Semiconductor and consumer electronics assembly operations typically process several, if not dozens of products at the same time, on the same manufacturing lines. In many cases, the products are not physically distinguishable from one another. As a result, physical mixing of multiple chip types can take place during assembly. These mix-ups appear to be defective products because, when installed in completed PCs, they do not operate to specifications. Entire lots of semiconductors were unnecessarily returned to the manufacturer. Investigation identified the problem as item level mixing between production lots during the assembly manufacturing operation. Therefore, replacement lots had to be shipped to the customers. Additionally, dozens of other lots of material had to be returned from the warehouses and re-tested at the assembly sites to ensure no other lots had mixed units, a huge cost to the manufacturer.
The semiconductor assembly sites’ request was to eliminate product mixing. Not only would this eliminate the chip manufacturer’s cost of recalling many lots of material, some of which might not have been mixed, but would also improve customers’ satisfaction.
Investigation indicated that mixing was generally occurring at only a few assembly steps. Since only a few items were usually mixed up between lots and part marking was already part of the assembly manufacturing process, a unique identifier was proposed to be added to every unit made in each lot. Additionally, at those selected manufacturing steps where mixing could occur, automated readers would be installed to ensure that each unit was part of the batch being processed and that no mixing had occurred during processing.
Upon implementation of additional marking and reading at the selected operations, mixing of products was eliminated and customer complaints were reduced from a “Top 10 Issues” item to non-existent.
Note: The factories providing the manpower and equipment needed to re-test/quarantine products no longer had to ensure availability of this manpower or equipment. Additionally, the distributions centers which had been handling the returned materials discovered a significant reduction in manpower and time required to manually handle the issues of customer returns.n