Ryan
After looking at these pictures I would agree with Werner that the drilling
is not the greatest. I am even more concerned about the appearance of the
copper in the first picture. This has many of the earmarks of a high plating
density. This reduces cost, but at the expense of copper uniformity and
ductility.
Best regards
Lee
J. Lee Parker, Ph.D.
JLP Consultants LLC
804 779 3389
----- Original Message -----
From: "stephengregory5849" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, April 22, 2008 6:53 PM
Subject: Re: [TN] Via barrel cracks
> Hi Ryan!
>
> Have your pics up! They're at:
>
> http://stevezeva.homestead.com/files/Via_Barrel.jpg
>
> http://stevezeva.homestead.com/files/Via_Barrel_2.jpg
>
> http://stevezeva.homestead.com/files/Via_Barrel_3.jpg
>
> Steve
>
> ----- Original Message -----
> From: "Ryan Grant" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Tuesday, April 22, 2008 5:08 PM
> Subject: Re: [TN] Via barrel cracks
>
>
> Steve,
>
> I would much appreciate your help with posting these pictures.
>
> Thanks,
> Ryan
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Franklin D Asbell
> Sent: Tuesday, April 22, 2008 3:55 PM
> To: [log in to unmask]
> Subject: Re: [TN] Via barrel cracks
>
> Would you have an image for posting?
>
>
> ===================
> Hi Technetters,
>
> I have a case of via barrel cracks (E crack) and I would like to know
> possible causes.
>
> The crack is circumferential and occurs at the center of the via. The
> hole appears smooth, i.e., no glass nodules or tearout and there is
> neither positive nor negative etchback. Of course there is some
> wicking, but only about 25um max. The copper thickness is 20um at the
> crack and roughly 35-40um at the knee. Although, at the initiation
> point of the crack, the copper thickness is only 10um, but that could be
> due to stretching and subsequent thinning of the copper. Around the
> periphery of the crack are micro-voids in the resin about 30um. It is
> triangular shaped, so I can't tell if it is resin recession or a
> laminate crack.
>
> In other words, this via pretty much looks normal, except for one thing,
> which might be an artifact of stretching and cracking of the via. For a
> span of about 60um on the vertical of the via, at the crack, there is a
> roughness that slightly reduces the copper thickness. The surface of
> the copper at this point appears both rough and black in color.
>
> This board has seen two reflows and a hot functional test before final
> failure.
>
> The board shop's initial response was speculation of the OSP soft etch
> attacking the copper, but this particular via has solder mask plugging
> both sides of the via; therefore chemicals after solder mask cure can
> not get into the via.
>
> In case it matters, at one time, we have had occurrences of this board
> shop "re-working" panels after copper plating by placing the panel in a
> tank of etchant, then re-running the board through copper plating.
> (They do panel plating).
>
> I'm a little suspicious of their FA, so I would like some independent
> opinions and places for me to dig into.
>
> Thanks for any help,
> Ryan
>
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