Influence of Secondary Impact on Printed Wiring Assemblies—Part I: High-Frequency “Breathing Mode” Deformations in the Printed Wiring Board

Design rules for portable electronic device are continuously striving for thinner printed wiring assemblies (PWAs) and smaller clearances because of ever-increasing demand for functionality and miniaturization. As a result, during accidental drop and impact events, there is an increased probability of internal secondary impact between a PWA and adjacent internal structures. In particular, compared to the initial impact, acceleration pulses caused by contact during secondary impacts are typically characterized by significant increase of amplitudes and frequency bandwidth. The resonant response in the thickness direction of printed wiring boards (PWBs) (termed the dynamic “breathing mode” of response, in this study) acts as a mechanical bandpass filter and places miniature internal structures in some components (such as microelectromechanical systems (MEMS)) at risk of failure, if any of them have resonant frequencies within the transmitted frequency bandwidth. This study is the first part of a two-part series, presenting qualitative parametric insights into the effect of secondary impacts in a PWA. This first part focuses on analyzing the frequency spectrum of: (i) the impulse caused by secondary impact, (ii) the energy transmitted by the dynamic “breathing” response of multilayer PWBs, and (iii) the consequential dynamic response of typical structures with high resonant frequencies that are mounted on the PWB. Examples include internal deformable structures in typical surface mount technology (SMT) components and in MEMS components. The second part of this series will further explore the effects of the breathing mode of vibration on failures of various SMT components of different frequencies.

[1]  Stephen P. Timoshenko,et al.  Vibration problems in engineering , 1928 .

[2]  A. H. Shah,et al.  Harmonic waves in a periodically laminated medium , 1982 .

[3]  Zhaowei Zhong,et al.  Advanced experimental and simulation techniques for analysis of dynamic responses during drop impact , 2004, 2004 Proceedings. 54th Electronic Components and Technology Conference (IEEE Cat. No.04CH37546).

[4]  T. T. Mattila,et al.  An approach to board-level drop reliability evaluation with improved correlation with use conditions , 2013, 2013 IEEE 63rd Electronic Components and Technology Conference.

[5]  M. Pandey,et al.  Analysis of Frequency Locking in Optically Driven MEMS Resonators , 2006, Journal of Microelectromechanical Systems.

[6]  A. L. Morales,et al.  An adaptive pneumatic system for the attenuation of random vibrations , 2015 .

[7]  Jian Liu,et al.  Nonlinear model and system identification of a capacitive dual-backplate MEMS microphone , 2008 .

[8]  Pradeep Lall,et al.  Stress–Strain Behavior of SAC305 at High Strain Rates , 2015 .

[9]  M. Sillanpaa,et al.  Testing and multi-scale modeling of drop and impact loading of complex MEMS microphone assemblies , 2012, 2012 13th International Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems.

[10]  Aaron Brown,et al.  Simulation of Secondary Contact to Generate Very High Accelerations , 2015 .

[11]  A. Polycarpou,et al.  Measurement and Modeling of Normal Contact Stiffness and Contact Damping at the Meso Scale , 2005 .

[12]  Suresh Goyal,et al.  Improving impact tolerance of portable electronic products: Case study of cellular phones , 1999 .

[13]  Peter Eberhard,et al.  Comparison of Analytical and Experimental Results for Longitudinal Impacts on Elastic Rods , 2003 .

[14]  W. Baker,et al.  A Split Hopkinson Bar Technique to Evaluate the Performance of Accelerometers , 1996 .

[15]  L. Rufer,et al.  Wide-band aero-acoustic microphone with improved low-frequency characteristics , 2013, 2013 Transducers & Eurosensors XXVII: The 17th International Conference on Solid-State Sensors, Actuators and Microsystems (TRANSDUCERS & EUROSENSORS XXVII).

[16]  J. Achenbach,et al.  Time-Harmonic Waves in a Stratified Medium Propagating in the Direction of the Layering , 1968 .

[17]  Moustafa Al-Bassyiouni,et al.  Experiment and Simulation of Board Level Drop Tests With Intentional Board Slap at High Impact Accelerations , 2014, IEEE Transactions on Components, Packaging and Manufacturing Technology.

[18]  Chwee Teck Lim,et al.  Drop impact survey of portable electronic products , 2003, 53rd Electronic Components and Technology Conference, 2003. Proceedings..

[19]  M. Sillanpaa,et al.  Drop qualification of MEMS components in handheld electronics at extremely high accelerations , 2012, 13th InterSociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems.

[20]  Abhijit Dasgupta,et al.  Influence of Secondary Impact on Failure Modes in PWAs With High Resonant Frequency , 2015 .

[21]  Izhak Etsion,et al.  Analytical Approximations in Modeling Contacting Rough Surfaces , 1999 .

[22]  G. X Li,et al.  Drop test and analysis on micro-machined structures , 2000 .

[23]  E. Habtour,et al.  Modeling Approach for Predicting the Rate of Frequency Change of Notched Beam Exposed to Gaussian Random Excitation , 2014 .

[24]  Fadi M. Alsaleem,et al.  An Investigation Into the Effect of the PCB Motion on the Dynamic Response of MEMS Devices Under Mechanical Shock Loads , 2008 .

[26]  Herbert Kolsky,et al.  Stress Waves in Solids , 2003 .

[27]  D. Frew,et al.  A modified Hopkinson pressure bar experiment to evaluate a damped piezoresistive MEMS accelerometer. , 2009 .

[28]  J. Greenwood,et al.  Contact of nominally flat surfaces , 1966, Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences.

[29]  Andy Zhang.  High acceleration board level reliability drop test using Dual Mass Shock Amplifier , 2014, 2014 IEEE 64th Electronic Components and Technology Conference (ECTC).

[30]  Pradeep Lall,et al.  Mechanical Shock Reliability Analysis and Multiphysics Modeling of MEMS Accelerometers in Harsh Environments , 2015 .