[SI-LIST] Re: Current capacity of a Solder Ball
- From: "Matt Kaufmann" <mkaufmann@xxxxxxxxxxxx>
- To: si-list@xxxxxxxxxxxxx
- Date: Wed, 5 Feb 2003 18:00:35 -0800
Brian,
if you're talking about flipchip bumps, the current capacity per bump is
limited by electromigration of the thin stackup of metal layers between the
solder bump and the die pad (UBM=Under Bump Metallization). Different
bumping technologies use different UBM stackups and some are more
susceptible than others so it depends on who is doing your bumping/UBM.
Bascially, the issue is that under HTOL conditions, the current combined
with the temperature will promote electromigration/consumption of the UBM
materials. If they get consumed, the bump will open. It also depends on
the size of the bump/UBM pad.
The following factors play into this: junction temp during HTOL testing, UBM
size, life expectancy goal (MTTF). Bump solder type can also play a role.
K&S (Flipchip Technologies) has a bunch of data that gives max allowable
current capacity per bump as a function of Tj (in order to meet 10,000hr
MTTF). Depending on the bump pad UBM size, the current capacity can range
from 45mA to 120mA (at Tj=150C) and higher if Tj is lower. This data is
available on the the K&S web site
(http://www.kns.com/prodserv/flipchip/pdf/design-gde/foc.pdf).
Note: this data is only applicable to the K&S bumping process. It does not
apply to other bumping processes since they typically use different UBM
systems - although the K&S UBM tends to be on low end of electromigration
resistance - not bad but just less resistant than other UBM systems (K&S or
others may respectfully disagree).
Regards,
Matt
Matt Kaufmann
Principal Engineer - IC Assembly and Packaging Development
Broadcom Corporation
2451 Mission College Blvd.
Santa Clara, CA 95054
408-922-3183(desk)/408-464-9354(cell/pager)/408-922-1023(fax)
mkaufmann@xxxxxxxxxxxx
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Brian Schieck
Sent: Wednesday, February 05, 2003 5:04 PM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: Current capacity of a Solder Ball
All I want is the current capacity.
Consider power delivery
Balls > Plane > Wires or Bumps
If my IC needs 20 Amps DC for core support how many bumps are needed to
supply this? I know the capacity of the ball pads on the bottom
(cu thickness / width / size ). I know a blind via (filled can carry 400 ma)
and I can use multiple vias / ball pad/.
I know the planes can handle more than 20 AMPS. I know if
it is Wirebond each 0.9 mil wire can handle 900 ma. So how much can a ball
carry underrated? I'll figure out what I would like to apply as a derating
i.e. the addition of balls till I'm comfortable with the power delivery.
I want to design quantity of Balls to a real spec. I want to decide my
margin.
I know that 400 ma is bull. Balls can pull AMPS.
Brian Schieck
NVidia Corporation
2701 San Tomas Expressway MS B22-221
Santa Clara, California 95050
Direct Phone # (408) 486-2697
Corp Phone # (408) 486-2000 x62697
Local Fax # (408) 486-8078
Corp Fax # (408) 486-2200
Email bschieck@xxxxxxxxxx
-----Original Message-----
From: James.Freeman@xxxxxxxxxxxx [mailto:James.Freeman@xxxxxxxxxxxx]
Sent: Wednesday, February 05, 2003 4:30 PM
To: Brian Schieck
Subject: RE: [SI-LIST] Current capacity of a Solder Ball
Hi Brian,
How are things. Are you looking at a bump or a ball for this info?
Jim Freeman
-----Original Message-----
From: Brian Schieck [mailto:BSchieck@xxxxxxxxxx]
Sent: Wednesday, February 05, 2003 11:13 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Current capacity of a Solder Ball
Does any one know what the current carrying capacity of a solder ball is?
How is the capacity determined? Is the capacity derated to account for
temperature and voids?
for a 60 mil solder ball.
Brian Schieck
NVidia Corporation
2701 San Tomas Expressway MS B22-221
Santa Clara, California 95050
Direct Phone # (408) 486-2697
Corp Phone # (408) 486-2000 x62697
Local Fax # (408) 486-8078
Corp Fax # (408) 486-2200
Email bschieck@xxxxxxxxxx
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