EPSI INC.  -  Electronics Packaging Solutions International Inc.
P.O. Box 1522, Montclair, NJ 07042 USA, tel.: +1 (973)746-3796, fax: +1 (973)655-0815

• Predicts time to first failure (3P Weibull) or any other % failure (2P).
• Computation time
Very fast (about 2 sec.)
• Easily handles multiple thermal conditions (Miners rule)
• Inexpensive...
• Good for examining material/design changes.

• Currently used for eutectic Pb/Snsolder.
• Based upon the accuracy, ease of use, and program cost the SRS code appears to be a “best buy”."
Wavrik et al., Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy’s National
Nuclear Security Administration

Ref.: R. Wavrik, J. Aragon, J. White, P. Vianco, A. Kilgo and J. Sweet, "Comparison of Solder Fatigue Life Models to Experimental Data",
presentation given at 2006 Components for Military & Space Electronics Conference, 10th Annual CMSE Conference, February 6-9, 2006,
Los Angeles, CA.

"Simple PC based model (not FEM) which executes quickly...."
"Over 300 part types / board combinations evaluated by the SRS code..."
"SRS code does a good job of predicting time to first failures (also life remaining)"
Wavrik et al., Sandia National Laboratories - US Department of Energy's National Nuclear Security Administration.

Ref.: Wavrik, R., Aragon, J., White, J., Vianco, P., Kilgo, A. and Sweet, J.: "Experimental vs. model prediction comparison of solder joint
fatigue life for COTS components", in presentation at 2004 International Military & Aerospace / Avionics COTS Conference, Exhibition &
Seminar, August 3-5, 2004.

“It is important to understand that this model predicts the reliability performance of the solder joint as a
whole and thus, is an excellent screening tool for identifying potential trouble spots in terms of selected
materials, solder joint configuration, or use condition…Since the finite element analysis is computationally
intensive, its use should be limited to only those critical cases identified by the SRS assessments as requiring
further evaluation…”.
Paul T. Vianco and Steven N. Burchett, Sandia National Laboratories

Ref.: Paul Vianco and Steven Burchett, “Solder Joint Reliability Predictions for Leadless Chip Resistors, Chip Capacitors, and Ferrite Chip
Inductors Using the SRS™ Software”, SANDIA REPORT, SAND2001-1665, Unlimited Release, August 2001.

"The SRS model results were substantiated with a life prediction model developed at the University of
, Hunter et al., Storage Technology Corporation & University of Colorado.

Ref.: Hunter, B., Subbarayan, G. and Rose, D., "Characterization of PCB expansion using moiré interferometry and the impact of expansion
variability on the life of solder joints", Proceedings, InterPACK'99 Conference, EEP-Vol. 26-1, Advances in Electronic Packaging, ASME,
June 13-19, 1999, Maui, Hawaii, pp. 875-882.

"The simulation results are in accord with the experimental results, meaning SRS model describes the
behavior of the BLP package's solder joint accurately"
,  Choi et al., LG Semicon, Korea.

Ref.:Choi, K-S., Kim, Y.-G., Choi, S., Park, I.-S., Lee, J.-H. and Ku, J.-Y., "Solder joint reliability of the BLP package", Proceedings, IPC /
SMTA Assembly Expo, Providence, RI, October 24-29, 1998, pp. S19-3-1 - S19-3-6.

"Today the most popular intermediate and high order models use accumulated strain energy as the correlating
parameter to estimate the solder joint life.

Figure 4 shows the correlation between calculated strain energy and measured joint fatigue life a/A, where a
is the characteristic number of cycles to 63.2% failures and A is the minimum load bearing area in the joint.
The strain  energy density (AW) in the figure is calculated with the SRS software but the slope is consistent
with other strain-energy based models for SMT assembly reliability. This SRS model has been validated with
several different components including 116 and 220 I/O ceramic CSPs.

The intermediate order models calculate the strain energy in one thermal cycle within a few minutes whereas
the high order models (FEM) take from approximately one hour to one day to provide the solution.
Dr. Savolainen et al., Nokia Group, Helsinki, Finland.

Ref.: Savolainen, P. and Tommi Reinikainen, T., "Measuring the manufacturability and reliability of electronic assemblies", Chip Scale Review,
Vol. 2, No. 5,  November-December 1998, pp. 61-66.
Copyright EPSI Inc.


"The Clech SRS (Solder Reliability Solutions) model is widely accepted by industries, and has been
implemented  as a PC-based design-for-reliability tool that enables quick parametric studies of critical
package and board properties"
, in CMAP Report, University of Toronto, Canada.

Ref.: MIE 2004 Term Report, Part II, Review of Thermal Fatigue Prediction Models, Center for Microelectronics Assembly and Packaging
(CMAP), University of Toronto.

"SRS (Solder Reliability Solution) Models predicted that you would see over 1000 thermal cycles more before
failure with a double sided reflow BGA than with  a single reflow. Tests actually proved that"
, S. Gregory, IPC
TechNet Forum, July 2003