10-01-2017, 06:33 PM
Apart from a few colour TVs such as the GECs mentioned above double sided PCBs are very rare in vintage (pre 1980) domestic equipment. Multilayer boards are not seen at all.
There are 2 types of double sided PCBs, with plated through holes and without. PTH boards have a conductive sleeve in each hole which joins the bottom and topside tracks. This used to be a complex and expensive processing step so you won't find PTH on vintage domestic kit. What you will find is pins or rivets to join top and bottom side track. Or component legs will do it. All subject to dry joints on both sides of the board.
Desoldering older PCBs can be tricky without causing damage as the copper is often not well attached to the board. Fortunately the tracks are usually quick big and widely spaced so it's easy enough to bodge a reliable repair with wire, often using excess lead length on a replacement component.
Unsoldering an old double sided non-PTH PCB will often lead to the topside track being damaged. For much component removal, from single and double sided PCBs, I usually cut the component out, melt the solder and tap the PCB on the bench. Then clean up with a sucker or wick.
There are 2 types of double sided PCBs, with plated through holes and without. PTH boards have a conductive sleeve in each hole which joins the bottom and topside tracks. This used to be a complex and expensive processing step so you won't find PTH on vintage domestic kit. What you will find is pins or rivets to join top and bottom side track. Or component legs will do it. All subject to dry joints on both sides of the board.
Desoldering older PCBs can be tricky without causing damage as the copper is often not well attached to the board. Fortunately the tracks are usually quick big and widely spaced so it's easy enough to bodge a reliable repair with wire, often using excess lead length on a replacement component.
Unsoldering an old double sided non-PTH PCB will often lead to the topside track being damaged. For much component removal, from single and double sided PCBs, I usually cut the component out, melt the solder and tap the PCB on the bench. Then clean up with a sucker or wick.
www.borinsky.co.uk Jeffrey Borinsky www.becg.tv
