Low-Cost Testers: Are They Really Low Cost?

Initial ATE capital investments can affect overall test manufacturing costs as shown in this analysis, which compares a $5000 semiconductor tester with a $900,000 system (purchase price). The application is wafer testing of logic die, and the product has a five-year lifetime. Variables affecting cost include tester throughput, wafer test escape rate, and test system capital cost. Factors considered in the analysis include (1) the number of test systems required and the cost effect of capital, floor space, and manpower, (2) the quality of test and the effect of escapes on subsequent manufacturing operations; and (3) the effects of tax credits on the two options. Results of the comparison show that a major factor is escape from wafer test. Even a low escape rate justifies the use of the $900,000 general-purpose system over the $5000 low-cost tester. Throughput differences also tend to negate any initial cost advantage with the LCT. When total systems are considered (four LCTs are needed over the five years), total capital costs tend to converge. A major asset of the GPT is its flexibility, making it again more attractive than the LCT.