Hi all--

I'm in the process of gathering some information, data and
microphotographs on the base material anomality we (inappropriately)
term "Crazing", which in IPC's-T-50 and IPC's_A-600 define crazing as:

CRAZING - "An internal condition that occurs in reinforced laminate base
material whereby glass fibers are separated from the resin at the weave
intersections.  (This condition manifests itself in the form of
connected white spots or 'crosses' below the surface of the base
material.)  It is usually related to mechanically induced stress."
[Ref.  IPC-T-50]

Technically, IMO neither the term or the definition is correct for the
anomaly (condition), and we shouldn't misuse the term "crazing"; but
(IMO) due to industry use, we're stuck with it.  IMO, the definition
does not suitably describe the anomaly, because it implies crazing is
"interconnected measles".

Limited examination of currently available surface photo's of "crazing"
suggests that "crazing" is the end result of a shear stress (along or
across) the reinforcing material yarns that causes a local separation
between the resin and reinforcing material, along the surfaces of the
fiber yarns or between the fibers in the yarn(s).  This changes the
index of refraction of light in the base material so we can see the
lighter colored (whitish-like) window screen like pattern which is an
IPC-A-600 "External Observation" termed "crazing".  The anomaly
(crazing) only occurs along/in the reinforcing material yarns, it never
occurs in the resin "squares" between the yarns.  This is probably due
to the lower modulus (elasticity) of the resin and the strains are not
sufficient to fracture the resin.

THE GOAL

The goal is to obtain sufficient technical data to submit a request to
the IPC's (eventually the international community) Terms and Definitions
Committee to change the definition of "crazing" to a more appropriate
definition (we shoud change the term, but there are too many spec's in
use that contain the term (grandfathering).

SO WHAT COULD YOU DO

You guessed it, what we need is some good technical information, data
and photo's to document (what we as an industry have mis-termed)
"crazing", and (at least) made the definition "better" (more technically
correct).

The following is a "want/need" hit list:

1  Could you provide X-Y (preferred) or Z-axis photographs of "crazing"
to document the condition?

2  Could you provide ultrasonic or SLAM or other imaging of crazing?

3  Does "crazing" occur in industry?  and if so, what is/are the
cause(s)?

5  Have you ever had any (documented) functional failure(s) in
applications where the applied voltage is < ~250Vac or < ~300 Vdc?

5  Could you provide any other information?

Your efforts in this task will be greatly appreciated and should be sent
as indicated below.

Many thanks in advance,

Ralph

--
Ralph Hersey

Ralph Hersey & Associates
3885 Mills Way
Livermore, CA 94550-3319
PHN: 510.454.9805
FAX: 510.454.9805
e-mail: [log in to unmask]

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