designed with light sources positioned as low as 0.18mm, causing light to leak to adjacent areas. In response, ROHM raised the position of the light source to 0.49mm, virtually eliminating light leakage. This makes it possible to use smaller LEDs (approximately 18x smaller in volume than conventional reflector-type LEDs), contributing to greater application space savings.

2. Contributes to longer application operation by reducing standby current consumption

1) Newly developed molded resin reduces degradation due to aging
ROHM developed a new molded resin that significantly reduces brightness degradation due to high temperature operation, even for short wavelength products such as blue. For example, during accelerated high temperature testing with blue LEDs (85°C, IF=20mA, 1,000hrs operation), an improvement  in the residual luminosity rate by approx. 80% over conventional products was observed.

2) Support for AEC-Q102 sulfuration testing
Until now, ROHM LEDs have been designed to comply with AEC (Automotive Electronics Council) -Q101, the international standard for high reliability in automotive applications used for discrete products, but more recently has obtained certification under the AEC-Q102 standard for optical devices. This new regulation also includes sulfuration testing, which is expected to lead to even greater reliability in applications such as automotive and industrial systems exposed to severe environments.




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