Looking for clarifications, please...

In J-STD-001A, Section 6.6.4.5-'Meniscus Spacing &Trimming' it was stated
that '...Components SHALL be mounted to provide a visible clearance between
the coating meniscus (on each lead) and the solder connection', making it
mandatory for Class 3;  If  products in Classes 1 & 2 did not meet the 
process
control requirements, this condition was mandatory, too.  Otherwise, it was 
a
Recommended condition for Class 1 or 2.

In my pre-release copy of J-STD-001B, the statement reads ' ... Components 
SHOULD be mounted...' in that way.  I see no interpretation of the word 
'should'
in section 1.4  and , as well, no differentiation among the Classes.

1) Is the interpretation cleared up in the released version of -001B?
2) Has the requirement really changed since the previous revision?


In IPC-A-610B, Section 3.2.4- 'Component Installation-Vertical - Radial 
Leaded'
and 4.2.3- 'Soldering-Meniscus in Solder', the 'clearance-required' 
condition is
 illustrated.  It's clearly shown that meniscus in the PTH is unacceptable 
for
Class 3 assemblies.  With certain provisos, however, meniscus in the holes 
is
acceptable for Classes 1 & 2.

As a Class 2 house (for now), wary of unnecessary costs- such as those
associated with spacers or special lead forming- we periodically debate the
intent of this requirement.

3)The clearance requirement is for more than just inspectability, isn't it?
4) What aspect of reliability is potentially compromised when the meniscus 
is
allowed in the holes?
5) And in what ways will this breakdown manifest itself?
6) Where may I find  technical papers or test data that will help to 
illustrate this condition?

Sincere Thanks - in advance - for all replies.





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