March - April 1999
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Lack of Test Strategy Delays Package Introductions
Two examples of test delaying package acceptance are the near-CSP packages, TSSOP 8-lead and MSOP 8-lead packages.The acceptance and use of the 8-lead TSSOP was delayed for over two years due to the equipments inability to handle and locate devices for test. To date, in fact, only two handlers can accommodate an X4 configuration and the rest have X1 and X2 contact capabilities.
Multi-site testing is critical to this package which, among other device types, is used for Serial E2 memory (which has long test times). In addition, due to the package's aspect ratio, small size and mass, conventional PVC tubes will not allow parts to move freely and jam continuously. Jam rates of 1:50 were common in the earliest handlers. A year after the first handler was developed, a new tube design, made of polycarbonate material was employed to replace the costly aluminum tubes and the unusable PVC tubes.
This package has been in customer's hands for almost two years awaiting a test handling solution, and it still doesn't have one. The key to resolving this problem would have been NOT to design a dual-sided package whose body length, adjacent to the leads, is shorter than its width at the lead tips.
This is the same problem associated with the TSOP, Type I, which can only be handled in slow and costly pick and place handlers and requires the use of expensive trays instead of cheap tubes.
The MSOP is only slightly better than the TSSOP because it is a square-shaped package, and tubes designed for the TSSOP were readily and cheaply adapted to fit. However, the lack of an inexpensive, fast and reliable multi-site test handler continues to limit total capacity, industry-wide acceptance and use of this package, as well.