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April 2012

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Subject:
From:
Steve Gregory <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Steve Gregory <[log in to unmask]>
Date:
Thu, 12 Apr 2012 09:00:06 -0400
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text/plain
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Hi Paul!


Sorry I didn't get your photos posted yesterday, got rather busy yesterday,
but I have them posted now:

http://stevezeva.homestead.com/MV_Void_with_Barrel_Crack_01.jpg

http://stevezeva.homestead.com/MV_Void_with_Barrel_Crack_02.jpg

http://stevezeva.homestead.com/MV_Void_with_Barrel_Crack_03.jpg

http://stevezeva.homestead.com/MV_Void_with_Barrel_Crack_06.jpg

http://stevezeva.homestead.com/MV_Void_with_Crystal_01.jpg

http://stevezeva.homestead.com/MV_Void_with_Crystal_02.jpg

Steve

-----Original Message-----
From: Paul Reid [mailto:[log in to unmask]] 
Sent: Wednesday, April 11, 2012 3:06 PM
To: TechNet E-Mail Forum; [log in to unmask]
Subject: RE: [TN] Micro Stacked Via, solid copper plating, voiding

Hi Victor,

I do not know that this is covered by IPC documents or not but I know that
it can be a problem. 

Microvia voids have typically been acceptable if you do not violate the
minimum thickness requirement of the copper in the barrel of the hole. 

What we have is an enclosed void that has plating solution in the void by
default. The void cannot be plating closed without solution being trapped in
the void. This makes the void very susceptible to conductive anodic filament
(CAF) type of failure if there is a crack the goes to the void. I spent
years looking for that crack and finally found one.
Most voids do not produce a crack but on two occasions I have found cracks
into voided microvias. 

It is why I suggest that voids be avoided in any high end application.
It is not a standard but it is my take on this problem. Voids in plated
closed microvias should not be allowed is my suggestion to the 6012
committee.

I have sent pictures to Steve Gregory to post on his web site. You'll note
the plated closed microvias voids with cracks in the barrel on the microvia.
In two pictures you will see a blue crystal that is still in the microvia
that is from the plating solution. It is rare to find the blue crystal
because microsectioning flushes out the blue crystals during processing.

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 Victor Hernandez
Sent: April 11, 2012 11:14 AM
To: [log in to unmask]
Subject: [TN] Micro Stacked Via, solid copper plating, voiding

Fellow TechNetters:

   I have searched for IPC documentation and/or Inductry Standards
concerning the acceptance/guidelines for solid plated micro via voidibg.
I did not locate any.  Can someone confirm that and/or provided guidance as
to which document covers that anomaly.

Victor,


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