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December 2013

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Subject:
From:
Joyce Koo <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Joyce Koo <[log in to unmask]>
Date:
Thu, 5 Dec 2013 21:57:52 +0000
Content-Type:
text/plain
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text/plain (99 lines)
1. If it is qual.   Fail it.
2. If is on going product, what is deviation from the process?
3. Any visual or suspect location need to cross sectioned to assess the impact at vendor's site based on agreed method.
4. Design and PM got the final call for the risk of using such stuff (depend upon how much design margin is in the product and functional critical assess). Your legal can sort out the cost and impact and who pays what.
My 2cents. Glad don't have to call a shot :-).

Product that are built around function alone have not been designed at all, but merely engineered. -prof. Ashby
  Original Message
From: Ed Hare
Sent: Thursday, December 5, 2013 4:35 PM
To: [log in to unmask]
Reply To: TechNet E-Mail Forum
Subject: Re: [TN] Crazing


Paul,

I consider the argument false logic based on the idea that one can see too
much at high magnification.  This idea is simply not true.  One should be
able to diagnose crazing without fear of overstating the problem in
microsections.

Ed Hare


On Thu, Dec 5, 2013 at 1:05 PM, Paul Reid <[log in to unmask]> wrote:

> 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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--
Ed Hare
gmail - [log in to unmask]
gvoice - 360-453-7550


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