Testing Next-Gen PCB Designs

All that is great for MetorGraphics to sell their next design software, but there is software and there are designers, not all are good, and those that are are few and far in between ;o(

Also, its 1 thing to design a "Fantastic PCB that does this and that" and all, then you have to give the PCB to the manufacturer, they build the boards for you, test every interconnect on their flying-prober or the like and give you boards with validation of interconnection...

next step

your board goes off to the assembler and they come back with "Oh great who the F designed this board, we don't care what it does, how are we supposed to test it? did you guyz even think of that?" Oh but we designed it with This brand new fantastic software that did everything for us... did you enable option XYZ to enable testpoints/testability, I'm sorry, we can manufacture this board for you, but we only have a 26% test coverage..

This is what I mean by "There is software and there are designers"

Testability is unfortunatly not included in the design process, unless they need to check for signal-A and signal-B on the cct diagrams, that is useless from the standpoint of the PCB assembly house, as you the customer wants 100% of the board 100% tested, but generally fail to realise that your brilliant circuit cannot be tested, cause you either forgot about the testing process or just didn't know about it..

Its always great to read what the software is capable of doing, but this is from the sales desk of that company, its then to the designer of those boards to "know" what they are doing, Software doesn't make the designer.

The field I work in from day to day is the testing manufacture, I take the PCB CAD model and then report to the customer how much coverage they have on their new PCB's and at times 26% coverage is pretty good, then a overly happy customer gets a bit unhappy cause the board may need redesigning, some customers that have walked that road before come and talk about the testing process, but sometimes they too still forget some important aspects..

Some boards are simply just not designed for test, or they will pack 1/2 the test points under a top area that you cannot push down upon cause of BGA's or SMT caps (those that crack are a problem) you cannot counter test probing force if there is spare "land" to place a support.

As designs get smaller and smaller, and the test points become closer and closer together there are difficulties becoming problematic in the testing field (placing test pads under the ends of IC's is the worst I have had)

The most interesting PCB I have had was a flexi-board type, it then folded into 3 dimensions with differing parts going in different directions, those designers work miracles, component placement so that a high component on 1 part of the device fits into a low component space on another section once folded, but also these guys built testability into the design, ALL nets were routed to the surrounding "biscuit" to allow the tester to get a complete coverage.

ok enough rambling now, you can wake up :P