It is packaged using the Tape & Reel (TR) method since it is a clock IC. The peak reflow temperature (Cel) amounts to NOT SPECIFIED to be essentially indestructible. Logic circuits based on PLL BASED CLOCK DRIVER logic use this electronic frequency generator.
SI51218-A06431-GMR Features
SI51218-A06431-GMR Applications
There are a lot of Silicon Labs SI51218-A06431-GMR Clock Generators applications.