Hi,

I need help interpreting the following requirements from IPC-A-600D. 
Section 11.3 solder mask adhesions contains table A, which indicates that 
a maximum of 5 percent solder mask loss over bare copper is acceptable for 
class 2, using IPC-B-25 Board or production board coupons. Theoretically, 
if an entire board was tape tested, the same criteria would apply.

Section 11.6 on solder mask cracking and scratches states that scratches 
are unacceptable if they extend through the solder mask and expose the 
copper conductor.

After more years in the PWB business than I now care to admit, I have some 
sense of the differences between adhesion and scratches. However, I 
recently have had a PWB supplier dance me around these requirements. I 
cannot explain why some exposed copper due to adhesion loss is acceptable 
and exposed copper from a scratch is not acceptable.

Any thoughts?

Ray Willey
Merix Corporation