PREDICTIVE AND ANALYTICAL METHODS FOR RAPIDLY ASSESSING THE RELIABILITY OF COMMERCIAL ELECTRONIC PACKAGING FOR MILITARY/INDUSTRIAL ENVIRONMENTS

Transcription

1 PREDICTIVE AND ANALYTICAL METHODS FOR RAPIDLY ASSESSING THE RELIABILITY OF COMMERCIAL ELECTRONIC PACKAGING FOR MILITARY/INDUSTRIAL ENVIRONMENTS S. Rahman, K. K. Choi, T. Zhang, and J. Tang Center for Computer-Aided Design (CCAD) The University of Iowa Iowa City, IA September 17, 2002

2 OUTLINE Objective of this Project A Simulation-based Methodology Experimental Validation Effort In-plane Displacement of ASAT 144 Package Out-of-plane Displacement of CSP Assembly Accomplishments in 10/01-9/02 Future Efforts

3 OBJECTIVE Develop a physics-of-failure- and simulation-based prediction methodology which would allow for rapid assessment of the reliability of advanced packaging technologies Project started in January 1999

4 SIMULATION-BASED METHODOLOGY Chip Scale Package Part: ASAT 144 b1 b3! Input h1 b4 Molding Compound Die Chip Die Attach h3 h4 Geometry h2 Rigid Carrier solder ball Material Properties h5 PCB Load (Temperature)! Stress Analysis b2 Nonlinear FEA Temperature, C C! Output Deformation, Stress, Strain, etc. Fatigue Life -55 C Time, s Full-Scale FEA of CSP is computationally prohibitive

5 SIMULATION-BASED METHODOLOGY A Three-Step Process for Durability Analysis GLOBAL DEFORMATION ANALYSIS Simplified Solder Joint Model Equivalent Model Relative Displ. Time History CRITICAL SOLDER JOINT ANALYSIS Detailed Model of Actual Solder Joint Displ. Input from Global Analysis Calculation of Stresses & Strains FATIGUE LIFE ANALYSIS Critical Plane Method Assessment of Durability and Reliability PATRAN ABAQUS PATRAN ABAQUS DRAW [In-house Developed]

6 SIMULATION-BASED METHODOLOGY Global Deformation Analysis Critical Joint 11ú1mm=11mm Center 11ú1mm=11mm Equivalent brick/diamond model for solder joint Coarse mesh for solder joint; detailed mesh for other parts Calculate displacement field of critical solder joint

7 SIMULATION-BASED METHODOLOGY Critical Solder Joint Analysis Von Mises Stress High-fidelity mesh for critical solder joint Apply displacement field from global analysis Calculate stresses/strains at critical solder joint

8 SIMULATION-BASED METHODOLOGY Fatigue Life Analysis

9 EXPERIMENTAL VALIDATION Experimental Work at RC and RSC ASAT 144 Package (with solder balls removed) In-plane displacement measurements of package by HASMAP (this year) Out-of-plane displacement measurements of Package by Shadow Moiré Testing PCB In-plane displacement measurements of package by HASMAP (CTE calculation) CSP Assembly (package & board soldered together) In-plane relative displacement measurements of the farthest solder joint by HASMAP Out-of-plane relative displacement measurements of various solder joints by HASMAP (this year)

10 IN-PLANE DISP. OF PACKAGE ASAT 144 Package RT to 125 C

11 IN-PLANE DISP. OF PACKAGE ASAT 144 Package RT to 35 C RT to 90 C

12 IN-PLANE DISP. OF PACKAGE Raw Pixel Data x y delta_x delta_y x y delta_x delta_y x y delta_x delta_y RT to 125 C Raw pixel data were translated to physical displacement measurements

13 IN-PLANE DISP. OF PACKAGE Raw Experimental Data In-Plane (x) Displacement, µm 9 6 min: µm max: 8.17 µm y, mm x, mm RT to 125 C

14 IN-PLANE DISP. OF PACKAGE Fitted Experimental Data (Full) In-Plane (x) Displacement, µm Fitted Plane (Full) max: 7.6 µm y, mm x, mm RT to 125 C

15 IN-PLANE DISP. OF PACKAGE Fitted Experimental Data (Quarter) In-Plane (x) Displacement, µm Fitted Plane (Quarter) max: 7.6 µm y, mm x, mm 6.50 RT to 125 C

16 IN-PLANE DISP. OF PACKAGE Results from FEM (ABAQUS) - Quarter Model In-Plane (x) Displacement, µm FEM (ABAQUS) max: 8.11 µm y, mm x, mm 6.50 RT to 125 C

17 IN-PLANE DISP. OF PACKAGE Comparison of Results FEM (ABAQUS) max: 8.11 µm Fitted Plane (Quarter) max: 7.6 µm 6 6 In-Plane (x) Displacement, µm 5 In-Plane (x) Displacement, µm y, mm x, mm 6.50 y, mm x, mm 6.50 FEM (ABAQUS) Experiment

18 OUT-OF-PLANE DISP. OF ASSEMBLY CSP Assembly - Motivation 200 Temperature, C C From Sep 2001 presentation -55 C Time, s Step 1 (T = 125 C) Step 3 (T = -55 C)

19 OUT-OF-PLANE DISP. OF ASSEMBLY Past FEM (ABAQUS) Prediction Relative Displacement, u i (t), m 8E-06 4E E-06-8E-06 u 3 (t) u 2 (t) u 1 (t) From Sep 2001 presentation Time, s FEM predicted out-of-plane displacement to be larger than in-plane displacement - Need to be verified with experimental data

20 OUT-OF-PLANE DISP. OF ASSEMBLY Relative Disp. (ASAT 144 Package & FR4 PCB) u 3,top HASMAP Analysis u 3,bot Input: RT to 125C Output: u 3 = (u 3,top - u 3,bot )

21 OUT-OF-PLANE DISP. OF ASSEMBLY Identification of Solder Joints center y middle of edge x corner

22 OUT-OF-PLANE DISP. OF ASSEMBLY Applied Temperature History Temperature (C) Hold Time = t 2 t C Step 2 35 C Step 1 t 1 t 2 Time (s)

23 OUT-OF-PLANE DISP. OF ASSEMBLY Relative Out-of-plane displacements by FEM Middle of edge Corner Middle of Edge (µm) Corner (µm) t 1, t 2 (sec) 60, 1060 (hold time = 1000 sec) , 1700 (hold time = 1000 sec) , 2400 (hold time = 1000 sec)

24 OUT-OF-PLANE DISP. OF ASSEMBLY HASMAP Measurements at RSC Middle of edge Left Corner Right Corner Corner (µm) Experiment (a) HASMAP Measurement 1 HASMAP Measurement 2 Middle of Edge (µm) Left Corner (µm) Right Corner (µm) Avg. (µm) (a) Average of two sets of readings (01/02 04/02)

25 OUT-OF-PLANE DISP. OF ASSEMBLY Comparison with HASMAP Results Corner Middle of edge Relative Out-of-plane (z) disp., µm 9 6 min: µm max: 6.72 µm Corner 7.15 (Test) 5.6 (Test) Middle of Edge t 1 = 60 s t 2 = 1060 s 5 4 x, mm Center y, mm 0

26 OUT-OF-PLANE DISP. OF ASSEMBLY Recent (8/02) Shadow Moiré Testing at RSC 21 C (1.5 Fringes) 79 C (1.75 Fringes) 125 C (2 Fringes)

27 OUT-OF-PLANE DISP. OF ASSEMBLY New (8/02) HASMAP Results at RSC Corner (µm) Experiment (a) HASMAP Measurement 1 HASMAP Measurement 2 HASMAP Measurement 3 Middle of Edge (µm) Left Corner (µm) Right Corner (µm) Avg. (µm) Significant variability in the data - need to perform fatigue life sensitivity analysis

28 ACCOMPLISHMENTS IN 10/01-9/02 Experimental Validation In-plane displacements in package Out-of-plane displacements in CSP Assembly Technical Report In progress Benchmark of ABAQUS Creep Law (discussed on January 8 meeting) Informal meetings at UI/RSC January 8, 2002 (RC) April 16, 2002 (UI) August 27, 2002 (UI)

29 FUTURE EFFORTS Improved correlation process for validating outof-plane displacement Bring the part/board assembly up to 125 C for 2 hours. Take the first set of measurements Ramp down to 75 C. Take a second set of measurements Ramp down to room temperature. Take a third set of measurements Hold the part at room temperature for 2 hours. Take a fourth set of measurements The RC/RSC/UI teams will further discuss this new measurement process during working meeting today

30 FUTURE EFFORTS Sensitivity analysis of fatigue life with respect to solder ball displacement January 2003 is the target date for completing sensitivity analysis, remaining correlation on ASAT 144, and internal technical report Crack initiation vs. propagation lives Assess feasibility of both the model and the experimental measurement techniques Consider evaluating 2-3 different package types SuperBGA from Amkor/Anam EasyBGA from Intel