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Discussion in 'Electronic Basics' started by Continuum, Jun 28, 2005.

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  1. Continuum

    Continuum Guest

    What is the difference between hole mounted components and surface
    mounted components?

    Which is better?
  2. Ban

    Ban Guest

    There is no difference electrically, just size and package.
    Since there is no difference, the question of better doesn't even arise. You
    just take whatever is your preference.
  3. Bob Myers

    Bob Myers Guest

    "Hole mounted" (i.e., "conventional lead") components have
    long leads (attached pins or wires) which are intended to
    go through plated holes in printed-circuit boards, and then
    are soldered into place (either by hand or via various automated
    methods, the most common/generic type being "wave"
    soldering). "Surface-mount" components are just what the name
    implies - rather than wirelike leads, these components generally
    have short tabs with flat surfaces, or often simply metal "bumps"
    on the sides/bottom of the package, which are placed against
    conductive pads (without holes) on the surface of the PC board.
    Such components are typically placed into position on the board
    using automated "pick and place" equipment, held there via an
    adhesive paste (often the same paste which carries the solder),
    and soldered to the pads using various "reflow" methods
    (in which the solder paste is melted - "reflowed" - in place,
    AFTER being deposited, to create the soldered connection).

    Which is better is too open-ended a question - better from
    what perspective? SM components will often (if properly
    placed and soldered) result in a more reliable product, are
    certainly smaller (allowing more components per unit area),
    and with little or no leads to speak of, SM components don't
    have the problems which result from "parasitic" lead inductance
    (such as lowered self-resonant frequencies for capacitors, etc.).
    On the other hand, they're certainly more difficult for the hobbyist
    to deal with (and even for pros to deal with, without the proper
    equipment) in terms of construction, probing, and servicing of SM-
    technology boards. Surface mount technology has become the
    manufacturing method of choice for most high-volume electronics
    production (which has had the side effect of making conventional
    through-hole versions of some parts somewhat more difficult to find),
    but may not be the best choice for low-volume production or for t
    he hobbyist.

    Bob M.
  4. PeteS

    PeteS Guest

    << There is no difference electrically, just size and package.>>

    True at a basic level, but not at high frequencies. Bob noted lower
    parasitics, and that's important in high speed interconnects (in fact,
    even 0603 has high parasitics when presented with 2.5Gb/s pairs). For
    really high speed stuff (up to 10Gb/s pairs) we're moving to 0201 and
    even 01005 for things like series caps and pullups.

    I agree with you that in a lot of cases, you choose what you prefer (or
    need for the product), though.


  5. Ban

    Ban Guest

    Right, but 1GHz and up has never been done with through-hole parts. People
    used stripline with special HF parts and it hasn't changed that much today.
    And if the OP has to asked this question, he will not be into this kind of
    specialized engineering, but maybe wants to make a white LED supply which
    also pulses or is fading.
    For the normal hobbyist level it is actually easier to work with reasonably
    sized SMD parts. Very important are some intelligently applied design rules
    (here lies often the beginners fault) which usually require to modify each
    of the library parts. Hand-soldering requires specialized pads, keep-out
    areas, you also need to modify the silk-screen, so when a beginner uses the
    standard lib parts, he will place the components too close, the distance
    between signal and ground-pour is too small etc.etc. This will lead to
    frustration and failure in getting the circuit running. On the hobbyist
    level a certain understanding is needed, so it might be better to get some
    experience with soldering leaded parts...
  6. John Fields

    John Fields Guest

  7. Continuum

    Continuum Guest

    Thanks everyone for your extremely quick and well detailed responses.

    I was just wondering as I am just starting out with my electronics
    hobby and was
    wondering if learning to make PCB's is worth my time or if i should
    just use surface
  8. If you use surface mount parts, you _need_ a PC board. Circuits using
    through-hole parts can be made on perf board.
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