Soldering question for the more experienced

Hi, I've got a project that I'm working on and I'm having some trouble with a solder joint. I'm adding an optical output to a Minidisc deck. It's a low-cost deck and the output exists on the pricier models in this line. So the circuitry is there, just no Toslink transmitter. I located a transmitter and proceeded to try to solder it to the PCB. The holes were already there and they were filled with solder. My plan was to just heat the existing solder to insert the part. That wasn't working very well, so I ended up cleaning out a couple of the holes with a sucker and tried to solder the part in with new solder (flux filled "for electronics" solder). The problem is, the new solder doesn't stick to the board, just the post of the transmitter, making a lollipop-shaped stick with the lump of solder at the top. It doesn't make a good connection. I figured I just needed to buy some flux and clean that part of the board with it. The problem is, they have no flux at my local RS (back by the guns in the local hardware store). So I ask you experts, is this the right solution? Is there something else I should do? Where can I order some flux from inexpensively in the USA? Anything special to look for with flux for electronics projects?

Thanks!

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Matt

"Gravity. It's not just a good idea, it's the law!"
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Reply to
MattB
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It sounds like the pads are not being heated properly. When soldering, it is important to use a small tip that can touch both the lead and the pad simultaneously. A small bead of solder on the iron tip is also a requirement to conduct heat to both items properly. Also, I recommend a 700 degree (F) tip for most solder jobs. Check my page and the soldering tutorial- not really an exhaustive one, but useful.

Cheers!

Chip Shults My robotics, space and CGI web page -

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Reply to
Sir Charles W. Shults III

You're "cold-soldering", it sounds like to me. Heat the lead/pad, not the solder. Done correctly, the solder will flow to where it's needed. Done incorrectly, the result is much like what you describe: A solder "lolipop" on the end of a component-lead stick.

It's also possible that there is no copper on the "back" side of the board for the solder to grab - The actual connection may be either on the other side of the board, or partway through, on an internal layer of traces. You are aware that some electronic goods use boards with many different layers, aren't you? 11 layers are the most I've ever personally seen (And lord, what a pain to try to either solder or desolder) on a single board, but there's no theoretical limit to how many *COULD* be stacked up like a Dagwood sandwich.

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Don Bruder -  dakidd@sonic.net
Reply to
Don Bruder

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Matt:

Like Chip and Don said, but also, DON'T USE FLUX FROM THE STORE! It's highly acidic and will eat the board away. Just use the flux/resin-cored solder, and use a good soldering technique, as you're being advised. Good luck.

Ken

Reply to
Ken Taylor

highly

Thanks to all you guys. I'll try the methods mentioned and see how it goes. I think it's just a single layer board, there's not really that much to it.

Matt

Reply to
MattB

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I think your main problem is that the soldering iron you're using can't heat up the PC board enough, just the component leg. Get a higher power soldering iron.

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Reply to
Watson A.Name - "Watt Sun, Dar

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Matt, if this is a single sided board than how could you have solder in the holes?....What you need to do is to is heat the board and the wires at the same time, then add the solder to the board. It should crawl up the wire and form a fillet.......good luck, Ross

Reply to
Ross Mac

luck.

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Matt:

Check out any/all of these to verify your soldering technique:

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Cheers.

Ken

Reply to
Ken Taylor

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Cool...pictures and everything.....that should get things happening for Matt......

Reply to
Ross Mac

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A pictures worth 842 words (damn inflation.....)

Ken

Reply to
Ken Taylor

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