UB10 removes the wrong layers

[fieldeffect]

Hi

I am developing a 4-layer board (1 layer pair with top & bottom buildups), but accidentally I added a layer-pair and went routing on one of the added layers. Currently my design uses layers 1,2,3 and 6.

Layers 4 and 5 were invisible until I recently viewed the layer properties and clicked OK. They are empty and together they form the second pair of layers between the top- and bottom-buildup.

Now when I remove 1 layer pair the layers 3 and 4 will be deleted - that is WRONG in my oninion because it is the second pair of layers that you delete, layers 4 and 5.

Ultiboard also thinks that layers 4 and 5 will be deleted, it refuses to remove the pair while these layers are not empty. When you make sure that 4 and 5 are empty you can remove the second layer pair (layer pairs 2 >> 1) the result is that layers 3 and 4 have dissappeared, ant that the empty layer 5 is still in the board.

I tried the same by adding an extra pair (to become 8-layer). This adds layers 4 and 5 in the center of the stack, but they can only be removed when layers 5 and 6 are empty...

I assume this is a bug (UB10 Ppro), has anyone an idea how to fix this?

Thanks,

Hans 

[fieldeffect]

[edit by owner]

Hi Again,

I just found a dirty workaround for this. For those who are interested:

starting with layers:

TopBuildup - I1 - I2 - I3 - I4 - BottomBuildup

I3 and I4 are empty and should be removed. When they should not be empty, UB10 refuses to remove a layer pair.

I2 contains traces and copper areas that should remain the 3rd layer when all is done. But its contents must be saved temporarily because UB10 will delete layers I2 and I3.

1. Add extra top buildup, layers become:

    Top Buildup 2 - TopBuildup - I1 - I2 - I3 - I4 - BottomBuildup

2. Move all copper areas from I2 to TB2 (select only polygons and only this layer, properties >> position >> change layer)

3. Move traces from I2 to TB2 (traces and areas the same time generates lots of vias spontaneously and results in design errors) 

4. Remove 1 layer pair, now that I2, I3, I4 are all empty. Result is that I2 and I3 are gone

5. Move traces and copper areas from TB2 to I4 (separately).

6. remove 1 top  buildup layer, TB2 (now empty again) will be removed

Then it seems OK. No design rule errors occurred, I only had to allow some nets to be routed over other layers (I4 was never used before and needed to be added to Routing Layers of some nets.

It's a dirty way of course and it probably will fail when the design contains blind/buried vias (my design doesn't). I hope some support engineer will read this and conclude that there might be a bug here.

Hans