Optovate's founders have addressed an interesting challenge - to make a better light source using new semiconductor LEDs. The world wants more efficient lamps to replace incandescent bulbs without the drawbacks of CFL. Existing LED lamps are not really bright enough and cost down and novel form factors are major technology driver in the industry.
A leading trend in the LED industry for some time has been to use bigger single chips of about 1x1mm to get more light from a single device. These large devices have heat dissipation and current crowding problems as well as yield issues to deal with. Some LED companies have addressed this by making large arrays of more efficient 0.3x0.3mm chips that are individually placed and wire bonded to a single substrate. However using these devices present optical engineers with a big problem. The effective source size had gone up from 1x1mm to the size of the whole array: over 10x10mm typically. And as every optical engineer knows this means that the diameter of the optical element needed to produce a collimated beam had gone up to more than 100mm. This means that compact collimated lamps were difficult to produce with these new arrays.
Optovate recognised that a new approach was needed. If we could use arrays of small LEDs we could get efficient light output while dramatically improving heat dissipation. Further, if the LEDs could be made very small, and sparsely separated, then we could use a single array of precision TIR optics to efficiently collimate them. It turned out that 0.1x0.1mm square microLEDs on a 1mm pitch worked really well, but of course doing this on a GaN wafer would waste 99% of the wafer area.
It was realised that this could be solved by transferring the GaN micro-LEDs to another substrate. And if this could be done in a way that preserved their original lithographically defined positions there would be a huge advantage - a single array of individual collimating optics that was both thin and cheap could be 1 step aligned, saving a lot of cost. Pick and place machines were neither fast enough or accurate enough for this. Because there were so many transferred microLEDs (several hundred per lamp) then it was important to be able to electrode the devices efficiently. As the transfer process retained the LEDs original lithographically defined positions from the wafer it meant that lithographically defined electrodes could be used to electrode and connect the whole array in parallel rather than using expensive serial wire-bonding.
Optovate's founders have patented the extraction and placement of a sparse array of microLEDs from a wafer that enabled the whole semiconductor growth wafer to be used and aligned with an optical array. Better than that, they found it was possible to leverage the large area glass processing and lithography already used in the LCD industry to make huge arrays on inexpensive glass sheets. The founders also discovered that by thinning the glass down, the heat extraction from the sparse arrays could make the heatsinks required far thinner than used for the standard LED approach. This led to weight and further cost advantages
The use of this process enables large area substrates up to 1000x1000mm that can be cut down to the lamp size needed in much the same way as done routinely in the LCD industry for different size panels made on the same mother glass sheet.
The results speak for themselves, and today Optovate delivers the total technology package for future directional microLEDs.