This page contains resources on Printed Circuit Board (PCB) tools and assembly techniques that have been collected from various people and places for use by senior design students. Send questions to reese@ece.msstate.edu .
PCB tools that I have had personal experience with are:
The ORCAD tool has no restrictions on board size, and can do multi-layer PCBs. However, you must be connected to the University network in order to check out a license from our license server. The ORCAD tool also has an auto-placer which can be useful if you design has many components. The ORCAD tool is available on the MSU ECE PC lab machines; you can also get the installation CD's by talking to the ECE system admin.
The EAGLE layout editor has an advantage in that there is a freeware version available that can do two layer designs (top/bottom) up to 4 x 3.2 in, and the schematic editor can only create one sheet. However, the auto router is included, all libraries are available, and there is no limit on component count. There is no license checkout in the freeware version so you do not have to be connected to the network. The GUI does not follow 'Microsoft norms' so the learning curve is a bit steeper than it would be with other Windows tool.
There are other 'free' PCB tools available on the WWW. Please avoid those that only offer a PCB layout tool without schematic capture or that are tied to a particular PCB fabrication service. PCB layout tools without schematic capture are little more than drawing tools that let you put down PCB footprints and then have you manually draw traces between vias. While the learning curve on these types of tools is small, you will eventually wish that you spent the time to learn a tool that had more power or those that output files that are compatible with multiple PCB fabrication services.
ORCAD is installed on the ECE PCs in the PC room on the first floor of Simrall. You can also obtain installation CDs from Michael Lane, the ECE system administrator whose office is on the first floor of Simrall next to the PC lab. However, to run the software you must be physically connected to the ECE network (a wireless connection will not work) in order to check out the necessary software license.
There are many, many other companies which offer evaluation versions of PCB tools. Some are listed below.
TopLine Dummy Components has data sheets for all commercial PCB footprints. If you are trying to determine the dimensions of a footprint, or just figure out what it looks like, take look at this site.
Here are a few of the many PCB fab services available.
Dr. Reese will handle PCB orders. Before a PCB will be ordered, the PCB must be reviewed by Dr. Reese and you must have all of the parts that you plan to put on the PCB in hand (this is to prevent problems with mis-matched footprints). You must also have given Dr. Reese a test plan for the PCB that indicates how the PCB will be populated and tested (population/testing of the PCB must be done in stages, and you should have included test points on the design for checking each subsystem as you populate the board). When submitting your PCB files, you must first check them using the automated PCB file checker at www.FreeDFM.com. In the ZIP archive of your PCB files, you must include a README.TXT file that lists each file in the archive and its purpose, such as TOP SILKSCREEN, or BOTTOM COPPER, etc. Unless you have components placed on the bottom, don't submit a bottom silkscreen file. The README.TXT file must also have the X x Y size of the board in inches, to at least one decimal place. If you require a special board thickness other than the usual default of 0.062" or your board is a shape other than rectangular, talk to Dr. Reese as these boards may cost more. Even though most services claim 5-day turnaround, it always takes about 7-10 calendar days to get the board back. Dr. Reese expects copper fill to be used on both top and bottom of the boards for either ground or supply routing, so be sure that you know how to do this in your PCB tool of choice. Finally, the PCB files must be in Gerber 274X format - both ORCAD and Eagle have options for generating this format (they can also output older formats which may even be the default output format - you must use 274X format because this is what fab houses want).
The default wire sizes and spacing in both OrCAD and Eagle are conservative enough that these designs work with any of the PCB fab services that have been used in the past. For Eagle, the default wire size is 10 mil, and spacing is 8 mil. For ORCAD, the default wire size is 8 mil, and spacing is 8 mil. Most PCB fab houses allow tighter spacing/width than this, and if you need tighter spacing, then be sure that you follow the rules for whatever fab house your design will be sent to (talk to Dr. Reese if you need more information). Both ORCAD and Eagle have internal design rule check (DRC) tools that you can run to see if your design violates minimum spacing/width rules.
Note: PCB orders won't be checked for design correctness, they will only be checked to see if you have an appropriate number of decoupling caps and have followed a reasonable part placement for your design. The ZIP file you provide will be forwarded to the PCB vendor, who will build exactly what is specified in the files. Double check your design before you order boards.
There are three ways of prototyping with surface mount devices: