Hi Ian,

        Try Measurements Group, a division of Vishay. They are near Raleigh,
N.C.
Their phone number is (919)365-3800.  They make Strain Gages as well as
Photoelastic resins that do exactly what you want to do. We have used their
Strain gages to make the x/y as well as Z expansion measurements on our
laminate materials for several years now. I have also been exposed to their
Photoelastic materials which cause fringing to occur on expansion/contraction.

I hope thgis helps,
Les
>  From: Ian Boyton <[log in to unmask]>, on 3/3/99 11:28 AM:
>  Hi All
>
>  I want to carry out some stress measurements on pcb's to analyse the
>  weakest areas at various assembly and test processes. I can use the
>  latest technology in software to model the situations, but I'd much
>  rather use a quicker method. What I had in mind was some kind of spray
>  adhesive/lacquer which has brittle properties, thus under stress will
>  crack and be visible under scopes or UV light. Can anyone help out with
>  the name of supplier of this type of material and has anyone conducted
>  similar tests.
>
>  Thanks in advance
>
>  Ian
>
>
>  ______________________________________________________
>  Get Your Private, Free Email at http://www.hotmail.com
>
>  ################################################################
>  TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c
>  ################################################################
>  To subscribe/unsubscribe, send a message to [log in to unmask] with following
>  text in the body:
>  To subscribe:   SUBSCRIBE TechNet <your full name>
>  To unsubscribe:   SIGNOFF TechNet
>  ################################################################
>  Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section
>  for additional information.
>  For technical support contact Hugo Scaramuzza at [log in to unmask] or
>  847-509-9700 ext.312
>  ################################################################
>
>