FAQ

1. Why do you need to do open short test in assembly?
2. Why do you need an Open short tester integrated with handler?
3. Is it true that operating staff in assembly do not know test?
4. Is there is a difference between open short done on a dedicated OS tester and a functional tester?
5. Does IC assembly really need a open short tester or can assemblers wait for the result from Final Test?



1. Why do you need to do open short test in assembly?
 
a.
 Dies on wafer are functionally tested and if no faults are introduced during the assembly process, the assembled unit should be good and need Final Functional test only.
   
b.
 Assembly processes introduce faults, thus the assembled parts need tests to eliminate these faulty parts.
   
c.
 There is a need to know where these assembly faults arise so that they can be detected early to prevent huge losses arising from such failures.
   
d.
 Management need to know that Front End Assembly is able to deliver 100% faults free parts to Back End and Final Test or to its customers.
   
e.
 Open Short test after bonding is the only way to detect any assembly faults in Front End Assembly operation and to guarantee that customers receive good parts.
   
f.
 Customers expect that you deliver 100% good parts or you lose their business.
 
2. Why do you need an Open short tester integrated with handler?
 
a.
 Normally IC assemblers purchase handler and tester solution from different sources and integrate them.
   
b.
 The question would arise as to who is fully responsible for the integration? Is it the handler or tester vendor? Who would you call when you have a problem?
   
c.
 Qtest offers a one stop shop i.e. a complete tester and handler solution. Qtest will be fully responsible for an integrated solution and will provide after sales service including development of new test program for new devices.
 
3. Is it true that operating staff in assembly do not know test?
 
a.
 This is a fact and normally Final Test department undertakes open short tests on assembled parts.
   
b.
 However there is a cost that assembly department needs to pay for Final Test. Since Final Test department normally use expensive functional testers to perform OS test, the cost is high.
   
c.
 A dedicated OS tester handler is much more effective for detecting open short problems due to assembly than a functional tester. Most importantly this dedicated solution is cheaper and provides much more accurate results.
 
4. Is there is a difference between open short done on a dedicated OS tester and a functional tester?
 
a.
 Functional tester performs open short tests under power-on condition and this may be detrimental to the device tested.
   
b.
 Dedicated OS testers like the Qtest Panther perform open short test with no power to the DUT. This is much safer and would not cause any potential damage to the DUT even if there are bonding defects. The tests are also more precise and complete compared to that done with a functional tester.
   
c.
 It is cheaper to use a dedicated OS tester than a functional tester.  More importantly, the assembly department can perform OS tests on line and know the results immediately instead of waiting for weeks or months to detect problems in the assembly process.
 
5.
 Does IC assembly really need a open short tester or can assemblers wait for results from Final Test?
 
a.
 If you want to deliver 100% process fault free product to your customers, then you need to implement OS test in assembly.
   
b.
 If you want to detect immediately where assembly problems starts, then you need OS test in your assembly.