Processes and systems for spray deposition onto polymer substrates and via masks to produce flow devices

A process comprising:

• spraying molten metal droplets through a polymeric mask comprising openings and overlying and being spaced-away from a metal base to form raised metal structures extending from the base to a height at or below a lower surface of the mask;
• removing the mask to expose a recessed region defined between the raised metal structures;
• filing the recessed region with a substrate;
• spraying molten metal droplets to form a solid metal coating adhered to and enclosing the substrate;
• and
• removing the substrate to form an enclosed flow region defined by the solid metal coating, the metal base and the raised structures.

A process comprising:

• spraying molten metal droplets through a polymeric mask comprising openings and overlying a metal base to form raised metal structures extending from the base;
• and
• removing the mask to expose a recessed region define between the raised metal structures;
• and
• wherein the polymeric mask is positioned to provide a gap between a lower surface of the mask and the base surface, has a smoothness inhibiting adhesion of metal during the spraying, and has a composition and thickness to inhibit thermal deformation during spraying, such that molten metal droplets impact the base and agglomerate to form the raised structures having a height at or below a lower surface of the mask for facilitating release of the mask after the spraying.