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A novel way to solder Surface Mount ICs — Parallax Forums

A novel way to solder Surface Mount ICs

william chanwilliam chan Posts: 1,326
edited 2009-07-03 03:24 in General Discussion
I was recently thinking of asking my PCB maker to coat all the pads on my board with a fairly thick amount of solder.
Then all I have to do is to dip the smd ic legs into flux before placing it on the pcb and then into the oven.

No need for solder paste or stencils.

You guys think it will work?

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Comments

  • LeonLeon Posts: 7,620
    edited 2009-07-01 10:55
    I can't see any PCB supplier doing that, although I suppose you could ask them to leave out the solder-leveling stage. The solder will be uneven and you won't get reliable joints. I drag-solder fine-pitch devices - it's very fast and works very well.

    Leon

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    Post Edited (Leon) : 7/1/2009 11:02:23 AM GMT
  • mctriviamctrivia Posts: 3,772
    edited 2009-07-01 12:35
    apcircuits.com/ does this by default. though it is no a lead free solder.

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  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2009-07-01 16:18
    One additional problem with that much solder on the pads is that it will tend to form a crown (convex surface), which will make the components want to slide downhill. Without a really sticky flux, pins on multi-lead parts will end up in the valleys between pads.

    -Phil
  • WBA ConsultingWBA Consulting Posts: 2,935
    edited 2009-07-01 18:48
    There is a process called "Solid Solder Deposit" or SSD being performed by SIPAD Systems in Georgia (USA). They are the sole North American company performing this process. Basically, they screen print paste on a board, reflow it, wash it, flatten the solder (to remove the convex surface Phil mentions), and finally screen print an adhesive type flux onto the pads. The adhesive flux is the trick as it remains very tacky so that standard pick and place machines can be used. This is not an affordable process for typical products, but for certain assemblies, it is ideal (certain RF and microwave boards for example).

    I looked into it a few years and still have two sample boards here at my desk. I have the spec on the flux and tried to source it myself to create boards with SSD so that a kit could be offered to someone. All you would need then is a toaster oven to make a professionally looking SMT board from a kit. The adhesive type flux at that time was almost impossible to source, so I gave up on the idea.

    www.sipad.com/index.htm

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  • mctriviamctrivia Posts: 3,772
    edited 2009-07-02 06:37
    here is a picture of a circuit board made by advanced circuit. i soldered on the qfp prop with no problems in my reflow oven using the solder on the board and a little solder paste on the center bad. I did not try to do any of the other components this way because it is late and i misplace my flux pen. (I can't wait until I move in August and get my own workshop)

    It worked well.

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  • william chanwilliam chan Posts: 1,326
    edited 2009-07-02 11:53
    Have you verified that all pins are connected?

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  • mctriviamctrivia Posts: 3,772
    edited 2009-07-02 13:08
    not yet. visually it looks good I will be soldering on supporting hardware tonight and testing it works. will get back to you then.

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    propmod_us and propmod_1x1 are in stock. Only $30. PCB available for $5

    Want to make projects and have Gadget Gangster sell them for you? propmod-us_ps_sd and propmod-1x1 are now available for use in your Gadget Gangster Projects.

    Need to upload large images or movies for use in the forum. you can do so at uploader.propmodule.com for free.
  • pwillardpwillard Posts: 321
    edited 2009-07-03 03:24
    You might have better luck asking them to do what SCHMARTboards does. Create extra thick layers of solder resist so the part falls into the "grooves" left in the resist. It's a solder guide as much as a resist layer on their stuff.

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    There's nothing like a new idea and a warm soldering iron.
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