Hi Gerry,
Bill and I are doing well.
I concur with your thoughts. If you find something using a method that
is not required for the defect, it's still a defect.
I am not happy with the idea that because I found the crazing during a
microscopic examination it does not count.
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 Gerry Gagnon
Sent: December 6, 2013 8:21 AM
To: [log in to unmask]
Subject: Re: [TN] Crazing
Hi Paul,
Hope you and Bill B. are doing fine.
I am assuming that you you were looking for something else and detected
a "non-conforming" level of crazing.
In my mind, this is an easy one because you found the non-conformance
"along the way" while examining your microsection.
Let me give you an easier analogy.
While examining a region of an IST test coupon in transverse mount, I
find a tiny piece of material bridging two conductors at high mag.
Clearing away the conductor surfaces enough to measure if there is a
resistance, I get a value in the MegOhm range.
Is it a short?
Unless things gave changed, Bare board continuity thresholds will not
detect this phenomenon.
Let's also say that innerlayer AOI (if performed) has a very high escape
rate for this type of phenomenon or may not even detect it at all.
Is the phenomonon a short per IPC A-610?
My answer is yes, it is an unwanted connection, albeit a high resistance
connection, and is difficult to detect.
Does the fact that I found this short in a cross section under high
magnification, while I was looking for something else, change anything?
I don't think so, and I do not think IPC A-610 allows non-conformances
that are found "along the way".
Have a good one.
Gerry
> Date: Thu, 5 Dec 2013 16:05:41 -0500
> From: [log in to unmask]
> Subject: [TN] Crazing
> To: [log in to unmask]
>
> I was just on a conference call where we found crazing (a separation
> between glass fibers and the epoxy system), in a microsection. The
> fabricator stated that this had to be evaluated looking at a board
> macroscopically and could not be evaluated microscopically.
>
>
>
> Crazing is called out in IPC-A- 600 in section 2, paragraph 2.3.2 page
> 18, which is "Externally Observable Characteristics". In A-600 there
is
> picture of a microsection showing the defect but it states that a
> microsection is not required.
>
>
>
> In IPC 6012-2010 crazing is call out in 3.3.2.2, page 12, which states
> (I am paraphrasing), "Crazing shall not violate greater than 50% of
the
> distance between adjacent conductors..." The document then refers to
IPC
> A 600.
>
>
>
> What is your take on their argument that crazing should not be
evaluated
> microscopically as per IPC?
>
>
>
> 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]
>
>
>
>
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