-- JonathanKarpick - 03 Apr 2006

Creating Gerber Files from ProTel

(From discussion w/ DanielSantos)

Once you have your PCB all laid out, save the Gerber and Drill files using the following process:

1. Goto File -> Fabrication Outputs -> Gerber Files
2. The selections can vary by fab house, but these seem to be standard:
   • General: Inches, 2:3
   • Layers: Top Layer, Bottom Layer, Top Overlay, Top Solder Mask, Bottom Solder Mask (for a two sided board with silk screen on the top...)
   • Drill Drawing: nothing checked
   • Apertures: embedded apertures (RS274X) box checked
   • Advanced: no changes...
3. Save the resulting CAM file to something meaningful.
4. Go back to the PCB design and choose File -> Fabrication Outputs -> NC Drill Files
   • Same options as before, i.e., Inches, 2:3
   • Suppress trailing zeros, Reference to relative origin, optimize change location commands
5. If you re-named the .cam file, it might ask you to save a new .cam file - forget about it and delete the resulting cam file that only has drill holes in it.
6. In your "original" drill file, goto File -> Import -> Drill
7. Choose the folder for your project, which is should be named something like: "Project Outputs for XXX" where XXX is the name of your project.
   • Choose the .TXT file in that directory (something like Project.TXT, NOT StatusReport.txt)
8. Select the defaults and then close out the resulting log window.
9. Save the CAM file.
10. Verify that all of the layers look good - traces don't wander off into nowhere, the pads and soldermask areas look good, etc.
11. Go into the directory where all of these files have been saved ("Project Outputs for XXX")
12. Zip relevant files into an individual .zip file.
    • project.gbl, project.gbs, project.gtl, project.gto, project.gts, project.txt for me...
    • include .apr file?
13. Upload or e-mail to the vendor of choice.

Panelizing your design

If you want to panelize your design before sending it to the vendor, this is done with CamTastic.

1. In Altius, add a new CAM Document to the project
2. Import the Gerber and Drill files and double-check that all of your layers survived.
3. Choose Tools -> Panelize PCB and then select the whole board. (Very AutoCAD here). Click the right button when you're done.
4. Enter your desired gaps, columns, rows, etc.
5. Delete the extraneous exterior border that Altius add on all of the layers...
6. You can repeat this with other boards to get more than one design on a panel.
7. Export gerber and drill files again...

PCB Fab Houses

Places we've used for board production:

1. Sierra Proto Express
   • http://www.protoexpress.com
   • located in Sunnyvale
   • Contact: Lourdes, 800.763.7503 x9920
   • Used for their ability to do 0.031" thick boards (although this still requires a "custom" job)
   • Good with Stanford POs.
   • Not so great prices if you have to go custom (i.e., thin boards).
2. Sunstone
   • http://www.sunstone.com
   • Good tutorials on-line
   • Cheap for non-solder mask, non-silkscreened boards
3. ExpressPCB
   • http://www.expresspcb.com
   • Uses their own software
     • Software can't import or export - you're stuck with them if you use it!!
   • $59 for three boards, exactly 3.8 x 2.5 inches each
4. PCB Fab Express
   • http://www.pcbfabexpress.com
   • Used for the OL RF Stickybot boards.
   • 5 circuit boards for $65 in 5 days ( + $15 shipping?)
     • 2 layer, silkscreen, solder mask, 0.062" thick, no arrays
     • Up to 100 sq inches
   • DOESN'T TAKE POs for the above special
5. Olimex
   • http://www.olimex.com
   • Located in Bulgaria
   • Recommended by Surya and Chris in Ken Waldron's lab
   • 2 layer, silkscreen and solder mask, 0.062" thick, 6.3" x 3.9" for $33 plus $9 shipping
   • Different thickness costs $5 more
   • Turn time is 3-5 days, shipping takes 8-14 days (Fedex available for $50)
   • Will panelize for you or accept panelized boards, and will break boards apart for free
   • DOES NOT ACCEPT POs
6. Advanced Circuits
   • Have $500 off your first order deal
     • No minimum (it seems), so first order, if under $500, is free
     • Deal expires on 04/30/06

Surface Mount Soldering

Will and Yong-Lae have had success using the solder paste (Kester 286LT) on the hot plate. This didn't work too well for me. I think the solder paste is way beyond its usability date. (Storing it in a refrigerator would have helped maximize its life...). Using the hot plate, the solder never really flowed.

The following technique worked pretty well:

• Place component on pads on the PCB.
• Put a SMALL amount of solder paste on the pins. (You can start with just a couple of pins to get the component fixed and then resume with the rest of the pins).
• Use a soldering iron with a small/medium tip at 600 deg F to heat the pad and get the solder paste to flow.
• If needed, use regular solder and the soldering iron to beef up the joint.
• For fine-pitch components (like the TQFP pic), you can lay down a small line of solder paste over the pins. The surface tension should cause the melted solder to bead up on the pins unless you use too much paste.
  • If you use too much paste and you get some connected pins, use a solder wick to get it out. (This isn't all that easy - you can see a couple of pins shorted on the StickyBot controller board, but fortunately, these pins aren't connected to anything!!)

No hot plate required!