Hi Bill,
here are a few references (paraphrased). There's additional info in the
sections.

IPC-4101 section 3.8.3.1.6
h. voids are <0.075mm [0.0029"] in the longest dimension & don't occur in
void clusters any more than 3 voids in a 3.2mm circle.

IPC-A-600 section 3.1.1
Acceptable- Class 2 & 3
Voids less than or equal to 0.08mm [0.0031"] and doesn't violate minimum
dielectric spacing.

IPC-6012A section 3.6.2.3
No laminate voids in excess of 0.00315" (in Zone B).

Regards,
Mark


        -----Original Message-----
        From:   Brown, William G [SMTP:[log in to unmask]]
        Sent:   Tuesday, April 22, 2003 1:45 PM
        To:     [log in to unmask]
        Subject:        [TN] Voids / Air Pockets in Laminates

        Hi All,

        Does anyone know where I can find information on air bubbles or
voids within
        completed circuit boards?  We have a group here which is concerned
about any
        voids left when the laminates are pressed together, either within or
between
        layers, and the effects they might have at high altitudes.

        Are there any IPC specs which state allowable values or anything
like that?
        These are boards made with IPC-4101/ 40, 41 or 42 materials.

        Thanks for any help!
        Bill

        ############################################
        William G. Brown
        Senior Electrical Engineer - PWD Engineering Support
        > xBAE  SYSTEMSx - Information & Electronic Warfare Systems
        Phone: 603-885-4930     Fax: 603-885-5435
        ############################################

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