Easy to build rig prevents reflow soldering mishaps

reflow_soldering_rig

[Erich aka VK5HSE] performs quite a bit of solder reflow work, but has always been concerned about bumping his circuit boards once the solder has liquified and is ready to be removed from the heat source. He says that removing workpieces from toaster ovens often results in the unintentional jarring of a circuit board full of components sitting on molten solder, and he wanted to find a solution.

Using some off-the shelf components from a local hardware store, he built a rig that fits on top of a hot plate, allowing him to move hot circuit boards away from the heat source in a smooth controlled motion. The rig is pretty simple, not only preventing unwanted workpiece movement, but also making it easy to regulate the amount of time a circuit board is allowed to heat.

He suggests that his design is not absolutely ideal, and that it can easily be improved upon in several ways without adding significant cost to the project.

Comments

  1. Tomasito says:

    You could move the hot plate instead of the PCB, just my $0.2.

  2. KebertXela says:

    Twenty cents? Feeling generous today, are we?

    I think the whole point of this guy’s project is that moving the hotplate can shake the PCB sideways since it has to be in contact with the board in the first place. That would cause the same kind of damage this is trying to avoid, from what I can tell.

  3. jeicrash says:

    Or cheaper and easier, let everything cool down before moving it.

  4. biozz says:

    … i need to build a reflow toaster
    *throws soldering iron across room in frustration*

  5. jaspel says:

    Why not use an inductive cook top instead of killing the pcb?

  6. biozz says:

    @jaspel
    because
    1) PCBs burn at a much higher temp than solder and if your burning your PCB during a reflow your doing something wrong
    2) we have not yet discovered a species of tree that’s leaves are US currency

  7. biozz says:

    @jaspel
    oh one last thing … inductance cooking can produce current on the metal traces that can be high enough to fry chips or other components … in theory

  8. jaspel says:

    in practice, I use it frequently for component FA. High temp solder and flex circuits… yuck. Regarding traces in pcb (copper), thats exactly why it is preferred. Largest mass will be solder connections, works quite well with a stencil on BGA reflows.

  9. biozz says:

    @jaspel
    just because it works does not mean its smart

    i have never seen an inductive reflow oven ever and there has to be a resion for that
    keep in mind an inductance oven is a giant high current EMF transmitter and EMF and electronics dont mix

  10. jaspel says:

    true, although Ive been having pretty good luck with it

  11. biozz says:

    @jaspel
    you have got to be putting a ton of stress on your ICs and it has got to be lowering the life of your components

  12. Whatnot says:

    He’s aussie it seems, in australia you aren’t even allowed to replace a plug on an electrical appliance or light without being a certified engineer, weird people those aussie lawmakers eh.

    Anyway from the picture I thought the idea was to slide the assembly away, but it appears the idea is to pick it up as you would a serving tray? Seems less than ideal to me somehow, I’d mess that up half the time.
    So how about a way to make the hotplate recess a very short way, like 1cm (1/3″) and then have wheels/rollers to slide it away? Although that would need some clever yet simple and cheap way to move that hotplate down in a balanced smooth way.
    Or maybe simply add some wire to the 4 corners of the holder to another rectangle above it to stabilize then to a central pulley to pull it up smoothly, possibly controlled by a small motor to avoid the human error component.
    Just thinking out loud.

  13. Jaspel says:

    WR to destructive FA

  14. Bill D. Williams says:

    Ummm….No. SMD parts stick like GLUE to molten solder. No really – they aren’t going anywhere – even when the solder is liquid. Well, maybe if you flung it across the room.

    This is a totally unneeded “hack” frankly. Makes me wonder if the HAD poster has any reflow experience, otherwise he’d know this is unneeded and kinda silly. Just lift the board up – it’s not rocket science.

  15. Erich says:

    the feedback’s appreciated.

    the goal was to get uniform heating, with the help of the aluminium plate, that was a close approximation of the JEDEC heating profile, cheaply.

    I’m not sure you could achive uniform heating with an induction hotplate.

    The proof is in the good results with the 0.5mm and finer pitched devices.

    I figured why burn your fingers lifting the board, or worse, jar it, when you can gently lift it up to cool, and move the hotplate away easily.

    Each to their own!!

    Cheers,

    Erich.

  16. Mike says:

    @Bill D. Williams
    I came here to share a story but read your comment and you are so very wrong. Makes me think you’ve never even seen SMT parts.

    I used to do small production runs of a product I was selling using a toaster oven. It worked great. One day I carefully pulled the board array out of the oven and set it down. I couldn’t leave it in there because the oven would not cool fast enough to follow the reflow profile. So I thought enough time had passed but knowing it was still hot, I decided to move the board again, and ended up dropping in on my carpet. Almost EVERY SINGLE PART came sliding off the board and onto my carpet. Apparently I hadn’t left it long enough and most of the board was still molten.

    It was fun picking 0603s out of the carpet.

  17. Bill D. Williams says:

    Well of course they are going to come off if you drop it! You’ve missed the point completely BTW. See where I said “Well, maybe if you flung it across the room.” – I think that’s about the same as dropping it on the floor. Don’t you? Ok good. So we agree you’re wrong.

    Solution, don’t be a klutz and drop your boards on the ground. Geeze. What the eff?

  18. Mike says:

    What part of “stick like glue” includes “parts flying off”? You must use some pretty crappy glue.

    How about you don’t be all high and mighty about your supposed mad reflow skilz and STFU if you don’t have anything nice to say. Not all of us can be perfect like you. You’ll just have to accept that.

  19. Mike says:

    Oh, and as far as I’m concerned this hack keeps you from dropping the board, which you clearly “know” is a bad thing, so using your own logic, I fail to see how you can simultaneously think it’s “unneeded”.

  20. Bill D. Williams says:

    You mad.

  21. Eric says:

    for an easy means of lifting it… why not use like a rig using an emergency car jack? one of the little ones that twists up should easily and gently remove it from the hot plate, and its alreay locked as its raisedso you could take out the hot plate from underneath.

  22. biozz says:

    @Bill D. Williams
    i have SMD parts slide around all the time … i use vacuum tweeters and sometimes even a dab of hotglue to keep things steady

    luckily for me most of what i produce now are chips or threw hole components

  23. Bill D. Williams says:

    Epilepsy?

  24. biozz says:

    ohhhh a troll
    okay

  25. strider_mt2k says:

    Yes. Troll.

    Do not feed.

  26. Bill D. Williams says:

    It amazes me how many “arm chair” and “pretend” engineers HAD comment section has. It’s 98% guys that look at forums all day but never really build anything. They have all this surface knowledge, but can’t take the next step. It’s clear as day in the comments. The above is a perfect example.

    God forbid you should challenge them – they’ll always pull the “troll” card.

    It’s the one thing I don’t like about hackday. Is that, rather than inspire people to really get involved (well, the atmel uC tutorial was kick a$$) – instead it fosters and encourages people to be “electronic project voyeurs.” And that’s exactly the people it attracts. Not people that want to DO electronics, but people that want to live vicariously through other people successes. That’s not healthy.

    So you get to the comments – and every post by these guys is carefully crafted to not give too much information that might give them away. And it’s always has lots of random trivia and parts name dropping to make them sound as if they know what they are talking about. “Oh that 0603 flew right off my FR4! LOL! Good ting it was a atmega238 HAHAH I would have been screwed! LOL!”

    My point is that, it’s really transparent. And sad. I just wonder what HAD could do to change that? What do you think?

    My 2 cents.

  27. Electronic Project Voyeurs Annonymous says:

    @Bill D. Williams
    “electronic project voyeurs” – sigh – I know I have been one for a long, long time. Didn’t know there is a name for it, however. We even have our porn magazines, and you probably know them (I’m not implying you are one of us, though).

    Well, anyhoo, I don’t think HAD can do anything to keep us EPVs away, but perhaps it could lock the comments for registered posters only – you can’t comment unless you post at least one (accepted) project first. So, if anyone badmouths anyone else’s project, there is always a known and clear target for retaliation!

  28. Dstrcto says:

    I second the idea of lowering the hotplate away from the pcb. You could mount the plate to a hydraulic jack. The pcb could sit on a sheet of metal like a cookie sheet. Lowering the jack would pull the hot plate down and allow it to cool.

  29. Erich says:

    I too thought about lowering the hotplate from under a fixed PCB support plate, but the problem I saw was how to support the hotplate evenly up against the support plate for even heating, in a simple, uncomplicated manner.

    One thought was a wheelbarrow innertube which could be inflated and then deflated, but the framework to hold the PCB support started to look a bit complicated, and inflation seemed tedious.

    In the end, simplicity won, with the fulcrum at the back, support plate suspended in the middle, and a handle at the front to lift gently, with only 10 or 20 minutes fabrication time with stuff lying around. If it weren’t working so well, I’d make a small cam mechanism to lift the handle at the front.

    If I can encourage just a few of those put off by the apparent cost or complexity of SMD use to give it a try with little cost, then I’ll be happy.

    Cheers,

    Erich.

  30. dan fruzzetti says:

    Why not move the heat source out from under the equipment instead?

  31. anonymus says:

    @Bill D. Williams –

    normal reflow ovens have several zones, thus by the time the board comes out there’s no risk of components moving. This guy isn’t using a real oven with profiling and ones; he’s putting the PCB on an aluminum sheet on a hot-plate.

    Under those circumstances you can imagine that small jogs could easily move some components? Sure, most stuff is probably okay, but some ICs have enough mass to be easily moved with a small knock, and fine enough legs for it to be a problem.

  32. anonymus says:

    @OP –

    you say this can’t be used for double sided boards.

    could you try building an insulated ‘cover’ (just the top and two sides, like an ‘n’ shape) the goes over the plate and the PCB? Build a jig to keep the PCB and components just clear of the hot-plate.

    Then add a fan to help cool the solder?

  33. Bill D. Williams says:

    @anonymus
    in theory yes. In practice no.

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