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Surface mount Vs. lead mount. Which is better? — Parallax Forums

Surface mount Vs. lead mount. Which is better?

Velvet LeopardVelvet Leopard Posts: 47
edited 2004-08-16 13:11 in BASIC Stamp
Hewwo, all.· First I want to thank all the peole who have helped me out thus far.· I have just aquired a PCB layout software and am going to design and order a·custom board.· I have been told by several buddies and a few companies that I would find it better for my robotics apps if I used surface mount components instead of lead mount.· I can see how this would be true sinse surface mountable components are usually smaller, but what is the difficulty level of setting suface mount components on a PCB?· Also, way off topic, has anyone ever confronted a robotics type circuit with an actual PC DIMM RAM chip on it?· Like what comes out of a PC?· I read a book where they talked about such a thing.· Could this be possible or is the memory addressing just too much for a small controller to handle?· Thankies!· =^.^=

Comments

  • KenMKenM Posts: 657
    edited 2004-08-14 02:35
    If you have never done surface mount it is not terribly difficult, but does require some practice, patience and technique.

    ·
  • Velvet LeopardVelvet Leopard Posts: 47
    edited 2004-08-14 03:55
    Are there any "practice kits" or "learn to mount surface component" books out there?· I would love to be able to mount surface compnoents.· Thanks for the morale lifter.
  • jakjrjakjr Posts: 88
    edited 2004-08-14 04:14
    I think velleman makes a little SMD kit, all it does is flash a few leds with a smiley face background. But I guess it would be good practice so you dont muff up the "real thing".

    in fact, heres a link to that kit http://www.apogeekits.com/smiley_face.htm

    As far as pro's/con's go, all you'll gain by using SMD's is a smaller/lighter board and a headache from straining youre eyes soldering them·shocked.gif·. On the other hand with lead mounted·components you'll end up with an overall larger board and it will·(usually) weigh a "little" more, but... it will be much easier to solder.]

    As far as being hard to solder, Id rate 'em on a scale of 1 to 10 (10 being the hardest) a 7 or a 4. 7 using a regular soldering iron and no magnifacation,·4 using and iron with a very fine point tip and a magnifier.

    If you use some tweezers, a magnifier of some sort, and a nice fine point soldering iron (I prefer butane and of the ~80 watt equivalent range)·its not too too hard. The main thing is you need to be patient, and you need to take some breaks so your eyes can recooperate.

    It will also depend on what type of components you'll be soldering, generally stuff like resistors/diodes etc.·arent too hard to work with but stuff that looks like a centepede is where wou might have trouble.

    Post Edited (jakjr) : 8/14/2004 8:47:54 AM GMT
  • NewzedNewzed Posts: 2,503
    edited 2004-08-14 12:39
    For an excellent training kit, try www.solderingtech.com

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    Sid Weaver
    USB-powered Stamp Board

    http://hometown.aol.com/newzed/index.html
    ·
  • GadgetmanGadgetman Posts: 2,436
    edited 2004-08-16 10:39
    Maybe a moot point, but...

    Some PCB production services have the 'hole count' as a factor in the price.
    (Drilling them takes time and effort)

    And doing it manually is a pain in the posterior.
    (Somehow, there's always one or two holes out of alignment with the others when you're drilling holes for a 40 pin IC.)

    I have in my extensive collection a Sharp computer where the chips have had their pins bent outwards so that they could be surface-mounted.

    In a RAMDisk for another computer (an Epson PX-4) they've soldered in one RAM chip using through-hole pins, then they've 'piggy-backed' 3 more on top of that one(soldering it in pin-to-pin) with just the Chip-Select pins bent out and with individual wires soldered to them.

    You could even cut a hole the size of the IC and have solder pads around the edges, then bend out the pins of the IC and have it 'sunk' into the PCB if you want a thinner result.
    (I can't remember seeing it done with IC's, only caps and Xtals)
  • cyberbiotacyberbiota Posts: 79
    edited 2004-08-16 12:05
    Vicor "sinks" their power module IC chips throught the board.· And these are big chips (1 by 2 inches).· They call it "In Board Mounting."· Makes for an interesting looking board, but I would think the machining/millwork costs would kill you.· I doubt that it would save money on hole count.



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    Dr. Peter C. Charles

    Director, Research and Technology
    CyberBiota, Incorporated
    Peter.charles@cyberbiota.com
    http://www.cyberbiota.com
  • GadgetmanGadgetman Posts: 2,436
    edited 2004-08-16 13:11
    It's only an alternative if you make the board yourself and have a good saw at hand, but it's a trick worth remembering.
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