Kelly,

I believe that you must have been in a hurry when you grouped
electromigration, "intermetallic growth" and dendritic growth in a single
category, but so much misinformation is being passed around about
intermetallics, I feel it necessary to add a correction.

You said that "intermetallic" growth and electromigration and dendritic growth
are the same and caused by the presence of moisture.  "Intermetallic growth"
is caused by the diffusion between two metals in contact with each other to
form compounds of those metals, and is not in any way related to the other two
growth mechanisms, and the presence of moisture is not a causitive nor an
inhibitor.  Increasing temperature when the two metal are in contact will
increase the intermetallic growth rate and the intermetallic gets thicker, but
does not produce metallic shorts between conductors or BGA lands.

Another slight change in the information about "whiskers".  Whiskers are made
up of a single crystals that mainly grow from thin coatings or platings of
pure tin or nearly pure tin  coated/plated and where the coating/plating is in
compression.  It can happen with Sn96, Sn99, but much less likely with Sn63.
Fusion of the coating helps, but is not a whisker eliminator.  Whisker
formation is most likely when the temperature is near 60 degrees C. and
moisture of the enviornment is elevated.

Phil HInton

################################################################
TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c
################################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body:
To subscribe:   SUBSCRIBE TechNet <your full name>
To unsubscribe:   SIGNOFF TechNet
################################################################
Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information.
For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312
################################################################

################################################################
TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c
################################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body:
To subscribe:   SUBSCRIBE TechNet <your full name>
To unsubscribe:   SIGNOFF TechNet 
################################################################
Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information.
For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312
################################################################