Related Topics:

How Netex Sorts Gerber data into Wire Endpoints

Importing Wire Data from AIF

Adding Wire data directly into the Job File

How Wires are Output in GDSII

Wire Syntax for ASCII output


Importing Wire Bond Data

While an IC package does not usually include wire bonds in the layout, the wirebonds connecting the die to the package are a critical path in modeling the electrical path from the die to the circuit board. NETEX-G can import wirebond data either from a Gerber file or from a ascii table. However because of 3D nature of wire bonds they cannot be treated exactly as just another conductor layer.

Wire Bonds From Gerber Data

Some package layout programs can output the wirebond layer as just another Gerber file. Several rules apply about how the Gerber data must be produced:

  • The wire shall be a Gerber draw (not an outline) from die pad to bond wire; the direction is not significant. There should not be any additional vertices in the draw. The diameter of the draw aperture should match the diameter of the wire bond and should not change in a given layer.

  • Only wires should be drawn on the wire layers. Die pads, finger pads, metal information, should be on a separate layer.

  • wires that cross in the X,Y plane (even if in the real world do not cross because they have different heights at the crossing location) should be separated into different Gerber files.

The screen shot of the Gerber files (as displayed in GBRVU) for a leadframe are shown below.

leadframe with wires viewed as Gerber data

Gerber File Color Description/Comment
FRAME.GBR RED leadframe metal. This particular design was converted from an AutoCAD wire bond document used by the assembly house to Gerber using ASM 500.
WIRES.GBR YELLOW wires from bond attach point to die pad. This is a "draw" of diameter 0.025 mm. These were polylines in AutoCAD with width= 0.025 mm.
WIRES2.GBR BLUE wires from bond attach point to die pad. These are "down" bonds and were on a separate Gerber layer.
BALLPAD.GBR CYAN flash indicating the node or port where the Spice or S-parameter measurement will be made. (The spice model for each net will be calculated from the die side of the wire to the point on the package indicated by the small yellow ball pad.) These were added in AutoCAD to the leadframe drawing as the bond diagram normally doesn't include such information. They could have been added interactively in NETEX-G but it was much faster to array a circle on its own layer in AutoCAD and then flash them during the DXF to Gerber conversion.

If you would like to examine the Gerber data you can download the file (15KB zipped).


Benchmark Files

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