Reactive multilayer systems (RMS) are new developed die attaching method, allowing the creation of fast, hermetic and homogenous joining between the circuit carrier and the components. RMS are based on multiple nanolayers made of two different materials such as Al/Ni, Ti/Ni, Ni/Si and Zr/Si, and are fabricated using thin-film deposition techniques. Applying electrical impulse on the sandwiched layers creates an exothermic reaction, allowing the melting and rapidly solidification of materials. As this process generates high temperature of more than 1000°C, exact measurement of this thermal energy should be addressed in order to control and optimize the joining process and to improve the local heat dissipation in order to sustain the functionality of the microsystems.
This work presents in-situ temperature measurement of reactive multilayer systems for self-soldering and micro-joining applications. The temperature characterization of the reaction is made using thick-film Pt temperature sensor embedded in low temperature co-fired ceramics (LTCC) substrate to capture the temperature during self-propagation. Different isolation materials to cover the sensor are used, analysed, and tested to create an efficient in-situ and cost-effective temperature sensor. Optimization of the joining/soldering materials is conducted by adding 2 µm Sn layer covering 10 µm of sputtered Al/Ni-based RMS for modified and unmodified roughness of the carrier. Temperature and velocity of the reaction are influenced by the modification of the surface morphology carried by UV laser ablation.
The self-propagation is carried on ceramic carrier as well as using joining process with different ceramics and Si chips for temperature and tensile tests to investigate the strength, hermeticity and reliability of the joining.