I've done rigid-flex PCB designs a number of times in the past but it was long enough ago that I cannot remember how I solved this issue. My design has three sections – the main board, the flex, and a daughter board. The flex obviously connects the two rigid boards. The problem is that I cannot seem to place tracks across where the split lines are defined, meaning using the interactive routing tool I can't run traces from the main board over the flex to the daughter board. When I place a trace and move it so that it crosses the line, the error I see is this:
Altium clearly thinks that just because I go from a rigid section to a flex section, that I am going outside the board outline (which is not true). I have no idea what the poly region is, and I do not see anything on the "Multilayer" layer indicating a poly region.
My board stackup is shown below:
I have tried running tracks on all of the four layers and all of them behave the same way.
How does one draw tracks across different sections of a rigid-flex design? My guess is the problem has something to do with the stackup but I can't place my finger on it.
I am using Altium Designer 18.1.7.
Best Answer
Using Altium Designer 19.0.15, there is the option to change the clearance for "Split Barriers" which allows you to keep the standard board outline clearance and still rout on rigid-flex boards. In the picture below, the highlighted cell allows you to cross flex-to-rigid boundaries when set to zero.