Madhusudhan,


I happened to get same question recently, my opinion is this:


The current limitation is not the balls, but the bondwires and the
copper lines from balls to chip. The current capacity of bond wires is:


             
I =  sq root(K/2P) x (Pi x D exp2/L)  x  sq root Delta T 

Where 

I = current in amperes
K = thermal conductivity in Watts/cm/Centigrade
P = resistivity in Ohm/cm
D = diameter of wire in cm
L = length of wire in cm
Delta T = temperature rise in Centigrades

Thus, a "normal" 0.001 inch (25um) gold bond wire will be able to carry
0.22 amperes. Just an example.

But noone designs a 25um BGA bond wire for such constantly high current.
At least what I think. Intermittantly, no problems, a 25um gold bond
wire can withstand 5 amperes during some milliseconds.

Likewise, you can calculate the current capacity for the balls, which
ought to have a magnitude higher current capacity.

Inge



-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Madhusudhan Kulkarni
Sent: den 15 februari 2007 04:43
To: [log in to unmask]
Subject: [TN] BGA ball current

Hi,

what is the current rating of BGA ball(standard ball sizes).

Regards
Madhusudhan Kulkarni

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