Dropping in FIDS
The final step in preparing our masks for the RDL process is to drop in any fiducials and targets needed. These cannot be placed prior to clipping and knockout as they would have been deleted.
Our normal practice is to draw the fiducials into a separate file. Then at the last step we merge the fiducial/target with the array data.
The fiducials and targets vary layer by layer so we actually produce three files:
200mm_via1_fid.gds - fiducials and targets for the via1 mask
200mm_via2_fid.gds - fiducials and targets for the via2 mask
200mm_rdl_fid.gds - fiducials and targets for the rdl mask
The UBM mask and the solder bump mask do not need additional fiducials or targets.
GDSFILT - Merge Files
We will use Artwork's GDSFILT program to merge the arrayed data with the proper FID file. While GDSFILT has a GUI, I like to use a batch file since it can be easily modified for the next similar project.
Here is the gdsfilt syntax and a short explanation that will do the merging ....
We will merge FILE_A (TOP_A) with FILE_B (TOP_B) to create file MASK (TOP).
gdsfilte.exe FILE_A MASK TOP_A -add FILE_B -combine TOP TOP_B -unixcmdline
Yes, the order of the files and structures is a bit convoluted ...
Here is our batch file .... (line breaks just for clarity)
echo merging RDL array with fids c:\wcad\gdsfilt\gdsfilte.exe rdl_bf_targets.gds rdl_mask.gds WAFER -add 200mm_rdl_fid.gds -combine TOP wafer_fid_coordinates -unixcmdline echo merging VIA1 array with fids c:\wcad\gdsfilt\gdsfilte.exe via1_bf_targets.gds via1_mask.gds WAFER -add 200mm_via1_fid.gds -combine TOP wafer_fid_coordinates -unixcmdline echo merging VIA2 array with fids c:\wcad\gdsfilt\gdsfilte.exe via2_bf_targets.gds via2_mask.gds WAFER -add 200mm_via2_fid.gds -combine TOP wafer_fid_coordinates -unixcmdline
Here is a snapshot of the RDL mask with a fiducial placed in one of the knocked out regions:
Here is a snapshot of the VIA2 mask with a target placed in one of the knocked out regions:
If you wish to examine the final masks files along
final_mask_and_fids.zip 4 MB zipped GDSII files.
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