Hi Craig
re book: fascinating, and THANK YOU.
For metals that strain harden like copper, nickel and especially austentitc stainless (300 series) that is a mistake.
I will add titanium to that list. It's 'aggressive' or nothing. Rub it, it heats and work hardens, and you are out the window.
With this heavy copper board I can have a trace only 2.3mm wide having a conductive area of 1mm square. I assure you it is very seductive to be able to make traces that can handle high currents in such narrow widths.
Oh yes!
I had a commercial servo drive PCB like that. It failed: the mfr did not allow for the special needs of the heavy copper layer, and managed to 'dry joint' some of the heavy current connectors. Photo attached.
Cheers
Roger