UPDATE: Solder Paste is now available!
In the past, we have hosted a few classes about the art of solder stenciling. Each time we do, we get quite a few requests for some kind of video coverage so people can learn at home. While we are still working on getting live video coverage for our classes, we have come up with a video specifically about solder stenciling. Check out our Stenciling Tutorial:
Solder stenciling is a great skill to have, even if you're only making one board! We use solder paste stenciling for pretty much all of our boards and it is a great, quick way to solder dozens of tiny SMD components. Not to give anything away, but as you know, tomorrow is New Product Thursday and we just might be announcing solder paste as one of the new products. Hope this video helps!
For a capstone project in college, I followed SFE's stencil tutorials.
I do want to make a few comments.
* If you need a cheap good stencil, use mylar 3mil from Pololu.
* If you use anything flexible, you need to match the thickness of your circuit board. Follow SFE's tutorial to know what I mean.
* Never tape the mylar stencil to the bench you're working on. Use heavy smooth surface objects to keep it in place.
* Be liberal with the solder paste as first. You'll use a razor edge to wipe it off. (Be gentle!)
* After you get your solder placed, IMMEDIATELY wash the stencil. I used distilled water and rubbing alcohol. If you don't, you run the risk of having problems with future use (not enough solder in places).
Also, keep the stencil protected. I kept my tube it came in.
Good tips!
I laughed when I realized he had a beard at 5:30 but not before or after that.
Those 5 o'clock shadows really creep up on you!
Beard skills provided by Chuck Norris.
Hmm, sure would have liked to see the board cook on the electric skillet. Most of the magic is seeing the parts wiggle and line up due to surface tension. I compare it to making your own prints in the darkroom and seeing the image appear. Never gets old.
Please, please!
It would be great if someone put up a tutorial for freehand solder paste usage. When I first started learning really serious soldering a year ago, I saw all these videos for using stencils, and I saw tutorials on how to solder QFN chips with regular solder and hot air, but no one said anything about using solder paste freehand! That is WAY easier than using solder and hot air, but doesn't require getting any stencils. I do pretty much all of my soldering with freehand paste and a hot air gun now, and its amazing! Why aren't there any tutorials on that! I had to learn it from an EE friend of mine.
-Taylor
Lol I finally got around to attempting some surface mount components a week or so ago (when the power went out). I applied my solder paste freehand (from a tube with plunger and syringe) to a small Sparkfun perforated board and soldered on some 0603 components (LEDs and resistors) with my butane iron. I was going to use the hot air attachment but I decided to just use a tip because I'm not very good with the air yet and it can get to be a lot hotter than I think it is.
It worked well but I can't imagine doing it with a 100 pin QFN or something. I can not draw at all and my hands tend to shake so for anything complicated I would definitely use a stencil.
I would love to see Sparkfun sell precut stencils that cover all package types so we can do one of test boards just using those (for pasting or applying resist).
QFN chips are easy. As said above, you don't need to paste each pin separately, just run a line down the row of pins, and if you get too much just use the corner of a piece of paper or something to wipe off the excess (I have some fine q-tips I use). Then just heat up the board with hot air or your plate until it reflows. I still haven't gotten the hand paste perfect, so a few pins are usually bridged, but thats easy enough to clean up with a soldering iron. All in all it is way less frustrating than doing it with just an iron and solder.
EDIT: I should mention that I have a very nice stereo zoom microscope i got off craigslist. That makes all this way, way easier. If you want cheap, check out the Madell tech chinese scopes, like this one: http://madelltech.com/m4-3.html We have a similar model from the same manufacturer at work, and its actually very nice!
Doing it free hand is easy enough and for 1 prototype I would definitely do that.
ICs are simple you just drag a trail of solder paste across the pads, do not bother doing them individually with reflowing the solder doesn't stick to the pcb surface anyways.
Using an electric baking tray (like in the video) is a very cheap and efficient way.
I've done solder paste freehand at an internship- this was the standard method for single-part attachment for testing. We had syringes full of solder paste with fine-diameter needles, and a compressed-air system regulated by a pedal to activate the flow. This took very steady hands (and a giant microscope). With a great deal of practice I got down to parts with six pads in 0.9mm^2 (about 0.12mm^2 per pad)
Tl;dr - it is possible, but slow and difficult
What thickness Kapton/Mylar film/steel should I buy to make my own stencils? The steel in the video looks warped, but that wasn't a con mentioned. Is warping a problem?
I am very new to SMD and I just received several chips from Digikey. I was dismayed at the size of them and was beginning to wonder what I had gotten myself into. This is an awesome video and the timing is great. Luckily for me my costs are not super critical in my proof of concept so I can fork out the extra needed for a custom PCB and Stencil.
You guys are great!
Awesome video, thanks guys!
Perhaps a silly question, but how is the stencil created? Is it photographically etched like PCBs or something?
They are laser etched.
Be sure to order Sparkfun Solder Paste with your next order!
(Hey, new product Idea for those Chinese New Year slow weeks.)
Good tutorial! Does anyone have any tips for stenciling a board with components on both sides?
A long time ago they were applying an orange adhesive between the pads to keep the components on the bottom side in place. You can still find it on some boards.
Good Question. Double sided boards can be very tricky. Start out by pasting and populating the side with the flattest components. This way when you do the other side it will be easier to create a jig to hold it in place. When you create the jig for the second side, try to match it up with the level of the board you are pasting, you want it as flat and smooth as possible.
Reflowing double sided boards can be difficult as well, almost more difficult than just pasting it. Professional reflow ovens sometimes have chain systems that can suspend the board above the conveyor so the bottom side components don't get moved around during reflow. The surface tension of the paste will usually hold all the components on the bottom as long as they are not too heavy. As far as reflowing in a toaster oven or something similar, the best advice I have is trial and error. Hope this helps.
Do you have any good sources on where to have stencils made? Buying a $10,000 laser cutter for a few projects seems like a waste. Does Sparkfun have a laser cutting service?
www.Pololu.com
I Like your Icon because of this link
This is a local Boulder company I use.
I bought a $600 Chinese laser cutter and replaced its controller with a $50 EiBot board like this one so I could drive it via simple ASCII commands over USB. Writeup begins here. You'd still need to either convert the stencil plot files into something InkScape can read or write a simple program to convert it into serial
command the EiBot board understands.
I believe they mentioned for the plastic ones it was made by http://www.ohararp.com/Stencils.html
Good guide, this seems to be a mutch quiker and profesional way of soldering PCB's. I'm pretty new to smd.
These stensils? Can they be lasercut from plastics? Or is there any easier way?
~JWRM22~