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October 2001

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Subject:
From:
"Dorothy M. Lush" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Tue, 2 Oct 2001 09:42:09 -0700
Content-Type:
text/plain
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text/plain (80 lines)
Steven,

Many companies are working on this issue of rework where there is not any
room even for a ministencil to print on the board. What is being done now is
printing on the part itself of either solder paste or "sticky" flux then
part placement and reflow. I have been working with a local company that has
a rework machine that will do this and much more of course. They are also
working very closely with National on their parts of this type and size.
Email me directly if you are interested and I can get you their phone
number, etc. What kind of spacing are you dealing with and are there any
parts that cannot be re-reflowed around or under it/them?

Dorothy Lush
Manufacturing Engineer

> ----------
> From:         Steve Abrahamson[SMTP:[log in to unmask]]
> Reply To:     TechNet E-Mail Forum.
> Sent:         Tuesday, October 02, 2001 9:09 AM
> To:   [log in to unmask]
> Subject:      Micro SMD WLCSP Rework
>
>          Hello Technetters,
>
>         I was wondering if anyone elso is placing the National
> Semiconductor
> Micro SMD Component.  Our team in RTP was looking for some rework answers.
>         They are able to remove the part with a hot air pencil, but part
> replacement has been tough.
>         The 8 bump WLCSP (Waffer Level Chip Scale Package) is only 1.4mm x
> 1.4mm- smaller than an 0805 component.  The rework machine vacuum tube
> cannot handle the component, and the mini micro stencil process is almost
> impossible because the components are packed together so tightly- it is
> not
> easy to get sufficient tacky flux down on the .0065" diameter pad either.
> A
> redesign is not feasible.
>         Short of creating a special jig to hold the component in place as
> a
> hot air pencil is used to reflow, has anyone got any ideas.
>         National Semiconductor tells me to use the same process as we
> would
> for any CSP, but this part is just too small for the SRT rework machine.
>
>         Has anyone dealt with solder ladden preforms that are in the sub
> .010" range?
>
>         Here is the WEB site of the package.
>         http://www.national.com/packaging/other.html#microSMD
>
>
>         Steve A
>
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