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Future: 0603 versus 0402 parts

Discussion in 'Electronic Design' started by Joerg, Mar 13, 2007.

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  1. MassiveProng

    MassiveProng Guest

    Where did you get that weight figure, and the velocity figure?
    The ball is moving. No accounting for that?
    We are trying to deflect the ball, so shooting directly at it
    doesn't get you anywhere. It must be struck from the side with
    respect to its direction of travel. That's obviously not what you
    got.
    One must first get one's impact energy figures correct, which you
    haven't.
    It sure would, if the ball were struck at an angle of incidence
    other than perpendicular.

    In fact, such a strike creates a torque arm. Do you even know what
    that is?
     
  2. John  Larkin

    John Larkin Guest

    If he has 0402 dimensions that work better than mine, I'd be stupid
    not to ask. I'm not afraid to admit that I don't know everything.
    Since about 1965, originally with Chartpak and rubylith on mylar.
    Nowadays I have a really good fulltime guy to do it for me... a decent
    layout, with a thousand parts maybe, tends to exceed my attention
    span. But I do discuss the design with my layout guy all through the
    process, and do the final tweaks (like cosmetics and signal integrity)
    myself. I occasionally lay out something small, usually a test board,
    all by myself just to keep in practice.

    And sometimes I do initial placement for him, when it really matters.
    Since I can change the schematic to optimize the layout, I can do
    things he can't.

    FPGAs are great: I can tell him to connect those 12 12-bit A/D
    converters to that BGA whatever way looks nicest, and we can assign
    the FPGA pins later, whichever way he decided to do it. Comes out
    beautiful, like a butterfly's wing.

    How long have you been doing pcb layout? Still do it?

    John
     
  3. John  Larkin

    John Larkin Guest

    Sure I got it wrong. Big deal. My ego's not so fragile that a typo on
    a sheet size is going to damage it. It's not like I ordered a thousand
    reams of 11x14 paper or anything.

    You got the legal size thing wrong. So what?

    John
     
  4. John  Larkin

    John Larkin Guest


    I was offering to walk you through it, but I guess you're not
    interested.

    2.6 grams at 330 m/s, whacking a 5 kg bowling ball dead-center in free
    space, gets it going about 0.17 m/s.

    Is that what you got? What's the approximate time/force applied to the
    ball?
    That wouldn't change the results much.

    John
     
  5. krw

    krw Guest

    John, That's a ThreeDong reply. Not bad, but the best I've seen
    Dimbulb award *seven* dongs. Keep up the good work!

    ....and yes, Dimbulb, the whole Universe is laughing behind your back.
     
  6. krw

    krw Guest

    scale it as you see fit, Dimbulb. Oh, I forgot. You don't know how.
    Of course it is, Dimmie. It's moving towards us. If it weren't, we
    wouldn't be worrying about it, now would we.
    I didn't see John say anything about direction, Dimmie. Delta-V is
    the only thing important here.
    He has better numbers than yours. Oops, I forgot that you don't have
    numbers; no math.
    I'd didn't know they chalked nukes.
    TORQUE ARM??? Collision? In space?? HAHAHAHAHAHAHAH

    Damn Dimmie, that's the dumbest thing you've said in weeks!
     
  7. Rich Grise

    Rich Grise Guest

    As usual, Big Dork is wrong yet again - legal size is 8 1/2 X 14.
    (I can't understand why everyone wants to keep feeding that troll.)

    11 X 14 (or, probably more correctly, 14 X 11) is that old-style line
    printer paper - I don't know if it ever had an official letter designation.

    Cheers!
     
  8. Jeff L

    Jeff L Guest

    Having mounted at least a few million parts recently, stay with 0603's or
    even 0805's unless you need the space savings. The 0603's have some sort of
    3 digit number on them usually to help identify the value, and 0805 and
    larger have enough room for 4 digits so 1% resistors are not written with
    something cryptic. Some people prefer to use larger parts, even 1206's to
    make the product bigger! See below - People often don't like to pay 10k+ for
    a device that makes a altoids can look huge!


    Reliability might even be a little better with the larger parts due to the
    larger solder joints, and apparently more current noise can be produced with
    0402 resistors due to the higher current density.

    I don't even bother looking at Digikey for production prices. I can buy a
    typical 5,000 piece reel of 0603 resistors from $5 to $10 CND.
    Something's wrong then. We just placed about 110,000 (110k) 0402's and ended
    up with about 10 tombstones - and most of these were attributed to poor
    placement accuracy (I need to do / get done a calibration for the placement
    heads on our main chip shooter if I ever get time, as 1 or 2 (out of 12) of
    them are out about 2 to 4 hundredths of a mm (0.02 - 0.04 mm)). It's amazing
    that good pick and place machines can place parts accurately at the speeds
    they run - ours (turret design) places most part sizes one at a time at 0.15
    seconds per part with (when calibrated) a 3 sigma variance of 0.08 mm! On
    our newer assembly line, the fine pitch placer is accurate to 0.025 mm @ 3
    sigma!

    We do notice that there seems to be a lot more mispicks with 0402's. We
    typically assume 1 to 3 percent part wastage due to mispicks for larger
    parts in a larger production, but I think some 0402's approach 5% or more.

    One other thing is that 0402's require fairly new machinery - 0603's can be
    mounted with much older machinery (there are machines that are over 20 years
    old that will still mount 0603's very reliably at reasonable speeds). Using
    parts no smaller then 0603's and SOT 23's allows the use of old equipment,
    and thus possibly offers a shorter manufacturing lead time or possibly a
    cheaper production as the machines have been paid for.

    0603's and bigger are also much easier to inspect visually.
    Good choices!

    1206's still have there uses too (other then dissipation / voltage /
    capacity reasons) - they are good for making it bigger! People see things
    like cell phones getting cheaper as they get smaller and then costing
    nothing, as long as you sign up for a basic contract, so they start to
    associate smaller = much cheaper! How can you, in most cases charge 10 - 20K
    for a product with a surface area of a couple of inches!? Repair / rework /
    modifications are easier for the people unskilled in micro soldering with
    large parts.
    Yes, they will be around for a long time yet!
    The QFN's are not a problem - I just mounted over 900 of them yesterday, and
    only had a couple of failures, all of which were on the same panel, which
    was due to that particular board shifting during the solder paste printing
    process (didn't use the post print inspection, as the lot was small and the
    process is generally very reliable). Reworking them is also fairly easy. You
    do have to be careful when you design the footprints though. DFN's also have
    very little problems. I've never worked with a chipscale package, but they
    seem to be like miniature BGA's - which are not too bad to mount either, as
    long as the proper gear is available.

    Jeff
     
  9. Rich Grise

    Rich Grise Guest

    Woody to Buzz Lightyear: "YOU! ARE! A! TOY!!!!!!!!!" ;-)

    Cheers!
    Rich
     
  10. Rich Grise

    Rich Grise Guest

    .
    Do you?

    If so, please enlighten us.

    Thanks,
    Rich
     
  11. Rich Grise

    Rich Grise Guest

    Well, I bet you've ordered at least a box at least once in your life,
    if you've ever had a 14" carriage line printer. ;-)

    Cheers!
    Rich
     
  12. Jeff L

    Jeff L Guest

    See commonts inserted below:

    I have never seen this problem, and have produced a lot of boards with a
    large variety of parts. Ever see 1206's, 0603's, 0402's, a few 2220 caps,
    QFN's fine pitch QFP's and BGA's all on the same board? Or fine pitch BGA's
    with all 1206's? We just did a fairly complex board with 0.4 mm pitch parts
    (those are not nice), tons of 0.5 mm pitch parts including large QFP's,
    SOIC's, DPAK's, littered with 1206's a few 0805's and some 0603's. It's all
    in designing the footprints and solder paste stencil correctly.
    See comments in other post! 1206's are about 1.5 to 2 times as expensive as
    an 0603. Don't use Digikey prices for production prices. 1210's are for
    specialty purposes, eg voltage / wattage / capacity issues.

    Jeff
     
  13. Joerg

    Joerg Guest

    If enough care is taken, yes, it can work well. Most of my boards are
    also rather mixed. The extreme was a board with 0603 on there but also a
    DIP because the LM331 doesn't come any other way.
    I know but Digikey price ratios for reel qties are usually a pretty good
    indicator when weighing one technology against another. Sometimes they
    even beat distributor "pre-haggling" prices.
     
  14. Jeff L

    Jeff L Guest

    People want their Cell Phones, camera's, Ipods and PDA's smaller and
    smaller, with ever increasing features and always lower cost, this is the
    result.

    As you noticed, the uBGA's and CSP's are an option! The parts are almost
    always available in more traditional style packaging. QFN's and DFN's are
    easy as long as everything is designed correctly. They are easy to put down
    in production along with placing them manually. Although I haven't mounted a
    CSP, BGA's pose little problems also if done right, but you need a way to
    reflow them if done manually.

    If you look at low cost things like PC motherboards, they don't use the
    smallest technology possible - they use what works best. They don't use
    CSP's and micro BGA's unless there is a very good need for them. Notice that
    for the most part they use 0603's! Even some consumer stuff even to this day
    still uses through hole. Look at a typical TV main board or a stereo board.

     
  15. MassiveProng

    MassiveProng Guest


    You are as retarded as the officer in "Under Siege".

    "We'll see what we'll see, now won't we?"

    Yep, you even beat him in the retard realm you exist in.
     
  16. MassiveProng

    MassiveProng Guest


    Nope.
     
  17. MassiveProng

    MassiveProng Guest


    The scenario, dumbfuck, was a .22 and an 11 pound bowling ball, you
    fucking retard.
     
  18. Jeff L

    Jeff L Guest

    I know what you mean - after working with a bunch of 0402's, I sometimes
    confuse 0603's with them!
    So, there is nothing wrong with using larger parts - the suppliers keep
    pushing smaller is better (I think to push sales of new assembly equipment,
    and to cover the investment costs of the production of smaller components).
    I see no benefit in going smaller unless there is no room. I do however see
    lots of problems in going smaller. Mostly reliability concerns and
    production costs (especially hidden ones - ie change this resistor for this
    mod now takes 5x longer and may be less reliable).
    That's nasty!

    I once resoldered my entire old laptop's motherboard (P2 233) littered with
    0201's with a 1/8" chisle tip soldering iron! This fixed the intermittant
    problem when you twisted it a bit.
     
  19. MassiveProng

    MassiveProng Guest


    If you strike a spheroid in space or anywhere else, and you hit it
    at a point that is NOT on its line of travel, you create a torque arm,
    which in turn imparts a spin on the spheroid, you retarded ****.

    So actually, your reply is the dumbest thing you've said in at least
    one post. I'm sure you'll top it soon, however.
     
  20. MassiveProng

    MassiveProng Guest


    Easy to tell where this idiot's mentality is. Look what the
    retarded **** watches.
     
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