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Thread: Soldering help.

  1. #1

    Default Soldering help.

    Recently I have been having trouble with the left CTRL on my mechanical keyboard needing excessive pressure. I purchased a new switch (Cherry MX red) and replaced it yesterday. Everything worked fine until I went to use it today and the switch didn't work at all.

    I have attempted to resolder it to the PCB and it will work for a brief time before not working again. If I melt the solder on either terminal of the switch I get the same results.

    Not sure if it matters but I'm using copper braid to de-solder the components.

    Any help appreciated.

  2. #2
    acorn

    Default



    Quote Originally Posted by huskvarna View Post
    Recently I have been having trouble with the left CTRL on my mechanical keyboard needing excessive pressure. I purchased a new switch (Cherry MX red) and replaced it yesterday. Everything worked fine until I went to use it today and the switch didn't work at all.

    I have attempted to resolder it to the PCB and it will work for a brief time before not working again. If I melt the solder on either terminal of the switch I get the same results.

    Not sure if it matters but I'm using copper braid to de-solder the components.

    Any help appreciated.
    I thought "dirty contact's" on the board or switch, leading to a dry joint(s). Dry joint's are usual suspects in intermittent faults, if suspected they should be redone as opposed to touching up.

    Then old circuit board (lead solder joints) and you applying new solder (possibly lead free). In this case, I'd suggest prostitute yourself to obtain compatible lead solder.

    Then I thought this thinking is killing me and gave up on it. Have a look here might be of some use. Or look here for soldering tips.

    Effin useless; I know, I'm used to it by now!

  3. #3

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    First thought is pretty much what acorn said. Use a little flux on there to clean up the contact(s) and be sure to use an appropriate flux core solder.

    Second thought would be a cold joint. Make sure you are using enough heat. Put a little solder on the tip of your iron to increase contact and transfer the heat. This is a common reason for cold joint, without a little solder to bridge the gap between iron and contact, the contact doesn't heat up properly, and you end up just kinda glopping solder on top of it rather than actually connecting with it. This joint will then fail under stress (say the stress of some guy hitting it with their finger repeatedly). Ideally you shouldn't need to "spread" the solder over the contact.. when it's the right heat, the solder should naturally wick down and cover the contact.

    If you board starts bubbling/plastic melts/smoke arises.. you've used too much heat ;p

  4. #4

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    Quote Originally Posted by acorn View Post
    a
    Then old circuit board (lead solder joints) and you applying new solder (possibly lead free). In this case, I'd suggest prostitute yourself to obtain compatible lead solder.
    Hmm... The solder I've been using contains lead but I'm pretty sure the board is lead free. May be worth finding some lead free solder.

    Edit: I've tried to take a picture of my Connections but I don't have a good enough camera. Visually my work looks the same as all the other connections.

  5. #5
    acorn

    Default



    Quote Originally Posted by huskvarna View Post
    Hmm... The solder I've been using contains lead but I'm pretty sure the board is lead free. May be worth finding some lead free solder.

    Edit: I've tried to take a picture of my Connections but I don't have a good enough camera. Visually my work looks the same as all the other connections.
    First, Iíd respectfully suggest that you have that the other way around. The board is old and more lightly has lead solder joints, If your solder has been bought in the last few years itís more probably lead free. New bad joints are hard enough to spot, they usually are simply not shiny or dull grey color.


    BoundCoder raises a good point with temperatures, if your iron cannot deliver enough heat quickly enough, what happens it the heat transfers throughout the component being soldered and destroys it outright. A good rule of thumb is, if you cannot make the joint in less than two seconds, your iron is not powerful enough. I used to have a 50w iron with a very fine tip, when it was being used on large area joints it was loosing all itís power and resultantly delivering a lot less than 10w. The result was it destroyed a lot of components before I eventually threw it out the window in a fit of temper. If you were originally using an underpowered iron - the switch could already be damaged, this would be consistent with the symptoms you are currently experiencing.

  6. #6

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    Quote Originally Posted by acorn View Post
    First, I’d respectfully suggest that you have that the other way around. The board is old and more lightly has lead solder joints, If your solder has been bought in the last few years it’s more probably lead free. New bad joints are hard enough to spot, they usually are simply not shiny or dull grey color.


    BoundCoder raises a good point with temperatures, if your iron cannot deliver enough heat quickly enough, what happens it the heat transfers throughout the component being soldered and destroys it outright. A good rule of thumb is, if you cannot make the joint in less than two seconds, your iron is not powerful enough. I used to have a 50w iron with a very fine tip, when it was being used on large area joints it was loosing all it’s power and resultantly delivering a lot less than 10w. The result was it destroyed a lot of components before I eventually threw it out the window in a fit of temper. If you were originally using an underpowered iron - the switch could already be damaged, this would be consistent with the symptoms you are currently experiencing.
    I know the switch isn't the problem as I've tried two different switches as well as manually connecting the the termanals on the PCB with wire (works for any other key). also the keyboard is reasonably new (CM Storm Quickfire TK) so the soldier may be lead free (my solder contaims 40% lead). Also I replaced the led backlight without issue.

    However I might dig the big iron out of the shed and try again.

  7. #7

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    Also, to iterate further...soldering is not gluing...bring your iron to temp...'tin' the heated tip by first wiping with a damp sponge or cloth, then apply a bit of solder to the tip...then, with your components secured in a clamp or brace, solder at the ready...wipe the iron clean again with the sponge...the tip should appear very shiny-silver...

    Place the iron tip evenly connecting the component lead, and the foil-pad, approximately 2-seconds, then feed just a touch of solder at the three-points (component-lead, foil-pad, and iron-tip)...the pause before applying the solder is to bring the other parts to temp...you may first need to attach a metal-clamp to act as a heat-sink to keep from burning up the component...also mind that you don't heat the foil-pad for too long that it looses it's bond from the board...

    Don't over-feed the solder...in the moment it takes to just get a nice flow...remove the solder, then the iron...

    When the solder is applied to these three points...it should flow out shiny, and not appear to be rolling around...if it's rolling around, or balling up, you may need to degrease the area (when cool), use an electronics safe flux, and/or different solder...

    The de-soldering braid should work okay, but I prefer the vacuum-bulb type (generally avoid compressed-air as it can blow solder bits into all kinds of places and short the works out)...

    Next thing...the component must not be bumped in the slightest bit for about 1-2 seconds after removing the iron...this can create a cold-joint too, as it basically winds up being somewhat mechanically attached, but insufficiently, or unreliable conductive... (gently blow on it to cool).

    Regards,
    -Marka

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