High quality 99.9% Pure C1100 grade Copper Modules presion machined with +/-0.01mm tolerances.
Machined by a certified manufacturer which comes at a cost of about 3X what knock off "so called copper" modules from asian suppliers cost. There are lots of low grade cheap Axiz standard style modules coming from asian suppliers that can have detrimental effects to the lasers operation. Lower thermal efficiency of diode modules using low grade copper can cause fast degredation leading to premature diode failures. Lower grade copper becomes very brittle where it is thinnest. Magnify an image of the lens threading on low grade copper modules you will see the threads are not perfectly clean and have burs and chips in them. When a lens is threaded in and out particles flake off the threading and contaminate the module housing. These particles can find their way to the diode window and damage, destroy or for capless diodes get right on the dye causing fast degradation of the laser. Lower grade copper can be identified by looking at the threads, rounded or square edges or even the flat surfaces. Pure copper will be visibly smooth but if there are pits or chips under magnification those are lower grade copper and dangerous for your diode. Another good test of the quality of a copper module is to thread a lens in and out of your module several times then tap the module on a white sheet of paper and see if any particles fall out and land on the white background.
For our solid thermal back halfs extra machining cuts to get a raised seat to make precise pressured contact with the back of the 9mm diodes for optimal thermal extraction into the module is essential for proper operation of the higher power 9mm diode. This is a hard cut as it requires a special cutting tool that can go at an angle around the threading in the back half. If the solid back half you are using is just flat it will not make proper contact with the back of the diode since the 9mm diode presses in just past flush to ensure proper seating and side thermal contact with the laser diode.