GENT, BELGIUM – Ucamco is proposing to include CAD netlist in its Gerber electronic data transfer format and seeks user input on the concept.

"Our principal aim is to make life easier for electronics design, manufacturing and assembly professionals by facilitating clear, unequivocal communications prior to production," explained Karel Tavernier, managing director.

In the new proposal, new X2 object attributes allow the inclusion of CAD netlists in Gerber fabrication data. These enable the following:

• The component reference designator, pin number and net name – a row in the CAD netlist - can be attached to the component pads in the Gerber file.
• The netlist can be attached to any conducting object.
• The component reference can be attached to any object, so it is now possible, for example, to identify all the legend objects belonging to a given component.

The goal of the Gerber netlist is to facilitate upfront communication between the different parties involved in design, assembly and automation. To this end, and for example:

• A CAD netlist attached to pads defines the position and orientation of external components, which is essential for assembly and for complete board display.
• By using netlist names, even simple viewers can display netlists without the need for special algorithms to compute connectivity.
• The netlist provides a powerful redundancy check during CAM input, reducing the probability of image errors to virtually zero.

The new capability is fully compatible with existing and legacy applications and files as the new attributes do not affect the image.

The CAD netlist information and attributes are not mandatory, so if they are not needed to process a Gerber file, they can be skipped and the file remains valid, Ucamco said. While the attributes provide useful fabrication data, the company adds, it is not necessary to expend development effort to include them in design and manufacturing processes if they are not seen as bringing any benefit to a particular application. 

The proposed new development overlaps to some degree with IPC-D-356 but the design goal is completely different. While IPC-D-356 aims to provide a data input method for bare board electrical test, Gerber netlist, rather than to drive testers, aims to facilitate upfront communication, prior to manufacturing. Accordingly, it does not contain the adjacency list, fiducials, and other information needed for electrical test.

"The advantages of the Gerber netlist lie precisely within this limitation as it is easier to understand and implement than IPC-D-356," Ucamco said.

The proposed new draft specification is available here; comments are welcome at This email address is being protected from spambots. You need JavaScript enabled to view it..

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