Surface mount components

Discussion in 'General Electronics Chat' started by coldpenguin, Jun 4, 2010.

  1. coldpenguin

    Thread Starter Active Member

    Apr 18, 2010
    165
    9
    I usually use breadboard and solderless breadboard when making my circuits, with through hole components.

    I am struggling with my latest project, to get it in the box, this is due to the number of wires I am having to run for connecting up the breadboard.
    To reduce these wires, I could trasnfer to a PCB.

    I could either go half-way, and do a single sided etch myself, which would leave several wires (mainly Gnd and +Ve busses I reckon) which would be workable I think.

    Or I could go for a double side PCB fab. like that in another post.

    If I were to go to PCB, are there advantages also to going to SMD at the same time? I haven't really used them before, so I am not sure how difficult it would be to implement. There are around 8 resistors, and 2-3 caps I would need to implement. Would this be a good size to practice on, and, if it goes real bad, would it not be possible to try and drill through the pads and go through hole anyway? (assuming that I ensure that there are no tracks the other side.

    There are four major components on the board.
    1) LCD connector, not SMT capable
    2) Wireless transceiver, not SMT capable
    3) Dallas 1307, I currently have through hole,
    4) PIC 16f877A, I currently have through hole

    would it be worthwhile trying to do these as SMD or should I start small and just do the resistors?
     
  2. ELECTRONERD

    Senior Member

    May 26, 2009
    1,146
    16
    The wireless transceiver certainly would work better with SMT components. Some SMT packages can be difficult to solder to, such as QFN and BGA. If you decide to incorporate SMT, I'd use SOIC or similar packages.
     
  3. Bychon

    Member

    Mar 12, 2010
    469
    41
    Trying surface mount on a small scale is a good place to get some practice.

    Once upon a time, I saw a device that looks a bit like a tiny drill press. It's purpose was to hold the tiny surface mount parts against the board while you solder. A spring loaded dingus is pulled down on the tiny part and the spring pressure makes the part hold still while you solder.

    You might not need one, but I thought is was a very convenient device. Just trying to be helpful.
     
  4. Markd77

    Senior Member

    Sep 7, 2009
    2,803
    594
    I soldered up my first surface mount board today. Helped a lot by videos from youtube.
    There was a PIC10F202 in sot23, a transistor in sot23 and some 1206 and 0805 resistors and capacitors. I found getting a tiny bit of solder on the board with solder wick on one connection, touching that pin with the soldering iron while holding the component down with a toothpick and then going round properly worked for me. The first few joints were hard work, but it got easier.
    Amazingly it works.
     
  5. retched

    AAC Fanatic!

    Dec 5, 2009
    5,201
    312
    I used to use a pencil with an eraser. Use a standard potato chip bag clip and a stand or "helping hands" to hold the pencil in place. The eraser presses the chip against the PCB. A little solder paste works well.

    When you go SMD, get yourself solder paste and some stencils. That way you "print" or "squeegee" the solder paste onto the PCB then with the iron in one hand and the pencil in the other, make a few passes with the iron and you are done.

    Sometimes you dont even need to touch the leads.. The heat and capilary action will do the work.
     
  6. ELECTRONERD

    Senior Member

    May 26, 2009
    1,146
    16
    To hold SMT IC's down I usually cut a sliver of tape and tape the IC to paper. Then I take a short length of the stranded wire and pull out the thin pieces of copper wire from it. Next, I tape down a piece of that wire and affix one of them to a pin and finally solder to it.

    You could also try the "dead-bug" approach and bend the pins alternately upward and downward.
     
  7. GetDeviceInfo

    Senior Member

    Jun 7, 2009
    1,571
    230
    after going to surface mount, I use through hole only when forced. I flux the pads, tin them, then using a darning needle to hold the package in place, fuse each pin with a sharpened iron.
     
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