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Hand soldering LCC package

Discussion in 'Electronic Design' started by Robert Scott, Mar 8, 2007.

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  1. Robert Scott

    Robert Scott Guest

    I have in the past hand soldered SOIC packages for prototypes using a microscope
    and a soldering pencil. But now I am faced with a chip that is only available
    in an LCC package - the kind with the contacts under the chip. It only has 8
    pins. Is there any hope that I can solder this chip using hobbyist's tools?

    Robert Scott
    Ypsilanti, Michigan
  2. DJ Delorie

    DJ Delorie Guest

    Sure. Put solder paste on the pcb (very little), place the part, and
    use the iron to reflow each pad.

    Or, use a hotplate to get all the top-side SMD parts, then an iron for
    everything else. I have some leadless resonators I soldered with a
  3. Hawker

    Hawker Guest

    I have been able to solder these with a good Pace "mini wave" tip if the
    lands extend out far enough. For IPC-7851 lands there might not be
    enough land. For IPC-782 you should be good. The problem is that LLC
    parts usually have a ground power pad. This is for thermal dissipation.
    Sometimes you can get away with not soldering it, sometimes you can't.

    Some of your ability to hand solder this depends on the PCB finish. If
    it is HASL or Immersion silver you will have better luck than Immersion

  4. Robert Scott

    Robert Scott Guest

    Well, the land is under my control because I have not yet laid out the PCB. I
    intend to use Advanced Circuits in Colorado to make my prototypes. Should I
    order the bare-bones board without soldermask?

    Robert Scott
    Ypsilanti, Michigan
  5. Robert Scott

    Robert Scott Guest

    Excuse my ignorance, but what is a hotplate? Are you talking about a kitchen

    Robert Scott
    Ypsilanti, Michigan
  6. Hawker

    Hawker Guest

    No your going to definitely want solder mask on this one.
    Is this a typical 0.5mm pitch LLC?

    I had assumed you already had a PCB. If you can afford it do Immersion
    Silver for this board as HASL, even though it solders better, is often
    nto flat enough for good LLC soldering. The biggest problems I have had
    with LLCs is opens due to the part not laying flat. For just a few you
    should be able to make HASL work, but I wouldn't use it for production
    on any board with LLCs, BGAs, or .65mm pitch or finer.

    As to your hot plat comment. They are basically industrial versions of
    the home hot plate with metal table. Often chemistry folks have these
    for keeping things warm. People also have had good success using
    convection toaster ovens, especially when used with processes like the
    SIPAD process (google SIPAD).

    Me I have access to a fully stocked contract manufacture for my stuff so
    I only get to the kind of stuff your talking about when I am putzing in
    the lab late night and I can't pawn if off on someone else who does it
    all day long. My soldering is getting worse and worse as I get lazy.

  7. Ben Jackson

    Ben Jackson Guest

    LCC (Ceramic Leadless Chip Carrier) isn't the kind with contacts only
    under the chip. The pads extend up to the side, and there is no center
    pad. Are you talking about Analog iMEMS devices?

    Perhaps you mean QFN or LFCSP, but I don't think those go down to 8 pin.
    An LCC land pattern looks huge compared to QFN.
  8. DJ Delorie

    DJ Delorie Guest

    Yup. You know how your stove has, say, four "burners" on it? So you
    can cook four things at once? I've got a single-burner electric
    hotplate, normally used in dorms or apartments for cooking one thing
    at a time. I just cook circuit boards on it. I have a syringe of
    solder paste, and either manually dab it onto all the pads, or etch a
    brass stencil to squeegee the paste on.

    Hotplate experiments:
    The hotplate:
    Brass etching:
    The idea: Skillet
  9. Mark Harriss

    Mark Harriss Guest

    I'm soldering a QFN68 pin package by hand:

    1. By keeping the component stored in a jar with lots of silica gel and
    a moisture indicator, the first samples I was sent made no mention of
    the "pop-corning" effect caused by absorbed moisture turning to steam
    and cracking the package.

    2. Using a 400W stove element hooked to a temperature controller to warm
    the board to 120 deg C to preheat the board and dry the component. This
    also provides a slowly cooling base to reduce thermal stresses.

    3. I made a spring steel clip attached to holes drilled into the edge of
    a sheet aluminium base: the clip holds the component in position while
    you tack solder a corner and the aluminium base transfers heat from the
    hotplate to the board.

    4. After a corner has been tacked down with solder and while the board's
    still on the hotplate I run a small iron around the edges of the
    component drawing a blob of solder as I go to leave a clean join on each

    5. After soldering the hotplate gets turned off to allow cooling down of
    the board with a thermocouple monitoring the component temp.

    I'm playing around with IR reflow using a toaster oven but I need to get
    some extra flux to add to the solder paste as it doesn't seem to flow
    too well and lots of small balls of unflowed solder paste show under the
    microscope. The IR oven shows promise but always needs reworking at present.
  10. Robert Scott

    Robert Scott Guest

    How did you know? Yes, it is an accelerometer.

    Robert Scott
    Ypsilanti, Michigan
  11. Rich Grise

    Rich Grise Guest

  12. jasen

    jasen Guest

    Yeah, a stove "burner" with a flat metal surface.

    portable Single burner hotplates are available if your kitchen ventilation
    isn't upto the task of removing the smell of hot resin.

  13. DJ Delorie

    DJ Delorie Guest

    PLEASE don't use your regular kitchen stuff (or even the kitchen
    itself) for PCB work. The chemicals involved in PCB work should never
    come in contact with the same utensils you cook food with.

    My hotplate is dedicated to PCB assembly, and lives in my office next
    to the soldering iron.
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