Well yes and know. Those LEDs also have silicone inside the phosphor and it’s not sintered (Cree has never mentioned this as far as I know). I mentioned the article regarding sintered phosphor here.
I’m pretty sure it’s not a premolded part since it encapsulates the bond wires (see the OSRAM document somewhere above). It’s very likely molded around the mounted die.
They talk about the types of materials used here: Link
I know it’s not very “silicone-like” but that’s based on the “typical” silicones we know. Even cheap Fujik is quite different (hard and almost brittle).
The white stuff shows no flexibility at all, it breaks, and makes a scratching noise when I rub it with my forceps. It has at least the hardness of bakelite, or maybe it is ceramic.
I know, the CSLNM1 I have here are packaged in the same stuff. Again, I see no reason why this couldn’t be a filled silicone compound. It behaves like one under the tip of a soldering iron too (gets crumbly around 300°C, never melts). And the advantages in this application are obvious.
How could they cast ceramic around the die + phosphor + bond wires (nicely visible in your pic btw)? They clearly mold this in place.
Aaaaanyway… my point was that there’s fragile bond wires embedded in there and that may be why they mention not to put pressure on it.
There are ceramic adhesives which are used in bulbs because of low thermal expansion at high temperatures.
Just because it is “ceramic” does not mean it is solid like a rock.
It can be made into epoxies or other stuff.