Here is the abstract you requested from the MASH_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.
|Quantitative Characterization of True Leak Rate of Micro to Nano-Liter Packages using a Helium Mass Spectrometer|
|Keywords: helium fine leak test, quantitative measurement, true leak rate|
|The helium mass spectrometer based fine leak test has been used extensively in the industry for the detection of fine leaks. However, only the time variant apparent leak rate measured by the spectrometer is used as a basis for comparison/characterization. This can lead to erroneous results when applied to micro to nanoliter packages. This paper presents a procedure to measure the true leak rate of packages using the helium mass spectrometer. The proposed method is based on the fact that the profile of the measured leak rate signal depends only on the true leak rate and the volume of the package. Prior knowledge of the volume of the package enables the determination of the true leak rate by performing a weighted regression analysis of the data. In addition we experimentally characterized the effect of the following on the procedure: 1) Uncertainties associated with the desorption of helium that is bombed onto the package surface and 2) Instability of the spectrometer during the initial part of its operation due to helium present in the ambient air that leaks into the spectrometer. Implementation of the method to a package subjected to three different test conditions yielded a consistent value for the true leak rate in every case, thereby verifying the robustness of the method. The accurate true leak rates provided by the method allow evaluation of new bonding materials/processes and package designs fast and effectively.|
|Arindam Goswami, Student
University of Maryland - CALCE
College Park, MD