Dicing of HB-LED devices embedded in copper substrates

Abstract

High-brightness light emitting diodes (HBLEDs) are often embedded into a heat sink layer, providing an efficient and inexpensive method of expanding the surface area necessary to dissipate heat generated during operation. Copper (Cu), copper tungsten (CuW) and Molybdenum (Mo) layers offer high-performance thermal management due to high thermal conductivity and a low thermal resistance.Classical dicing techniques, such as laser or diamond blade cutting, face a number of constraints and challenges when used to cut Cu and CuW embedded LED chips, such as fast wear of the blades, low speed and heat damages. The Laser MicroJet® technology, combining a hair-thin water jet with a high-power laser beam, offers wear-free, fast and damage-free cutting of LED devices.The singulation of copper embedded LED devices has been successfully performed using the Laser MicroJet® technique. Q-switched solid-state lasers operating at a wavelength of 532nm and a repetition rate of 30kHz were combined with 40-mm diameter water jet. Copper substrate thicknesses of up to 600mm were processed with good cut quality, despite large film thickness non-uniformities. Secondly, 50-mm thick copper layers deposited on sapphire wafers were also diced successfully with 14 passes at 200mm/s. Thirdly, CuW wafers with a thickness of 250mm have been diced with an excellent quality.High-brightness light emitting diodes (HBLEDs) are often embedded into a heat sink layer, providing an efficient and inexpensive method of expanding the surface area necessary to dissipate heat generated during operation. Copper (Cu), copper tungsten (CuW) and Molybdenum (Mo) layers offer high-performance thermal management due to high thermal conductivity and a low thermal resistance.Classical dicing techniques, such as laser or diamond blade cutting, face a number of constraints and challenges when used to cut Cu and CuW embedded LED chips, such as fast wear of the blades, low speed and heat damages. The Laser MicroJet® technology, combining a hair-thin water jet with a high-power laser beam, offers wear-free, fast and damage-free cutting of LED devices.The singulation of copper embedded LED devices has been successfully performed using the Laser MicroJet® technique. Q-switched solid-state lasers operating at a wavelength of 532nm and a repetition rate of 30kHz were combined with 40-mm diameter water je...