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By SOI_Sentinel
#4980
Read through it when it was first posted. Well written and I don't see any obvious holes. It is true that most people won't need to go to this extent, although I don't know how many or large of items people are ordering :)

Very interesting, may I suggest some latex surgical gloves? Cheap, disposable, helps to keep the hands more sanitary.

Now, to find some decent and inexpensive solder paste. I have syringes to fill.

As for Pololu, I haven't been there in ages. Good for general robotics, and the costs of laser cutting + materials are very fair. I might have to pick up a sailplane plan online and see what they'd quote me for cost :)
By nall
#4981
great tutorial, sparky!

it cleared up quite a bit. especially, how to get stencils made without paying an arm and a leg.
By murphyr
#4995
Do the parts need to be placed before the paste dries, dose it matter, does it work better one way or the other?

If the parts are placed before the paste dries, does it ‘glue’ the parts to the board?
Or will I still need to be really careful not to disturb part placement until reflow?
By zilym
#4999
Just got done reading the solder paste and reflow skillet tutorials. Excellent! Thanks Sparky for all the great work you and the SparkFun guys do!
By meander
#5017
how can you do it without the stencils?
By wiml
#5022
If you're not using a stencil, you can dab the paste on carefully with the syringe, or a toothpick, or a pin.
By mcollas
#5023
Firstly, would alignment be easier if the stencil had a red tint instead of being completely transparent? That way, the red stencil over green solder mask would show up as very dark, and the cut-outs over tin would still show up as bright.

Secondly, have you guys considered offering a stencil pooling service? You might even be able to get Pololu to cut the stencils up, leaving you with just the job of mailing stencils out. Just about everyone could win from this:
  • Pololu gets more business because you're sending it their way. They're getting big orders which are less hassle.

    Spark Fun gets even happier customers who can have a stencil included with their board at around the same price as the board. If you get enough volume there might even be some profit in it.

    There should be a lot less hassle than with the PCB service because there is only one layer.
    Spark Fun customers get cheap stencils without the $20 tooling charge so they can afford them even for small boards. Postage is halved for customers because the board and stencil are put into the same envelope.

    US Postal Service gets a little bit less money - I think they'll be OK.
Michael
User avatar
By sparky
#5066
Can you dab paste onto a board - sure. Will it work - probably not. You'll have solder jumpers all over the place. But don't take my word for it. Try it and tell us how to *make* it work.

Can BGAs be done with a hot plate : yes! But how are you going to test the connections? Time to whip out the trusty x-ray inspection machine. No, really :)

Pooling service : I would *love* to. Pololu is willing to give us good pricing structure so that we can offer the same $20/$1 service. Unfortunately we can barely cover the PCB service right now. We are hoping that Steve or Martyn will help setup enough DRC filters that we can simply continue the PCB service. Once that happens, then we can think about the stencil service. For now, I have to point you towards Pololu (tear). Tell Jan I sent you...

-Nathan