Chip Manufacturing · Topic 13 of 16
0%
Chip ManufacturingLesson 13 of 16
Wafer test
Testing each die on the wafer before it's cut out.
What you’ll learn
- What wafer sort does
- Why test before dicing
- How bad dies are marked
Why it matters
Testing early avoids spending packaging cost on dead chips.
Explanation
In wafer test (wafer sort), a probe card contacts each die's pads and runs electrical tests. Failing dies are recorded so they can be discarded after dicing.
This screens out defects before the expensive packaging steps.
Visual explanation
Key terminology
- Wafer sort
- Electrical test of dies on the wafer.
- Probe card
- The fixture that contacts die pads.
- Bin
- A category assigned by test results.
Example
A die that fails at-speed tests is binned as bad and not packaged.
Common mistakes
Watch out for:
- Assuming all testing happens after packaging — much is done at wafer level first.
Real-world application
Speed binning at test sorts otherwise-identical CPUs into different products.
Explore related concepts
Continue learning
Wafer test
Up next
Dicing
Chip Manufacturing
Cutting the wafer into individual dies.
Continue learning →