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July 2000

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Subject:
Re: Reflow Issue
From:
"Tempea, Ioan" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Tue, 18 Jul 2000 12:31:48 -0400
Content-Type:
text/plain
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text/plain (68 lines) 
Tom,

the first thing to check is the date code on the components. Most likely
they are old and the leads are oxidized, hence the dewetting you describe.

What to do with the bad components, this is the question. I dont think you
should try tinning them, since with their fine pitch you'll end up with tons
of shorts.
If you are using more sorts of solder paste, try one with a stronger flux
for these assemblies.

Or maybe the leads are not oxidized, but only not coplanar, so some of them
don't even touch the paste, so they will not form a joint.

Good luck,
Ioan

> -----Original Message-----
> From: Thomas Han [SMTP:[log in to unmask]]
> Sent: Tuesday, July 18, 2000 12:17 PM
> To:   [log in to unmask]
> Subject:      [TN] Reflow Issue
>
> Hi all,
>
> I have been noticing on our last batch of boards that we ran, some of the
> tsop flash chips were not reflowing properly.  I am not getting very good
> toe fillets on the chips and some appear as though they are just sitting
> on
> top of the reflowed solder.  This board has a good component mix(i.e. BGA,
> QFPs, PLCCsocket, SOICs, total(325-350)).  Other components reflow fine,
> but for some reason these TSOPS are not.  Is there something that we are
> overlooking?
>
> Your input would be greatly appreciated.  Thanks in advance
>
> Tom
>
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