Does the solder paste have Silver adds?
Inge
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From: "Bev Christian" <[log in to unmask]>
Sent: den 11 June 2010 17:40
To: <[log in to unmask]>
Subject: Re: [TN] Weird formation of voids
> Stewart,
> I lieu of a Dave Hillman Friday quiz, consider this it. And you WIN!
> Using an SEM and then carefully examining those pictures and the shape and
> placement of the "voids" we were able to determine that it is exactly as
> you describe. We are now in the process of hitting our grinding paper
> supplier "up the side of the head" for a crappy lot of product.
>
> Bev
> RIM
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Stewart McCracken
> Sent: Friday, June 11, 2010 11:36 AM
> To: [log in to unmask]
> Subject: Re: [TN] Weird formation of voids
> Importance: High
>
> Hi All,
>
> Looks as though sample preparation condition is less than ideal. Sample is
> a little rounded and it appears that the voids might in fact be embedded
> debris from the polishing equipment(?) I'm sure Vladimir would agree - get
> it in the SEM to be sure! Need some better imaging and if possible EDS -
> these will go a very long way to confirming what's going on. Lumps of
> silicon carbide can really make a mess of a x-section. If you don't have
> access to a SEM, you could etch the structure and look for abnormal
> /unusual structures surrounding these features. Etching would also help to
> refine the soft edges on a x-section (provide a more natural edge) and let
> you see if you have shrinkage or gas voids (look at shape) filled with
> grinding debris.
>
> Contaminated mats on a polishing station could explain the pattern of
> occurrence and the feature. As always though, more info about condition
> would make diagnosis easier!
>
> Kind regards,
>
> Stewart
>
> Stewart McCracken
> MCS Ltd.
> Centre House
> Midlothian Innovation Centre
> Roslin
> Midlothian
> EH25 9RE
>
> m. +44(0)7711 541735
> t. +44(0)131 440 9090
> f. +44(0)131 440 9085
> e. [log in to unmask]
> w. www.themcsgroup.co.uk
>
>
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of stephen gregory
> Sent: 11 June 2010 16:21
> To: [log in to unmask]
> Subject: Re: [TN] Weird formation of voids
>
> Hi Bev!
>
> Got your picture today, and have it posted now:
>
> http://stevezeva.homestead.com/Bevs_Ball.jpg
>
> Almost looks like little pieces of dross. I wonder if something is going
> on with the solder paste? Or leaded reflow profile with a lead-free BGA?
>
> Steve
>
> --- On Wed, 6/9/10, Bev Christian <[log in to unmask]> wrote:
>
>
> From: Bev Christian <[log in to unmask]>
> Subject: [TN] Weird formation of voids
> To: [log in to unmask]
> Date: Wednesday, June 9, 2010, 9:51 AM
>
>
> TechNetters,
> I am sending a picture to Steve to post. I have labs in three locations.
> One of them has seen weird voids in cross-sections of BGAs while the other
> two locations have not. For the lab that has seen them, the
> cross-sections were prepared by different people on different days for
> different products, using the same equipment. The voids are not in all
> balls cross-sectioned but may be only in one of two of the balls in a row
> of multiple solder joints examined.
>
> Have you seen anything like this? Do you know the root cause?
>
> Vlad,
> You know what is going on, so please don't respond.
>
> Bev
>
>
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