Posted by IC: Tue Dec 13, 2005 2:25 pm    Post subject: Dendritic growth after autoclave test

Dendritic growth on plastic resin along the lead shoulder area was observed after 96 hrs of autoclave test on a 16 mils external pitch surface mount device that cause electrical short. 

Anyone has idea on the likely causes?

Posted by Guest: Tue Dec 13, 2005 3:47 pm    Post subject:

What is Autoclave Test?

Posted by FARel Engr: Wed Dec 14, 2005 8:50 am    Post subject:

Autoclave is pressure cooker test: 168 hours at 121 deg C/100% RH/2 atm.

Dendrites are fern-like or snowflake-like surface patterns that result when metal atoms (such as those coming from package leads) are dissolved in moisture and then redistributed on the surface under the influence of an electric field, such as when the device is biased.

Maybe you have some contam in your autoclave chamber or on the package itself that made the autoclave moisture acidic and helped dissolve the metal of your package leads. These dissolved metal atoms became mobile enough to form dendrites when bias was applied to the device.

Posted by Guest1: Wed Dec 14, 2005 1:48 pm    Post subject:

Thanks for your reply. We will look into this aspects. Meanwhile you have any idea on how the package surface contamination is generally monitored or measured.

Posted by Guest: Mon Dec 19, 2005 1:17 pm    Post subject:

Ionograph test. It measures NaCl ppm per area.