SparkFun Forums

[lukemalpass]

I know you can get stencils cut for PCBs or some houses provide stencils with the boards, but I do 90% of my boards at home and a lot of them are SMD and I like to use paste where I can.

At the moment I apply it from a syringe and it does the job fine for 0603 caps and the likes, but for things like ICs I still hand solder as its much quicker than dispensing the paste on all the close together pins by hand and it just gets messy. The same applies once I get down to QFNs and 0402s.

My question is, does anywhere sell a kind of generic stencil that is just a stencil containing all the standard SMD footprints like QFNs of most sizes, 0402,0603,0805,1206, SOIC, SSOP etc... so that I could just place the
part of the stencil over the pads and apply the paste over it?

If not does anyone know the best place to get a stencil done at a good price and would anyone else be interested in them? If so I can order multiple.

[ohararp]

lukemalpass...if you put together a gerber file with what you would like to do I could certainly cut something closer to your specs. Personally, I think a custom stencil for each of your complete pcbs is the way to go.

[lukemalpass]

My problem is a probably make 3-4 custom PCB one-offs a week (just personal learning or cool stuff to play with) and so its one of those things I would never go to the length of getting a stencil done, but at the same time would like a half-way point of having at least a stencil for certain common pads.

When I get time hopefully this week I will try to get a complete gerber of all pads I can think of.

What size do you recommend to keep stencil too? As I can always split them into multiple if required.

[MichaelN]

I don't see how such a "generic" stencil would work for me, since I pack in the components pretty tight.

It is certainly a dilemma. While Ryan's stencils are very good quality & value, sometimes you really don't want to wait. I even looked at getting my own "cheap" laser from China, but concluded I couldn't justify the cost when I can get a stencil for $25 from Ryan...

I think you'd be best to look at improving your syringe dispensing system. Commercial tools use a pneumatic arrangement to allow precise dispensing, and I'm pretty sure there are hobbyists who have managed to replicate something similar.

[lukemalpass]

I have the finest tip for the paste, but I find the problem is not the amount that comes out, but the fact that it doesnt tend to break from the tip and instead when I have just enough paste on and try to lift away the paste comes with it, not staying on the pads at all. I overcome this with the larger 0805+ size pads as it sticks to the pad just fine, but anything lower doesnt and it becomes awkward.

I was thinking if I got the stencils I could cut out the pads for specific ICs and passives very close to the holes so they could be placed in pretty fine but still have enough kapton around to allow the paste to the applied over it. Its just an interesting idea I keep thinking of trying.

[ohararp]

I could see that on a board that maybe you would want a qfn/dfn/tssop stencil to do your fine pitch parts and then do all the passives by hand.

However, once you have used a stencil once for all your parts it will be hard to go back. I tell you what...like any good "dealer" the first sample will be free for you. Cover shipping and I'll cut you a stencil at no cost.