Printable catalog (PDF)
OK so boards came in, and there’s 80-100 to be assembled. They’re pretty simple boards: 1 8-pin micro, 3 resistors, 1 capacitor and 2 4-pin header plugs. Since it takes a long time to solder, I designed the board for mass-manufacture: surface mount parts!
Eventually everyone needs to make a lot of PCBs (at home), the best way to do this is to use solder paste and a reflow oven. Since EYEBEAM has a laser cutter I can use it to make a screening stencil and a registration frame. (You can also buy stencils from your 4pcb.com and probably a bunch of other PCB manufacturers) Then it’s super fast to make tons of PCBs. Just silkscreen on solder paste (available at digikey), place the components, and bake!
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First, cut out a frame from 1/16″ acrylic the same size as the PCB, this will be the registration frame
The PCB should be a perfect fit
Extract the stencil info. I took the stop layer, viewed it in GC-prevue, printed it to a file (ie. PostScript), then opened it in CorelDraw which is set up to print directly to the lasercutter
Cut it out in 2-3 mil Mylar
Register (align) the screen on the frame and tape it down
Now…use a biz card or something similar as a squeegee. Lay down a bead of tasty solder paste…
[gv data="http://video.google.com/googleplayer.swf?docId=6066848196815777770&hl=en"][/gv]
OK now you have a board with solder paste dots
Place the components with your tweezers
[gv data="http://video.google.com/googleplayer.swf?docId=-1907760876743714269&hl=en"][/gv]
Repeat 80 times, and put them into the toaster. 200 degrees for 4 minutes, 300 for 2 and then 450 until the paste melts, then 300 for a minute to cooldown.
Yay you are done! now all thats left is the thru hole parts…
FEED
wowzers — your bake cycle is quite a bit longer than what I use… Although the toasty look on boards can be somewhat endearing…
Comment by engyn — August 3, 2006 @ 1:20 pm
Hmm. I just ‘guessed’ what do you use?
Comment by ladyada — August 3, 2006 @ 2:27 pm
i use 325 for about 3 minutes. I also tend to watch my boards carefully in the last minute to see if things are reflowing. Of course, since I don’t do large batches the way you do its probably easier just to have a recipe and go with that. I’m sure there is a great deal of oven variability though.
I think I started watching so carefully because i didn’t like the smell when I burned my boards…
Comment by engyn — August 3, 2006 @ 2:51 pm
Is the solder safe to use (health-wise) in an oven? Is it non-lead? Or do you have an oven dedicated just for that use?
Comment by ken — August 3, 2006 @ 3:48 pm
Unless it’s RoHS compliant it has lead in it. Personally I love lead based solder because of how nice it flows. The lead free stuff is okay but it’s just not the same. If you use a toaster oven for soldering write “NOT FOR FOOD” on it like I did and never use it for food (RoHS or not). My toaster oven was $15.00 at Walmart and was inexpensive enough to buy a second one for food.
Comment by Bob Darlington — August 5, 2006 @ 9:05 am
I’m sure there are nuances here, but my general answer for the first question is no. Dedicated oven under all circumstances.
Comment by engyn — August 5, 2006 @ 9:24 am
How did you cut the stencil?
Comment by tony — November 18, 2007 @ 3:51 pm
Hi,
I have been trying to bake a board today. After a bit more than 390 degres, the PCB board started to bend and made a weird sound.
I can notice that you have ordered the PCB through a company to make the layout.
I wanted to know what PCB do you recommand me as I am doing the layout through a router (milling machine).
Thanks
Comment by Eric BADEr — March 27, 2009 @ 12:21 pm
this is a really old and not so good version of the project. its being ‘redone’
Comment by ladyada — March 27, 2009 @ 12:25 pm
This is really good,but we want to know when to bake the PCB’s.Can we refer the manufacturing date code.If the thing is like that in which week we can bake the pcb.
Comment by Shivakumar — June 1, 2009 @ 5:32 am