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Jetting- a new paradigm in dispensing of Light Emitting Diode Products...

Bob Hoffman, Asymtek, Carlsbad CA, USA...

Today's advanced packages for electronics are required to meet a wide range of requirements for reliability, size and cost. Wire bonded, molded devices soldered to printed circuit boards with surface mount technology still prevail in low cost electronics (televisions, VCR's, washing machines, etc). As the need for portability, performance, or reliability increases, so do the challenges in packaging necessarily increase. The attention is on the size and performance constraints of notebook computers, mobile phones, gaming devices and other handheld portable electronics. Virtually all of these devices have multiple LED's within them. The latest environmental regulations that prohibit the use of the most common interconnect material (lead-based solder) will force the packaging engineer to sharpen all the tools in his tool box to be ready to produce products in keeping with these requirements. Packaging of power LEDs has its own challenges, in the requirement to handle large amounts of heat, maintain color purity and produce a rugged package for outdoor and automotive use. And the mantra "smaller, faster, cheaper" has turned into a fevered battle cry, as with all electronics manufacturing today. The number of dispensing applications in the production of LEDs is increasing. One of the newer opportunities is in the application of yellow phosphors to blue LED's to make white light. Other applications call for different phosphors to make red green and blue light. These phosphors are born in either an epoxy or silicone base material that can be applied at very high rates in individual shots, while flying over an array of LEDs in wafer or discrete form. Further, silicone encapsulants, thermally or electrically conductive epoxies and gasketing materials are being dispensed in today's power LED packages. Spray processes found commonly at the PCB assembly level are flux application, before reflow and conformal coating after assembly. Theses processes for LED's have demands often in excess of the "normal" manufacturing process, for the sake of heat and light extraction, color purity and lead free compliance. Flip-chip manufacturing techniques are now being adopted to increase the extraction efficiency. Only a small portion of the energy consumed in a powered LED is given off as light. The majority of the energy must be dissipated in the form of heat, an...

Document Keywords

Jetting - A New Paradigm in Dispensing of Light Emitting Diode Products en us divisions asymtek documents papers 2005 10 jetting new paradigm dispensing of light emitting imaps nordson asymte k

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Apply adhesives, sealants, powder and liquid paints, and coatings with precision dispensing equipment from Nordson. In addition to industrial coating and surface preparation machinery, Nordson also produces...

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