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SX20AC/SS / SX52BD soldering — Parallax Forums

SX20AC/SS / SX52BD soldering

LemonLemon Posts: 34
edited 2005-03-06 17:32 in General Discussion
Hi all - Looking at my latest creation - or the paper-napkin schematics for what might be - I thought to my self: Why on earth·am I still using those "huge" DIP chips, when SSOP is like four times smaller, and has a lot more techisc kind of look on a PCB (i.e. the SXKey lookes more cool - I think - than the SX Tech board it self).

So, young and naive as I·sometimes pretend to be, I bought·a box of·10-cent 20 pin SSOP chips (not the sx, but some cheap gadgets witch functionality I don't even care to check out), just for verifying if I was in fact able to solder the tiny things on to a copperclad board - wich I wansn't freaked.gif

Does this mean I'm too fat-fingered to solder SSOP components or do people in general just avoid SSOP unless they have a machine to do the soldering?

If the first (fat-fingered) version is closest to the truth (i.e. if SSOP _can_ be hand soldered) is there a kind soul who could point me towards some material (online or books) on the subject?

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Why do·they call it a spacestation? There's hardly "space" for anything in there.
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Comments

  • frdchangfrdchang Posts: 14
    edited 2005-02-18 22:02
    hello,

    the way i solder SSOP components is by lathering the pins with solder. (just glop it in)

    then use a copper wick to wick away the excess solder.
  • James NewtonJames Newton Posts: 329
    edited 2005-02-18 22:08
    http://www.sxlist.com/techref/smds.htm

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    ---
    James Newton, Host of SXList.com
    james@sxlist.com 1-619-652-0593 fax:1-208-279-8767
    SX FAQ / Code / Tutorials / Documentation:
    http://www.sxlist.com Pick faster!



  • LemonLemon Posts: 34
    edited 2005-02-18 22:11
    Hehe I tried weldering it one pin at a time with a 0,5mm/0,2inch tip - it looked as silly as it sounds. I'll try with copper wick in 142 minutes when my next test-PCB is done in the etching tank.

    Thank you James, I'll try both wick and the sxlist-walkthru [noparse]:)[/noparse]

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    Why do·they call it a spacestation? There's hardly "space" for anything in there.

    Post Edited (Lemon) : 2/18/2005 10:16:56 PM GMT
  • Paul BakerPaul Baker Posts: 6,351
    edited 2005-02-18 22:19
    there are two common ways for hobbyists, the first is drag soldering here is a good video showing the technique: http://www.howardelectronics.com/navigate/videoclips.html·(its the 3rd video).

    Second is using solder paste and heating the pad only.

    Both have thier advantages and drawbacks, James' link talks about some of the issues. First and foremost if you doing hand soldering, you need a quality, temperature settable iron with a very small tip.
  • LemonLemon Posts: 34
    edited 2005-02-18 22:24
    Oops, that should have been 0.02inch, and not 0.02.

    Thats a lot of clips paul [noparse]:)[/noparse] actually more than one looks interesting.

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    Why do·they call it a spacestation? There's hardly "space" for anything in there.
  • KenMKenM Posts: 657
    edited 2005-02-19 02:13
    What works well for me is a standard soldering tip, but a chisel shaped tip is better.

    Liberal amounts of liquid flux.

    1.Tack two opposite corners

    2. Then with a small amount of solder on the tip, "wipe" it across the leads. ( I did not yet see the video suggested in a previous post, but assume it does the same/similar)

    3. Clean any bridges with solder wick

    When I return from this business trip in Japan, I will snap a photo of my amature work and post it.
  • ForrestForrest Posts: 1,341
    edited 2005-02-19 02:30
    You'll also find it's easier to solder SMT chips on commercially produced printed circuit board compared to boards you've etched at home. Commercially produced boards have solder mask in between the chips legs (to prevent solder bridges) and they already have soldered pads (which reduces the amount of solder and time required to make a solder joint).
  • LemonLemon Posts: 34
    edited 2005-02-19 02:30
    Please do KenM, at the moment I'm trying to figure out how to remove the bridges without removing all the solder thereby detaching the chip. I got all weekend, the next three weekends and·100 pcs of 10-cent ssop ICs·to get it right.

    Btw. did I mention I'm quite a cavetroll with a solderingiron - but it's about to change, or so I have descided.

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    Why do·they call it a spacestation? There's hardly "space" for anything in there.
  • LemonLemon Posts: 34
    edited 2005-02-19 02:52
    Forrest << True, but I can garage-produce a square meter of 2-layered PCB, at the cost of 10 squareinch commercially produced PCB. So with my tiny budget, I prefere spending more time and less money [noparse];)[/noparse]

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    Why do·they call it a spacestation? There's hardly "space" for anything in there.
  • Jim PalmerJim Palmer Posts: 23
    edited 2005-02-19 03:06
    I have not done this myself for I only do a couple of new boards a month, but this has to be one of the cooler ways to do SMTs - In a toaster oven: www.seattlerobotics.org/encoder/200006/oven_art.htm

    I create my own boards with the Press-n-Peel stuff and I unfortuantly don't have any way to add a soldier mask, so the soldier drag method has not worked out so well. However, I do use the following technique: www.circuittechctr.com/guides/7-3-1.shtml

    with the a few changes:

    1) I make the pads for the smt only as large as the pins
    2) Before putting the chip on the board, I tin all of the pads with very little soldier with the exception of one pad the has some extra
    3) I use tweezers to hold down the chip (straddling the board when the chip is close to the edge) and touch the iron to the one pin with the extra soldier and check alignment
    4) For the rest of the pins, I use .38mm 60/40 soldier, touch the iron to trace paths close to the pins, but I leave room to touch the solder on the trace path between the tip and the chip.

    The trick here was the tining of the pads before putting chip down. I have found in the past that trying to get the solder to flow up under the path and onto the pin would frequently fail due to a lack of heat transfer as only a small spot on the pin would actually touch the copper. With the pad lightly tinned, it seems to collect where it can transfer the heat to the pin.

    Ok, so admittedly, I am not a professional and I am sure I would get beat-up for not using flux, but the joints are shiny and seems to be quite strong.

    If I ever do slip and add too much solder and it jumps across pins, I use soldier removal braid on those pins. I try to time it to leave a little, but usually (as you hinted) end up taking it all up and just redoing those pins.

    Good Luck

    Jim
  • Paul BakerPaul Baker Posts: 6,351
    edited 2005-02-19 04:15
    check out www.sparkfun.com·, they offer pcbs at $2.50 per sq inch, no minimum dual sided w/ solder masks and silkscreen. Its the most affordable "the works" service I've found (actually Jim McCorison found it).
    Only draw backs are that its 8mil min (proper pads for 8mil chips is 6mil) and its a 2 week turnaround.
    Lemon said...
    Forrest << True, but I can garage-produce a square meter of 2-layered PCB, at the cost of 10 squareinch commercially produced PCB. So with my tiny budget, I prefere spending more time and less money [noparse];)[/noparse]

  • LemonLemon Posts: 34
    edited 2005-02-20 14:58
    Thank you guys.
    I have just made a perfect connection of a 20-pin SSOP "thing". Using a LED and a 6V battery, I have verified that there are no bridges between the pins. I found that I get the best result using a generous layer of a German "l
  • ForrestForrest Posts: 1,341
    edited 2005-02-20 15:19
    FYI if you have a lot of excess flux the board - I'd recommend removing it with isopropyl alcohol and a cotton swab. The reason is most no clean rosin based flux will harden after it's been heated to activation and it's non-conductive. If there's still some flux that hasn't been heated to activation - then it should be removed because unactivated no clean flux IS slightly conductive.
  • LemonLemon Posts: 34
    edited 2005-02-20 15:24
    Hmm, that would be a problem. I'll better go isopropyl alcohol shopping then. Thanks

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    Why do·they call it a spacestation? There's hardly "space" for anything in there.
  • KenMKenM Posts: 657
    edited 2005-03-03 03:50
    As Promised, my feable surface mount soldering of an SX.

    A "pro" would tell you that this is a mediocore job at best. There is far too much solder on the pins.



    Post Edited (KenM) : 3/4/2005 4:00:13 AM GMT
    sx.jpg
    601 x 581 - 217K
    sx.jpg 216.8K
  • LemonLemon Posts: 34
    edited 2005-03-03 04:04
    I'm still at the trial'n error stage.

    I noticed the chip is labelled SX18AC/SO - is that an older version that is not available anymore?

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    Why do·they call it a spacestation? There's hardly "space" for anything in there.
  • BeanBean Posts: 8,129
    edited 2005-03-03 04:05
    That doesn't look too bad.

    Looks like you have something between pins 8 and 9. Might just be a piece of lint ???

    Bean.

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    Check out· the "SX-Video Display Module"

    www.sxvm.com
    ·
  • KenMKenM Posts: 657
    edited 2005-03-03 04:07
    Yeah, lint.

    I have been using that guy for several months so far w/o a problem.

    k
  • KenMKenM Posts: 657
    edited 2005-03-03 04:21
    I noticed the chip is labelled SX18AC/SO - is that an older version that is not available anymore?
    Yes, it is an old version no longer available, like the soon to be SX18/DP when parallax runs out of the 1200 or so in stock.
  • LemonLemon Posts: 34
    edited 2005-03-03 04:30
    Am I the only one who thinks that SOP would be the perfect combination of the (almost) SSOP size and the DIP easyness of soldering? Oh well, thats kind of off topic i think.

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    Why do·they call it a spacestation? There's hardly "space" for anything in there.
  • KenMKenM Posts: 657
    edited 2005-03-03 14:58
    For me personally, for a one-off project I don't mind the surface mount stuff.

    For a project that will (has been) sold, where I may have to build 6 to 10 of an item, I prefer a DIP package.
    For me, a DIP package can be soldered into a board much faster and easier than I am capable of doing surface mount, and you know what they say.....time is $$.

    My $0.02

    Ken
  • LemonLemon Posts: 34
    edited 2005-03-03 15:09
    Time is $$, but I seem to have more time than $$. If I was to make money on my applications, I'de be willing to live with DIP, but the weight of i.e. a DIP based PCB vs. the weight of a SOP or SSOP PCB means the world if I was to place an SX in my indoor RC airplane, or inside my highly outdated cellphone in the attempt to give it extra features.

    But Im getting the hang of SSOP soldering anyway, there by saving another inch of valuable space (and weight).

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    Why do·they call it a spacestation? There's hardly "space" for anything in there.
  • Guenther DaubachGuenther Daubach Posts: 1,321
    edited 2005-03-03 16:30
    Hey,

    SMT is also a question of the developer's age. I have met younger people who were able to solder SMT components to a PCB in an almost dark room. When I try to do this, I need

    1st - my glasses
    2nd - plenty of light
    3rd - a magnifying glass
    4th - at least one drink to calm down my hands
    5th - a small tip on my soldering iron, and finally
    a lot of good luck
    smile.gif

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    Greetings from Germany,

    G
  • SteveWSteveW Posts: 246
    edited 2005-03-03 16:39
    You missed out the magic of a squirt of reflow flux - makes everything a thousand times easier.
    (I also need the right amount of coffee - too much, or too little, and I shake all over the place [noparse]:)[/noparse]

    I scored one of these http://smtinspection.com/mantis_detail.htm on ebay a while back - they're superb.
    For documenting stuff, I've also got an old Intel QX3 play microscope - now superceded by
    http://www.playdigitalblue.com/products/qx5/info/ which looks a lot better (much higher resolution, faster frame rate, cheaper)
    Probably not good enough to work under, but definitely a good inspection tool, and $80 isn't too bad at all.

    Steve
  • Paul BakerPaul Baker Posts: 6,351
    edited 2005-03-03 16:57
    Has anyone thought of a project to do smt soldering involving an X-Y table and a Z axis arm holding a soldering iron? It would likely still require manual application of the flux and the solder to the iron tip. I'd imagine the most fool-proof way to program a solder action would be to do what assembly line robot programmers do; dry run the action and the controller would repeat the action. This could alieviate bad eyesight/shaky hand problems. To cut on component cost you could eliminate the drive of the X axis and simply use it as a manual positioning axis.
  • Guenther DaubachGuenther Daubach Posts: 1,321
    edited 2005-03-03 17:03
    Steve,

    this was a good tip - I have just ordered one of the Digital Blue microscopes. When I have it here, I'll give you a report on how useful it is.

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    Greetings from Germany,

    G
  • LemonLemon Posts: 34
    edited 2005-03-03 17:45
    Guenther Daubach said...
    Hey,

    SMT is also a question of the developer's age. I have met younger people who were able to solder SMT components to a PCB in an almost dark room. When I try to do this, I need

    1st - my glasses
    2nd - plenty of light
    3rd - a magnifying glass
    4th - at least one drink to calm down my hands
    5th - a small tip on my soldering iron, and finally
    a lot of good luck
    smile.gif

    My list includes:
    1st·- plenty of light (or something to keep the soldering iron away from my fingers).
    2nd - A nice balance of water and (dare I say tobaco) to keep my mind focused and the smell of burned fingers from reaching my nose.
    3rd - How do you do with just one drink? My hands would be out of control with a drink in one hand, and only a solderingiron in the other to keep the balance. Two drinks for each hand will definatly even out the weight ratio of left and right hand and keep'em both steady. But not 6 drinks thou, since the last to goes straight to the forehead and pulls down towards the solderingiron, leaving a "Harry Potter" style scar.


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    Why do·they call it a spacestation? There's hardly "space" for anything in there.
  • LemonLemon Posts: 34
    edited 2005-03-03 17:48
    Paul >> I was thinking about sort of the same device, but for drilling and not soldering. Seems the holes for DIP are imposible to make in a straight line when I go beyond an 8-pin row, even when using laser sighting for precission.

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    Why do·they call it a spacestation? There's hardly "space" for anything in there.
  • Beau SchwabeBeau Schwabe Posts: 6,568
    edited 2005-03-03 17:59
    Lemon said...
    ...straight line...

    My trick is to "ping" the holes first to create a small divot so that the drill does not have
    a tendency to wander. I'm not sure what the proper name for the tool is, but I could
    post a picture I guess. It basically is a 'pick' with a very sharp point at one end, and
    a large base at the other end that you can hit with the palm of your hand. It takes a
    little bit more time, but it does the trick.

    Also for the drill, I have a jeweler’s variable speed drill with a snake attachment.
    (speedometer cable with a very small drill chuck at one end, motor at the other.)

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Beau Schwabe - Mask Designer III

    National Semiconductor Corporation
    (Communication Interface Division)
    500 Pinnacle Court, Suite 525
    Mail Stop GA1
    Norcross,GA 30071
  • Paul BakerPaul Baker Posts: 6,351
    edited 2005-03-03 18:11
    Lemon:
    Do you have a dremel? how about getting a dremel drill press?

    Beau:
    I do in essence·the same thing, I use a hand drill with a 1/32" bit and the trigger speed control set to barely rotate at full depress, then I put the bit in the dremel and drill away. I quickly learned that even at the lowest speed, the dremel will skid across the surface without a divot. I use the dremel because it is much easier to control by gripping with both hands and doing a straight plunge. Though a jewelers drill with snake attachment would be even easier.
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