Wireless bonded LED technology, often referred to as “flip chip” or “delta chip," offers several key performance benefits. Though the technology was first introduced to the industry about a decade ago, the widespread growth in popularity of high-power LEDs in recent years combined with the increasing adoption of LED technologies in high-performance applications have prompted design engineers to begin to look more closely at the unique benefits wireless bonded LEDs offer. What is a wireless bonded LED?
The main difference between traditional and wireless bonded LEDs is the way they run current. Traditional LEDs use a wire bond to create an electrical pathway at the PN junction. Specifically, the electrical bridge is extended from the positively charged top of the LED die to a negatively charged contact pad at the bottom of the die.
Wireless bonded LEDs use the same type of chip wafer as conventional LEDs. During packaging an extra step is added where the chips are formatted to have both P and N terminals placed on the bottom of the pad. The current is passed between the bottom pads creating a wider bonding surface than conventional wire bond LEDs. At the same time, the package profile of wireless bonded LEDs are about half the size of traditional LED packages.
Figure 1: LED with traditional bonding
Figure 2: LED with wireless bonding: Wireless bonded LEDs provide enhanced heat dissipation, greater durability and superior light performance compared to traditional LEDs
These simple structural differences between traditional and wireless bonded LED technologies have a significant impact on performance in terms of heat dissipation, durability and light performance.
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Several drawbacks of this article:
1. Misnomer of calling flipchip as wireless! The latter term is deeply entrenched in mobile communications as is the former term in the chip interconnect industry!! You need to call a spade a spade...
2. Preaching to the choir! Most readers of EE Times are already familiar to flip chip which has been around for decades now. What I would have liked to see is a cross-section of an actual device and not cartoons.
3. Better, quantified data to backup claims made -the authors makes comments about LED arrays but does not show any data to backup. Irrespective of the interconnect method, thermal cross talk between LEDs joined at the substrate is always going to be a problem and I don't see this proven by data.
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