Inveracious Enhancement Effect of Light Efficiency in Solder Paste-Bonded Deep-Ultraviolet Light-Emitting Diodes

Deep-ultraviolet light-emitting diodes (DUV-LEDs) show wide applications in sterilization and disinfection, air and water purification, and biochemical detection. However, the light efficiency of DUV-LEDs is greatly affected by the chip-bonding material and technology. In this work, we investigated the inveracious enhancement effect of light efficiency in solder paste-bonded DUV-LEDs. The DUV-LEDs were packaged with different usage amounts of Sn-based solder pastes for chip bonding. The light output powers of these solder paste-bonded DUV-LEDs have remarkable rise after 48-h lighting time, and their maintenance rates increase to 104.9%, 112.3%, and 126.8% for the DUV-LED-S1, DUV-LED-S2, and DUV-LED-S3, respectively. Furthermore, under a UV + cleaning treatment, the DUV-LED-S1, DUV-LED-S2, and DUV-LED-S3 enable the higher light efficiency enhancement of 2.5%, 16.4%, and 39.3%, respectively, owing to the efficient removal of organic film on chip surface and the elimination of light loss influence. The UV + cleaning treated DUV-LED-S3 displays higher light output power than the untreated DUV-LED-S3 under various lighting times. The results indicate that the inveracious enhancement effect of light efficiency could be efficiently avoided by the UV + cleaning treatment. Our work opens a meaningful guidance and solution for the inveracious light efficiency enhancement effect of DUV-LEDs in solder paste packaging.