Electronics > Manufacturing & Assembly

Recommendation for a stencil frame and a squeege

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peter-h:
I need to assemble a panel about 15x20cm. Not often, maybe 10 a year. But it wants to be something which is not totally awful.

I tend to use JLCPCB for the stencils, which last time came in at some huge size (roughly A3) and I had to cut them down.

I see loads of these things for sale, at all different prices. For example Olimex in Germany sell a stencil holder for €950:
https://www.olimex.com/Products/Tools/StencilPrinters/
and at that price it ought to be gold plated! But their squeeges are reasonably priced. Olimex don't sell to the UK under €200...

Then I see some on Ebay where even the most expensive are 1/5 of the Olimex price, but obviously these will be chinese and some/most will be junk; the £80 ones are visibly crap
https://www.ebay.co.uk/sch/i.html?_from=R40&_trksid=p2334524.m570.l1313&_nkw=solder+paste+printer&_sacat=0&LH_TitleDesc=0&_odkw=stencil+holder&_osacat=0
Also all the Ebay ones I can see need framed stencils.

My boards are double sided so I need a means of supporting them underneath while printing the topside.

I use a hot air gun to reflow the solder.

Most of the time (a day or so) is spent placing the components.

Any suggestions much appreciated.

jmelson:
I use PCBway, and their stencils also are pretty big.  Way bigger than the board.  But, I had a plate with notched bars for the board to sit in, and was able to rig a hinge to it and clamp the stencil frame to the the hinge with C clamps.
Before that, I made my own stencils out of 0.003" brass shim stock, and those were made to be just about 50 mm bigger than the board.  I used masking tape as the hinge.  So, an unframed stencil can work fine, expecially with less than cutting-edge lead pitch on components.

I'm not sure the commercial stencil holders are any better than the thing I made up myself.

As for a squeegee, I use a piece of 0.025" thick brass shim material.  It is visible to the left in the second picture.  I also have a shower tile squeegee from Ikea that works, but is harder to clean.

Jon

phil from seattle:
For what it's worth, JLCPCB lets you change the size of the stencil.  Not only that, if you reduce the size of the stencil by a relatively small amount, it drops the shipping cost quite a bit.

Mangozac:

--- Quote from: jmelson on June 16, 2021, 03:41:06 pm ---I'm not sure the commercial stencil holders are any better than the thing I made up myself.

--- End quote ---
Yeah I don't think it's any worse (and possibly better) than our standard Chinese stencil holder. We have it purely for prototyping and backup if our automatic printer were to fail.


--- Quote from: phil from seattle on June 16, 2021, 07:07:54 pm ---For what it's worth, JLCPCB lets you change the size of the stencil.  Not only that, if you reduce the size of the stencil by a relatively small amount, it drops the shipping cost quite a bit.

--- End quote ---
Indeed, there's really no reason not to order a stencil with your prototypes these days when you can reduce the stencil size down so it has no impact on freight cost.

48X24X48X:
I would recommend using a framed stencil. It provides stability and flatness on the stencil. I don't use any stencil printer and only lay the stencil on top of the PCB. Have been doing this for more than 40K of PCB down to 0.4mm pitch. Only during 1 off prototype I would use the smaller custom size without frame JLCPCB stencil. Before that, even for prototype I would used framed ones but the amount of waste I created prompted me to reserve them for production run only. At times, I would have 50-60 framed stencil that is not being used anymore. For low volume, even those cheapest stencil printer in the links you posted works fine. It all depends on your technique to apply the paste and a good USD5 squeegee.

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