Invited Paper VT+EN+TF-TuA1
The Relationship Between Moisture Ingress, Hermeticity Testing, and Internal Gas Analysis (IGA) of Hermetic Structures

Tuesday, October 29, 2013, 2:00 pm, Room 202 C

For countless decades we have relied on Mil-Std 883 Method 1014 to insure not only military, but medical, telecommunication, aerospace, aviation, automotive, and hi-rel commercial devices were hermetic. The Howl-Mann equation, based on the ideal gas law, provided the fundamental theory necessary to relate air-equivalent leak rate measurements to tracer gas bombing pressures, times, and Pass/Fail points. Over the past three decades we have tried to find a relationship between moisture ingress and measured leak rate, and only in the last decade have we made fundamental progress toward that goal by using a highly sensitive leak detector and a specially designed mass spectrometer. Moisture ingress departs from ideal gas behavior because of it’s polar nature and the “three monolayer theory” proposed by Aaron DerMarderosian suggests that there is a surface migration component which is often overlooked. This paper will review leak test and IGA data taken over the past 40 years on commercially manufactured hermetic devices with the hope of identifying both dependent and independent variables which will help us predict moisture ingress, and as a result, reliability.