Low-Yellowing Phosphor-in-Glass for High-Power Chip-on-board White LEDs by Optimizing a Low-Melting Sn-P-F-O Glass Matrix

Hee Chang Yoon; Kouhara Yoshihiro; Heeyeon Yoo; Seung Woo Lee; Ji Hye Oh; Young Rag Do

doi:10.1038/s41598-018-25680-6

Low-Yellowing Phosphor-in-Glass for High-Power Chip-on-board White LEDs by Optimizing a Low-Melting Sn-P-F-O Glass Matrix

Sci Rep. 2018 May 9;8(1):7412. doi: 10.1038/s41598-018-25680-6.

Authors

Hee Chang Yoon¹, Kouhara Yoshihiro², Heeyeon Yoo¹, Seung Woo Lee³, Ji Hye Oh¹, Young Rag Do⁴

Affiliations

¹ Department of Chemistry, Kookmin University, Seoul, 136-702, Republic of Korea.
² Yamato electronic Co., Ltd., Kagoshima-Ken, 899-0401, Japan.
³ YEK GLASS Co., Ltd., Seoul, 06093, Korea.
⁴ Department of Chemistry, Kookmin University, Seoul, 136-702, Republic of Korea. [email protected].

Abstract

We introduce a low-melting-point (MP) Sn-P-F-O glass ceramic material into the phosphor-in-glass (PIG) material to realize an 'on-chip' chip-on-board (COB) type of phosphor-converted (pc) white light-emitting diode (WLED) with green (BaSr)₂SiO₄:Eu²⁺ and red (SrCa)AlSiN₃:Eu²⁺ (SCASN) phosphors. The optimum Sn-P-F-O-based ceramic components can be sintered into the glass phase with a facile one-step heating process at 285 °C for 1 min. Specifically, these soft-fabrication conditions can be optimized to minimize the degradation of the luminescent properties of the red SCASN phosphor as well as the green silicate phosphor in PIG-based white COB-type pc-LEDs owing to the low thermal loss of the phosphors at low fabrication temperatures below 300 °C. Moreover, the constituents of the COB package, in this case the wire bonding and plastic exterior, can be preserved simultaneously from thermal damage. That is, the low sintering temperature of the glass ceramic encapsulant is a very important factor to realize excellent optical qualities of white COB LEDs. The optical performances of low-MP Sn-P-F-O-based PIG on-chip COB-type pc-WLEDs exhibit low yellowing phenomena, good luminous efficacy of 70.9-86.0 lm/W, excellent color rendering index of 94-97 with correlated color temperatures from 2700 to 10000 K, and good long-term stability.