Al, 

The IPC committees are currently looking at the IPC-D-275 and the IPC-RB-276
and are updating the referenced data. We have changed a number of the
technical numbers, however, when pushing the limit, we prefer to have good
test data to go with any requests for change. 

In addition, any changes must be able to be provided by a majority of the
board suppliers. We would not want to mislead a designer by placing something
in the standard that can only be reliably manufactured by only a few select
suppliers. If you see it in an IPC standard, than you should be able to get
it from most suppliers. 

In some cases, we may caution the designer that the information is leading
edge and may need additional considerations.

Regards, 
Gary Ferrari
Chairman,  IPC-D-275