In response to your questions both Grades 1 and 3 copper foils
are readily available and the price difference between them is
small. Their cost effectivness depends on the end use
requirements. The answers to some questions will help you and
your supplier determine the best alternative.

Why was Grade 7 originally specified? Was it because of 
resistance to inner layer cracking? Then Grade 3 is the better
alternative. Was it because a high frequency circuit is being
used? If so then a low profile foil should be used. Is Grade 7's
very low profile an important charcteristic? The a drum side
treated foil in the appropriate Grade 1 or 3 is the better
choice. Other considerations may also be factors.


Sid Clouser
Gould Foil
Eastlake, OH


Reply to message from [log in to unmask] of Thu, 25 Jan
>
>We are the design agent and user of printed circuit boards. Just recently 
>one of our board suppliers requested a material change 
>from: 	Rolled & Annealed Copper {IPC-MF-150, GR 7} on both sides 	of 
>0.031" FR-4 Laminate.
>
>to: 	Electrodeposited Copper {IPC-MF-150, GR 1} on both sides 	of 0.031" 
>FR-4 Laminate.
> 	
>			OR
>
>	Electrodeposited HTE Copper {IPC-MF-150, GR 3} on both 	sides of 0.031" 
>FR-4 Laminate.
>
>My question is which of the above material configurations is the most 
>available and the most cost efficient.
>
>Thank You One And All
>
>
>