Chemical compatibility of LEDs

Glass Cap Test

The so called Glass Cap test is a method to investigate the chemical compatibility of materials to LEDs in an accelerated lifetime environment. High power LEDs are prone to failure mechanisms called browning (discoloration of silicon lens near conversion layer, causing drop of luminous flux) and corrosion (discoloring of lead frame silver coating, also causing lumen flux drop). Both failures are caused by volatile compounds that migrate into the lens and the coating, respectively.

The glass cap test operates high power LEDs together with material samples under accelerated lifetime conditions in a sealed environment. Thus it can predict long-term interactions of materials like glues, sealing, pottings, etc. with LED performance.


  • Analysis of polymers for LED vicinity applications
  • Chemical compatibility of glues/adhesives for LEDs

Technical Specifications

  • up to 20 LEDs simultaneously
  • up to 100°C ambient temperature
  • Measurement of color and brightness by use of a LED Analyser
  • Universal PCBs


Chemical and Physical Analytics

Chemical and Physical Analytics
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