Solder/desolder presentation

Discussion in 'General Electronics Chat' started by aamirali, Jan 3, 2013.

  1. aamirali

    Thread Starter Member

    Feb 2, 2012
    415
    1
    Hi,

    I am preparing presenation on soldering
    1. I have to tell how to identify dry joint. is it right link
    http://mercedes-190.co.uk/topic/6581171/1/

    Any other way to do this.

    2. Also what is heating element inside the iron.
     
  2. t06afre

    AAC Fanatic!

    May 11, 2009
    5,939
    1,222
    As I see it a dry solder joint is a solder joint. That is not proper. The joint may have degraded over time. Due to heat cycling, vibration, chemical reaction, and so on. In production it can also be a joint completely free of solder. A dry joint may also have been caused by dirty/greasy solder surfaces. This is not so common in the industry. The unskilled hobbyist may also use to little heat and solder. And hence cause a poor solder joint. But some may refer to this as cold solder joint. But I will say it fits the description for a dry solder joint. On this web site I found a lot examples of the latter
    http://forums.xbox-scene.com/lofiversion/index.php/t613193.html
    Use Google and search for dry solder joint. You will find a lot of pictures much better than your example
     
  3. nerdegutta

    Moderator

    Dec 15, 2009
    2,515
    785
    Completely off topic, but my father had a Mercedes 190 for 22 years.

    He sold it 6 months ago, and regrets it. Everytime we're talking about his new car, he says:"... but that's nothing compared to the Mercedes!"


    Sorry!
     
  4. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,386
    1,605
    A dry joint is one with less solder then required. In the attached image most joints show a generous fillet of solder, while the suspect joints have much less. When subjected to mechanical stress such as vibration a dry joint may fracture and give no contact or intermittent contact.
     
  5. SPQR

    Member

    Nov 4, 2011
    379
    48
    So a "dry solder joint" is different from a "cold solder joint"?
    (though the former can certainly lead to the latter).
     
  6. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,769
    969
    dry = not enough solder
    cold = inadequate heating of the leads (or lands) /poor solder adhesion to one or the other or both


    IPC has TONS of information/pictures/posters/dvds,etc.. on soldering (most not free though but readily all over the internet)
     
  7. takao21203

    Distinguished Member

    Apr 28, 2012
    3,577
    463
    A solder joint failed from exposure to stress (vibration, high voltage etc.) is NOT a dry joint.

    A dry joint is a failed joint. Some solder compositions don't take movement well. It depends on the flux. They can produce joints like shown in the picture, with a barely visible fracture.

    They may work some time, but then will fail prematurely.

    A cold joint is a joint where the solder failed to make contact with both sides. Often these don't have proper fillets structure. Often bad flux is the cause, or inexperienced operator.

    It could also be the material especially on thick metal pins. The flux might not be the right one, so the pin looks like it is covered, while indeed, it is not, or what's worse, there is only a loose contact.

    Before you make a presentation about soldering, you should have many years experience with soldering, and you should have come accross many PCBs.

    If you spread wrong information, this does not help anyone.

    Unfortunately not everything on the internet is up to standards.

    If you must, I suggest you consult a good book about soldering, and try to find some PDFs online. Solder manufacturer's might be the right place to look for such PDFs.

    tin/lead or tin solder wire is only one of many compositions used for industrial soldering.
     
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