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MANUFACTURING TESTING

by George Martin

Start ı The Problem ı A Possible Solution ı Test Setup ı POP Quiz ı Final Exam ı Sources and PDF

THE PROBLEM

Iıve got a design using one of the Motorola Coldfire micros being built in small quantities. Iıve got four to six units that will not pass the production procedures for loading code and operating in a system.

There are several methods that can be used to get these units up and running. First and foremost is a visual inspection (i.e., looking for wrong parts, parts oriented incorrectly, and of course, shorts and opens on the printed circuit board). The visual inspection could be done by an assembly-level person using the proper documentation. If one of these problems is found, there may be the same problem on several other units. Or, perhaps thereıs an area on the board prone to develop solder shorts.

The next method is comparing a working board to a non-working board, which could be performed by a technician using test equipment. This would work well if the micro came up and ran but an isolated feature did not function properly. Perhaps one of the serial ports wouldnıt receive data.

The final method is to sit a hardware design engineer down with the BDM pod and a set of schematics looking for problems. If the design is new, perhaps there are some marginal timing or signal requirements that are not completely understood. This is an expensive proposition and, if thereıs no design defect, probably one that you canıt justify. Add up the numbers and youıll see how much it really might cost.

This is the problem I find myself with. This product line will never see high quantities and build lots will be around 10 to 30 units. Letıs explore the option of writing test software to diagnose the defective units.

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