Performance and Reliability of Polymer-based Sensor Packages at High Temperatures
|Kustantaja||Tampere University of Technology|
|Tila||Julkaistu - 9 kesäkuuta 2017|
|Nimi||Tampere University of Technology. Publication|
This work concentrates on the reliability of polymer-based sensor packages at high temperatures and the changes occurring in their materials at different temperatures. The structures were aged using several high temperature tests including thermal cycling, step stress and thermal storage tests at several temperatures around 200°C. The effects of high temperature on several commercial polymer-based printed circuit boards (PCB) and electrically conductive adhesives (ECA) were analysed from an electrical and mechanical perspective. Moreover, changes in material parameters due to aging were studied to achieve a more profound understanding of the effects of high temperatures.
The temperature of 180°C seemed to be low enough not to cause reliability problems in the polymer-based packages studied. Additionally, a good performance in thermal cycling testing up to 180°C was achieved. At 200°C degradation was seen on the surfaces of the polymer materials and their mechanical properties gradually declined. Good electrical performance was nevertheless achieved with suitable material choices. A temperature of 240°C was shown to be too high for extended exposure of the materials studied. With careful material choices relatively good electrical performance was achieved, but FTIR showed dramatic and rapid degradation with most of the polymerbased materials at this temperature. The degradation was much more severe than at 200°C, and the mechanical properties also showed drastic impairment at 240°C.
Material selection was shown to be absolutely critical for the reliability of the whole polymer-based package. With poor PCB material interconnections failed much earlier than with more stable PCB materials. Additionally, ECA selection was also important. This thesis showed that polymer-based electronic packages can withstand high temperatures, especially for limited exposure times. However, it is crucial that all materials present are able to withstand the selected temperatures.