Spectrum PCB foil delamination

[Diminished]

Something tells me this machine isn't going to power on. I've never seen a PCB do this before.

[dp11]

Very common in PCBs of the eighties. I wouldn't worry.

[Diminished]

Very common in PCBs of the eighties. I wouldn't worry.

I'm surprised. This isn't my first brush with a vintage PCB, but it's a new phenomenon to me.

What causes it? Moisture? I know this machine was stored in a garage for a good long while.

It's surprisingly regular and pretty in places.

[IanS]

It may have been like that from new - https://www.reddit.com/r/AskElectronics ... like_this/

[Diminished]

It may have been like that from new - https://www.reddit.com/r/AskElectronics ... like_this/

Ah, so the solder has actually flowed under the foil! I wondered why the wrinkly bits resisted fingernail pressure.

Thanks.

Guess I'll go ahead and mod the video then, and we'll see if she lives.

[1024MAK]

Something tells me this machine isn't going to power on. I've never seen a PCB do this before.

That’s not foil delamination. It’s either solder having run/flowed under the solder mask, or the solder mask having been effected by cleaning chemicals. It does not normally affect operation.

Mark

[Diminished]

I get it. So they're actually just lumps of solder on top of the foil, but under the mask? That makes more sense.

[Lardo Boffin]

Its pretty normal for Sinclair PCBs (and possibly others) based on the ones I have seen. I even have ZX81s that have that going on. Not as bad but there all the same.

[1024MAK]

Yeah, on boards that have not been repaired, it got there during manufacturing of the board. But sometimes when soldering replacement components, especially where a lot of heat and solder is needed, some extra may flow under the solder resist!

I’ve seen similar on on other non-Sinclair boards as well.

Mark

[fordp]

My Spectrum 16K was like that from new. It had no impact on it working.

[daveejhitchins]

This effect is caused by the PCB being HASL'ed (Hot Air Solder Leveled) before the solder resist was added. So then, when the board went over the solder wave, the solder under the resist melted and crinkled. Very common for a while - then the penny dropped

Dave H

[Kazzie]

Many thanks for the explanations: I've seen the same phenomenon several times, but didn't know the details behind it!