Fatigue measurement setup under combined thermal and vibration loading on electronic SMT assembly

In this work we introduce an experimental setup for combined thermal and vibration experiments which provides well-defined load conditions, ability of in-situ load measurement and rigging-free or know-rigging behaviour of the experimental setup. A test vehicle and an associated mount as well as in-situ measurement approaches were developed and tested. This novel setup offers test vehicle clamping options which represent system conditions including rigging for qualification purposes (see figure 1) or enable fatigue research which rely on constant rigging-free load conditions (see figure 2). The specimen is a standard PCB with mounted SMT components. Typically vibration will be done as a sine dwell with frequencies in the range of 50 Hz…1 kHz. The setup may be used for isothermal vibration experiments at room, lower or higher temperatures (e.g. −40°C or 125°C) but it enables vibrations experiments at temperature cycling conditions as well. A low weight mount and PCB design targeting temperature cycling with reasonable gradients of about 1 K/min. Combined with integrated PCB heaters even local component heating is enabled. Dependent on the temperature condition either optical or capacitive contact-free in-situ displacement or deflection measurements can be utilised (see figure 4 and 12). The latter is very important for small or 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 (see figure 13 and 14).