Abstract: Described in this document is a process for making heat transfer devices such as cold plates. The cold plates can be made by 3-D printing a polymer substrate, applying thermal spraying deposition of metal over the substrate, dissolving the substrate for removal to form an enclosed flow region through for passage of heat transfer fluid. Molten metal droplets can be sprayed onto the substrate having a surface region comprising a water-soluble thermoplastic to form metal splats on the surface region at a splat temperature and surface properties such that the metal splats penetrate and interlock to form a solid metal coating adhered to the polymer substrate. A dissolvable substrate can facilitate removal by contacting with a solvent to form the enclosed flow region defined by metallic surfaces, and also can enable complex geometries and enhanced heat transfer performance without the need for extensive machining.

Abstract: An apparatus and method for the production of small, uniform sized droplets. The apparatus is a droplet generator including a housing defining a chamber for holding a material to be ejected therefrom, an inlet and a droplet outlet communicating with the chamber. The housing is coupled to a pressurizing system connected to the inlet for applying pressure pulses to the chamber. The housing includes a vent in communication with the chamber for relieving pressure in the chamber. The vent has an effective size so that during application of the pressure pulse the chamber is pressurized to a pressure effective to eject a droplet of the material therefrom and thereafter the chamber is vented through the vent at a rate sufficient to prevent further discharge of droplets. The droplet generator produces molten metal or alloy droplets and is particularly suitable for generating single droplets on demand in manufacturing techniques using droplet deposition.