From the very start of his career, the young engineer took part in the development of LEDs, from chips made in small quantities to products for the mass market. “As a result, I was able to more extensively enter many areas of development than would be possible today,” says Brunner. He gained experience in product development as well as production, spending a year in Malaysia at an Osram Opto Semiconductors plant. Today, the 44-year-old is head of process development in the backend segment of Osram Opto Semiconductors, a Siemens subsidiary founded in Regensburg in 1999. The backend segment encompasses installation and arrangement of the chips in their housing, the design of the housing, and development of the manufacturing process.

The 86 inventions and 137 patents by Brunner over the past 17 years serve as a kind of “roadmap” depicting the spread of LEDs. Whether backlighting of mobile telephones and keyboards, automobile headlights, replacement for conventional lighting elements such as incandescent bulbs, or use as light sources for projectors – LEDs are found everywhere today. Every application requires a special design of the light-emitting diode, which Brunner has achieved with his continuous flow of inventions. While backlighting of mobile telephone displays requires the smallest possible LEDs, an automobile headlight requires the highest possible luminance.

In addition, light-emitting diodes place special demands on their housing materials. “In addition to exhibiting optical transparency, the material must above all be resistant to radiation and able to withstand high temperatures,” Brunner explains. This is because the light-emitting diodes must be able to withstand short-term heating to temperatures of 260 degrees Celsius when they are being soldered to a circuit board, without displaying any adverse impact on quality. In operation, an LED develops temperatures of up to 150 degrees Celsius directly at the chip. The housing itself may reach 125 degrees Celsius. “The great advantage of LEDs is their longevity, so naturally the plastic that makes up their housing also has to be extremely robust,” says Brunner. At the same time, the housing must provide optimum heat dissipation. Many of his 137 patents protect the unique design of LED housings in combination with specially developed plastics. The chip is surrounded by high-performance optically transparent materials; today, these are mainly special silicones. Many LEDs are also equipped with reflectors made of high-performance thermoplastics that are particularly good at reflecting light. In this way, developers have been able to steadily increase the efficiency of LEDs.

The success of LEDs is due in part to gradual development of colored lighting. Here, too, Brunner was involved in the development of many new products. LEDs radiate light in “saturated” colors – in the colors of the rainbow, in other words. White light, unsaturated and purple colors are achieved by light conversion. Many of Brunner’s inventions are the result of investigations into which luminescent materials can produce the desired colors. Today, LEDs are available in all shades of white, from cold white to warm white. As a result, they play an increasingly important role in general lighting. LEDs may also make a significant contribution to reducing CO2 emissions because they are considerably more efficient than incandescent bulbs or halogen lamps. They exceed even the efficiency of energy-saving bulbs, while also displaying a much longer service life.