[Maarten]

I think we can all agree that in case of tin whiskers, no good ones will remain in the end and that most samples we encounter sport whiskers to some degree, regardless whether they were Dutch made or British made (I don't know exactly which factories produced them).

The only thing that I cannot guarantee is that Philips never experimented. Around 1962/1963 the first cases of tin whiskers in OC170/OC171 may have already popped up which would inevitably trigger the kwallab (quality department) to start experimenting. Maybe the outcome of this experimenting was "just don't bother and release the AF12x series" but the outcome could also have been to adopt some production lines to other processes (too little, too late evidently). Also, I don't know what role Matsushita played as (the only?) second source manufacturer for those types. They may have combined the Philips license with their own establised TO1/TO7 manufacturing processes. I've never seen other types and brands of Japanese transistors suffering from whiskers (but they could have).

So I can guarantee that if you spot a random AF11x, it should be assumed to be filled with whiskers, but I cannot guarantee that there aren't whiskerless AF11x at all.