Colloquium aankondiging

Faculteit Engineering Technology

Afdeling Production Technology
Master opleiding Industrial Design Engineering

In het kader van zijn/haar doctoraalopdracht zal

Bart Terpstra

een voordracht houden getiteld:

Evaluation of electrically conductive adhesives for high temperature applications



Every contemporary car contains about 60 to 100 sensors for many different applications. Failure of a single sensor can have big consequences for the functionally of the complete car. Therefore, these sensors have to be very reliable when subjected to extreme environmental or internal conditions. A Sensata fuel sensor needs to cope with increasingly higher temperatures because of the trend that engines are becoming more compact and temperatures are going up. In the future, these increasingly higher temperatures could lead to problems with the electrically conductive adhesive that is used to bond certain electrical components in a fuel pressure sensor. The conductive adhesive used is an epoxy resin with a silver flake filler, also known as ‘silver epoxy’.

The goal of this master thesis is to select a new electrically conductive adhesive that can withstand higher temperatures. As a guideline for this assignment, the renowned six sigma ‘DMAIC’ approach and various six sigma tools were used.

As a first step the evaluation was narrowed down to silver filled epoxies after a comparison between different electrically conductive adhesives. For these silver filled epoxies insight was gained in all possible failure modes by doing a comprehensive literature study. To evaluate the performance in practice close to a hundred samples were made with six different high temperature resistant silver epoxies and tested on high temperature and moisture resistance according to automotive standards. Samples were analysed afterwards by ‘Scanning Electron Microscopy’ and ‘Differential Scanning Calorimetry’.

The literature study, tests and sample evaluation revealed a root cause for silver epoxy failures as a result of high temperature exposure. Also based on the knowledge gained, requirements and specifications for silver epoxies were defined and used as a method to rank the different silver epoxies. This resulted in a small selection of the most promising candidates that are further evaluated using a Design of Experiments. The result is the selection of a new silver epoxy for Sensata along with optimized process settings.