[SI-LIST] Re: Flip Chip Solder Ball inductance

  • From: Bi Han <mike_bihan@xxxxxxxxxxxx>
  • To: Aubrey_Sparkman@xxxxxxxx, weirsi@xxxxxxxxxx, si-list@xxxxxxxxxxxxx
  • Date: Tue, 20 Sep 2005 09:10:02 -0700 (PDT)

Hi:
 
Thanks for your all's message.
 
I think solder ball and bonding wire will have their self inductance. As 
friends pointed out, loop inductance is more complicated.
 
Below is my opinion on the impact from environment.
If there is matching resistor (to gnd) on the IO pad, thus the loop inductance 
should be simply adding those bonding wires and vias. Those routing traces were 
matched and should not be counted into loop inductance. 
 
Loop is "Driver - Bonding - trace - Bonding - resistor - Bonding - REF plane 
-Bonding - back to Driver". 
 
If there is no matching resistor on the IO pad, then the routing trace will 
impact SI severely, its inductance should be added into loop inductance. 
 
Above is my personal view, I've not read related topics very extensively. So, 
maybe someone can make it more clear.
 
thanks,
Han
 
 
Aubrey_Sparkman@xxxxxxxx wrote:
Han,
Inductance requires knowledge of the complete loop or an assumption of the 
complete current path. Where is the other solder ball? 

Aubrey Sparkman 
Enterprise Engineering Signal Integrity Team
Dell, Inc. 
Aubrey_Sparkman@xxxxxxxx 
(512) 723-3592

-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On 
Behalf Of Bi Han
Sent: Tuesday, September 20, 2005 8:55 AM
To: weirsi@xxxxxxxxxx; List` Si
Subject: [SI-LIST] Re: Re: Flip Chip Solder Ball inductance

I guess I could use VIA formula (5*H*ln(4h/d)) to estimate the inductance, 
since that applies to both via and bonding wire. It should works fine generally 
for bump.

Steve: why you think it does not make sense? 

Maybe its inductance is too low so that trace parasitics start to dominate over.

thanks,
Han


steve weir £º
Bi, the inductance of a single ball makes no real sense. If you do find=20 such 
a formula, be careful to identify the assumptions about the rest of=20 the 
path, and make sure that they also apply to your circumstances.

Steve
At 05:25 AM 9/20/2005 -0700, Bi Han wrote:
>Hi:
>
>Is there any quick formula to estimate the solder ball inductance, 
>given=20 the geometric size, such as diameter/height.
>
>thanks,
>Han
>
>
>
>---------------------------------
> 
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>F8=
=CE=DE=C0=AC=BB=F8=D3=CA=BC=FE=C9=A7=C8=C5=B3=AC=B4=F3=D3=CA=CF=E4
> =D1=C5=BB=A2=D6=FA=CA=D6=A3=AD=CB=D1=CB=F7=A1=A2=C9=B1=B6=BE=A1=A2=B7=
> C0=
=C9=A7=C8=C5
>
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