In a message dated 11/8/01 12:40:03 PM Central Standard Time,
[log in to unmask] writes:

Graham,

It's not for the operating temperatures but for the assembly temperatures.

Larry Tawyea


> Hello Technet
> A question for bare board gurus.  Is there a difference in reliability
> between high Tg and regular Tg FR-4 ( IPC-4101/24 vs IPC-4101/21) in a
> vehicle type application?
> The end use application is less than Tg of /21 material, so not in the
> glass transition range for either material.
>
> Typically - is the CTE different between these two?  (I expect that depends
> on the manufacturer to some degree).  If there isn't a high temperature
> operating requirement, why select the high temp FR-4?
>
> Thanks!
>
>
>
> regards,
>
> Graham Collins
>