Our top tips and tricks for engineers: Revising test programs
If you've clicked on this blog, you're probably aware that test programs for ATE will eventually need to be updated. There are a plethora of reasons including - fixing bugs, optimizing test algorithms, updating test limits, and adding or removing tests, etc.
For purposes of data analysis over a long period by using a yield management system (YMS) like yieldHUB, it's essential that data over multiple versions of the test program can still be associated on a per-test basis, through test program updates.
Here are some of our top tips and tricks that we thought might be helpful so you are ready to analyze your data, even across several months:
1) Keep a version number in the test program name and be consistent.
For example: MFGYH2218_FT_01 and when revised this becomes MFGYH2218_FT_02.
In yieldHUB, programs are unique based on the whole length of the program name. This way, it is very easy to distinguish between program versions. It's also easy to put together multiple versions of a program for analysis since you can search for the test program name without the version number.
2) Ensure that the test numbers are unique.
Every time a test program is revised, check that your test numbers are unique! This should be a routine check, especially if new tests are being added.
Unique test numbers allow for automated handling for the retesting of tests within a single die. It can also avoid confusion on which tests is being referred to.
For efficiency in database queries, test numbers may be used as index fields so it is ideal if they are unique in a test program.
3) Have the same test number across multiple versions of the test program.
This point is very important for long term data analysis. Using test numbers for referencing, indexing and connecting tests across test program revisions will be much more efficient on the database.
4) Use unique test names across multiple test program versions.
Although it's not as critical as keeping the test numbers unique, to avoid confusion among the users, especially the new ones, test names should be kept unique.
It's also possible to use test names as the basis for generating unique test numbers using algorithms like MD5 or CRC16. This is especially true for certain testers that can only generate a series of numbers as test numbers and the test developer has no control on which test number gets assigned.
5) Keep the sequence of tests the same.
This will cause the test list to look the same across versions. However, keep in mind if tests are added or removed, the sequence will differ. Therefore, it's ideal to keep the sequence the same (as much as possible).
In the past we've noticed when customers don't add revision numbers to their test program name, this can result in unexpected data and confused users. When this happens customers often lodge multiple tickets and they require support from us. While we're always here for our customers, this time consuming process can be avoided by simply following our suggestion above.
At yieldHUB we are also able to offer customers a solution when their test systems make it impossible to control the test numbers. By paying for custom work, we can assign consistent and unique test numbers to their data
We hope some of our tips and tricks will help you keep on top of your YMS. Not only can this reduce the cost of getting your data online, but it can also help reduce the cost of maintaining your data.
Want to know more? You're welcome to check out some of our case studies here.
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