So I have this little circuit board thing(don't ask what it is, I don't really know myself, that's why I'm trying to fix it) that my friend stepped on and broke the usb male end off of. He said I could have it if I could fix it. Ok so anyway, I figured it would be a simple matter of soldering the piece back on and that the solder connections were the only things that were broken. But, when i took a better look at it, I discovered that the metallic area on the board where the connections from the usb male end thing attached (as in green part of the board and metallic part of the board) were broken off. I didn't even know that that could happen. So, is there a way to fix this? I can't solder the connections back, because it won't stick without those little metallic pieces. Thanks in advance for the help.
I feel if you were able to take some reasonable pictures of the top and bottom of the board, and put them up on the web somewhere, and link to them, you would stand a better chance of getting help on this. Cheers Don...
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Don McKenzie
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You have three or four problems to overcome, as I see it:
Attach the USB male end to the board.
Make the connections.
Fix anything else you broke.
Uhh....
1 & 2 were solved at the factory, but if you've ripped the traces off the board (the traces are the little metallic tracks), then you can't really put them back easily. So you have to deal with these separately. I would fix the wiring, then _carefully_ glue the male connector to the board with epoxy, after roughing up the board.
Alternately, you could cut a short "pigtail" off of a USB cable and use that instead of a connector.
The normal material to use for repairing or modifying boards like this is wire-wrap wire (no one uses it for wire wrap anymore, and many call it 'mod wire' now). It's an insulated, #30 wire. I _think_ you could get it at Radio Shack. Any small, insulated wire can be made to work, but mod wire is way better.
You mentioned in another response that it's already had an attempted repair -- I'd do my best to clean all of that off before I did anything in a forward direction: you want to get down to nice clean board and proceed from there.
Be prepared for it to just not work when you're done. USB connections have to be impedance controlled, and you'll be messing that up with your repairs. Whether you mess it up enough to screw it up is unknown until you give it a try. Additionally, you may have cracked other traces on the board when you stepped on it, so even if you get the USB part right it may still not work. Please don't let that stop you, just don't fling yourself off a bridge if it doesn't work.
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Tim Wescott
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Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html
The part that looks like a little board or card is the "board" or more formally the "substrate". This is usually made out of epoxy-glass, which is usually a material called "FR-4". The "FR" in "FR-4" stands for "fire retardant", it probably refers to the epoxy used, and it's probably not what people really use any more. Cheaper consumer goods use a phenolic paper board -- it's what you'll find in clock radios and the like. It's weaker, it burns at a lower temperature, and it smells funny when it gets hot. It's also extremely cost effective if you don't ask too much of it. Really expensive equipment may use Teflon-glass or ceramic for a substrate, but I doubt you'll see that in any consumer equipment.
The metal part is made of copper, it form the circuitry and each 'wire' is called a 'trace'. AFAIK it's made by plating onto the board.
Boards can be:
- Single-layer, single-sided (cheap clock radios, again): All the traces are all on one side. This is very inexpensive to produce, but the layout of the traces is very constrained.
- Single-layer, double-sided (probably what you have): There are traces on both sides, and most of the holes are plated on the inside so a circuit can be carried from the top side to the bottom. More expensive, but quite versatile.
- Multi-layer: This is built up from a bunch of really thin double-sided boards that are glued together in a special press. I am _not_ up on the whole process, but if you don't mind spending $$$ you can have about as many layers made as you're willing to pay for. The job of laying out a really tight circuit is considerably eased, but each layer costs more $$$. Computer mother boards are often 4 layers, and it's a miracle that they aren't six or eight or more, given what they do. Someone spends a _lot_ of design time on those!
There's a coating over all of the board except the parts that you want to solder to. It's called "solder mask" or sometimes "solder resist". It protects the board from inadvertent solder bridges during manufacture, and from corrosion afterwards.
All the writing on the board (usually in white paint) is called the "silk", because it is silk-screened on (actually all the layers are silk-screened on).
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Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html
IIRC, low speed USB is not required to maintain a specified impedance, and if the board is part of a keyboard or mouse, it is likely to be low speed USB.
To the OP: If you're going to try to fix this, clean up the mess as best you can. Determine if you're dealing wth a multilayer board (if so, I would say "forget it") But if you luck out and it "is" actually fixable, I strongly suggest you use an active liquid flux for the repair job. This will make soldering much easier, given what you have to work with. Do not just grab a handheld iron and go to town... You can remove the flux later.
I suspect however your bigger problem is going to be mechanical stability once you do get the connnector reattached. And as Tim mentions, high-speed USB devices do get concerned about impedance, but if you're really careful, you should be able to get "close enough" with your repairs.
If this device is simply a USB jump drive doo-hickey, for $10 you can just go buy another one. (Unless there are critical files on it you need..?) Best of luck. - mpm
ok, so I'll post a pic. One thing that I probably should mention at this point, is that the usb male end was soldered onto the board itself. Another thing: I bought another male end (just a little bit of good news, as the old one had all the tabs melted off from previous repair attempts).
Here is my photobucket album thing with the pics. My camera wouldn't focus on the board, so I had to use a magnifying glass thing to get the details.
Will the usb thing I have still work? Thanks to Tim, your a big help, Tim. I'm gonna put another pic of the side, b/c I have no idea what multi layered substrate looks like. Is this liquid flux intended to fix the traces? Where do I get it?
I love these electronics sites, by the way. I don't know what any of it is, but it is fascinating. I like the intricate stuff. Just thought I'd throw that in there.
If you mean will the USB connector that you already have work -- yes, probably. The wires will make it easier than trying to work with the stubs on the old connector (they're not melted off unless your friend's dad was doing something profoundly odd, by the way -- surface mount parts just don't have long leads on them).
You don't care if the board is multi-layer. You just care about getting to any broken bits and fixing them. Multi-layer boards can be hard to recognize unless they happen to have the inspection windows left in.
Liquid flux will not fix the traces. It may just make the soldering easier.
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Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html
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