Here is the abstract you requested from the DPC_2009_Biomedical 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.
|Gas Compositions in Sealed Medical Device Enclosures|
|Keywords: Gas Compositions , Medical Device, hermetic seal|
|More than 30 years ago, serious field failure incidents demonstrated that too much moisture within sealed microelectronic packages in mission-critical military and space applications impaired the functional reliability of those components. The main cause of failure due to moisture was galvanic corrosion of contacts and metal interconnects on IC chips. Sealed, implantable medical devices are equally mission-critical (in their own way) and are equally vulnerable to the deleterious effects of moisture. Implantable devices in vivo must maintain seal integrity with no internal materials outgassing to control internal moisture concentrations. This is not reliably occurring in the field with growing consequences, both medically and legally. The two principal causes of excessive moisture in any sealed enclosure are materials outgassing and/or failure to achieve or maintain the enclosure’s hermetic seal. Focus has traditionally been on controlling leaks to prevent elevated moisture. This focus continues with new capabilities for helium leak detection approaching 1x10-13 cc atm/sec, a more than four orders of magnitude improvement. However, little real data have been published differentiating between hermeticity loss and materials outgassing as root causes of elevated moisture. In fact there is debate as to whether leaks in the 10-13 range even exist, or are of practical significance. Internal gas analysis data for 200 archival units of various types of microelectronic packages is reviewed. Materials outgassing is the cause for excessive moisture levels in ~75% of the sealed devices that are noncompliant to the 5000 ppmv maximum moisture content called out in military specifications. Engineers responsible for hermetically sealing medical devices can use the information presented here for materials and process improvements designed to minimize moisture and other harmful volatiles in sealed enclosures. The paper also touches briefly on other gaseous species that degrade performance in sealed enclosures. These include oxygen, hydrogen, ammonia, and volatile hydrocarbon compounds.|
|Richard Kullberg, Technical Affiliate
Oneida Research Services Inc.