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Common SMD size

Discussion in 'Electronic Basics' started by Michael, Jan 31, 2006.

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  1. Michael

    Michael Guest

    What is the most common (of the larger) SMD sizes for resistors, caps and
    the like?

    The style number is what I'm after.

    Larger the better, for me and unsteady hands but don't want something being
    phased out either.

    Thanks.
     
  2. The sizes are the length and width in hundredths of an inch. The
    largest common size is probably 1206 (12 hundredths long by 6
    hundredths wide or .12 by .06 inch). But there are lots more parts
    values available in 0805 size. Unless overall size is at a premium, I
    normally use 0805 instead of smaller sizes, just because the pick and
    place tolerances are less of a problem. The yield is essentially
    100%. They are also lots easier to hand rework than the smaller sizes.
     
  3. Joerg

    Joerg Guest

    Hello Michael,

    Besides the 1206 and 0805 that John mentioned there is also MINI-MELF.
    They are round which can be good and bad. I kind of like them because
    you can loosen the tweezer grip a wee bit, roll them onto the pads, tack
    one side and then solder.

    Regards, Joerg
     
  4. 0402 or 0603. Don't worry about the tinier ones for a while.
    Then use 0805. You'll still be able to buy them, in a fairly full
    range, but a bit more expensive.

    Best regards,
    Spehro Pefhany
     
  5. Pooh Bear

    Pooh Bear Guest

    You forgot the wink ! ;-)
    Don't forget to buy some tweezers. And whatever you do, don't sneeze whilst
    placing them !

    Graham
     
  6. I bought some of those when I was starting SMT prototyping, mainly
    because they still have the colour bands for value marking.

    I hate them! They roll around everywhere and my tweezers wont hold
    them properly for some reason. I can't read the colours anyway (even
    with magnification), they look wrong somehow.

    I use standard 0805 now, much nicer.
     
  7. John Larkin

    John Larkin Guest

    Like the other guys, I think 0805 is a good choice. Get some decent
    lighting and magnification... even 1.75x drugstore reading glasses
    work pretty well with 0805's. SMD is *not* difficult.

    John
     
  8. Phil Hobbs

    Phil Hobbs Guest

    It isn't hard if you're using a board. It took me awhile to learn how
    to do do reliable dead-bug style prototypes with SMTs, but it's possible.

    And for hacking around, it's much easier to stand the 0805s up like
    billboards instead of flat. It looks ugly, but the tweezers never slip,
    and you can get the iron into the tightest-packed places that way.
    Prototype SMT boards usually die by having pads cooked off them(*), and
    the billboard trick speeds up soldering significantly.

    Cheers,

    Phil Hobbs

    (*) Various s.e.d denizens have recommended using one via per pad, to
    reduce this problem, but I dunno--that's a lotta vias.
     
  9. Rich Grise

    Rich Grise Guest

    Do parts that little have any kind of markings, with any rhyme or
    reason? Or do you just have to remember which bin you picked it
    out of?

    Never mind, some do, some don't. I got out my 5X illuminated magnifier,
    ;-) and looked at a dead video adapter that's loaded with little things
    that look like coarse-ground black pepper, and a couple of them had
    "103" without the quotes printed on them, so they're probably resistors.
    They're about 0.08" x 0.05". =:-O lessee - there's a couple caps: Nope,
    they just looked bigger because they're pinkish beige, rather than black.
    Ooh! There's a big'un! No markings, but it's about 0.12" x 0.06". Oh,
    there it is, "L4" is screened next to it. ;-)

    Sheesh! Not my cup o' tea, thanks - I guess I'll go the FPGA route and
    let somebody else solder the stuff down. ;-P

    Cheers!
    Rich
     
  10. One great thing about SMT is that all my prototyping stock fits into a
    single small box of envelopes, which goes on the bench in front of
    me. I have a wall full of plastic drawers for the through hole stuff
    (which I rarely touch),
     
  11. Joerg

    Joerg Guest

    Hello John,

    Once I passed 40 I realized that I needed 3x drugstore glasses for that.
    Bought them more by accident, tried them on, and "ahhhh". It's also
    safer to solder with glasses in case an electrolytic decides to put on a
    pyrotechnic show.


    SMD is *not* difficult.
    Sometimes I find that it is even easier than thru-hole. No more turning
    around of the board. But it sure is a drag getting older while all the
    stuff shrinks to less than 0402.

    Regards, Joerg
     
  12. Jim Thompson

    Jim Thompson Guest

    But you're still just a baby ;-) ... I'm just weeks away from 66 :-(

    ...Jim Thompson
    --
    | James E.Thompson, P.E. | mens |
    | Analog Innovations, Inc. | et |
    | Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
    | Phoenix, Arizona Voice:(480)460-2350 | |
    | E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
    | http://www.analog-innovations.com | 1962 |

    Global Warming is God's gift to the Blue States ;-)
     
  13. Michael

    Michael Guest

    0805's it is then although It looks like searching digi key that 1206 is
    readily available for 1/4w resistors.

    I think I'll stick with the larger for resistors, only because I shake like
    Don Knotts anymore.

    Is that the case with most popular cap values as well?

    Is 1206 just as available as 0805 in caps?

    I did some 0805 today but those 0603 would drive me nuts.

    I've just been placing with some scotch tape and tacking one side under an
    overhead magnifier.
     
  14. John Larkin

    John Larkin Guest

    I seem to break the parts a lot if I stand them up. The end caps come
    off.

    These snap-apart boards are slick for small protos and test circuits:

    http://www.beldynsys.com/singledual.htm

    I just snap them apart and attach them here and there to a piece of
    copperclad with hot-melt glue. Solder on a few SMB connectors and
    bigger parts, and wire it up.

    For anything more serious, lots of people, like AP Circuits, will do a
    small batch of 2-side plated-thru boards for $60 roughly.

    John
     
  15. Forget capacitors. But all the 0805 resistors I use have the resistor
    code printed on them (white on black), even the 1% ones. And I am
    near sighted enough to read them without additional magnification.
     
  16. Check out 0.1% resistors, for example. And compare the price of
    typical bypass or C0G capacitors in 1206 vs. 0805. or 0603. OTOH, 0402
    tend to come in reels of 10K, which is double that of
    I think their stock is biased towards the older parts, compared to
    Asian production stock, but here's Digikey's stock situation:

    Capacitors

    size # of different parts
    1206 1336
    0805 1798
    0603 1976
    0402 1432
    0201 716

    Resistors

    Thick film Thin film

    1206 6364 127
    0805 6375 1420
    0603 5167 1219
    0402 2585 268
    0201 252 29

    0805 is very comfortable to deal with. I still find 0402 a bit tiny
    and tend to lose a few in solder blobs or ejected into space from the
    carrier tape. But okay for a prototype or two-- the last one I did had
    75 or so 0402 caps and resistors per board, though I needed a shot of
    single-malt by the time it was done.

    Best regards,
    Spehro Pefhany
     
  17. I'm right in the middle. ;-) I don't normally wear glasses, but
    have a pair of +1.75s for close work. Anything stronger and I get
    nauseous. I'm looking for a pair of +1.00 or +1.25s for computer
    work but the drug and dollar stores never seem to have ones bigger
    than my displays. I like tiny fonts on large screens. ;-)
     
  18. Drug and dollar stores? Why don't you go to a proper optometrist and
    optician (ophthalmologist wouldn't hurt either at your age, he or she
    will check for glaucoma), lay down a few Franklins, and get some nice
    purpose-made optical wear. Your eyes will thank you.


    Best regards,
    Spehro Pefhany
     
  19. Phil Hobbs

    Phil Hobbs Guest

    Pure brute force, tsk tsk. Of course, for someone who puts 48V forward
    bias on a diode, what can one expect? ;)
    Those are cute, thanks. I'll have to order some. But once I have the
    SMTs on there, I'll have to restrain myself from attaching them to the
    board upside-down with Krazy Glue.
    Yah, I know I can get that done...but I have way too many rocks to push
    to do my own PCB designs too, alas.

    Cheers,

    Phil HObbs
     
  20. John Larkin

    John Larkin Guest


    I knew I should have been a lumberjack.

    Tsk tsk. It's sad what years of sniffing Krazy Glue can do to a fine
    mind.

    John
     
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