Finger contact problem

[jjustice]

I am designing a finger contact that needs to have the fingers at different lengths. This is to allow for hot pluggabilty, GND first, the PWR, then signals.

The EXPOSED COPPER TO BE PLATED USING ELECTROLESS NICKEL IMMERSION GOLD (ENIG) PER IPC-4552.

For this type of wiping contact I have always used the spec: FINGER CONTACTS: NICKEL PLATING PER IPC-6012 TABLE 3-2 CLASS 3 UNDER GOLD PLATING PER IPC-6012 TABLE 3-2, CLASS 3.

To create fingers like this the supplier links them all together and electroplates them, then the connection is broken in final routing out of the board shape.

This will not work however for contacts of differing lengths.

So questions (yes there are some after this lengthy read!)
1. Could I get away with using just ENIG for these contacts? If so, is there risk of the gold wiping away to expose the nickel? These boards are probably not going to be plugged in and out many times, once or twice really.
2. Could I use a surface router to remove only the trace? If so, is this an expensive and rare process?
3. Any other ideas? (i.e. tracking internally to the edge??)

ThanX in advance

JJ
When the going gets tough, the tough go mountain biking.

[JimR-OCDS]

I am designing a finger contact that needs to have the fingers at different lengths. This is to allow for hot pluggabilty, GND first, the PWR, then signals.

The EXPOSED COPPER TO BE PLATED USING ELECTROLESS NICKEL IMMERSION GOLD (ENIG) PER IPC-4552.

For this type of wiping contact I have always used the spec: FINGER CONTACTS: NICKEL PLATING PER IPC-6012 TABLE 3-2 CLASS 3 UNDER GOLD PLATING PER IPC-6012 TABLE 3-2, CLASS 3.

To create fingers like this the supplier links them all together and electroplates them, then the connection is broken in final routing out of the board shape.

This will not work however for contacts of differing lengths.

So questions (yes there are some after this lengthy read!)
1. Could I get away with using just ENIG for these contacts? If so, is there risk of the gold wiping away to expose the nickel? These boards are probably not going to be plugged in and out many times, once or twice really.
2. Could I use a surface router to remove only the trace? If so, is this an expensive and rare process?
3. Any other ideas? (i.e. tracking internally to the edge??)

ThanX in advance

JJ
When the going gets tough, the tough go mountain biking.

Check with your PCB vendor. I recall my vendor using what is called "Selective Gold Plating." We had to plate pads on the inside of a board.

Jim