Soldering - Solder Paste

Discussion in 'General Electronics Chat' started by CraiGDaniel, Oct 4, 2012.

  1. CraiGDaniel

    Thread Starter New Member

    Oct 1, 2012
    20
    0
    I have started experimenting with solder paste and i'm struggling.


    I am only applying a little bit dragging it over the pads and then placing the component and heating it up.

    All goes well however i'm always left with bridges in the solder, too much to make it worth my going around with a wick as it would take forever.

    Is there any way to combat this? I'm using a quite low amount of paste but i'm also working with tiny components where the pads are very close together. .

    Any tips?
     
  2. BSomer

    Member

    Dec 28, 2011
    433
    106
    Do your boards have a solder mask or are these home made boards without a solder mask? It kind of sounds like the solder isn't flowing properly to the pads and pins. You could try using a small pointy thing (tooth pick) to dab a little paste on each pad instead of draging the paste across all the pads.
     
  3. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,388
    1,605
    How are you heating this up? Hot air or an iron? Hot plate?

    Generally as the solder paste starts to heat up it expands, but as soon as it melts it is drawn to the pads and tabs and cleans itself up.

    If you are still getting massive shorts then you have too much paste. You need surprisingly little, I was "trained" by mil-spec and Nasa certified operators.

    It helps to have a microscope to see what you're actually doing too. You aim is to make a small dab on every pad. A syringe by itself can kill your fingers getting paste out, I found a "gun" type of manual dispenser that works very well.
     
  4. Markd77

    Senior Member

    Sep 7, 2009
    2,803
    594
    I'm a newb to solder paste, I've only done a couple of boards, but maybe it isn't getting hot enough.
    I've noticed that the solder melts, then a little later it flows really nicely.
     
  5. shortbus

    AAC Fanatic!

    Sep 30, 2009
    4,013
    1,531
    You sure that the first part"the solder melts" isn't just the flux liquefying? I think this is whats happening when as ErnieM says "solder paste starts to heat up it expands" The flux then starts to out gas and the actual solder melts and flows.
     
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