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Subject:	Re: The Great Broken Via Mistery
From:	"Goodyear, Patrick" <[log in to unmask]>
Reply To:	TechNet E-Mail Forum <[log in to unmask]>, Goodyear, Patrick
Date:	Thu, 4 Oct 2012 23:52:24 +0000
Content-Type:	text/plain
Parts/Attachments:	text/plain (71 lines)

That is what big heavy scrub brushes are for, washing hogs.

pat

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Robert Kondner
Sent: Thursday, October 04, 2012 4:46 PM
To: [log in to unmask]
Subject: [TN] The Great Broken Via Mistery

Hi,

  The other week I had posted about broken vias on an expensive PCB with filled vias. 

Well, let me inform folks about what really happened.

1.       There were no bad vias. The profile used  was low, only 221C at one
measured spot. They used leaded paste and lead free BGAs. 

2.       After pulling a part they found nice shiny reflowed pads and nice
round BGA balls that had never contacted.

3.       Today they fluxed and reflowed a dead board and it came back to
life.

4.       The Altera reflow process guidelines (AN 353) had errors in the
reflow tables. The Altera "Engineer" confirmed the data was good.  

Now I don't know who started this Bad Via story but my guess is a CM how screwed up doing a profile. Better to point fingers towards the board house is my guess Their "Engineer" thought that if parts got to 250C they would stop working. So using leaded paste on lead free parts was a really smart move. 

This is a classic case of people using data they think is good and forget to think, ask and observe. 

Such a big world, so many problem to solve and so much hogwash in so many heads.

Bob K.

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