TY - JOUR
T1 - Temperature-controlled transfer and self-wiring for multi-color light-emitting diode arrays
AU - Onoe, Hiroaki
AU - Nakai, Akihito
AU - Iwase, Eiji
AU - Matsumoto, Kiyoshi
AU - Shimoyama, Isao
PY - 2009/8/12
Y1 - 2009/8/12
N2 - We propose an integration method for arranging light-emitting diode (LED) bare chips on a flexible substrate for multi-color inorganic LED displays. The LED bare chips (240 νm × 240 νm × 75 νm), which were diced on an adhesive sheet by the manufacturer, were transferred to a flexible polyimide substrate by our temperature-controlled transfer (TCT) and self-wiring (SW) processes. In these processes, low-melting point solder (LMPS) and poly-(ethylene glycol) (PEG) worked as adhesive layers for the LED chips during the TCT processes, and the adhesion force of the LMPS and PEG layers was controlled by changing the temperature to melt and solidify the layers. After the TCT processes, electrical connection between the transferred LED chips and the flexible substrate was automatically established via the SW process, by using the surface tension of the melted LMPS. This TCT/SW method enabled us to (i) handle arrays of commercially available bare chips, (ii) arrange multiple types of chips on the circuit substrate by simply repeating the TCT processes and (iii) establish electrical connection between the chips and the substrate automatically. Applying this transfer printing and wiring method, we experimentally demonstrated a 5-by-5 flexible LED array and a two-color (blue and green) LED array.
AB - We propose an integration method for arranging light-emitting diode (LED) bare chips on a flexible substrate for multi-color inorganic LED displays. The LED bare chips (240 νm × 240 νm × 75 νm), which were diced on an adhesive sheet by the manufacturer, were transferred to a flexible polyimide substrate by our temperature-controlled transfer (TCT) and self-wiring (SW) processes. In these processes, low-melting point solder (LMPS) and poly-(ethylene glycol) (PEG) worked as adhesive layers for the LED chips during the TCT processes, and the adhesion force of the LMPS and PEG layers was controlled by changing the temperature to melt and solidify the layers. After the TCT processes, electrical connection between the transferred LED chips and the flexible substrate was automatically established via the SW process, by using the surface tension of the melted LMPS. This TCT/SW method enabled us to (i) handle arrays of commercially available bare chips, (ii) arrange multiple types of chips on the circuit substrate by simply repeating the TCT processes and (iii) establish electrical connection between the chips and the substrate automatically. Applying this transfer printing and wiring method, we experimentally demonstrated a 5-by-5 flexible LED array and a two-color (blue and green) LED array.
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U2 - 10.1088/0960-1317/19/7/075015
DO - 10.1088/0960-1317/19/7/075015
M3 - Article
AN - SCOPUS:68249144815
VL - 19
JO - Journal of Micromechanics and Microengineering
JF - Journal of Micromechanics and Microengineering
SN - 0960-1317
IS - 7
M1 - 075015
ER -