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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