Lee given 2007 IEEE Components, Packaging and Manufacturing Technology Society Exceptional Technical Achievement Award
Chin C. Lee, Ph.D., professor of electrical engineering and computer science and director of the Materials and Manufacturing Technology graduate concentration, was presented the Exceptional Technical Achievement Award from the
Fluxless soldering and bonding technology joins two materials or objects together using solders, alloys with low melting temperature, without the use of flux, an organic material that enables the bonding action to occur. The flux removes oxides from the solder and shields the molten solder and the metals - to be bonded - from further oxidation.
Without flux, bonding with solders is nearly impossible because the oxide layer adhering on the surface of the molten solder becomes a barrier that blocks tin atoms, or commonly used solders that contain more than 50 percent tin, from “seeing” the metals to form chemical bonds. The melting temperature of the oxide layer is very high and it does not melt at the bonding temperature used.
Bonding using solders is necessary in many products, including certain electronic devices, because the bonding temperature is within the temperature range that most electronic components and electronic materials can sustain.
However, there are specific devices that cannot be exposed to flux, including laser diodes, fiber optical components, photonic devices, micro-electro-mechanical systems devices, biomedical devices, and future flip-chip and three-dimensional integration technology. Flux and flux residues can stay in sensitive regions of the device and deteriorate device performance. For hermetic, or airtight, devices, the trapped flux can slowly release harmful chemicals with time, making hermitic sealing impossible.
The fluxless bonding technology completely eliminates the use of flux. This is made possible by removing the root of the problem, or solder oxidation. Oxidation is prevented in solder fabrication and during the bonding process, allowing for the soldering of devices that cannot be exposed to flux.
Lee received a bachelor’s and a master’s degree in electrical engineering from