What is the final device and what is its expected service environment? I would confirm the operating temperature range with the customer before I did anything else. Ask them if they meant capable of withstanding those temperatures for reflow purposes, not operating temps. Operating temperatures would normally be on the assembly or final device requirements, not the PWB fab drawing. If they are the required operating temperatures, then the question is for how long must they operate at those temperatures, and then you have many other issues to deal with besides the PWB material. You would need to validate that each and every component on the BOM can also operate at those temperatures, and the same for all materials used (epoxies, conformal coating, etc,). With the exception of oven profiling equipment or combustion monitoring equipment or something of that sort (and those are usually thermally insulated), those "operating" temperatures are extremely harsh and unusual. The listed temperatures may also be ESS test temperatures, as the general range for those would be the same except Fahrenheit, not Celsius. 

I must emphasize, talk to your customer.

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Pradeep Menon
Sent: Thursday, May 09, 2013 6:09 AM
To: [log in to unmask]
Subject: [TN] Operating temperatures

We have a requirement specified in the master drawing of couple of PCBs which indicate that the operating temperatures as below.

1.            -50°C to 200°C operating PCB.
2.            -40° to 150°C operating PCB.

Will a high Tg material FR4 meet this requirement. Or will Polyimide be required. Any general inputs on this since we could not find the operating temperature in the TDS of the materials

Rgds

Pradeep

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