A Prize-Winning Idea
The Nobel Prize in Physics was jointly awarded in October 2014 to Isamu Akasaki, Hiroshi Amano and Shuji Nakamura, “for the invention of efficient blue light-emitting diodes, which has enabled bright and energy-saving white light sources.” Importantly, EB Industries has been helping companies manufacture LEDs for decades. The technology EB Industries uses for precision welding solves many of the challenges in the production of LED light bulbs and LED chips.
Precision Welding in LED Light Bulb Manufacturing
The design requirements for an LED light bulb are substantially different than those for an incandescent bulb. One of the biggest challenges faced is that the LED bulb needs to fit into the same physical envelop as the incandescent bulb it is replacing. This requirement does not leave much room for conventional fastening techniques such as screws or rivets. Additionally, high-powered LEDs can generate significant localized heat causing problems for plastics, glues, and epoxies.
Precision welding technologies, such as laser beam or electron beam welding, apply a very narrow beam of energy that is concentrated in the area of the weld joint, resulting in a very small heat affected zone. This characteristic of the weld has three advantages over other welding technologies. First, the weld can be applied very close to electronic circuits and LED chips without risk of damaging the circuitry or other components such as plastic retainers. Second, there is minimal distortion in the part because only a small amount of material actually melts and flows. Third, the weld is very thin, consistent, and visually pleasing, eliminating the need for secondary machining operations post weld.
LEDs are manufactured following a process that is very similar to the process used in the manufacturing of semiconductors. The manufacturing process includes a number of steps including silicon wafer fabrication, deposition, masking, etching and doping. Precision welding is widely used to build the equipment that performs these steps.
The biggest advantage to utilizing precision welding is that it creates hermetic seals with minimal heat distortion of the underlying material. The manufacturing steps mentioned above involve precisely locating material, strong chemical reactions, high pressures, and tight control of temperature. The different chemicals and compounds used for forming the chip, or controlling the temperature of the process, need to be precisely located and routed without the risk of cross contamination. Precision welding is very useful in creating sealed channels for this purpose. The welds cause minimal distortion of the precision plates that the chips are formed on, and yet provide leak tight joints, which can withstand high temperature and pressure cycling.
Electron beam welding, in particular, has another advantage in chip manufacturing as it can weld refractory metals relatively easily. These types of metals are used because they have low coefficients of thermal expansion and high thermal conductivity, which helps keep the chip precisely located and removes heat from the manufacturing process. However, these same properties make the material difficult to weld. Fortunately the high power density of EBW can melt and join refractory metals.
LEDs Help Make EB Industries Green
As a point of note, EB Industries upgraded all the lighting in its facility to LEDs as part of its effort to make its facility more energy efficient and “green.” This initiative has greatly helped reduce our energy bill, as well as our bulb replacement costs. One additional unexpected benefit that occurred is that our facility is brighter and more pleasant to work in. Our workers appreciate the consistent lighting across the entire manufacturing floor, making it easier to weld and inspect parts.