Studies of LED lighting structures on flexible substrates

Ciprian Ionescu; Norocel Codreanu

doi:10.1117/12.2325763

31 December 2018 Studies of LED lighting structures on flexible substrates

Ciprian Ionescu, Norocel Codreanu

Proceedings Volume 10977, Advanced Topics in Optoelectronics, Microelectronics, and Nanotechnologies IX; 109772L (2018) https://doi.org/10.1117/12.2325763
Event: Advanced Topics in Optoelectronics, Microelectronics and Nanotechnologies IX, 2018, Constanta, Romania

Abstract

These days we experience the in-going of Solid state lighting (SSL) in many domestic and industrial domains. Interconnection of LEDs on flexible substrates is one of the important directions of interest for different applications as backlights for flexible displays and flexible lighting sources or wearable devices^[1,2,3].

This paper presents the results of investigations related to interconnection of mid power LEDs on flexible substrates. Soldering of LED packages involves a thermal stress during soldering which has a possible negative impact on led string reliability, more present if lead-free soldering is used. By using a printed conductive paste for device attachment, the thermal stress is considerably reduced. Adhesive bonding as an alternative to soldering can be applied to low cost substrates as polyethylene terephthalate (PET). We present, based on infrared camera measurements the limits of power levels that can be applied for different flexible circuits, taking as reference LED structures on polyimide (PI) substrate and on glass epoxy (FR4). The thermal considerable thermal dissipation of the LEDs during operation and the specific attachment to foil with lower thermal conductivity will rise problems on the thermal design.

Citation Download Citation

Ciprian Ionescu and Norocel Codreanu "Studies of LED lighting structures on flexible substrates", Proc. SPIE 10977, Advanced Topics in Optoelectronics, Microelectronics, and Nanotechnologies IX, 109772L (31 December 2018); https://doi.org/10.1117/12.2325763

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