Developments for Highly Reliable Electronics - Experiments on Combined Thermal and Vibration Loading

Abstract

In this work we present an experimental approach for reliability investigations under coupled vibration and thermal loads. The approach overcomes drawbacks as undefined load conditions, no in-situ measurement option, and unwanted specimen behaviour e. g. rigging. A test vehicle and an associated mount as well as an in-situ measurement approach were developed and tested. The novel setup offers test vehicle clamping options which represent system conditions including rigging for qualification purposes or enable fatigue research which rely on constant rigging-free load conditions. The utilised specimen is made of standard PCB material and is assembled with SMT components. Typically, vibration load will be applied as a sine dwell with frequencies ranging from 50 Hz to 1 kHz. The setup may be used for isothermal vibration experiments at room as well as lower or higher temperatures (e. g. -40°C or 125°C). It enables vibrations experiments at temperature cycling conditions too. Mount and specimen are designed for a low weight and target for temperature cycling with reasonable gradients of about 1 K/min. Specimen integrated heater features even enable local component heating. Dependent on the temperature condition either optical or capacitive contact-free in-situ displacement or deflection measurements can be utilised. The latter is very important for small and low weight specimens since acceleration sensors usually add to much mass and strain gages are difficult to mount. Using the contact-free measurement systems high spatial and time measurement resolution can be achieved. First results on isothermal vibration experiments on SnAg1.0Cu0.5 solder joints will be presented.