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Decapsulation Dilemma - Melting Copper Wires

               

Proper device failure analysis can not be performed unless the sample can be decapsulated nicely.  Different plastic molding compounds and the internal features of the device react to the decapsulating etchant in different ways. As such, successful decapsulation of the part requires that the correct etchant recipe is applied.  But what if a failure analysis lab's standard recipes can not decapsulate a new device? The archived forum thread below discusses the decapsulation dilemma of the thread starter, who observed that the copper wires of his sample is being dissolved by the etchant he was using.

  

Posted by Rivs: Wed Aug 08, 2007 10:49 am    Post subject: HYSOL MG15F MOLDING COMPOUND

 

Guys need your idea on this.... We currently have an evaluation on copper wire bonding (2 mils) the problem is during failure analysis chemical decapsulation, copper wire were etched/dissolved after the unit is fully decapped using sulfuric acid. As experienced MG15F molding compound does not react on Nitric red fuming.

Hope you can give us any idea on how we can decap the parts without over etching/dissolving the copper wire.

Thanks.

 

Posted by Paulpang: Thu Aug 09, 2007 8:37 pm    Post subject:

 

Hi Rivs:

Try to use the formula: Sulfuric acid : nitric acid= 3 :1 or (2:1)
I am also working on copper wire decap in recently. Good luck in your FA process.

regards,
paul

 

Posted by Paulpang: Thu Aug 09, 2007 8:39 pm    Post subject:

 

Take note: sulfruic acid (96%), nitric acid (98%)-----paul

 

Posted by Rivs: Fri Aug 10, 2007 8:23 am    Post subject:

 

Hi Paul, Thanks for the response. I'll try this and give you feedback on the result. Anyway fyi I'ved tried this mixture in a 9:1 and 5:1 ration (Nitric:Sulfuric) but none of them worked.

Again thanks.

 

Posted by Paulpang: Sat Aug 11, 2007 7:41 pm    Post subject:

 

Hi Rivs:
The decap you finished by manual decap or auto decap? I carried out it by manual. Keep in touch....

regards,
paul

 

Posted by Rivs: Mon Aug 13, 2007 3:55 pm    Post subject:

 

Hi paul, I am doing it manually by submerssion method, the ratio you gave did'nt work, the Nitric acid just vaporized and the package of the unit is still solid, just like our mixture of 5:1 (Nitric:Sulfuric), are you successfull with what you did?

 

Posted by Paulpang: Mon Aug 13, 2007 8:44 pm    Post subject:

 

Hi Rivs:
It will be easy to control if you perform decap by manual. If the compound can not dissolve then,
1.) take the unit out of chemical.
2.) use aceton to wash the unit
3.) put the unit into chemical again
4.) compound still can not dissolve
repeat step 1 to 4.
thus, you'll find differnce.

By the way, what temperature did you set ? 250 deg would be prefered.

regards,
paul

 

Proceed to Page 2 of this archived forum thread...

 

      

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