Copper was one of the last common metals to become printable, for two reasons that are both consequences of why anyone wants it: it reflects the infrared wavelength most laser powder bed machines use, and it conducts heat away from the melt pool faster than the laser can put it in. Both problems now have answers.
Why it was difficult
At the infrared wavelength of a standard fibre laser, polished copper reflects most of the beam, which both wastes the energy and risks damaging the machine's optics. What energy is absorbed is then conducted away rapidly by the surrounding powder and solid, so forming a stable melt pool is hard. Early attempts produced porous parts and unhappy machines.
How it was solved
Green and blue wavelength lasers are absorbed far better by copper, and machines built around them print pure copper to high density. Higher power infrared machines with adjusted parameters manage it too. Binder jetting avoids the problem entirely by never melting anything in the machine, printing green parts that are sintered in a furnace afterwards, and it has become a major route for copper.
What it is used for
Heat exchangers and cold plates with internal channels no drill can produce, which is the flagship application because copper's conductivity is the whole point. Induction coils, whose complex three dimensional geometry is otherwise hand made. Electrical contacts and bus bars with consolidated geometry. Rocket engine components with integral cooling channels.
Practicalities
Pure copper is used where conductivity leads; copper alloys print more easily and are used where mechanical properties matter more. As with any printed metal, accurate features are machined afterwards, and copper machines poorly, so allow for that. And the supplier base is narrower than for steel or aluminium, so lead times reflect availability rather than build time.
Questions people ask about copper 3d printing service
Why was copper hard to 3D print?
It reflects the infrared wavelength standard lasers use and conducts heat away from the melt pool faster than the laser can supply it, so stable melting was difficult.
How is copper printed now?
With green or blue wavelength lasers that copper absorbs well, with higher power infrared machines, or by binder jetting and sintering, which never melts in the machine.
What is printed copper used for?
Heat exchangers and cold plates with internal channels, induction coils, electrical contacts, and rocket engine components with integral cooling.
Pure copper or a copper alloy?
Pure copper where electrical or thermal conductivity is the requirement. Copper alloys print more easily and suit applications where mechanical properties lead.