Question
When should I want to use infrared lighting on my Wafer ID application? When shouldn't I?
Answer
- In post-process wafers, the deposition of resist coated on the wafer surface may obscure the symbol.
Solution:
- Infrared radiation is highly transmissive and can penetrate the resist film, and if the red illumination model does not read the symbol as expected, it is worth trying a model with infrared illumination (In-Sight 1722 or In-Sight 1742).
- On the other hand, the infrared illumination model has a lower sensitivity of the image sensor than the red illumination model, which tends to result in a darker image. If you do not intend to transmit resist, red illumination may result in a higher reading rate. It is recommended to compare and verify with both models.
