quick pcb question

av read a number of topics were they say pcbs should be etched face down. whats the reason for this and should the pcb be facing down floating on the surface or face down on the bottom?

thanx

andrew2022 said:

av read a number of topics were they say pcbs should be etched face down. whats the reason for this and should the pcb be facing down floating on the surface or face down on the bottom?

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I don't make PCB's, but face down floating (or at least suspended) is usually best. As the copper is etched off it forms deposits which fall to the bottom, if the board is face up the deposits sit on the board, extending the etching time. If you etch face up, you can agitate the solution to shift the deposits.