What is Diffusion Bonding?
The diffusion bonding process joins layers of sheet metal together with heat and pressure. 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. A strong material and joint are created with the full properties of the parent metal.
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Steps for Diffusion Bonding
There are several steps to the diffusion bonding process, including:
- 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.
- 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
Diffusion bonding has a lot of benefits and is used for a variety of applications. Examples of both are included below.
- Application Uses:
- Applications exposed to extended temperatures, in which alloy mechanical joints could weaken due to 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.
Here at Fotofab, we use our etching process to manufacture the flat lamination layers that get bonded to form 3-dimensional structures. Diffusion bonding creates a single laminated sheet, with almost unlimited possibilities for internal part structures. A number of small, precision parts can be created within each laminated sheet. This service is great for parts thicker than 0.63 inches or for parts that require tight intricacies within a larger part. 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.