Would this method work?

[Apostrophe]

This is a question following beachycove's post in the Mac II, Quadra and Centris forum concerning capacitor replacement.

Now, first of all, let's get this out of the way--I don't want to have to melt, liquefy, or even touch lead (Pb) at all. DON'T SAY ANYTHING. We've already been there. For those of you who are thinking of giving the usual negative, don't-be-ridiculous replies, just accept it--I don't want to even touch lead. Please, no comments on how pathetic I am.

Now that that's out of the way...okay, so I want to replace capacitors in my Macs, right? So, what if I start it off by using the guidelines in beachycove's link--using wire cutters to cut the capacitor off the board. Then, since there will probably be no wiring left, could I a) solder two pieces of wire to the board using LEAD FREE solder, and then B) soldering the capacitor onto those wires?

Would that general idea work? I saw something similar to this on a RAM resistor in one of my SEs, where it had been clipped, and then someone had soldered it back on, simply connecting the clipped wire on the front side of the board with solder. I ended up clipping it again since I have 4MB in there, but would that idea work to replace capacitors without even desoldering anything?

-Apostrophe

 

[MacJunky]

Problem is that to properly apply the solder both surfaces have to be heated up to the point where the solder will melt.

As far as I have seen lead solder has a lower melting point than the lead free stuff so any leaded solder on the board will melt.

You _really_ _really_ are just far better off getting some desoldering braid and/or vacuum desoldering tool so you can remove most if not all of the lead solder then just apply nice fresh solder the the pads/vias/whatever.

Seriously. You cannot do this without exposure to lead. Now, if you have a solder paste.. perhaps. perhaps. It would not turn out pretty though.

 

[Mac128]

I don't want to have to melt, liquefy, or even touch lead (Pb) at all.

Not sure if this is a health concern or not, but basically, what MacJunky said. The repair on your SE most likely used lead, so that the two different solders melted together. So unless you cn get someone to do it for you ... plus, it is almost impossible to clip some of the caps. From the SE/30 forward you start to run into surface mount stuff, so nothing there to clip.

 

[Apostrophe]

Hmmm...Mac128, I'll keep in mind what you said about surface mount stuff, for my Centris and such. But for now, let's focus on my pre-SE/30 machines, namely the SEs and the 512k. (And the Apple IIc, but I'm not too worried about that one right now.)

First of all, assuming I clip a capacitor off the board and all that, is there lead present there on that surface?

Because then, all I'd have to do is to melt on a blob of lead-free solder big enough to cover the lead, so even if the lead did melt, it would be covered by the lead-free. (For instance, comparing solder joints on the back of a logic board to those on the back of an analog board--the analog board uses much bigger 'blobs' of solder.)

Then, with my newly lead-freed joint, I'll be able to heat up both surfaces and get it all to melt together. Or else I can find some sort of conductive glue, then just glue little bits of metal to the leaded joints, and then melt everything else on top of that...I dunno. I'm working on it. I'm still trying to think of ways to do this, taking into account what you have said so far.

Anyway, thanks for your comments. I'll think of something!

-Apostrophe

 

[MacJunky]

I know you said not to.. but seriously, stop being concerned about this.

really

Just get a vacuum desoldering tool at radio shaft and suck up all the leaded solder with that. Do it outside if you must but just do it.

With mine at least, the removed solder can be ejected after sucking it up so just get a little tin can or something to dump the old solder into.

Braid is another option that you might like more since you can just snip off the ..infected/contaminated.. section. However it is more exposed in general and you might not like that part of it.

This level of lead is not gonna do harm. If you must you can use gloves and a mask. But just suck it up and do it.

 

[JDW]

The author of this thread will not be convinced by any of this, but I offer it for the rest of you interested in knowing the caveats of going Pb-free in your soldering work:

It's All in the Whiskers

Tin Whiskers Photo

Electroplated Tin and Tin Whiskers in Lead Free Electronics

Aging Capacitors and Tin Whiskers (Low End Mac)

I could go on, but after reading this (you did read all those articles, right?) I am sure you get the point. There are also other issues of Pb-free solder being harder to work with, but I spare you those details.

Simply put, if you turn on a fan to blow fumes from your nose while you solder, and if you then wash your hands after your solder job is done, you need not worry one bit about poisoning yourself even in a tiny way. Indeed, if there is any thing to "worry" about, it would be the potential for electrical short failures induced by Pb-free solder "tin whiskers" some years down the line. It may take 10 years for that to occur, but without any Pb to prevent them, whiskers will emerge and grow to lengths longer than you may expect.

 

[Mac128]

Simply put, if you turn on a fan to blow fumes from your nose while you solder, and if you then wash your hands after your solder job is done, you need not worry one bit about poisoning yourself even in a tiny way.

Indeed, such vents in chemical labs protect their workers, along with filter masks. And you could always wear latex gloves. But I concur with your initial assessment.

 

[joshc]

Don't use lead-free solder - it requires a much higher temperature, is hard to work with, and is simply not as good as tin lead solder. Use the REAL STUFF, nothing beats it.

 

[Osgeld]

Ive always felt the goop inside the caps is much more toxic than normal soldering exposure to lead

+ i HATE the wire cutter method, you are really asking to rip a pad clean off the board with brute physical force

If you are seriously concerned about it, you could use a vent system (altho if your vaporizing lead you would burn tru the board, that smoke is flux) and gloves

 

[porter]

Ive always felt the goop inside the caps is much more toxic than normal soldering exposure to lead

Lead never leaves your body. So don't eat the solder.

 

[JDW]

Lead never leaves your body. So don't eat the solder.

I'm not sure what to make of the "don't eat the solder" quip as such is obvious for any of us adults reading this thread. As to the "never leaves the body" remark, that is not 100% true. But it is partly true in that Pb stays in the body a long time. I recommend this short John Hopkins University Report, noting the section on page 2 entitled "How does lead get into the body?" I don't say this in defense of Pb or leaded solder. I simply state it for "the facts." Even so, it is still important to consider that Lead Free Solder = tin whiskers = potential short circuits (which is more critical a point than just to say "lead free solder is hard to work with").

 

[Unknown_K]

Solid lead is not that big of a problem (doctors have been known to leave lead bullits in hard to reach places in people with no ill effects), but lead paint in solvents that will soak into you or lead fumes breathed in are bad.

 

[Osgeld]

Solid lead is not that big of a problem (doctors have been known to leave lead bullits in hard to reach places in people with no ill effects), but lead paint in solvents that will soak into you or lead fumes breathed in are bad.

course to actually vaporise lead you need heat over 800 degrees F, which in this case will destroy anything around it on a pcb well before hand

The flux smoke is not exactly harmless either since it is a mild acid, but a simple fan takes care of that

 

[JDW]

Here is further information on Pb-Free Soldering and Tin Whiskers, at the bottom of this Advanet Japan web page. Of course, the main reason for this company and so many others to move to Pb-free is "global regulation of Pb," as opposed to Pb-free solder being "the best engineering materials choice for electronics use." So if you decide to go with Pb-free solder, keep in mind that Whiskers can be a problem depending on the solder point spacing, and extra heat will be required.