The only ingame boron nitride right now is hexagonally-structured, akin to graphite. Cubic BN is diamond-like instead. This doesn't appear to make it any physically stronger, but it does have a number of superior properties such as increased density for smaller module components, superhardness, lower thermal expansion, and much better dielectric properties.
- Yield strength based on ingame BN, as ultimate strength is also identical. - Uses permittivity of ingame BN as I've not been able to find it, but so that it can be used in capacitors. - On refractive index change: cBN has an index of 2.1 which is closer to diamond's 2.4 than hBN's 1.7.