Trouble soldering to Pads

Discussion in 'General Electronics Chat' started by JoshEvelyn, Jun 24, 2014.

  1. JoshEvelyn

    Thread Starter New Member

    Jun 24, 2014
    I am no stranger to soldering and the process, but I have ran into a problem that no one seems to have heard of,

    We are a electronics manufacturing company and have never seen a problem like this before, where we try to solder Surface mount and Through hole components to the PCB and it doesn't stick to the pads. We tried a bare board and still it didnt solder. Even using alcohol cleaner has no affect.

    Is this a problem others have encountered?
  2. kubeek

    AAC Fanatic!

    Sep 20, 2005
    Could you post some detailed photos of the bare boards, and the badly soldered pads?
    I have seen a case where the silkscreen or soldermask were misaligned and covered the pads. Are you sure the soldermask is not covering the pads? What kind of finish is on the pads, HAL, gold plating, bare copper?

    What process do you use? I assume it is reflow for the SMD, but it might as well be hand soldered. Did hand soldering have better success? Were you at all able to solder anything?
  3. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    yep much more info needed..
    could be anything from a bad soldering iron tip/low heat transfer (assuming hand soldering since you said through hole but could be wave/selective) to board contamination to lack of flux,etc..

    what do you mean "we even tried a bare board"?
  4. MaxHeadRoom


    Jul 18, 2013
    Solder content?
  5. crutschow


    Mar 14, 2008
    Have you tried applying solder flux to the pads before soldering?
  6. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    What is the pad surface of the boards? Is this bare copper or is it solder covered?

    There is a possibility you got boards with incorrect metal (such as ROHS (no tin) solder) and your proccess cannot reach the liquid temperature.
  7. GopherT

    AAC Fanatic!

    Nov 23, 2012
    If the board was sprayed with high temp silicone or anywhere near high temp silicone oil you could have problems. Even HVAC motors near by can mist their lubricant. Alcohol will not remove it. You will need to physically polish it with something like Mothers swirl remover (white aluminum oxide grit that will make a mirror finish). Mothers is available at Auto Parts stores. Do not, do not, do not buy "car polish" that just adds more silicone.

    Buff once, while clean and repeat. This should remove anything that is preventing the bonding or flow. If that does not work, it is an alloy issue and you may need a higher temp soldering iron, silver solder, or lead free solder to make it work.