Here is the abstract you requested from the IMAPS_2007 technical program page. This is the original abstract submitted by the author. Any changes to the technical content of the final manuscript published by IMAPS or the presentation that is given during the event is done by the author, not IMAPS.
|Evaluation of Removal Rate of Cured Silicone Adhesive from Various Electronic Packaging Substrates by Solvent and Silicone Digesters for Rework Applications|
|Keywords: silicone, cleaning , rework|
|As microelectronic packaging gets smaller, silicone adhesives are being used more frequently due to their ability to handle wide temperature fluctuations and lower elastic modulus compared to other organic adhesives, such as epoxy. There are times when the electronic package may need to undergo reworking and the silicone adhesives will need to be removed by a means that causes minimal damage to the solder and wire bonds and other sensitive components. A common recommendation is to remove the silicone by swelling in solvent and gently picking the silicone adhesive from within the package. Blowing air and/or sonnication can help accelerate the process but it still may require physical manipulation of the part, risking damage. Silicone digesters are another means of removing cured silicone. They are comprised of weak acids or bases and remove silicone by breaking the siloxane bonds that make up the polymer matrix. They are able to penetrate into areas that are difficult, or impossible to reach, greatly reducing the risk of causing damage due to mechanical removal. The purpose of this study is to evaluate the rate of silicone removal by solvents and silicone digesters on silicones bonded to various substrates. The rate and effectiveness of these combinations was summarized by rating how quickly a change in silicone appearance was observed as well as when delamination and/or silicone dissolution in the case of silicone digesters. Silicone adhesives and Thermal Interface Materials (TIMs) were used in the evaluation of two commonly used solvents and two commercially available silicone digesters. Copper and aluminum panels were evaluated by using a ~ 0.5 mm thick layer of silicone to bond 2 panels together. The samples were placed incleaning solution for 24 hours at 40 degree Celsius and evaluated at specific intervals for any changes in appearance of silicone. Based on the performance of combinations of silicone, substrate and cleaner, the engineer can chose which method is best for reworking based on their own assembly configuration and materials.|
|Michelle Velderrain, Technical Specialist
NuSil Technology LLC