Advice from Product Engineers to Test Engineers
I wanted to find out the best advice a Product Engineer could give to a Test Engineer. So I started a discussion on LinkedIn. It turned into a lively debate with excellent contributions from experts and non-experts in the field. Today, I will share the most insightful advice with you.
Design and planning (Pre-production)
1. Get involved
Join the design discussion as early as you can. Organise a meeting between the test and product team, or even a chat over coffee. If you're caught for time, a group email or online chat will help share information
2. Be willing to work with the PE to influence design.
As a Test Engineer, you're likely to pick up on characteristics, trends and anomalies that the design and production teams won't. This is where a YMS tool or system comes in, to track data and share it with the team. It's easier to prove your point when you have charts and graphs to back it up. By sharing your expertise, you can influence the design at the start. This increases the chances of smooth production flow, and even reduced test time.
During testing (Post-production)
Make sure to use the latest DFM, DFT testability techniques
Use max 3% rule of thumb for additional die area allowed for testability
Look at the most difficult tests and move them to on-chip diagnostics if possible
Simplify testing, don’t complicate it
Simplify the load board & design it well to reduce sources of variation in production
Make documentation easy to find. Save it online so you and your colleagues can access it easily. This includes detailed info about failure modes to help FAB later if needed
Be cooperative with PE later on, if they need more information or a hands-on approach
Verify that the data generated is clear and correct. It should be readily available from a database
When possible, data-logging should be standard STDF
Use Unique Test Numbers (preferably hardcoded) instead of relying on automated numbering
Use Distinct Test Names based on some standard
ID critical tests
Datalog should reflect the exact test conditions for each test
Log the first failing vector cycle when a functional test fails
Consider using techniques in wafer sort for eliminating defective chips
Spend time characterizing and planning the design at the start. Store the data for review at a later stage
The wafer probe testing should clearly define functional from parametric fails & sequence the tests with this in mind
In conclusion, most of the advice from leading Product to Test Engineers boils to communication, planning and data. Communicate with the design and product teams at the start Assist in the planning and design phase. Provide data from testing and previous projects to prove your point. These will help each successive project to run smoother and smoother.