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June 2015

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Subject:
From:
Wayne Thayer <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Wayne Thayer <[log in to unmask]>
Date:
Wed, 3 Jun 2015 16:46:25 +0000
Content-Type:
text/plain
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Easy to tell--if you scratch at it and there's copper underneath the whole
blob, not just where the edge should be, then Louis is correct.
Wayne

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Louis Hart
Sent: Tuesday, June 02, 2015 7:47 PM
To: [log in to unmask]
Subject: Re: [TN] PCB blob defect

Let me disagree with Ted and say I think it is a fragment of plating resist
that did not get developed away. Compunetics has blue plating resists, if I
have observed correctly. I've never done that job myself but have seen stuff
in process.  The solder resist did not seem to set the area around the blob.
I'm not going to speculate about that behavior.  Louis Hart

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Theodore J Tontis
Sent: Tuesday, June 02, 2015 7:09 PM
To: [log in to unmask]
Subject: Re: [TN] PCB blob defect

It looks like a solder resist repair and they used blue instead of green. It
would be interesting to find out when the repair happened, at the board
house or assembly house. It's difficult to tell because the silkscreen looks
to be repaired as well. 

Ted T.

Sent from my iPhone

> On Jun 2, 2015, at 5:56 PM, Watson, Howard August <[log in to unmask]>
wrote:
> 
> Hi all,
> 
> My PCB fab knowledge is limited, and a very unusual defect was discovered
(too late) in assembly. I'm wondering if anyone has seen something like this
before, or has an idea what this could be. The blue color seems noteworthy
to me. This is for IPC class III, space. I will return this to the
fabricator, but I wanted to get educated in case there is a debate regarding
the cause. Thanks for your help!
> 
> Steve put the pictures here:
> 
> http://stevezeva.homestead.com/Howards_Blob.jpg
> 
> http://stevezeva.homestead.com/Howards_Blob_close.jpg
> Howard A. Watson
> 
> ______________________________________________________________________
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