Do you pay too much to have your products tested?
A fairly straightforward question alright…do you pay too much to have your products tested? One of our customers couldn’t figure out why the throughput they were achieving in the development floor was not the same as what the subcon was telling them when in full production, so the subcon was charging them for what our customer thought was the wrong test time. In fact the test time for a lot in production was significantly longer because of poor monitoring by the subcon of index time and delay patterns in production. The only thing under the control of our fabless customer was the test program and making sure that the hardware, program and calibration routines enabled fast set-up.
We were asked for our advice because we already provided them with their interactive YMS data analysis system and their IC production yield reports and alert system which was integrated in their email. So could we not do the same for test efficiency, maybe alert them as well if there were unexpected issues?
Our background is not limited to test and product engineering, but also includes test and wafer sort operations, so we knew fairly quickly what the potential issues were and how to get the required data in a seamless manner. We also worked with our customer to present the right and relevant information in actionable reports. There was no need for us or our customer to ask the subcon to do anything to get this up and running!
With a simple update of the program which we advised and some server-side work by us, our private cloud YMS product “yieldHUB” now produces reports on our customer’s test times and index times from all their test subcons. They can also see all the delays in production. Not necesarily what a foundry would want you to know very much about, but then you are paying for the time on the tester. Why should you not have accurate and up-to-date UPH, test time and index time information to share with your foundry for continuous improvement and cost reduction purposes?
The end result is that this system of automated reporting of UPH, test time and index time has driven our customer’s subcons to have more consistent index times (these can vary enormously if not monitored), better setup times and a closer collaboration with our customer when the tester time available is tight at the end of a quarter. Even better, with our unique web-based third-party license available for your subcons too, they will see exactly what you are seeing, which will help them with their throughput improvements for you. They will be able to share their successes with you on-line and you’ll be able to compare throughput between subcons and compare throughput and its components (setup time, test-time per unit, index time, handler delays etc) between the development floor and your subcons.