It depends on the minimum dieletric thickness, and where the scratch is 
in relation to any conductors. According to IPC-RB-276, 
scratches, dents or tool marks are acceptable provided they do not 
bridge conductors. Also, they shall not penetrate to 
a depth that reduces the dielectric thickness below the minimum.

On the matter of repair, I know IPC-R-700C lists methods for repairing 
PCBs which have been charred (involves a rough clean or removal of the 
affected area, followed by an epoxy fill); whether the same method may be 
used for repairing a scratched board, I don't know.

IPC-RB-276, "Qualification and Performance Specification for Rigid 
Boards," is available from IPC: $20 members/40 nonmembers.

Mike Buetow
IPC Technical Staff
2215 Sanders Road
Northbrook, IL 60062-6135
T: 708-509-9700
F: 708-509-9798
[log in to unmask]


On Tue, 3 Oct 1995 [log in to unmask] wrote:

> Is there a spec that requires repair of the top surface of a .062 thick FR-4
> PWB that has been scratched or abraided.  Second operations that removed
> small amounts of unwanted copper or a small trace section have scratched the
> surface from almost no depth to perhaps .010 deep.    
> 
> What is the spec?
> If repair is required, how is it done?
> 
>