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August 2002

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Subject:
From:
Charles Caswell <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Tue, 13 Aug 2002 11:19:23 -0500
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I hope you can change the customers mind. I can't think of any reason to do this unless they have some sever shock or vibe requirements and believe the extra solder is more secure. Several reasons not to as you have already mentioned. They are asking you to do something wrong and then will want you to be responsible when it fails. 
Charles Caswell
Process Lead, PCB
Frontier Electronic Systems

-----Original Message-----
From: Werner Engelmaier [mailto:[log in to unmask]]
Sent: Monday, August 12, 2002 3:53 PM
To: [log in to unmask]
Subject: Re: [TN] Solder fillet requirement


Hi Peter,
You write:
>One of our customers is requesting 75% solder fillet height on all the
>SMT Porcelain capacitors (0805 package size with taller profile) used
>for a RF application. We told them based on our experience that the
>excess paste volume (and wetting) can not be achieved by our SMT stencil
>process. IPC only requires 25% for class 2 products. But they are now
>specifying hand soldering these components.
>Can anyone see any reason for doing this? I am prepared to go back to
>our customer to convince them otherwise (reasons such as extra labour,
>process inefficiency, solder joint reliability etc.)
A: There may be some RF reason. However, every other indication is negative.
There is no SJ reliability gain. You may crack the CCs both because of the
uncontrolled manual soldering process and the stresses on the CC body from
the larger solder masses. And, of course, there is the added expense.

Werner Engelmaier
Engelmaier Associates, L.C.
Electronic Packaging, Interconnection and Reliability Consulting
7 Jasmine Run
Ormond Beach, FL  32174  USA
Phone: 386-437-8747, Fax: 386-437-8737
E-mail: [log in to unmask], Website: www.engelmaier.com

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