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Reply To: | TechNet E-Mail Forum. |
Date: | Mon, 4 May 1998 10:00:46 PDT |
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I, as a beginner, would like a few more answers.
1) How should be handled when a board design requires both Au wire bondings
and a solder reflow. Those two areas are about 50-100 mils away from each
other.
I do need a Au finish on wire bonding area obviouly. How about solder reflow
areas?? Can't I have the Same Au finish thoughout the board???
> Beside gold thickness, the amount of solder applied should also be
> considered. Per IPC-D- 279, "Design Guidelines for Reliable Surface Mount
> Technology Printed Board Assembly", Section 5.4.4. where gold or palladium
> plating is used, the gold or palladium content in the solder joint should be
> approx 3 %wt. or less. Here are our thinkess rules for Gold.
>
> Electrolytic AKA hard gold: Mostly for Wire bond
> Elecrtroles AKA Soft gold: Common 15 to 25 u" as long as it follows the 3%wt
> rule
> Immersion: Common 5 to 10 u" (Preferred in SMT assemblies, except edge
> finger connector)
>
> To calculate the weigth factors, these number might help
> Density of Gold = 19,300 kg per m3
> Density of Solder = 8,500 kg per m3
>
> Please ensure to have at least 100 u" of Ni beneath the gold.
>
>
> Hope that helps
> Michael Yuen
>
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_________________________________________________________________
Masatoshi (Bro) Suzuki |
Maxtek Components Corp. | Email: [log in to unmask]
P.O. Box 1480, M/S 13-035 | Voice: (503) 627-4025
Beaverton, OR 97075-1480 | Fax: (503) 627-4651
_________________________________________________________________
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TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c
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For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311
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