Dave Rooke provided me a good, and very valuable, lesson concerning fiber glass "cloth"
silane treatment. I always thought of silane as a simple wetting agent. He objectively and
imperically pointed out it molecularly cross links both with the glass fibers, and fiber
bundles, and the resin system used for bonding to ensure proper coating and
subsequent laminate integrity.

Obviously, not having seen the condition you describe, I cannot say for certain, but it
sounds as if the treatment (silane and coating) has not been successfully performed. This may
not have allowed effective resin to glass bonding in the B stage. It also seems certain, even
if the coating was as specified, the coating process failed somehow.

You may try "baking" a prepreg sample (to its full cure) and determine whether further
bonding is effected as it would in the C stage. This may be observed as the "voids"
"disappear" upon melting. You may also try laminating a specimen and see if the issue is
resolved.

2112 and 2113 glass styles are fairly resin rich as these styles have a fairly open weave.
The resin to glass ratio is in the area of 60%, as I recall. Therfore, resin content should
not be the issue. If resin starvation is the issue, the glass weave structure will be highly
visible through the resin.

In any event, this is not a normal property - as you already know. I certainly would take a
look at my supplier's records and try to determine if that particular lot was made under
effectively managed process conditions.

Earl Moon

################################################################
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
################################################################