I believe it would look like a condition called crazing.
Crazing looks like the glass fibers have air pockets around each fiber.
In the cross sections you would see some wicking where the copper
penetrates the air crack and then the fibers turn white or silver
colored.
This is a precursor to CAF or CFF type of growth.
Sincerely,
Paul Reid
Program Coordinator
PWB Interconnect Solutions Inc.
235 Stafford Rd., West, Unit 103
Nepean, Ontario Canada, K2H 9C1
613 596 4244 ext. 229
Skype paul_reid_pwb
[log in to unmask]
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Victor Hernandez
Sent: November 29, 2012 5:55 AM
To: [log in to unmask]
Subject: Re: [TN] Delta Tg on a Pb-free board.
Folks,
What I am asking is that if it is feasible for the woven fiber glass
cloth rods not to be conditioned to adhere to the resin system and what
would that anomaly look like in a cross section? Has anyone observed
laminate cross sections with such an animal? The observed anomaly
follows the glass rod curveature with no others flaws in the surrounding
laminate.
"X"
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Bev Christian
Sent: Wednesday, November 28, 2012 6:28 PM
To: [log in to unmask]
Subject: Re: [TN] Delta Tg on a Pb-free board.
I used to work for Fiberglas Canada, which at that time was a wholly
owned subsidiary of Owens-Corning Fiberglas and Duplate Canada which was
owned by Duplate US which was owned by Pittsburg Plate Glass. I digress.
Anyways, when glass fibers are made the hot glass fibers are sprayed
with a silicone which bonds to the surface of the glass. If they did not
do that the glass fibers rubbing each other would score and break the
glass. When the glass fiber mats are put into the prepreg and then
pressed and heated there is bonding between the organic ends of the
silicones sticking out from the glass fibers.
CAF occurs when water hydrolyzes those links between the resin and
silicone.
Bev
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
Sent: Wednesday, November 28, 2012 1:28 PM
To: [log in to unmask]
Subject: Re: [TN] Delta Tg on a Pb-free board.
The prepreg is laminated together under a high pressure/high temp roller
process or press inside of an oven. I can assure you the resin sticks
very well to the individual glass strands in standard FR-4. I suppose it
depends on the brand and type.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Chuck Brummer
Sent: Wednesday, November 28, 2012 11:52 AM
To: [log in to unmask]
Subject: Re: [TN] Delta Tg on a Pb-free board.
Vic,
What makes you think the resin and glass stick to each other? Having
worked in a prepreg treater I can suggest that when they make this
product a resin pump forces resin through the glass and coats both
sides. Once the resin is cured it sticks to itself surrounding the
glass bundles and holding them in place.
I have my doubts that the resin to glass has much of a bond.
Chuck
Charles W. Brummer | 3M Manufacturing Engineer 3M Electronic Solutions
Division 3M Canoga Park, 8357 Canoga Ave. | Canoga Park, CA 91304
Office: 818 734 4930
[log in to unmask] | www.3M.com
This message (including any attachments) may contain material,
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From: Vladimir Igoshev <[log in to unmask]>
To: <[log in to unmask]>
Date: 11/28/2012 09:08 AM
Subject: Re: [TN] Delta Tg on a Pb-free board.
Sent by: TechNet <[log in to unmask]>
One should keep in mind that the method doesn't specify a pass/fail
number!?
Regards,
Vladimir
SENTEC Testing Laboratory Inc.
11 Canadian Road, Unit 7.
Scarborough, ON M1R 5G1
Tel: (416) 899-1882
Fax: (905) 882-8812
www.sentec.ca
-----Original Message-----
From: Victor Hernandez <[log in to unmask]>
Sender: TechNet <[log in to unmask]>
Date: Wed, 28 Nov 2012 10:55:11
To: <[log in to unmask]>
Reply-To: TechNet E-Mail Forum <[log in to unmask]>,
<[log in to unmask]>
Subject: Re: [TN] Delta Tg on a Pb-free board.
Eric,
Thanks for sharing. This shared Test Method will test for laminate
properly cures to specifications. Now the question is. Is there a Test
Method for evaluating the woven fiber glass cloth adhesion property to
the resin system,?
"X"
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Honsowetz, Eric
Sent: Wednesday, November 28, 2012 8:35 AM
To: [log in to unmask]
Subject: Re: [TN] Delta Tg on a Pb-free board.
IPC-TM-650 2.4.25
eric
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Victor Hernandez
Sent: Wednesday, November 28, 2012 7:30 AM
To: [log in to unmask]
Subject: Re: [TN] Delta Tg on a Pb-free board.
Board guru,
Is there a test method, IPC Standard, for testing how well a laminate
has been cured, IS415.
"X"
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Zweig
Sent: Tuesday, November 27, 2012 4:11 PM
To: [log in to unmask]
Subject: Re: [TN] Delta Tg on a Pb-free board.
On Nov 27, 2012, at 4:46 PM, "Vladimir Igoshev. PhD"
<[log in to unmask]> wrote:
> Hello board gurus,
>
> We ran a DSC test on a Pb-free PWB and found that Tg1 was around 172C,
> while the second heating produced Tg at about 185C. Below is a reply
> from the board vendor, stating that there is no such a thing as
> undercured laminate for that specific type of material.
>
> I'd greatly appreciate any constructive comments.
>
> "...That type of delta Tg would only apply to dicy materials when Tg1
and Tg2 are less than the advertised Tg of the material.
> EM-827 is a high Tg, filled phenolic and as such for these type
phenolics, there is no delta Tg that signifies undercure.
> With filled phenolics like this both the Tg1 and Tg2 would be under
> the
advertised Tg to be undercure and this is not the case.
> As you cure more and more these type phenolics both Tg1 and Tg2 move
> to higher and higher values and the delta Tg remains about the same".
>
>
> --
> Best regards,
>
> Vladimir Igoshev. PhD
mailto:[log in to unmask]
>
> SENTEC Testing Laboratory Inc.
> 11 Canadian Road, Unit 7.
> Scarborough, ON M1R 5G1
> Tel: (416) 899-1882
> Fax: (905) 882-8812
> www.sentec.ca
>
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