Process Development and Reliability Evaluation
The masks are intended to speed product process development and acquire realistic manufacturability data. They can also be used to test established fabrication processes and measure their performance. Mask sets are useful to evaluate vendors and extract information on the repeatability or the tolerances of their process. Bumping suppliers can also use them to check on the long range stability of their production.
Beyond process development, the masks produce dies for reliability testing: for instance, bump shear tests or temperature and humidity cycling after assembly.
Masks for Standard Bumping (no RDL)
Two masks process:
- The first mask is the mask used to open vias in the polymer repassivating the wafer.
- The second mask delineates the UBM sites.
The mask set for conventional bumping consists of a mask to open contact holes on the bumping pads and a mask to define the UBM. The polymer and metallization processes determine the masks polarity. The designs can be used to evaluate the fabrication tolerances of positive or negative acting polymers, and can be used with additive or substractive metallization processes.
These masks can be built with the specific pitch and bump size required by the end user.
Masks for Wafer Level Packaging ( with RDL)
Four masks process:
- The first mask opens vias over the bond pad sites.
- The second mask defines the redistribution interconnect metallization.
- The third mask is used to open vias over the redistributed bump sites.
The fourth mask defines the UBM metallization.
Note: It is possible to build a three masks set to cut cost. This can be done at the expense of some compromises that must be acceptable to the end users.
- As GDSII files ready for transfer to your preferred mask shop.
- As chrome mask sets generated according to your specifications.