This Master Thesis in Mechanical Engineering analyses the mechanical resistance of the channelled structure constituting a Printed Circuit Heat Exchanger (PCHE) during the building process. A PCHE is a particular type of heat exchanger which is made by different laminae, machined by chemical etching to create pseudo-circular channel. The plates are welded together via Diffusion Bonding (DB). The DB is a welding technique based on the junction of pieces thanks to the contact of the different interfaces of the components to be welded, putting them in contact at high temperature without any external material. This procedure is helped by the presence of the external pressure and the elevate temperatures improve the phenomenon of the grain growth, fundamental process of that technique.