Making stencils for solder paste at home

Hot air/hot plate/toaster oven soldering with solder paste are generally much easier than soldering by hand for circuits with more than a few SMD components. And a soldering stencil to accurately place consistent amounts of solder is much easier than laying down trails of solder with a syringe -- and there's much less board cleanup of solder bridges to do when a more controlled amount of paste is applied.

Unfortunately for those of us who prefer to etch a few proto boards at home when possible to test out a basic design & build quick development boards, stencils generally cost $35 or more and take a few days to get back. This is a way, using the same tools as etching circuit boards, to build quick proto solder stencils. The quality probably won't live up to the stainless steel or mylar ones you'd buy, but you might be surprised.

Note that the same method can also be used to chemically mill other designs -- decorative pieces for jewelry boxes, shadow designs for projecting with a Luxeon, etc -- possibilities are endless.

This method as posted won't eliminate the cleanup work, and I'm sure there are refinements to this method that will make it all work that much easier/better. I look forward to comments from others on ways to improve the method.

Apologies for lack of pictures in the later part; to get the pictures here I did a quick run-through but didn't do the actual etch/solder paste application. Poor quality pictures are due to close shots with a cell phone camera.

Step 1 Before we begin

The method here is based on how I do circuit board etching -- which is likely very different from how you might do it. I've been etching circuit boards for a few years now and how I do it has changed quite a bit over that time as I find new tools & approaches. Almost any standard way of etching boards should work fine for doing this too; whether you do iron on, light sensitize boards, etc; just a bit of thought and you should be able to adapt this to work with your methods.

Comments

[dmhead]

This is a great way to help with making a solder stencil. Great post.

[sdookay]

forget the heating of ferric chloride. It'll etch just fine at room temperature. You don't want to breath ferric chloride fumes--it is extremely hazardous to one's liver. It is safe at room temperture as long as you don't swallow it or allow it on your skin.

If you want to etch fast you could use an acid bath such as muriatic acid generally available at hardware stores but also requires caution to use.

Ferric chloride has long been preferred for delicate etching of copper such as in photogravure. Generally to adjust the rate of etching--one adjusts the baum (viscosity).

All in all this seems cumbersome to do and copper isn't cheap these days so it might be worth buying mylar stencils after all is said and done. You can get 4 sq in mylar for $25 these days.

Otherwise, i am considering hand cutting mylar stencils as i have done some fairly intricate stencil cutting for silkscreen. it seems a lot less work actually than all of these and i expect can be done good enough with a bit of patience and some decent magnification.

[AtomSoft]

Which paste did you buy from them

[safeer123]

[e-mail]

[g1r9a6d8y]

I have just used this method to etch a stencil, TSOP48 with 0.5mm pitch and it worked flawlessly. I am really impressed with this process and definately will be using it again for other projects, thanks :)

[bob332]

excellent write up :) just wanted to let you know that sparkfun has a .cam file that does exactly what it should have been in eagle w/ a paste stencil that is correct - it is about 1/2 of the way through this article/tutorial - http://www.sparkfun.com/commerce/tutorial_info.php?tutorials_id=109

[DynamoBen]

You mentioned that you used a modified laminator. In what way did you modify it?

[tymm]

http://www.pulsar.gs/PCB/a_Pages/4_Products/4d_Toner_Applicator/TIA_Mod_Instructions.pdf

[sean1121]

Can't be found there any longer, mirrored here:
http://simnets.com/pub/pcb/TIA_Mod_Instructions.pdf

[wiml]

I haven't tried this stencil etch yet, but when etching PCBs I've found it helps to "bake" the copper after I've transferred the toner to it before I start etching. The idea is that it melts the toner on the copper and it helps to close up pinholes, etc. You can see when the toner goes to a darker, smoother black.

[tymm]

hmm; with pnp blue, if the transfer is successful I haven't had any problems. I've had issues with the paper transfer stuff -- pulsar even has another film to put on top of the transferred image to help with this (you do the paper transfer, remove the paper, then iron the other film on top to seal it). From what I can tell though the pnp blue handles this in one step.

[wiml]

I guess I should try the PnP. I've only used the paper stuff. (And I've used plain copier paper, which (amazingly) does work, just barely. Lots of paper fibers are left stuck to the board which leads to hairline shorts. I didn't actually expect it to work at all.)

[justDIY]

wow ... I can't wait to give this a try! thanks for sharing.

[dfowler7437]

You can use an image scanner to make better images of PCBs and other flat things. I have some examples an details at the link below

http://www.uchobby.com/index.php/2006/12/16/pcb-pictures-with-scanner/

[tymm]

Thanks -- I don't currently have a scanner; I should be able to get up some better pictures around the new year though.