Posted by Tom Wang: Fri Jul 07, 2006 12:55 pm    Post subject: ball shear failed

Hi:
Recently, my company suffered from a trouble. Because of a mass of ball shear low, a majority of of wb machine down. We did EDS and cratering and intermetallics, but no any abnormity was found. And we adjust the wb parameter and wp/bs/ds parameter, again and again. But the trouble is continued still. how difficult for us to get the cause root!!
Any good suggestion, please let me know
thanks a lot
best regards
yours
farel

Posted by FARel Engr: Fri Jul 07, 2006 2:26 pm    Post subject:

Hi Tom,

How about your bond pull readings - are they low too? Are all bonds affected - or just localized to certain bonds? Anyway, here's a little suggestion: cross-section bonds from several units. The objective is to look for anomalies such as voids at the following: a) bond pad metal layer; b) Al-Au intermetallic layer; and c) the ball bond itself. You need to know where and how the failure is occurring before you can correct it.

FARel Engr

Posted by Jefriz: Mon Jul 10, 2006 12:31 pm    Post subject: Deteriorating BST

Hello Tom,

Were there any changes in the materials, parameter specs, environmental conditions or clamp/insert design? Any changes on the method of doing BST? Do you have SPC monitoring on your bonding temperature? Was the product running already a long time (over 6 months) when the deterioration happened? Have you also consider doing FTIR on the fresh and prior bonding bond pads? Do this on the bondpads after exposing to heat. Do you have periodic cleaning of inserts (workholder) and spark rods?

I am sorry if I cannot give you direct solution on the problem but rather the areas where you can also consider.

Best Regards, Jefriz

Posted by Tom Wang: Mon Jul 10, 2006 2:26 pm    Post subject:

On Jul.1'06, we found this issue, but till now, no any one give a convincing answer. trouble is just like a hill. No BST is changed. oh, No, we have not SPC monotoring on bonding temp. we only do ball shear/wire pull for w/b.
what is FTIR?
below is the bst data:
47.5 50.6 34.9 32.3 32.0 34.8 27.5 29.1 37.9 43.9
20.3 21.7 23.9 28.6 23.8 23.3 23.2 23.3 29.8 28.7
58.1 23.6 21.4 12.2 30.9 29.3 21.7 21.8 23.1 17.3
the LCL OF spc is 35
any good suggetion, please help me
rga
farel