Workshop 3rd. October, Noordwijk (NL) Long-Term Use of electronics Reliability in Experiment & Simulation at Fraunhofer IZM Berlin H.Walter B.Wunderle B.Michel H.Reichl 1
Fraunhofer IZM Focus of Activities Materials, Reliability & Sustainable Development Micro Materials Environmental Engineering Substrate Integration Technologies System Integration & Interconnection Technologies PCB Soldering Training/Qualification and Micro- Mechatronics Polytronic Systems Wafer Level Integration Technologies Vertical System Integration Wafer Level Packaging & High Density Interconnects System Design System Design & Integration Advanced System Engineering Micromechanics, Actuators & Fluidics Material characterisation Process evaluation Reliability testing Failure analysis Sample production Training courses 2
Failure of Microelectronic Systems 125 0-40 C N ΔT F, sin(ωτ) % Prediction of Reliability necessary Microelectronic product failures Failures occur not only during usage, but also during different manufacturing stages such as wafer processing, packaging, and final assembly. Typical failures are cracks,delamination, buckling, warpage, popcorning, stress, voiding, fatigue, pattern shift, thermomigration, and electrical stress induced failures, such as hot carrier degradation, breakdown of thin oxides, and electromigration. The majority of these failures (65 %) are thermomechanically related. As clearly identified, reliability is one of the major challenges for the future in both microelectronics and micro/nano systems. 3
Potential Failure Mechanisms in SOP (System-on-Package) Microsystems Change in Capacitance due to Stress/Strain FLASCH RAM Solder Fatigue Via Cracking Interfacial Delamination PD / TIA µp CMOS / SOC MEMS DFB / TE RF / IC Dielectric Cracking Stress-induced Birefringence Design for Reliability Board Warpage 4
Development of new technologies and methodologies for reliability estimation 5
IZM Program Thermal Management Reliability & costoptimised design for cooling systems Material characterisation Implementation of advanced cooling concepts Virtual prototyping Technological support and processes: from hand-held up to high-performance Verification and testing Contact: Dr. Bernhard Wunderle, Mail to: bernhard.wunderle@izm.fraunhofer.de Dep. Micro Materials Centre Berlin, Head: Prof. Dr. B. Michel, Fraunhofer IZM, Berlin, Germany
IZM Program Micro Reliability & Lifetime Prediction Reliability testing & monitoring Most relevant testing conditions System Design for Reliability Multi-field & scale EMC Technology & Processes Reliability & cost optimised Failure analysis & lifetime prediction Physics of failuremechanisms Material characterisation & modelling as f(t, t, %, size) Nano-Reliability Structure-property correlation Contact: Prof. Bernd Michel, Mail to: bernd.michel@izm.fraunhofer.de Dep. Micro Materials Centre Berlin, Head: Prof. Dr. B. Michel, Fraunhofer IZM, Berlin, Germany
IZM Program Micro Reliability & Lifetime Prediction Reliability testing & monitoring Most relevant testing conditions System Design for Reliability Multi-field & scale EMC Technology & Processes Reliability & cost optimised Failure analysis & lifetime prediction Physics of failuremechanisms Material characterisation & modelling as f(t, t, %, size) Nano-Reliability Structure-property correlation Contact: Prof. Bernd Michel, Mail to: bernd.michel@izm.fraunhofer.de Dep. Micro Materials Centre Berlin, Head: Prof. Dr. B. Michel, Fraunhofer IZM, Berlin, Germany 8
Challenges in SIP Technology Development Wirebond failure Solder Fatigue by (micro-dac) Delamination at Encapsulation Cracks in Vias Crack in Die-Attach D. Vogel, K. Halser, C. Becker, B. Wunderle Die Crack 9
Analysis of Failure Mechanisms & Criteria Solder Fatigue Fracture Delamination Stress ε cr Inelastic Bhv. Creep Strain crit. Stress, K-factor Fracture Parameter G(ψ), J-Int 10
Micro Reliability & Lifetime Prediction Reliability testing & monitoring Most relevant testing conditions System Design for Reliability Multi-field & scale EMC Technology & Processes Reliability & cost optimised Failure analysis & lifetime prediction Physics of failuremechanisms Material characterisation & modelling as f(t, t, %, size) Nano-Reliability Structure-property correlation Contact: Prof. Bernd Michel, Mail to: bernd.michel@izm.fraunhofer.de Dep. Micro Materials Centre Berlin, Head: Prof. Dr. B. Michel, Fraunhofer IZM, Berlin, Germany
Primary Creep for Sn59Pb40Ag1and Sn95.5Ag3.8Cu0.7 Creep Strain (%) 1,50 1,25 1,00 0,75 0,50 Sn63Pb37 Sn96.5Ag3.8Cu0.7 1,0 E-5 s-1 1,0 E-6 s-1 At t = 0, the instantaneous creep rate is infinite. For small t it is greater than the steady-state creep rate, and after a long time, the instantaneous rate vanishes and the total rate is equal to the steadystate rate. This behavior seems to be slightly different for different solder compositions. 0,25 0,00 1,0 E-7 s-1 0 2000 4000 6000 8000 10000 0,75 Sn63Pb37 Sn96.5Ag3.8Cu0.7 Primary creep strain ε sat cr = ε p 1 exp Time (s) K n & ε s t + & εs t Creep Strain (%) 0,50 0,25 1,0 E-5 s-1 1,0 E-6 s-1 Primary creep rate & ε pr = n1 K ε sat pr n1 ( n1 1) (& ε ) ( t) exp K( & ε t) ss ( ) n1 ss 0,00 1,0 E-7 s-1 0 100 200 Time (s) 12
High-Speed Testing for Brittle Solder Joint Failure High speed ball shear test High speed ball pull test Board Level Drop Test Method of Components for Handheld Electronic Products. (JESD22- B111) Miniature Charpy test interconnection stress due to board bending is 2 orders of magnitude higher than that due to acceleration. 13
Epoxy Characterisation under Moisture 5000 110 4000 E, 30 C 105 E [MPa] 3000 2000 1000 0 0 85 100 Moisture Loading E, 90 C Tg [ C] 100 95 90 85 0 85 100 Moisture Loading Viscoelastic Master Curve DMA / tensile with moisture chamber Epoxy = ACA Cure Shrink (By Hg-Vol. Dilatometry) ΔV = 1.41 % CME [%] 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 0 85 100 Moisture Loading Modulus (MPa) 5500 5000 4500 4000 3500 3000 2500 C 2000 Wet Sample 1500 RH 85 % T = 30 C - 100 C Dry Sample 1000 T = 30 C - 150 C PC Sample 500 RH 85% T = 30 C - 150 C 0-4 -2 0 2 4 6 8 10 12 14 16 log t 14
Material Characterisation in the Nano-Region Force, Distance Indenter Thin Layer Substrate ε pl [%] 26 0 Force [µn] 300 250 200 150 100 50 0 Sim Exp 0 20 40 60 80 Distance [nm] Experiment Simulation until Agreement reached Determination of Parameters only in Coupling to Simulation possible B. Wunderle, R. Mrossko, E. Kaulfersch, O. Wittler, P. Ramm, B. Michel and H. Reichl. MRS Fall Meeting, Boston, USA, Nov. 2006 1 µm σ σ y E M E ε pl ε 800 nm AlSiCu E [GPa] σ y [MPa] M [MPa] 50 190 1400 15
Tool box for thin film reliability analysis Stiffness Nanoindentation / nanodma P Residual Stresses nanoraman / fibdac / Wafer Curvature specimen theory experiment Metal Fatigue N f = c 1 ( pl ) c ε 2-8 µm -4 µm 0 µm 4 µm 8 µm Fracture Toughness (Cohesive Strength) Indentation Fracture Test Interfacial Fracture Toughness 16
Exp. Characterisation of Interface Crack 4-Pt Bending Chisel Bending Pull-off Test 50 mm 30 mm 20 mm 700 600 (J/m 2 ) G C [J/m 2 ] Interface Strength 500 400 300 200 100 0 DCB MMB2 MMB3 MMB4 MMB5 TPB Curve Fit G c (ψ ) H.Walter, Oct. 38 40 422008 44 46 48 50 52 54 56 58 60 62 64 66 68 70 72 74 76 40 50 60 70 Mode Mixity (deg) Micro Materials Phasenwinkel Center Berlin, ψ Head: [ ] Prof. B. Michel Shriangi, Schlottig, Xiao, Wunderle, 2008 G > G c ( T 2, C, mat 1,, ψ ) Interface: Crack has angular dep.! Sim & Exp Development of new tests necessary (no standard) Close to tech, small, more than one design necess. 17
Solder Fatigue in Experiment and Simulation Experiment......and Simulation T N f N Periodic Thermal Load CTE Mismatch Failure by Solder Fatigue T N 125 C 0-40 FCOB N f Reliability via Coffin Manson ε cr Deform Creep Strain Solder Cracking B. Wunderle 18
DoE - Results for a Flip-Chip Assembly Solder Fatigue MTTF = f(d chip, d sub ) Die Crack σ chip = f(d chip, d sub ) Interface Delamination G IF,φ = f(d chip, d sub ) J. Auersperg Simultaneous evaluation of many failure machanisms as function of important (by DOE) variables Compact Model 19
Micro Reliability & Lifetime Prediction Reliability testing & monitoring Most relevant testing conditions System Design for Reliability Multi-field & scale EMC Technology & Processes Reliability & cost optimised Failure analysis & lifetime prediction Physics of failuremechanisms Material characterisation & modelling as f(t, t, %, size) Nano-Reliability Structure-property correlation Contact: Prof. Bernd Michel, Mail to: bernd.michel@izm.fraunhofer.de Dep. Micro Materials Centre Berlin, Head: Prof. Dr. B. Michel, Fraunhofer IZM, Berlin, Germany 20
Lifetime Prediction for Solder Fatigue BGA FC Diebond SMD Leaded TO220 B. Wunderle 21
Inelastic Material Behaviour for Lifetime Prediction Solder Bumps Wire Bonds Vias Creep Strain [arb.u.] ε Primäres Kriechen Sekundäres Kriechen Time [arb.u.] t Bruch Tertiäres Kriechen Force N σ 0.12 0.10 0.08 0.06 0.04 Au Bondwire, 25 μm E = 78.2 GPa 0.02 L 0 = 100 mm 50 v = 10 mm/min 0.00 0 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 Strain % ε 250 200 150 100 Real Stress [MPa] σ ε
Load Combination Example failure mechanisms u t C H2O Crack Chip P Die Pad Moisture + Temperature Accelerated moisture transport Popcorning Si Substrate Moisture/Temperature + Vibration Reduction of interfacial adhesion Mechanical interface load Temperature Cycling + Vibration Initial degradation by Temperature cycling Instable crack growth during vibration The combination of loads can be more critical than the single loads. Combined testing 23
Test Set-up u t C H2O Electricial In-Situ Monitoring/Loading: up to 256-Channels Resistance, Capacity, Inductance Temperature, Acceleration Digital I/O Active Power Control (Real-Time) System installation finished April 2008 Laservibrometer (IR-Camera) Optics (OCT, DAC) Climate Chamber T, RH 180 C 0-70 H2O 24
IZM Program Micro Reliability & Lifetime Prediction Reliability testing & monitoring Most relevant testing conditions System Design for Reliability Multi-field & scale EMC Technology & Processes Reliability & cost optimised Failure analysis & lifetime prediction Physics of failuremechanisms Material characterisation & modelling as f(t, t, %, size) Nano-Reliability Structure-property correlation Contact: Prof. Bernd Michel, Mail to: bernd.michel@izm.fraunhofer.de Dep. Micro Materials Centre Berlin, Head: Prof. Dr. B. Michel, Fraunhofer IZM, Berlin, Germany 25
Increasing polarity and chain length Molecular Dynamics 2.50E-007 3.0x10-6 2.00E-007 2.5x10-6 Diff D coeff. (cm^2/s) 1.50E-007 1.00E-007 5.00E-008 0.00E+000 E.D. Dermitzaki, J. Bauer, B. Wunderle, B. Michel Proc. EuroSimE, Apr 16-18, 2007, London, England 2007. Exp Experiment:98 C/100RH Diff D (cm^2/s) coeff. 2.0x10-6 1.5x10-6 1.0x10-6 5.0x10-7 0.0 98 C/ 100 rh Sim & Exp show correct tendencies Molecular Dynamics 98 C/100RH Sim MD: understand fundamental mechanisms High Potential with faster Computers scale zooming Adhesion Polymer: 23 H2O for 98 C/ 100 RH Result (as tested Sim & Exp): D and S are strong function of inner variables: - density, - polarity, - chain length, - stoichiometry, - temperature 26
fibdac Residual stresses at sub-µm Scale Passivation Silicon Flow Rate Sensor LPCVD with 300 nm membrane SiN34 Platinum Stress release Stress release by ion milling in focused ion beam equipment Stress determination from measured deformation field (right) Material data by nano-indentation D. Vogel, N. Sabate, J. Keller, B. Michel, theory experiment -8 µm -4 µm 0 µm 4 µm 8 µm Fraunhofer Prize 2005 27
Lifetime Estimation - test methods Low Cycle Fatigue of Lead-free Solders in Service Can we calculate critical lifetime under service conditions based on FEA, i.e. does the failure mechanism change? Does the acceleration factor AF depend on solder and/or component? Field cycles in service life acceleration transform, analytical or FEA based N = AF Feld N Test Number of test cycles required Analytical acceleration transform: rule of thumb N Feld = N Test ΔT ΔT Test Feld CM SnPb: CM 2 SAC:?????????? 28
Long time test methods for degradation of material properties St.-Anna-Mine, Saxonia Energy effective field tests at natural environmental conditions Temp Ausgebaute Strecke Temperature cycle : 8 C till ca. 200 C ( Experimental: max. 150 C) oven time Temperature chamber with air circulation Remote diagnosis and remote control In-Situ-Measurement technique for electrical control of specimens PC for control systems und data aquisition Measurement time 1 day years (relatively) Low costs Temperature profile: Heating up Heating rate max 4 k/min max. 8 ramps Hold time: warm/cold +/- 1K 29
Electrical Properties The external influences have effects on: Material Properties (Conductivity, Permittivity, Permeability etc.) Electrical Connections (Soldering Joints, Bumps, Bond wires etc.) Semiconductor (Charge Carrier, Latch-Up Effect, ESD etc.) Example: Power Supply with Electrolyte Capacitor High Temperature drying of Electrolyte higher Ripple-Voltage Cause Errors /Crash in Microcontroller!! 30
Simulation of Disturbance Simulation of Disturbance Calculation of Effect on Component Parameter Simulation of System Behaviour Surface Current on PCB Edge-Connector Temperature Distribution of a Quad-Micro-Coil-Array 31
Micro Reliability & Lifetime Estimation Experimental and numerical reliability FE-methodology to analyse moisture evaluation of vibrationally loaded solder diffusion in plastic packages joints Studies on popcorn effect System within Design thin plastic Reliability of area array Reliability packages testing like BGA, quad flat packages for Reliability CSP, WLCSP, FCOB & monitoring Reliable design for high-temperature Multi-field & scale Fundamental aspects Most of large relevant IC flip testing chip advanced packages conditions EMC attach to organic boards Reliability of micro/nano system packages Influence of process-induced defects on the reliability Development and application of failure Failure analysis Technology & Processes analysis techniques for ICs, including Stress analysis of HDI substrates, life of electrical deep-submicron & lifetime probing prediction (0.18 μm) Reliability & cost micro vias and testing Physics of failuremechanisms optimised Cost effective test concepts for system Test methods and fracture mechanics to integration characterize interfaces Electrical RF-test Modeling and measuring capabilities of cure shrinkage, thermal shrinkage Material and characterisation moisture Development of ESD-protection Nano-Reliability structures, swelling of polymeric materials & modelling influence of ESD on reliability Structure-property as f(t, t, %, size) correlation 32
Thank you very much for your attention! Time for Questions?