Thanks alot narfnarf for your information
thermal design problems/issues:
Its common to have a product come back afters its been sent out PCB and certain components resistors or IC op-amps or transitors that are causes to much heat burning the board what would cause this problems please? to much current or the part is not the right rating for wattage? or op-amp ,transitors voltage rating problem?
PROTECTION circuits in power supplys,op-amps,transistors should have protection diodes for the inputs,outputs,power,ground pins so if any surge of current it protects the IC pins or components
I re-phrased my question
What are 10 to 20 EE electronic designer "issues" or "common problems"?
I need to know the most common designer issues and common problems in general or basics for any PCB boards or circuits please?