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100 I-CONNECT007 MAGAZINE I JULY 2026 back to the discovery of electroluminescence by H. J. Round in 1907, but did not see much commercial- ization until the red-light LED was demonstrated by Nick Holonyak at GE in 1962. Holonyak is commonly referred to as the "Father of the LED." The devices were not all that bright, but they were much less power hungry than the neon orange light- emitting "Nixie tubes," which were common in the 1970s. They set the stage for the development of formats and colors: orange, yellow, green, and blue ushered in low power, high lumens per watt (lm/W). In home lighting, these long-lasting white-light LEDs have replaced incandescent bulbs, where most of the energy consumed is lost as heat. Efficiency has also increased rapidly. In 2000, a white light LED delivered roughly 20 lm/W; by 2010, it delivered 100 lm/W, and today the efficiency is sitting at an amazing 150–250+ lm/W. Display technology using LEDs has relatively quickly gone through several stages in package formats. Initially, it was the dome-shaped or tubular LED, familiar to many electronics hobbyists. These are still relatively large and are most often used for larger-format outdoor displays because the indi- vidual pixels cannot be easily distinguished at a distance; however, they are unsuitable for personal electronics. Developers created newer formats, including the first surface mount versions. What is truly amazing is that the internal construction of the original LED, a semiconductor die mounted on a lead frame with a bond wire and clear encapsulant, is nearly indistinguishable, conceptually, from modern LED packages. 1 The major difference is that today's microLEDs can be 1,000 to 10,000 times smaller than those early through-hole devices. Mini and microLEDs are often used in televi- sions, monitors, and smartphones. The technology progression for light-emitting electronic compo- nents is shown in Figure 1. This brings us to the present and the significant challenges of assem- bling devices as small as a mote of dust. The limita- tions of conventional pick-and-place assembly, the assembly of microLED displays, are summarized in the technology comparison chart shown in Table 1. MicroLED technology employs microscopic light- emitting diodes, typically fabricated from gallium nitride (GaN), that individually function as red, green, or blue pixels. Depending on display resolu- tion and application, driven by the distance of the viewer's eye to the display, LED devices used in displays may range from approximately 3 to 50 µm in size, with many advanced display architectures targeting device dimensions in the 5–20 µm range. For perspective, a human hair is approximately 70–100 µm in diameter. The manufacturing challenge is staggering. A 4K television contains more than 8 million pixels, and because each pixel generally requires separate red, green, and blue emitters, the display may require placement of over 24 million individual microLED devices. Future 8K displays may require nearly 100 million emitters. Therein lies the rub. Conventional pick-and-place systems, which excel at placing packaged compo- nents measured in millimeters, become increasingly challenged when required to handle millions of fragile semiconductor devices measured in microm- eters. At these dimensions, device handling, align- ment accuracy, throughput, contamination control, and yield become major obstacles to commercial- ization. Even a small defect rate can translate into thousands of failed pixels, and even a single pixel failure in a field of millions can be picked up by the human eye. F L E X I B L E T H I N K I N G " In 2000, a white light LED delivered roughly 20 lm/W; by 2010, it delivered 100 lm/W, and today the efficiency is sitting at an amazing 150–250+ lm/W."