Reverse engineering with CAM-350

[randychase]

This sounds more complicated than it really is. You have to follow some steps, and there is some work involved, and results may require some tweaking.... AND... there are a couple things that may cause some problems, such as composite planes.

Here are the steps. Please feel free to correct anything!

This assumes you have the CAD interface option. Check FILE SETUP ACCESS CODE to see if you do.

[randychase]

From the help file-
You cannot go back to PADS if the database contains a merged PCB.

Step and Repeat data are ignored.

Nets which have 10 times as many graphics as pins are not resolved as wires. The data goes back as graphics. Nets which have more than 20 junction points (t's or t-vias) are not resolved into wires.

Drill manufacturing data such as order of hits, tool id's, etc. do not go back. Drill hits are assigned to coincident padstacks.

Mill data does not go back.

Custom apertures do not go back; references will be as "Odd."

"Fingers" typically go back as customs.

Targets and thermal references go back as "Odd."

Device names do not go back.

Names of Vias (used in Nets) are VIAxxxx. Names of freestanding Vias are PSTKxxxx.

Part Type Names (in PADS) are always the footprint name.

Decal Names are the footprint name unless there is a name collision, at which point a number will be added.

Only 1 reference designator location is exported.

PADS has a limit of 99 vertices in a line or a polygon. Therefore, the interface breaks up lines/polygons with more than 99 vertices. Unfortunately, for a polygon, this means that only a graphic representing the outline of a polygon will be read back into PADS. There is no work-around for this.

PADS handles different padstacks for the same part by creating unique decals for each unique combination of padstacks. Therefore, the interface will create as many decals as it needs to represent each unique footprint. Also, because PADS rotates pads in padstacks when the part is rotated, and our system does not, all padstacks are "un-rotated" to create the footprint (if the part is rotated).

[randychase]

> Bring in the gerber and drill files.

> Understand what parts are on the board and are represented by the pads/silkscreen/drills. You will need to know pin sequences also. Which is pin 1? You can get away with not doing some homework here, but the database will be less complete. You can even get away without a drill file.

>Align the layers. Use the EDIT-LAYERS- ALIGN command or manually align them.


>If you don't have an NC drill file, and you have a fab drawing, use the utility TOOLS -NC EDITOR-UTILITIES-GERBER TO DRILL

>Create a border layer (if one does not exist). Make a new layer and copy the border of the pcb to it. In the layer table, call this BORDER


>Set up your layers so they map correctly. Note if a layer is electrical or graphic. Negative or positive planes. Put them in the order they should be. Delete layers that are not required in your pcb database, such as a solderpaste layer or soldermask layer.

>Convert drawn pads to flashes. UTILTIES-DRAW TO FLASH

[randychase]

Every gerber file has a netlist as part of it. It's the connectivity between pads. And you just defined those items in the previous step as pads.

Run UTILITIES-NETLIST EXTRACT.

Now you have a real netlist associated with your gerber files.

Just in case, run ANALYSIS-NET CHECK and this will find any endpoints of traces that did not snap to the center of a pad. They are electrically connected and in the netlist, but the trace being off the center will cause an error in PADS. You can manually edit the trace vertex to "snap" to the center of the pads to fix this. Turn FILL off (F hotkey) to make this easier.

[randychase]

This step is really letting CAM-350 know what elements are made into a part. This can be cumbersome and a little frustrating, but it gets easier.

>Turn off all layers but the top pads and silkscreen info.

>UTILITIES-BUILD PART

>REF. Click on the Ref Des now on the part. Select the location for the ref des.

>Select the outline of the silkscreen. This can be difficult on a crowded board. I recommend using parts as removed from other parts as you can. Sometimes this is impossible, as the outline is touching another part. You can edit the part afterwards, so no big deal.

>Enter pin sequence. A cool tool here for some parts is to use the Inline Pins tool.
End pin sequence.

>Enter footprint name. Pick something that makes sense.

Rinse and repeat for each different part on the board.

[randychase]

Now you are putting down parts where the existing pads/silkscreens are. You can switch parts, rotate parts during this.

The idea is to replace ALL the pads/graphical elements that make up parts, with the created parts from your CAM-350 library.

This is actually pretty easy. There are some things to watch out for, like the correct ref designator (though it can be changed later) and making sure the part aligns correctly.

Run a check on the netlist when you are done.

[randychase]

FILE-EXPORT-CAD DATA

I truly hope you made sure you have the option of exporting the correct database enabled in your security. If not, I am thinking the data is fine in the *.CAM database, and perhaps someone else with the output option could export it for you.

By the way, doing this is like playing some of the older computer video games (for those that recall Kings Quest, Leisure Suit Larry, etc).... SAVE OFTEN.

[mraynes]

Reverse Engineering instructions have now been uploaded on Downstream's website. They are also here under the CAM350 Instructions thread.