First of all I would like to thank the people who replied to my last
email on the electrical clearance. I borrowed the IPC-2221, design
guideline for PWB, from the CAD design group, and used the table 6-1 to
find out the minimum spacing between the external component
leads/terminations (A6).  Since most of my company products only require
15V or less, according to the table,  the minimum spacing requirement
would then be .13mm or 5 mil.

Again I checked the IPC -A-610 on solder balls/splashes in sec.4.1, and
found out that any solder ball with a 5mil or higher in diameter would
be considered as a defect.

I would like to know what is the maximum diameter of solder ball your
company will allow on your products between the leads of a fine pitch
component.  If I want to make sure the electrical clearance(5mil) is not
violated, I simply cannot have more than one solder ball with a diameter
of 1 mil for a 16 mil fine pitch IC, ( The spacing between leads is only
6 mil) or
a 3mil ball for a 20 mil fine pitch IC (8 mil spacing), and
a 4 milball  for a 25 mil fine pitch (9 mil spacing).
and what if the solder ball ( > 1mil) lies between the leads? Is it
going to be a reject automatically since the 5 mil clearance can never
be achieved anyway?

From what i have read so far, any solder ball greater than 5 mil in dia.
around the fine pitch component should be treated as a potential problem
to the dependability of the product.  Do you agree?

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