try with file: https://drive.google.com/file/d/0B7t43CPM6VA-RURVZDg0NGhuTEk/view?usp=sharing  I'll delect it from my Drive at Oct/28. What I did was the following: converted text to mesh. Combined all text meshes together. Extruded text meshes on Z axis. Did the boolean modifier to carve the plate. Applied the modifier to the plate. Delected the text meshes. Exported to STL.

Try with file https://drive.google.com/file/d/0B7t43CPM6VA-RURVZDg0NGhuTEk/view?usp=sharing (I'll delete it from my drive at Oct 28). 

I did the following:

1. Converted text to mesh.
2. Combined all text meshes together.
3. Extruded text meshes on Z axis.
4. Did the boolean modifier to carve the plate.
5. Applied the modifier to the plate.
6. Deleted the text meshes.
7. Exported to STL.