To begin, the laminate manufacturer freely admits the material will move, but only during the etching process.
The key they state is to first etch 80% of the copper, cure the material in an oven, then provide a final etch and a final baking cure.
(Image by Jeff Keizer)
When beginning work with a new material, you try to do as much research and get as much advice as possible.
You download the manufacturers documentation and talk with the manufacturers representatives, drill/router bit manufacturers and other PCB manufacturers who have worked on the material in the past.
After compiling all this information, a manufacturing process is developed which fits both the material and your own facility.