IPC-A-610B (issued January 96), chapter 10, covers SMD solder joints, but
only for externally view. §4.2 (fig. 4-15) says: "(...) blow holes, pinholes
(...) are nonconforming process indicators (...)".
But a "nonconforming process" is not the same as a "nonconforming product",
therefore see foreword ("Nonconforming Process Indicator Condition"): "
(...) not affect the form, fit & function of a product (...) the product
affected will be dispositioned Use as is (...) if the company does not have
a documented Process Control system (customer approved, J-STD-001, sic!),
then all Nonconforming Process Indicators must be treated as Nonconforming
Defects (...)"   voila!

Enough collective wisdom?

Sometimes I have the impression plane IPC should reevancelicate the short
basic principles of the requirement flowdown for electronic assemblers. The
backbone would be:

*       J-STD-001B (soon C) for soldered electronic assemblies.

        Based on J-STD-001B (as backbone), table 3-1 - and the up-dates
during the meanstime - for rigid pwb's the bones could be defined as:

*       IPC-2221 and IPC-2222 (rigid) and/or(?) IPC-D-279 (SMT) for
design/layout,
*       IPC-6011 and IPC-6012 and IPC-A-600E for PWB manufacturer (to refer
on the purchasing spec's!)

Other specifications (fishbones) would be adressed by the standard-inherent
requirement flowdown (IPC-SM-782, IPC-4101, IPC-SM-840, ev. IPC-CC-830 et
al)

Bernhard, near Zürich (for you: Zurich)

PS, to the guru's: there is a litte conflict between IPC-6012 § 3.11.1 (" ..
0.1% ..") and Appendix A, p. 27, §3.11.1 (".. 9.01% ..), it isn't?

        -----Ursprüngliche Nachricht-----
        Von:    Automatic digest processor [SMTP:[log in to unmask]]
        Gesendet am:    Freitag, 12. November 1999 07:00
        An:     Recipients of TechNet digests
        Betreff:        TechNet Digest - 11 Nov 1999 (#1999-367)


        At 10:45 AM 11/11/99 -0500, you wrote:
        >     Hi gang,
        >       We are cross-sectiong some solder joints, and are seeing
some
        >     voiding inside the joint itself, that appears to be "air
pockets" that
        >     were inside the joint when reflowed. There is no visible
indication
        >     externally of any voiding, but it is fairly prevalent inside
various
        >     component solder joints when cross-sectioned.
        >
        >       I cannot find criteria or mention of this in the
specifications I
        >     have. ANSI/IPC-A-610A shows voiding criteria for thru-hole
components,
        >     but none for SMD.
        >
        >     Does anyone have knowledge they can share on this topic? Is
there a
        >     spec on internal SMD joint voiding available? Do you guys and
gals see
        >     this occasionally in your joints?
        >
        >     Please, enlighten me with your collective wisdoms!
        >     TIA!
        >
        >     Jeff Hempton
        >     United Technologies Electronic Controls


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