Why do temperature-based FEA? Natalie Hernandez, PhD Product Manager, Sherlock 1 9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com
In a perfect world, your PCBA is in a perfectly controlled, relatively benign environment o Humidity control o Temperature monitoring o No vibration o No shock events 2 9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com
WHAT’S THE PROBLEM? 3 9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com
We are not in a perfect world! dynamic amic extreme me 4 9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com
UNEXPECTED SOLDER FAILURES Increasing number of companies reporting early life failures during the manufacturing process or during testing or in the field Classic solder fatigue approaches do not seem to be capturing these risks 5 9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com
WHAT’S THE CAUSE? 6 9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com
Why do electronics fail when they experience temperature changes? A. We use lots of different materials o Semiconductors, Ceramics, Metals, Polymers o B. We bond these different materials together o Plating, Solder , Adhesive o C. These materials expand/contract at different rates o 9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com
Why do electronics fail when they experience temperature changes? o Two different expansion/contraction behaviors o Because solder is connecting two materials that are expanding / contracting at different rates (GLOBAL) o Because solder is expanding / contracting at a different rate than the material to which it is connected (LOCAL) 9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com
Why do electronics fail when they experience temperature changes? o This differential expansion and contraction introduces stress into the solder joint o This stress causes the solder to deform (aka, elastic and plastic strain) o The extent of this strain (that is, strain range or strain energy) tells us the lifetime of the solder joint o The higher the strain, the more the solder joint is damaged, the shorter the lifetime 9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com
Drivers for Solder Joint Thermo-Mechanical Failures Knowing the critical drivers for solder joint fatigue, we can develop predictive models and design rules Volume of Solder Thickness of Solder CTE of Component Solder Fatigue Properties Elastic Modulus (Compliance) of Component Length of Component CTE of Board Elastic Modulus (Compliance) of Board 9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com
Let’s throw system - level effects into the mix… OVER-CONSTRAINED BOARDS 11 9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com
Let’s throw system - level effects into the mix… COATING/POTTING/UNDERFILL T 2 1 F 1 1 A E A E 1 1 2 2 12 9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com
MIRRORING Will underfilling the BGA help? Avoided in earlier designs (challenges with rework o and X-ray inspection) Increasingly required due to higher densities and higher Based on Darveaux Model o speed memory Reduces lifetime by 2X to 4X, but numerous o organizations struggle to predict behavior Based on Darveaux Model * * * Meifunas, M., et al. "Measurement and prediction of reliability for Ye, Yuming, et al. "Assessment on reliability of BGA package double-sided assembled." High Density double-sided area array assemblies." Electronic Components and Packaging and Microsystem Integration, 2007. HDP'07. International Symposium on . IEEE, 2007. Technology Conference, 2003. Proceedings. 53rd . IEEE, 2003. 13 9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com
WHAT’S THE SOLUTION? 14 9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com
Temperature-based FEA Facilitates the assessment of system-level effects due to thermal and vibrational o stresses. This is exceptionally important for the automotive and aerospace industries. 15 9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com
Example Problem http://dx.doi.org/10.1109/ICEP.2016.7486818 16 9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com
Example Problem – 3D Model 17 9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com
Example Problem: Incorporating temperature dependence Temperature-dependent Laminate properties: Elastic Modulus Temperature Elastic Modulus -55 27000 25 24804 125 17000 Temperature-dependent Solder properties: Elastic Modulus and CTE Temperature Elastic Modulus -100 38941.1 2.37e-5 150 18996 2.59e-5 18 9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com
Natural Frequency Results NATURAL FREQUENCY 900 Natural Frequency (Hz) 800 700 Temperature (C) Frequency (Hz) 600 500 -55 781 400 0 761 300 200 25 752 100 105 661 0 -100 0 100 200 220 475 Temperature (C) -55C 0C 25C 105C 220C Temperature 19 9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com
Experimental and Simulated first mode shape at 105C 1 st Natural Frequency: 663Hz http://dx.doi.org/10.1109/ICEP.2016.7486818 20 9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com
Harmonic Vibration 105C -10C Damage: 8.4E2 Damage: 5.8E1 There is a clear decrease in damage as temperature decreases. 21 9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com
WHY DO TEMPERATURE-BASED FEA? 22 9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com
Why do it? o Unless you’re in a perfectly controlled, benign environment, there will be combined events impacting the PCB. 23 9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com
WHY DO IT IN SHERLOCK ? 24 9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com
Why do it in Sherlock? o Users can quickly model their boards and run temperature-based FEA with/without using Ansys or Abaqus. o Sherlock provides more accurate Fatigue predictions. Can current FEA tools provide fatigue predictions? NO 25 9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com
Summary o Understanding the responses of your PCBAs under today’s environmental stressors is key to answering that ultimate question, “When will my board fail?” 26 9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com
Looking ahead… Key Features in Sherlock 6.0: Humidity-driven Failure Modes o Via Fatigue Predictions o SolidWorks Integration o 27 9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com
Thank you for listening! Questions? 28 9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com
Dr. Natalie Hernandez, Product Manager, Sherlock o nhernandez@dfrsolutions.com o Mark Musitano, Senior Sales Engineer o mmusitano@dfrsolutions.com o 29 9000 Virginia Manor Rd Ste. 290, Beltsville MD 20705 | 301-474-0607 | www.dfrsolutions.com
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