I am looking for some discussion on acceptability of solder on gold fingers per IPC-A-610.
I've searched the archives and have not found my answers there.

IPC-A-610, section 10.1, page 10-3 says: 
Solder, any metal other than gold, or any other contamination in the critical contact area of the fingers is a Defect - Class 1,2,3.

At face value, I would interpret that to say that ANY solder found in a visual inspection on a gold finger would be considered a defect.

The solder we are seeing is from indiviual solder spheres from the solder paste and are being missed by the assemblers and process inspectors.  They currently believe that if the solder contaminate on the gold finger is not visible with a 4x magnifcation, it is not a defect.

The gold fingers under inspection are designed at .040" wide.
There is one QFP on the PCA that has solder pads that are .011" wide

My question is.....To inspect the gold fingers and determine if a PCA is defective or not.....What magnification level is appropriate when inspecting these gold fingers.

Information/Discussion:
Per table 1-2 on page 1-6, suggests for lands > 0.0394 a Magnification for inspection of 1.5x to 3x with a max referee of 4x.

However, the last sentence of paragraph 1.8 on page 1-6 states "For assemblies with mixed land widths, the greater magnification may be used for the entire assembly.

If this PCA has some land widths designed at .011" wide, then according to the last sentence of paragraph 1.8, I would say that  per table 1-2, an inspection magnification of 7.5x to 10x with a max referee magnificaton of 20x would be appropriate, and any solder that is visible on a gold finger at that magnifcation level is a defect.

Is my interpretation flawed?  too stringent?  Comments?

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