SMD/SMT work/rework air/IR

Discussion in 'Electronics Resources' started by cowasaki, Jun 28, 2011.

  1. cowasaki

    Thread Starter New Member

    Apr 3, 2011
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    I have been working with normal components for years but have decided that I really need to get the kit for surface mount. Basically some of the components I need are not available in any other form.

    As I am starting from scratch with SMD what is the best setup?

    hot air or IR ?

    Any examples of good setups?

    What other stuff do I reasonably need?

    Flux - I have only ever used solder with flux running through it ???

    Solder paste - I take it that is put a blob of this where I need solder ??

    Hand tools?

    Has anyone seen any really useful tutorials etc ?


    Thanks in advance.
     
  2. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,394
    1,607
    Well I actually prefer to work with SMD parts, even for breadboarding.

    You did not state if you are building complete boards and what quantity, and are they single sided or double sided (the parts, not the traces). So here goes a lot of stuff...

    For hand assembly you will never go wrong with a very fine tip conventional iron. However, the finer the tip the faster they oxidize and become darn near useless. I go thru a $30 tip on my Metcal every month or so (but my company pays for em).

    For the very finest leads hot air is the way to go, I have a Kendal 898D I got off EBay similar to that one. I don't use the conventional iron side. Make sure the one you pick is for 110 volts.

    Many distributors sell solder syringes, little balls of solder in a flux slurry. Lead or lead free, and all are about the same. Just squeeze out a small dot on each pad.

    If you want to reflow an entire board you can actually just use a hotplate for single sided boards. I have a machine with pusher hands that moves small parts over 3 hot plates (pre heat, flow, post heat cool) and does a fine job on the bench. For larger boards I used to have a chain furnace, 3 hot air zones, put parts in one end and they come out the over end nicely flowed. Note for double sided parts you just run them thru twice, and for small parts the solder surface tension keeps en in place when re-re-flowing the bottom side to get the top side. Some ovens do not have a bottom element for the reflow zone so they may not even re-re-flow in those.

    Ovens are expensive so skip them unless you have the production income to amortize.

    Several pairs of tweezers, large and small are necessary too. And get some pre-fluxed solder wick too. Some type of mangefier too, I have a nice microscope to work under but a magnifying glass works too.

    So much for the "short" answer. Ask away if you have more questions.
     
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  3. cowasaki

    Thread Starter New Member

    Apr 3, 2011
    15
    0
    Thank you for a very comprehensive reply Ernie.

    I can do either single or double sided boards. I have a complete PCB manufacturing setup from MegaUK (kitD) http://www.megauk.com/pcb_kits.php plus a through hole machine. I also have Eagle CAD.

    I am only making prototypes and will have the actual boards (when they are for commercial use) made for me from the Eagle files.

    I have only ever replaced the odd blown diode or transistor with SMD (and then often with a non SMD version)

    I have seen the actual system you mentioned (I am in the UK so its 240 volts for me :) ) when I was looking at systems there seem to be both IR and AIR systems. Once you go down one route forever will it control your destiny :eek:
     
  4. c_omalley2002

    Member

    Mar 18, 2010
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  5. KJ6EAD

    Senior Member

    Apr 30, 2011
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  6. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,394
    1,607
    Too bad, the first hot air wand I got is wired for 220, and it sits here collecting dust.

    If you were closer I could pass it to you. But if you were closer you'd be on 100 like I am.
     
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