SMD soldering

Discussion in 'General Electronics Chat' started by xxxyyyba, Aug 4, 2014.

  1. xxxyyyba

    Thread Starter Member

    Aug 7, 2012
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    I have some experience with basic soldering (resistors, capacitors etc). Which equipment is used for soldering SMD? It would be hard to do it with regular soldering iron I think.
     
    Last edited: Aug 5, 2014
  2. sirch2

    Well-Known Member

    Jan 21, 2013
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    Look at some tutorials on youtube. Buy some cheap components and practice. It's not that hard after some practice
     
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  3. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    For a few parts one could use a regular soldering iron.. like for larger lead simple stuff
    For anything else..
    hot air gun for doing a few parts. ($60 to 600+)
    reflow oven for doing whole boards at a time. ($50 if DIY to $200 or so for a cheap Chinese batch oven to thousands for a professional oven/tunnel)

    "solder paste" is used vs solder wire which is just a mixture of micro solder balls typically suspended in a flux that could be tack to help hold parts down,etc...
     
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  4. ErnieM

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    Apr 24, 2011
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    It's really not very hard, the worst part of SMD soldering is starting to do some.

    Got two bucks? For that you can get a practice board you throw away when you are done. That way you don't waste anything "expensive."

    Some of us (me for one) actually prefer to use SMD parts for hand made breadboards (without a formal PCB).

    You can get by with just a regular iron with a fine tip (some prefer broad tips), but do add in thin solder and some fluxed solder wick. Thin solder to prevent blobs and wick to remove the ones you make anyway.

    I'd stay away from solder paste for a while, wait for the day you are good but want to get better.
     
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  5. xxxyyyba

    Thread Starter Member

    Aug 7, 2012
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    I have old PC motherboards so I can practice on them too :) Thanks fo replies
     
  6. jpanhalt

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    Jan 18, 2008
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    I agree with ErnieM. I use SMD, not so much for space saving, but because they are easier. Albeit, I do not go smaller than the 805 size. If I were younger with steady hands, I would consider going smaller. I just use a temperature controlled soldering iron with a fine tip.

    John
     
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  7. MrChips

    Moderator

    Oct 2, 2009
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    I do SMD soldering by hand all the time. Get the finest soldering iron tip (0.38mm) and finest solder wire (0.79mm).
    I use 0805 parts and SOIC when available.

    You will need either two soldering irons or a tweezer tip in order to remove SMD resistors and capacitors.
     
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  8. takao21203

    Distinguished Member

    Apr 28, 2012
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    I do them with a broad tip and just any solder wire. SOIC is easy, but TQFP can be hard if the pads are too small.
     
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  9. xxxyyyba

    Thread Starter Member

    Aug 7, 2012
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    @MrChips
    Is it possible to remove smd resistors and capacitors with solder wick?
    By the way, I watched few videos on youtube about soldering/desoldering SMD using hot air. If there are components very close to component I want to desolder, how can they be protected from desoldering?
     
    Last edited: Aug 5, 2014
  10. sirch2

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    Jan 21, 2013
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    I find the trick with TQFP packages to be very accurate positioning. Take plenty of time to ensure the pins are exactly on the pads (and this means a good steady working surface with the board held still and somewhere to rest your arms). If they are slightly off side-to-side then the gap between the pin and the next pad is small enough for it to bridge and it is hard to remove the bridge.
     
  11. ErnieM

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    Apr 24, 2011
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    I find the trick with TQFP packages to be very accurate positioning and get one corner pin soldered down, then do the opposite corner. Then go back and reflow the first, then next joint to relieve any stress from any slight movements.

    Now check your work. With but two pins soldered it is easy to remove and reposition.

    Then solder the rest. "Flood and drag" works for many people where you make a big blob of solder and slide it down the pins. I just do each pin individually, skipping several pins so I'm not heating up one small section too much.
     
  12. Gdrumm

    Distinguished Member

    Aug 29, 2008
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    I've tried a few different things to magnify the work area.
    I'm not really happy with any of them.

    Any thoughts on what works best for magnification?
     
  13. sirch2

    Well-Known Member

    Jan 21, 2013
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    I use a headband magnifier, something like this http://r.ebay.com/9ocHse

    I also have a big illuminated desktop magnifier on an angle-poise arm which is good for inspection but I find it too close for soldering and the like.
     
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  14. MrChips

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    Oct 2, 2009
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    I use a microscope. Now I would really like a Dazor speckFINDER but $5000 is a tad too much for me.
     
  15. ErnieM

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    Apr 24, 2011
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    I have a wonderful Bausch+Lomb microscope which I used for years, but now I find a headband magnifier much much easier to use.
     
  16. jpanhalt

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    Jan 18, 2008
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    I have a nice binocular dissection scope too, but I also prefer the headband magnifier -- at least for 805's. For the 402's and 201's, if I need something that small, I am in the wrong profession.

    John
     
  17. kuch128

    Member

    Mar 7, 2011
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    I also find the flux pen dispensers a life saver when dealing with TQFP packages and the like.
     
  18. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    I often use a blob (or two!) of bluetak to hold the IC in position. Generally you put it across two corners, to the PCB so it doesn't touch the pins or pads (because it can make them greasy). That gives you time to get the IC positioned perfectly.

    Then I solder tack one or two corner pins to hold the IC secure, and remove the bluetak.

    Then I do a flood drag to solder the pins.
     
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  19. takao21203

    Distinguished Member

    Apr 28, 2012
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    Recently I messed up two 68ec020, got adapter PCBs for them but the pads are way too small, so you need perfect alignment on all sides.

    Apparently I did not get it right, cant get the solder off from all sides.

    Have to bake them off some day or sarifice the boards and burn them off (but no need to do it).
     
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