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October 2003

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Subject:
From:
Dave Hillman <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Wed, 15 Oct 2003 18:14:43 -0500
Content-Type:
text/plain
Parts/Attachments:
text/plain (118 lines)
Hi Dave, Daan and folks! I would be the first person to tell you that the
visual appearance of a solder joint does not necessarily reflect the solder
joint's integrity/reliability - that's how we got stuck with the "bright
and shiny" solder joint myth which resulted in thousands of needlessly
touched up solder connections. However, the external appearance of a solder
joint can show indications of solidification phenomena (we are dealing with
a molten metal!) - movement of a solder joint results in surface ridges
(aka a disturbed solder joint), extended/slow cool down ramps can result in
surface texture (aka grainy solder joint). The "BGA scaling" could be a
reflection of too little heat (incomplete solidification) or too much heat
(excess grain growth/structure). Either way, the reflow profile of the
assembly needs to be reviewed and corrected - unless there is some kind of
thermal issues with the assembly you should not be getting the "scaling"
effect. We have run into this on occasion and resolved the issue by
improving the reflow profile. Good Luck.

Dave Hillman
Rockwell Collins
[log in to unmask]



                      Daan Terstegge
                      <[log in to unmask]        To:       [log in to unmask]
                      >                        cc:
                      Sent by: TechNet         Subject:  Re: [TN] BGA Scaling
                      <[log in to unmask]>


                      10/15/2003 02:00
                      PM
                      Please respond to
                      "TechNet E-Mail
                      Forum."; Please
                      respond to Daan
                      Terstegge






Dave's photo's can be viewed on
http://www.smtinfo.net/forum/index.php?showtopic=22
Clicking on the thumbnails gives a larger picture.

Dave, you could have posted these pics yourself, although the bmp-file
needed to be converted to a smaller jpeg to get an acceptable filesize.

B.T.W. to me this doesn't look like a bad condition, it's obvious that the
ball has fully reflowed.

Daan Terstegge

----- Original Message -----
From: "Dave Chapman" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, October 15, 2003 8:03 PM
Subject: Re: [TN] BGA Scaling


> Daan Tertegge will be posting the pictures on www.smtinfo.net Thanks Daan
> And thanks to Sr. Ellis for the correction.
> Dave C.
>
> -----Original Message-----
> From: Dave Chapman
> Sent: Wednesday, October 15, 2003 10:57 AM
> To: [log in to unmask]; [log in to unmask]; Dave Chapman
> Cc: [log in to unmask]
> Subject: RE: [TN] BGA Scaling
>
>
> Dave I sent you a couple of pictures, I could not send through Technet.
> Dave C.
>
> -----Original Message-----
> From: [log in to unmask] [mailto:[log in to unmask]]
> Sent: Wednesday, October 15, 2003 9:48 AM
> To: [log in to unmask]; [log in to unmask]
> Cc: [log in to unmask]
> Subject: Re: [TN] BGA Scaling
>
>
>
> Hi Dave! Can you further define "BGA Scaling"? Its a term I am not
familiar
> with.
>
> Dave
>

>
>                       10/14/2003 08:43
>
>
>       -----Original Message-----
>       From:  Dave Chapman
>       To: [log in to unmask]
>       Subject: Re: [TN]  BGA Scaling
>
>       I am interested to find information on BGA scaling effect and
>       solution, we saw this phenomena yesterday with a ERSA Scope
>       demonstration. I have searched archives here and at SMTNET but no
>       good information.
>       Dave Chapman
>       Circuit Service

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