What is Diffusion Bonding?
The diffusion bonding process joins layers of sheet metal together. Thin sheets of metal are stacked together in a vacuum, then heated to 50-80% of the base material’s melting point while pressure is applied. This procedure of heating and applying pressure causes some of the electrons from each sheet of metal to migrate to its neighboring sheet until the stack is internally joined together. The result is a strong material, and joint, with the full properties of the parent metal.
Steps for Diffusion Bonding:
- Part Prep: The surface of the pre-etched component must be clean, flat, and have a recommended finish better than 0.4µm RA. This is to limit contamination of the surface.
- A wide range of metals can be used, including Aluminum, Copper, Gold, Inconel, Moly, Nickel, Silver, Stainless Steel, Titanium, and more.
- Single layer thickness typically in the range of 0.003” to 0.025” (depending on feature requirements).
- Heat Applied: In a controlled environment, heat is applied as radiant, induction, direct or indirect resistance.
- Pressure Applied: The pressure is applied in a single direction at a low 3-10MPa pressure. This is to deter deformation of the part.
- Part Finishing: After the bonding process is complete, the parts typically will go through a simple cleaning to ensure the surface is free of residue.
- Removal from the frame (if necessary)
Diffusion Bonding Benefits/Uses:
- Application Uses:
- Applications exposed to extended temperatures, in which alloy mechanical joints could weaken due to very high temperatures. Bonding the layers of metal reduces the risk of malfunction in service.
- Thermal/Heat diffusion on an application, such as a chipboard. Flowing liquid or gas through layers extracts heat from metal to help system cooling.
- Possible Products:
- Fotofab has manufactured heat sinks, shim assemblies, medical device capillaries, biomedical implants, fuel cells, and extrusion dies
- Methods Available (depending on the metal specifications):
- Solid State Diffusion Bonding – bonded without filler material.
- Activated Diffusion Bonds – utilizes plating material. Common plating includes Copper, Nickel, Silver, and others.
- Liquid Interface Diffusion (LID) Bonding – uses molten plating/braze alloys.
Using our photo etching process, Fotofab manufactures each of the flat lamination layers which are bonded to form three-dimensional structures. Together with heat and pressure, diffusion bonding can create a single laminated sheet, with almost unlimited possibilities for internal part structures. Numerous small, precision parts can be created within each laminated sheet. If a part needs to be thicker than 0.63 inches or needs tight intricacies within a larger part, this may be the perfect option. An added bonus is that part complexity does not add to the cost!
Is diffusion bonding right for your needs? Request a quote or give us a call to discuss your project.
Learn more about the Metals We Etch.