Would you like the laminate to survive or would you really 
prefer plated-through holes and the circuitry to survive?  What 
is the environment and how fast will the heat be applied?  The 
heat will transfer differently.  If you want the plated holes 
to survive, how thick is the board and how many layers?

If you are only talking about the laminate with no circuitry
or plated holes, FR4, GETEK, Cyanate Ester, Polyimide, BT, 
PTFE, etc. should handle that temperature and time but will 
discolor.

If you are talking about a finished board encountering that 
temperature then we can use IPC as a point of reference.  
IPC-600D 2.6.8 (IPC-RB-276 3.10.1) Thermal Stress test for 
plated holes is conducted by floating a sample on solder at 
288C (550F) for 10 seconds.  

Many FR4 multilayer circuit boards can handle a continuous 
float to 20 seconds or so.  If the time is extended to 45-60 
seconds, you will see discoloration of the dielectric material, 
reduced copper thickness in the plated holes and copper 
circuitry may start to lift on the outerlayers.

The survivability is dependent on many things in addition to 
those mentioned.  If you give more details I'm sure others will 
comment further.

Darren Hitchcock
[log in to unmask]
(503)359-2658



Jim Moritz <[log in to unmask]> Wrote:
| 
| Can anyone suggest the lowest grade of laminate 
| that can withstand
| 320 celsius for 45 seconds?
| 
| Thanks for your help.

Jim ES&D

***************************************************************************
* TechNet mail list is provided as a service by IPC using SmartList v3.05 *
***************************************************************************
* To unsubscribe from this list at any time, send a message to:           *
* [log in to unmask] with <subject: unsubscribe> and no text.        *
***************************************************************************