Lead containing solders are often used to reduce the thermal exposure of temperature sensitive components on printed circuit boards during conventional reflow processing. This paper describes a new joining process that enables fluxless, lead-free soldering of similar and dissimilar materials at room temperature with no thermal damage to surrounding components. The joining process is based on the use of multilayer foils as local heat sources. The foils are a new class of nano-engineered materials, which consist of thousands of alternating nanoscale layers comprised of elements with large negative heats of mixing, such as Ni and Al. With a small thermal or electrical stimulus, controlled, self-propagating reactions can be initiated in these foils at room temperature. By inserting a multilayer foil between two solder layers and two components, heat generated by the reaction melts the solder and consequently bonds the components. Since the heat generated is localized to the bonding interface, significant heating of the components is avoided and thermally sensitive components are not damaged. Materials with dissimilar coefficients of thermal expansion can also be joined, due to the limited and localized heating. This paper will provide several relevant examples of reactive multilayer joining in metal-metal and metal-ceramic systems, but it will focus on a case study where surface mount connectors were joined to printed circuit boards using a eutectic Au-Sn solder alloy. Details will be provided on the thermal exposure of the components during joining, performance verification testing that was performed after bonding, and the process advantages that were gained.