Composite Layers

[getkrv]

Hi,
What do you mean by Composite layers, and why pdf files of composite layers are required to compare with gerber files, as our new fab house requires this for our multi layer board. Any one knowing please share your thoughts.

Thanks,
KRV.

[blessing]

Hi KRV,

Composite layers is a single layer of gerber that consists of more than one layer of Gerber embedded in it. Usually Composites consist of positve and negitive images individually combined. This is useful when you may want to lets say remove an area of a round pad (which is on a positive layer) by placing a trace or fill across the area to be removed (which would be on a negitive layer). Combining them as a composite would give the output required.

Composte layers may also be converted to a single layer by CAM tools but this may change the shape & size of certain entities though very less and usually very limited. It is a time consuming process when the board is dense.

Usually pdf files are not required by manufacturers. Not sure why manufactuer wants it but it could be to confirm to see if all the composites are combined correctly to give the final correct image.

Hope this helps.

BS