Electrostatic discharge (ESD) can't be added into the chip in wafer level packaging, and there can be outgassing issues where overflowing sulfur material affects the chip’s brightness. Wafer level package has its merits in certain applications, such as high lm/W applications, but it is not always suitable for general lighting products.
Clients higher thermal requirements of above 100℃ has also led to the rise of EMC or SMC material in LEDs. EMC is capable of sustaining a junction temperature of 130℃ because of its better heat dissipation, which allows it to run on higher temperatures. The design of the chip can either be CSP phosphor on die, or flip chip and phosphor. It can be placed on top of carrier, or even without a carrier. Ceramic substrate, metal or other materials can also be used along with EMC.
The advantages of CSP white chip design is it can drive higher currents and at higher flux. As flip chip decreases in size, currently some white chips measure 1.3 x 1.3 mm and are only 150 micron thick, there can be new LED applications. Other emerging flip chip designs include flip chip on board, where 25 to 50 LEDs are packaged using wire bonding or without handling.