(Certified Best Practice by BMPCOE)
Autonetics Electronics Systems (Boeing North American A&MSD) - Anaheim,
Rockwell Autonetics Electronics Systems' (AES') current method of electronic components screening includes component environmental stressing including source-inspection surveillance of environmental stressing performed at the vendor. Receiving and inspection is also performed at Rockwell AES for those components which are not source-inspected. Rockwell AES additionally performs in-circuit and printed wiring board functional testing, environmental stressing and assembly functional testing, and system burn-in and test.
Even with this screening, Rockwell AES was concerned with the quality of parts and cost impact of rework on higher level assemblies, including the system level. A component yield reporting and corrective action program was therefore initiated. The program approach is to collect component yield data by collecting data on which components fail during board, assembly, and system level testing. Component defect reports are issued on a monthly basis. The first report was issued in April 1989.
Rockwell AES collected the following data for a particular program. From April through September 1989, over 450,000 components were tested during the board, assembly, and system level testing. There were 50 components which failed and had to be replaced. The distribution was integrated circuits (ICs) - 54%, resistors - 20%, transistors - 18%, capacitors and diodes - 4% each. These figures related to the following parts per million (PPM): ICs - 375 PPM, resistors - 50 PPM, transistors -385 PPM, capacitors - 20 PPM, and diodes - 100 PPM. Within the 450,000 components, there were 646 different part types of which 30 part types were responsible for the 50 component failures. Further data analysis showed that one transistor part number was involved in 56% of the replacements.
Rockwell AES currently analyzes the data to determine which component vendor is responsible for which failures. This data is then used to develop a software process improvement. This index is combined with the vendor's quoted price to determine the total projected cost, thereby determining which vendor will be awarded the contract.
Long-range plans for the program include the development of vendor/Rockwell AES component teams to evaluate performance data, indicate corrective actions, identify components requiring additional screening or tests, and evaluate corrective actions. Rockwell AES, together with the vendor, will develop the acceptance criteria for those parts which meet and those which exceed the 100 PPM criteria. Rockwell AES will continue to award contracts based on the real cost of components, not just the quoted cost.