Hi Chris,
Make sure its the wire bond and not the bonding wire that failed; in my experience it is the wires that are more susceptible.
Depending on the thermal excursion and the geometry, you can get both overstress and fatigue failures. The ductility of the Al-bonding wires is pretty low.

 The FA is a great big 'IT DEPENDS'.
Werner


 

 

-----Original Message-----
From: Chris Mahanna <[log in to unmask]>
To: [log in to unmask]
Sent: Mon, May 10, 2010 5:48 pm
Subject: [TN] LED wiring bonding


It's all LEDs these days!

We have an FA that shows poor wire bonds to GaAlAs/GaAs in microsection after 
assembly.  The failure is seen in the parts per hundred across different lots 
and slightly different part numbers of LEDs.
The assumption would be that LED wiring bonding defects are very rare.   Is 
there something particular about these?  Or is it the crimping and/or Pb-free 
assembly that is pulling them apart?
The ones that seem more susceptible are GaAlAs  Double Heteros.

Thanks.

Chris


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