Soldering and electronics question

Discussion in 'General Off-Topic Chat' started by Harsky, May 4, 2008.

May 4, 2008
  1. Harsky
    OP

    Member Harsky Madmin

    Joined:
    Aug 2, 2004
    Messages:
    5,263
    Country:
    United Kingdom
    I was practising some soldering on some old unused MP3 player and I noticed if I try and pull out the plug the headphone jacks are attached to, it lifts up everything including the small square where normally solder is applied to make it come into contact. Sorry if I can't explain it better but I was wondering if something like that happened, can it be repaired?
     
  2. FAST6191

    Reporter FAST6191 Techromancer

    pip
    Joined:
    Nov 21, 2005
    Messages:
    21,737
    Country:
    United Kingdom
    It sounds like you are lifting the trace up.
    Repair ranges from trivial to complex, bad quality (but still works) to excellent (better than you started with) and can be expensive or it can be cheap. You would be lucky to get two of those "features" however.
    http://www.circuitrework.com/guides/guides.shtml
     
  3. Harsky
    OP

    Member Harsky Madmin

    Joined:
    Aug 2, 2004
    Messages:
    5,263
    Country:
    United Kingdom
    Urgh, that guide is just melting my brain but from what I skipped through, it's something like this

    http://www.circuitrework.com/guides/7-3-1.shtml

    The "pads" that they mention is the ones I have trouble with. If I used brute force (okay, I know that's not the right way) it lifts those pads out and then I have nothing to solder them to at all. How can I reapply those pads?
     
  4. coolbho3000

    Member coolbho3000 GBATemp Kikkoman Naturally Brewed SoySauce Fanatic

    Joined:
    Apr 29, 2007
    Messages:
    2,095
    Location:
    Kikkoman Factory
    Country:
    My fix for lifted pads is to cut the trace with a needle and solder directly on to the copper trace.
     
  5. FAST6191

    Reporter FAST6191 Techromancer

    pip
    Joined:
    Nov 21, 2005
    Messages:
    21,737
    Country:
    United Kingdom
    I agree that site has a bit of a throw in the deep end.
    I had a player or two that did the same thing (postively moronic move to have solder as a mechanical joint if you ask me) but that is surface mount stuff.
    Technically it is correct but it is aimed at far smaller components that what you are likely playing with which changes things a bit and is about adding stuff for the first time where there is a piece of metal to bond to (solder does not bond to polyboard all that well).

    One of two things is likely to happen:
    1) you lift a layer from the polyboard
    2) you lift the trace

    If you do not break the trace try and rebond it. Superglue should be fine for polyboard (assuming it is not a multilayered one) but for other stuff it is best to use some resin (hot superglue evaporates and it stings like hell when it gets in your eyes, not to mention it sticks to everything (see a dodgy forensics show: it is a fingerprint grabbing tool)).

    If you do break the trace then coolbho3000 is on the right track, I usually try to create a new solder pad as soldering to a trace especially for a mechanical type joint is no fun (unless you are in schoolboy PCB realms in which case it is usually OK). Jumping it to a unused section is a good one (be damn sure it is unused however) or attaching a piece of foil.

    Another thing I like to do is make a tearaway strip with foil, thing about tearing a sheet of paper almost in half so you have two "legs", holding it by the "feet" you still have a little bit of give before it goes unlike a solid joint which will cause what you see when you started the thread. Sidenote I read something this in a robotics journal a few years back and while it is fairly obvious to me (how many people make the point of failure in something easy to replace) it may be covered by a patent or three somewhere.
     
  6. Harsky
    OP

    Member Harsky Madmin

    Joined:
    Aug 2, 2004
    Messages:
    5,263
    Country:
    United Kingdom
    Thanks. This reminds me of how I got to this situation and why I still can't figure out what the problem is. I was trying to desolder a headphone jack that was soldered to a PCB. Four of the legs are soldered to the pads and I got rid of a lot of the solder with patience and a desoldering braid. Then I had to try and prise it off and that's where the problem comes in. Even though there is virtually no solder on the legs which is connecting to the pads on the PCB it still manages to lift up one of the pads and I'm left with 3 pads on the PCB which I can solder onto without problem and one pad which is missing the solder pad because it's still stuck on the leg of the headphone jack.

    I did follow coolbho3000's advice a while ago where I followed the trace and scraped off a little to reveal the copper so I could try and solder onto but this was just asking for the wire to quickly fall off since the trace is wire thin. I am still new to soldering and I have most of the basics down but this is one of the problems that keeps giving me nightmares.

    Edit: Also, forgive me for even thinking this but how could supergluing the pad back on the PCB work?
     

Share This Page