How to check the PCB design for manufacturing(DFM)

Question

I am interest in PCB design ,As to design for manufacturing ,Can somebody share some guidelines or linkes to learn? Can pcb fab house be available for this job?

Answer 1

Most PCB shops will work with Gerber and Excellon drill files, which your PCB design software should be able to create. If it can't, dump it and switch to a decent EDA package.
While Gerber is a good standard which should avoid a good deal of possible misunderstandings you still need extra documentation files. Talk about it with your shop, what do they need? What format? Layer stacking is one thing which comes to mind.
While your EDA software can automagically create Gerber files from your design you still want to verify those, since there are many options and a small mistake may go unnoticed. There are several Gerber viewers around, for instance there's the free GC-Prevue.

Answer 2

One of the primary things you'll want to do when designing a PCB is to make good use of the Design Rule Check (DRC) function in your PCB program. The DRC lets you check your PCB desgin to make sure the board house you choose can manufacture it. This includes things like minimum space between traces, minimum space between vias, minimum copper surrounding vias, etc. The DRC typically lets enter values for each of the measurements that it is capable of analyzing. The values you want to use depend on what PCB manufacturer you use. For example, here is an example of the capabilities of a board house I use (Sunstone PCB). The software I use to make PCBs is FreePCB. The users's manual for FreePCB lists the following DRC measurements it can make (page 63, these are the minimum allowed distances):

• trace width
• pad to pad
• pad to trace
• trace to trace
• hole to pad or trace
• hole to hole
• annular ring (pins)
• annular ring (vias)
• board edge to any copper
• board edge to hole
• copper area to copper area

Most of these are covered by the 'minimum trace/space' statistic on Sunstone's webpage. Minimum trace/space is the minimum trace width and the minimum spacing between traces. This generally holds for any copper feature to any copper feature so it probably applies to the trace to trace and copper area to copper area rules. From reading Sunstone's webpage it looks to me like this should be 6mil, but when in doubt, be conservative and choose the highest number you think it might be. You have to get clever with some of these - the fields in the DRC don't always correspond 100% to the capabilities pages of the manufacturer.

And never forget that mils are 1/1000th of an inch and NOT millimeters!