Dropping in FIDS

The Unit Cell Design

The Wafer/Die Settings

Matching Existing Die

Generating the Array
with GDS-SR

Plating on RDL/UBM

Clip to a Round Boundary

Knocking Out Openings

Dropping in the FIDS

Solder Stencil Issues

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:

RDL mask with fiducial merged into the array.

Here is a snapshot of the VIA2 mask with a target placed in one of the knocked out regions:

VIA2 mask with fiducial merged into the array.

If you wish to examine the final masks files along
with the separate files that were created for the targets
and fids you can download them from the link below:

final_mask_and_fids.zip 4 MB zipped GDSII files.

NEXT Special Requirements for the Solder Bump Mask ...