Thanks Wolfgang and others who have replied on and offline so far. I always
think I have the right answers but really know better.

I have several reasons for asking this question. The first relates to who is
doing what out there just out of curiousity. Next, IPC has developed
relatively new reliability and design requirements for surface mount solder
joints as 9701, 785, and 279 as examples in addition to 7095 and, of course,
782. Also, IPC, according to Jack, has had its great 610 adopted by the DoD.
Finally, while realizing 782 is a set of guidelines, as most all IPC
documents have been for years up until recently, I wonder how many folks
have the resources, or dedication like Wolfgang, to whittle, cut, scrape, or
otherwise come up with better, lesser, or more pad sizes.

I have worked with comanies as HP, Nortel, NG, and Celestica who used their
vast resources to come up with very different land patterns and pad sizes
for some parts. I recognize the component manufacturers also have the
wherewithall to do the same. Additionally, like the round pad string earlier
in this month's forum presented some interesting and, to me, realistic
possibilities for non BGA pads and the ability to minimize, mitigate, or
otherwise prevent small chip devices from tombstoning let alone moving - period.

What I'm really after, if we accept all our solder joints to IPC STANDARDS,
not guidelines, how can we not design to the guidelines without having to
spend so much extra effort refining them to be STANDARDS, or rules.

A very small company I am continuing my contract with, has reached a
critical point where they/I must decide what direction in which to proceed.
With but two designers, we are faced with decisions concerning a starting
and staying point and path. We can go all IPC, go with the "big boys proven"
land requirements, or go with component supplier recommendations.

Sure, I can use my stuff gathered and continually evolving over the years or
have a library created using available guidelines and hope to refine them
over the years. Furthermore, if all my suppliers are accepting in strict
accordance with IPC 610, as an example, surely I must design to them
especially in light of my first paragraph's important issues. These
reliability requirements are based on considerable research using IPC
guidelines, aren't they Werner and associates?

Earl Moon

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