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September 1998

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Subject:
From:
Matthew Park <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Fri, 11 Sep 1998 14:12:49 PDT
Content-Type:
text/plain
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text/plain (81 lines)
Hello e-mailer, jschreiner who left no official name in the forum.

I got a feeling the heatsink covering the entire board is causing the
unusual reflowed solder condition.  No matter how good a convection
reflow oven could be, metallic heatsinks adversely affect reflow
temperature performance.  You probably took into the consideration when
profiling the board with the huge heatsink, however, one example; can
you control the cool-down rate of board?  There could be some other
factors that hinder reflowing solder.  I don't know that because of it
is Friday and I wanna go home soon.  Some solderology guru's maybe can
answer it.  I suggest you re-profile the board without the heatsink and
reflow some boards.  And see whether you get the same condition or not.

regards
Matthew Park
NII-Norsat International Inc.


>Date:         Fri, 11 Sep 1998 16:36:40 EDT
>Reply-To:     "TechNet E-Mail Forum." <[log in to unmask]>,
[log in to unmask]
>From:         Werner Engelmaier <[log in to unmask]>
>Subject:      Re: [TN] Soft Solder
>To:           [log in to unmask]
>
>Hi 'jschreiner',
>Are you sure you have wetting to the leads? What you describe is not
'soft
>solder', whatever that may be, but sounds like not metallurgical
connection.
>You should be able to tell, because if you do not have wetting, there
will be
>no solder on the lead surface that was nearest the pad. That could
mean, (1)
>the reflow profile is too low ( especially with a large heat sink in
place you
>shopuld be measuring it), (2) you have none solderable leads, because
of (a)
>contamination, (b) maybe Alloy 42 leads.
>
>Werner Engelmaier
>Engelmaier Associates, L.C.
>Electronic Packaging, Interconnection and Reliability Consulting
>7 Jasmine Run
>Ormond Beach, FL  32174  USA
>Phone: 904-437-8747, Fax: 904-437-8737
>E-mail: [log in to unmask]
>
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