The PC Board Page
Here's a great meta-tutorial on how to think about designing and making a circuit board from scratch. Lady Ada is your friend. http://www.ladyada.net/make/mintyboost/process.html
We've been using the Eagle editor. It's a free download from http://www.cadsoft.de and a decent schematic/PCB editor that all the cool kids are using. (Though I'm not as cool I used it for the motor controller, daughterboard, and remote pcbs). Jtfoote 12:22, 17 February 2008 (MST)
Here's a schematic tutorial: http://www.instructables.com/id/SXU9BO166NEQHO8XFU/
How to make a A Custom Library Part in Eagle If you'd like to make your own part in Eagle, this tutorial will be very helpful.
The con-subd library has DB9 - DB25 connectors. There are a bunch of RJ45s in the Amp library.
Lady Ada says to import custom graphics into EagleCAD use the importbmp.ulp script. I did this with the SWARM logo on the daughterboard and it came out great.
About Eagle: the schematic editor is a little funky, sometimes it doesn't join wires to components even if they seem to be touching exactly. It will warn you about this during the electrical rules check, but it's not obvious what is going on at first. To fix, add a junction (green dot tool) to pins, or zoom and drag things on top to make sure they are connected.
As far as the PCB goes, be sure to turn off mirroring for all layers.
Eagle v 5.0 now runs natively on the Mac!
Jonathan has Gerbmerge, a Python program that will "panelize" printed circuit boards. More information on gerbmerge is here: http://claymore.engineer.gvsu.edu/~steriana/Python/gerbmerge/
Checking your PCB:
You should use a Gerber viewer to double check the generated files. The board should appear transparent as viewed from above, with all the holes, traces, solder pads, etc. lined up. A common mistake is to recreate the Gerbers and forget to do the same for the drill file. If you've moved anything the pads and holes won't line up, and the Gerber viewer will make this obvious.
Rick recommends Pentalogix Viewmate to check out Gerber files. Free for PCs. Lady Ada also recommends "gerbv" (Mac?) and "GC-prevue" (Windows). Google is your friend here.
Also try printing out an actual size board, glue it to cardboard and install mounting hardware, etc. to verify clearance around mounting holes, connectors, etc.
I recommend checking in everything that you send to the fab into Subversion. With all the moving parts, having a working copy that you can reorder easily is handy. It's also a great idea to make a public parts list at Digikey. It's pretty easy, and to order parts for new boards is just a button click.
All the SWARM pcb's are in Subversion here: http://svn.lee.org/swarm/trunk/pcb/
Rick designed the Illuminator, Tad designed the Aggregator, Mark designed the Sound Module, and Jon designed the Daughterboard and H-Bridge motor controller. Any of those folks would be happy to help.
We've used Advanced Circuits (domestic) http://www.4pcb.com and Golden Phoenix (China) for PCB fabrication. Advanced Circuits is faster, but you pay for it. They also have annoyingly aggressive sales people. Definitely use the Advanced Circuits free design-rule checking service http://www.freedfm.com for the Gerbers regardless of where you send them to be fabricated.
Solder Paste, Hot Air Guns & PCB's Oh My!
Hot air reflow (soldering) of circuit boards speeds up the assembly process and also gives your boards a neat, professional appearance. The four main things you will need are a digital, temperature controlled heatgun, a solder paste syringe,a syringe plunger, and syringe tips. An assortment of dental picks and tweezers is always handy when working with SMT parts.
I use a Steinel HL-2010E Heat Gun. I dropped some cash for the 25th Anniversary Kit which is available at Amazon (!) http://www.amazon.com/Steinel-Heat-Gun-25th-Anniversary/dp/B000MUO0VS You can also find this heat gun elsewhere on-line if you don't want to buy from Amazon.
Purchase some No-Lead solder paste from Ameritronics. It has a six month shelf life without refrigeration and a 1 year shelf life if you store it in the 'fridge when not in use. A 10cc syringe lasts a long time! http://www.ameritronics.com/lead-free_solder_paste_RoHS_nolead-10cc.htm
Syringe tips are also available from Ameritronics. Syringe tips allow you to place just the right amount of solder on the pads; these are HIGHLY recommended. Ameritronics sells a neat syringe tip assortment pack (scroll to bottom of page): http://www.ameritronics.com/dispensing_needles_blunt_industrial_tapered_paste_tips.htm
- NB:DO NOT use the smaller stainless tips with the solder paste; the paste is too viscous to pass through these tips. Ameritronics recommends using PLASTIC syringe tips with their Zero Lead solder paste.
You'll also need a cheap plunger for the solder paste syringe also available from Ameritronics: http://www.ameritronics.com/plungers.htm#Econo%20Plungers
When I have more time, I'll add a little tutorial on doing hot air reflow with a heat gun.
Coating your PCBs
It is very rare to need to coat PCBs, however, naked PCBs and the playa DO NOT MIX. Here is the procedure that I used for coating the illuminator boards. The same procedure is going to be used for the IMU boards.
1.Git yerself a can of Krylon UV Resistant Clear Matte finish acrylic coating;It's Krylon # 1309 (the UV resistant thing is very important) (try Pearl Art or Flax, they have it in gloss. Center Hardware -might- carry it, call first)
2. Make sure all the boards are clean and free of oils, etc; use rubbing alcohol to GENTLY clean them (small parts don't like being nudged).
3. Carefully mask off all pins, programming headers, leds, and parts that you don't want clear coated.
4. Place boards on a clean surface preferrably away from dusty areas
5. Give each board a liberal spray coating
6. Allow to dry (dries in 10-15; can handle the boards after two hours)
7. Turn boards over and repeat
NB: For exposed electrical connections that can't use a standard connector, I recommend using Star Brite Liquid Electrical tape
Recommended PCB Fab houses
- http://4pcb.com - Jeff Keyzer recommended on DorkbotsSF 6-09-09
- http://www.surface-art.com/ - Mark Lakata recommended on DorkbotsSF 6-09-09
- http://www.sfcircuits.com - I don't have any personal recommendations about these guys yet, but they are in the Bay Area, which is nice.
Recommended PCB and cable Assembly houses
- Jeditron Technologies Corporation, 44137 Fremont Blvd. Fremont, CA 94538 - Julian Flores - Sales Manager 510-226-1383. They assemble custom cables. Very reliable according to Lee and Jeff Keyzer
- http://www.assemblymastersltd.com PCB and cable assembly comes recommended by zsradding
- http://www.meritronics.com/ in Santa Clara recommended, they did a job for Don French with through-hole and surface mount PCBs in the low hundreds count.
Recommended PCB Software
- ExpressPCB "which is actually a decent if dumbed-down PCB editor" but locks you into their fab service.
- Cadsoft EAGLE - Limitations to free version: 1 schematic sheet, 2 signal layers. New Lite version has less restrictions Jtfoote 02:08, 27 May 2010 (UTC) widely used and recommended
- http://www.gpleda.org (Linux / Mac) - Windell Oskay recommended on DorkbotsSF 6-09-09