Removing relay without damaging pcb (plated through holes)

If using a desolder tool and solder braid still leaves it stuck it's often best to carefully wreck the component so you can treat each pin individually.

Make up a pyramidal truncated frustrum (Google) out of 4 pieces of tin- plate, wired together. Mask off that area around the relay, with the frustrum temporarily wired to the board. Mount board firmly in vice, near the relay. Pull and wriggle the relay when you apply heat from a hot-air gun directed into the frustrum. If you don't believe it will work try the technique with plated thru comps on a scrap board first. The hotter the air and quicker you are the better, if board starts to discolour there is probably some other mechanical restraint.

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

There is only one way: chop the relay up until you can get to each pin, and desolder those individually.

I however would open the relay and file the contacts, far easier option.

NT

gun

As it happens, the last week I've been working on industrial boards with plated-through soldering. Thick board so only tips of IC leads protrude, very thin signal traces, traces to tiny pads on both sides of boards of same pin in some cases and plated vias under ICs as well. I know if i'd used "proper " vacuum assist desolder or butcher-and-remove single pins , many of those traces/pads would have dislodged. I had to sharpen the points of my large adapted circlip pliers to get the extra purchase on the ends of these 14,16, and 28 pin ICs. Not one dislodged track using a paint-strip hot-air gun. Next time i'll have to take some before and after pics for the doubting thomases.

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

That's the way I'd do it.

That's the way I've done it.

on

I would just leave it as it is rather than knacker the board

Any recommendations on how to "chop up" the relay? Its a sealed plastic type.

Are the pins smaller than the plated through holes. or are they a tight fit? If there is any free space you can remove the solder, then heat the pin till the solder melts and gently bend it loose from the wall of the plate through hole. I've done it that way for decades, but you should practice on a scrap board first.

Sharp cutters like these:

Cut into it from the top and keep cutting stuff away until just the pins are left. Be careful cutting away the plastic bottom that you don't scratch through traces or otherwise accidentally damage the board.

If you have a *good* desoldering tool (with a vane pump etc.) it may be possible to suck almost all the solder out of the holes so they break away when wiggled without damaging the plated-through holes, but it's not always possible, and it runs more risk even with good tools and even if you have just cleaned the tool out.

I've used a Dremel tool to remove relays, as well as other components, by cutting them to pieces, carefully, of course. Then I unsolder one pin at a time. Unless you need to do failure analysis on the bad part.

Al

Which bit do you use? A grinder or a saw bit

Cutting off the relay is the hard bit, as many have quite hefty bits of steel in them. A cutting wheel in a die grinder (aka dremel) works, but can be slow.

NT

We just usually use the hot air bonder. Sorry had to go there.

on

Carefully destroy the relay without damaging the circuit board so that you have the stubs of the leads still sticking out from the PC board, then solder to them. if you're lucky, there'll be enough leads exposed so that you can just cut them and leave enough stub.