Printable Reactive Materials for Bonding and Joining

Latent energetic materials like reactive multilayers of Aluminum and Nickel can be used for a wide range of joining applications. By overcoming a certain start energy potential, both materials react self-sustainable and exothermic, providing heat for joining applications. Typically, those reactive multilayers are fabricated by physical vapor deposition showing periodical layer thicknesses in the nanometer range. Despite their excellent reactivity, these multilayered energetic materials have drawbacks, like the need for a support or substrate to be deposited on and often a high brittleness, making it difficult to use for MEMS due to necessary cutting and alignment. Here we report about the transfer of this reactive material concept into a printable paste. The advantages in using printing technology are the ease of deposition directly onto the joining parts. Additionally also curved surfaces can be printed and utilized. However, several challenges need to be overcome in using a reactive paste systems compared to the reactive multilayers. For instance, the powder sized nature of the materials, use of solvents and processing agents reduce the reactivity of such a system. We present the modification of particles based on Aluminum and Nickel powder and the preparation of a reactive paste thereof. The reactivity is measured with differential scanning calorimetry and thermogravimetric analysis and compared with reactive multilayers.