Roll-to-roll printed and assembled large area LED lighting element

Abstract

Novel continuous and mass customizable lightemitting diode (LED) lighting foil system, capable to produce adequate lighting levels for general lighting, was designed, processed, and characterized. Lighting element substrate was processed by roll-to-roll (R2R) printing using silver ink and automatic bonding of LEDs and current regulators on polyethylene terephthalate (PET) substrate using isotropic conductive adhesive (ICA). Demonstrator consisting of two basic lighting elements contained 98 LEDs and produced 860 lm when running with 25 mA operational current through the LEDs when using total electrical driving power of 8.4 W. Measured power conversion efficiency of the demonstrator was 31 % and efficacy 102 lm/W. Element produced 460 lx illumination level measured by an illumination level meter at element's central axis at distance of 1 m. At a distance of 2 m, illumination level was 110 lx, respectively. Temperature measurements with T3Ster thermal characterization instrument showed that when driving LED with maximum nominal driving current of 100 mA, LED junction temperature was about 120°C, when lighting element was in air in room temperature. Accelerated environmental stress tests consisting of 500 cycles from −40 … +80°C in aging oven and 1000 h in +60°C/95 % RH climate chamber were performed to test samples without any failures. In addition, over 700 bending cycles using 20 mm bending radius were performed to test samples without any failures, so bonding of LEDs were shown reliable according to these tests. Achieved results proved that thin, flexible, and large area high luminous flux lighting elements and systems can be processed based on plastic foil manufactured using R2R silver ink printing and R2R automatic bonding of LEDs and regulator components using ICA on that foil.

Roll‐to‐Roll Fabrication of Solution Processed Electronics

“…While a lot of attention has been spent in this study on the dimensions of the printed structures (line widening, film thickness, edge definition, and surface morphology) as a function of the inks’ viscosities and the printing speed, no values for the conductivity were reported. A similar product, albeit with lower resolution, has been prepared by Keränen et al, who used R2R screen printing of silver paste and a UV curable dielectric at 2 m min −1 on PET (Figure ) . In their case, a stack of silver/dielectric/silver was produced that was used as a wiring pattern to drive R2R assembled LED arrays.…”

Non-Contact Characterization of Flexible Hybrid Electronics by Synchronized Thermography

“…The layout of the electronics was designed to be compatible with R2R screen printing and mass customization. More detailed description of the sample design and manufacturing process is available in a previously published paper [2].…”

“…In this context, the implementation of flexible or even conformable lighting and signage elements which can be embedded as a solid part of the structural elements have drawn great interest especially in automotive and architecture industry since it provides more freedom for the designers. The technological maturity level of flexible electronics is however limited and thus conventionally fabricated light emitting diode (LED) chips, bonded on printed flexible substrates, are mainly used in this type of products currently [2]. In this paper, the combination of flexible electronics with conventional electronics is called flexible hybrid electronics (FHE).…”

Development of Continuous Roll-to-Roll Screen Printing System Using a Flat Screen

“…현 재까지 스크린 인쇄는 단독 구동방식의 평판 스크린 타입의 장비가 주를 이루며 [1][2][3][4][5][6][7][8] , 유연전자 제품에 적용하기 위한 롤투롤(roll-toroll) 형태의 스크린 인쇄 장비도 개발되어 활용되고 있다 [9][10][11] . 대…”