Here are some alternative numbers: >Solder Ball (63Sn/37Pb) The original email says 60mils for the solder ball. That's a pretty big ball. Most balls for BGAs are 20-30 mil depending on the pitch (1.0-1.27mm). I'll assume 30mil (0.76mm) which is typical for 1.27mm pitch BGA. Also assume 20mil final solder joint height and 25mil pad diameters. >Melting Temp: 183C (183C - not 189C) >Thermal Conductivity: 50 W/m-C (close enough) >Electrical Resistivity: 0.000000145 ohm-m (close enough) >Thermal Resistance: ~32.2C/W (not 40k C/W) >DC Electrical Resistance: ~0.24 mohm >Current to Melt We did some experiments that showed that even a small solder ball (0.3mm) can take >3A. The critical path is almost always the trace connected to the ball (~2.5A for a 4mil wide trace). Note: this applies to BGA balls - there are some different mechanisms that can occur with flipchip solder bumps. 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 steve weir Sent: Wednesday, February 05, 2003 1:07 PM To: mchan@xxxxxxxxxxx; BSchieck@xxxxxxxxxx; si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Re: Current capacity of a Solder Ball Moses, and Brian, that current number seems low by orders of magnitude. First, the electrical resistance is way off. For the resistivity value shown which seems about right at 8X Cu, and a rectangular section 0.2mm X 0.2mm X 0.6mm yields about 0.002 ohms. Similarly, the thermal resistance value of 41,000 C/W for a metallic object 24 thousandths thick cannot be right. Take a small glob of solder the size of a BGA ball on the bench and connect it to a 10V supply and a 100 ohm resistor. There is no way, that blob will get warm, much less melt. It will take multiple amperes to melt the foil leading to or away from the ball, and the foil will fail long before the ball. Regards, Steve. At 11:32 AM 2/5/2003 -0800, Moses Chan wrote: >Hi Brian, > >I asked the same question to the list a few months back and got the >following answer, below: > >Solder Ball (63Sn/37Pb) 0.0006 m >Ambient Temp. 34 Deg. C >Melting Temp. 189 Deg. C >Thermal Conductivity 50 W/m-C >Electrical Resistivity 0.000000145 ohm-m >Thermal Resistance 41026.51161 C/W >DC Electrical Resistance 0.297442209 ohm >Total Resistance 0.297442209 ohm >Power to Melt 0.003778045 W >Current to Melt 0.112702164 Amps > > >Moses Chan >Vitesse Semiconductor >Camarillo, California > >At 11:13 AM 2/5/03 -0800, Brian Schieck wrote: > > >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 > >------------------------------------------------------------------ > >To unsubscribe from si-list: > >si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field > > > >or to administer your membership from a web page, go to: > >//www.freelists.org/webpage/si-list > > > >For help: > >si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field > > > >List archives are viewable at: > > //www.freelists.org/archives/si-list > >or at our remote archives: > > http://groups.yahoo.com/group/si-list/messages > >Old (prior to June 6, 2001) list archives are viewable at: > > http://www.qsl.net/wb6tpu > > > >------------------------------------------------------------------ >To unsubscribe from si-list: >si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field > >or to administer your membership from a web page, go to: >//www.freelists.org/webpage/si-list > >For help: >si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field > >List archives are viewable at: > //www.freelists.org/archives/si-list >or at our remote archives: > http://groups.yahoo.com/group/si-list/messages >Old (prior to June 6, 2001) list archives are viewable at: > http://www.qsl.net/wb6tpu > ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu