1. 1. 1 Design, Analyses and Reliability in Electronic Packaging Prof. K. Padmanabhan School of Mechanical and Building Sciences
2. 2. 2 Contents Abstract Introduction Background of analysis Modelling Analysis Electric Thermal analysis Thermal Structural analysis Hygrothermal Effects Validation Conclusions
3. 3. 3 Abstract Create 2D and 3D models of dual and quad non- hermetic packages Evaluate the effect of Joule heating Evaluate effect of various stresses and failure criteria on its performance using an FEM software
4. 4. 4 Introduction Microsystem : - Building blocks of information technology - System packaged Packaging : - Bridge that interconnects the ICs and other components - Overlap of ICs and packaging.Types of IC package Through-hole package Surface mount package
5. 5. 5 Microsystems Packaging Roadmap
6. 6. 6 TYPES OF PACKAGES ICIC packagepackage materialsmaterials PlasticPlastic Thin film (Tape carrier)Thin film (Tape carrier) CeramicCeramic ICIC assemblyassembly SMT (Surface mountSMT (Surface mount technology)technology) PTH (Pin through hole)PTH (Pin through hole) DCA (Direct chip attach)DCA (Direct chip attach) ICIC interconnecinterconnec Peripheral (Quad flatPeripheral (Quad flat package)package)
7. 7. 7 FUNCTIONS OF PACKAGES 1. Shut out environmental influences 2. Enable electrical connectivity 3. Dissipate heat 4. Improve handling & assembly
8. 8. 8 Applications of IC Packages Mobile Phones PDA s Automotive Electronics Digital Cameras and Camcorders TVs and Monitors Signal Transmission and
9. 9. 9 Background of Analysis SPEL Semiconductor Ltd ICs manufacturing, assembly and testing company. Types of materials in Packages Metal package Ceramic package (Hermetic) Thin-film Multilayer Package Plastic Package ( Non-Hermetic) Functions of packages Mechanical Support Protection from environment Electrical connection to other system components Thermal considerations
10. 10. 10 PRINCIPLE : Electrical input is converted to heat by joules heating (I2 R loss) which then causes thermal strain, these thermal strains in turn cause structural deformation. COUPLED- FIELD ANALYSIS Combination of analyses from different engineering disciplines that interact to solve a global engineering problem. TYPES OF COUPLED-FIELD ANALYSIS Sequentially coupled physics analysis Direct coupled-field analysis. FAILURE THEORY Background of Analysis Contd
11. 11. 11 Modelling 1.35 X 1.7 mm 8L UDLMP 1.35 X 2.5 mm 12L UDLMP 4x4 mm 24LTQLMP 5x6 mm 36L TQLMP 7X7 mm 48L TQLMP 5X11 mm 56L TQLMP 9x9 mm 64L TQLMP
12. 12. 12 Analysis Electric-Thermal Analysis Thermal Structural Analysis Materials used Lead Frame and Leads - Copper Wire bonding - Gold Die - Silicon Adhesive for lead frame and die - Silver Epoxy
13. 13. 13 24L TQLMP Asymmetric Design
14. 14. 14 4x4 mm 24L TQLMP Top view of Lead Frame Top view of Wire bonding diagram
15. 15. 15 3D Model -24L With encapsulation Without encapsulation
16. 16. 16 5x6 mm 36L TQLMP Top view of lead Frame Top view of Wire bonding diagram
17. 17. 17 3D Model 36 L With encapsulation Without encapsulation
18. 18. 18 7 x 7mm 48L TQLMP Pin Configuration Top view of Wire bonding diagram Modelling
19. 19. 19 3D Model 48L TQLMP Without EncapsulationWith Encapsulation
20. 20. 20 5 x 11 mm TQLMP Pin Configuration Top view of Wire bonding diagram Modelling
21. 21. 21 3D Model 56L TQLMP
22. 22. 22 9x9 mm 64L TQLMP Top view of lead Frame Top view of Wire bonding diagram
23. 23. 23 3D Model 64L With encapsulation Without encapsulation
24. 24. 24 Material Properties MATERIA LS YOUNGS MODULUS (N/mm2 ) CTE (1/C) ELECTRICAL RESISTIVITY ( - mm) THERMAL CONDUCTI VITY (W/mm- C) POISSONS RATIO Copper 110.31e3 16.50e- 6 1.673e-5 401e-3 0.22 Silver epoxy 11.5e3 30e-6 8e-4 546e-3 0.35 Silicon 200e3 2.60e-6 1 130e-3 0.25 Gold 82.737e3 14.20e- 6 2.350e-5 317e-3 0.44 Filled epoxy 26e3 7e-6 - 0.0012e-3 0.25 Material Property for 4x4 mm 24L and 5x6 mm 36 L TQLMP
25. 25. 25 MATERIAL S YOUNGS MODULU S (N/mm2 ) CTE (1/C) ELECTRICA L RESISTI VITY ( - mm) THERMAL CONDUCTIVIT Y (W/mm- C) POISSON S RATIO Copper 110.31e3 16.50e -6 1.673e-5 401e-3 0.22 Silver epoxy 11.5e3 30e-6 8e-4 546e-3 0.35 Silicon 200e3 2.60e-6 1 130e-3 0.25 Gold 82.737e3 14.20e -6 2.350e-5 317e-3 0.44 Filled epoxy 33e3 1.5e-5 - 0.0012e-3 0.25 Material Property for 9x9 mm 64 L TQLMP Material Properties Contd
26. 26. 26 Elements Used Plane 55 Solid 70 Used for 2D electrical- thermal analysis Used for 3D thermal analysis(125C)
27. 27. 27 Solid 45 Solid 69 Elements Used Contd Used for 3D thermal- structural analysis Used for 3D Electrical thermal analysis
28. 28. 28 Plane 67 Elements Used Contd Used for 2D Thermal analysis
29. 29. 29 2D Temperature Distribution of 4x4 mm 24L TQLMP 2D Mesh View Temperature plot (Joule heating)
30. 30. 30 2D Temperature Distribution of 5x6 mm 36L TQLMP 2D Mesh View Temperature plot (Joule heating)
31. 31. 31 2D Temperature Distribution of 9x9 mm 64L TQLMP 2D Mesh View Temperature plot (Joule heating)
32. 32. 32 Co-efficient of thermalCo-efficient of thermal expansion (CTE)expansion (CTE) Methods to reduce CTE mismatchMethods to reduce CTE mismatch Substrate materials that have a CTE closer to the effectiveSubstrate materials that have a CTE closer to the effective CTE of the chip carrier or chipCTE of the chip carrier or chip Distance from the neutral points is as small as possibleDistance from the neutral points is as small as possible Thermal paths should be created such that heat is easilyThermal paths should be created such that heat is easily dissipateddissipated Introducing polymer under fill material between the chip &Introducing polymer under fill material between the chip & the substrate.the substrate. UNDER FILL
33. 33. 33
34. 34. 34 Meshed view and Boundary conditions for 4x4 mm 24L TQLMP With encapsulation Without encapsulation Boundary conditions
35. 35. 35 Temperature Distribution in 8L UDLMP
36. 36. 36 Temperature Distribution in 12L UDLMP
37. 37. 37 Electric and Thermal Results Electric plot Temperature distribution
38. 38. 38
39. 39. 39 Temperature Distribution
40. 40. 40 Deformation Due to Joule Heating
41. 41. 41 Thermal Structural Results Displacement Vector sum Von mises stress Stress intensity XY Shear stress
42. 42. 42 X component stress Y component stress Thermal Structural Results Contd
43. 43. 43 Analysis of 4x4 mm 24L TQLMP at 125C/24 hrs. Displacement Vector sum Von mises stress Stress intensity XY Shear stress
44. 44. 44 Analysis of 4x4 mm 24L TQLMP at 125C/24hrs Contd X component stress Y component stress
45. 45. 45 Thermal Shock Test (JESD22 A106B) Purpose of this test is to determine the resistance of the part to sudden exposures of extreme changes in temperature and alternate exposures to these extremes as well as its ability to withstand cyclical stresses Here the IC packages are baked in an oven for 125C/24 Hrs and the temperature is spiked to 260C for lead free product and 240C for leaded product for 5 to 10 minutes. If the baking temperature is higher than the glass transition temperature at this extreme heat the
46. 46. 46 Hygrothermal Behaviour Plastic packages are known for environmental attacks that reduce their function. Mechanical properties degrade over time ! Moisture plays havoc at elevated temperatures, in the presence of voids, defects and in low Tg plastics . Diffusion and osmotic pressure are the driving mechanisms for hygrothermal attack Evaluation methods and surface
47. 47. 47 HYGROTHERMAL ANALYSIS Tgw = (0.005Mr 2 -0.1Mr+1.0)Tgo Where, Fm = Mechanical property retention ratio, P = Strength or stiffness after hygrothermal degradation, Po = Reference strength or stiffness before degradation, T = Temperature at which P is to be predicted (0 C), Tgo= Glass transition temperature for reference dry condition Tgw=Glass transition temperature for reference wet condition at moisture content corresponding to property P, To = Test temperature at which Po was measured (250 C),
48. 48. 48Variation of strength with temperature Glass Transition Temperature
49. 49. 49 Temperature Vs Property Retention Ratio Plot
50. 50. 50 Temperature Vs Strength Plot of 9220ZHF 10L
51. 51. 51 Temperature Vs Strength Plot of EME G770HCD
52. 52. 52 DIE SHEAR TEST
53. 53. 53 Die shear test for 4x4mm 24L TQLMP Maximum permissible shear stress ( shear strength) [xy]max = shear force shear area Shear force : 10 kgf (actual measured value) Shear area : 4.5732mm2 Maximum permissible shear stress ( shear strength) [xy]max = 10* 9.81 4.5732 = 21.875N/mm2 Actual shear stress< Shear Strength (3.25 < 21.875)N/mm2 with encapsulation (1.301 < 21.875)N/mm2 for without encapsulation So our design is safe.
54. 54. 54 Azzi-Tsai-Hill Theory Where, 11 = X ( tensile / compressive) stress in MPa 22 = Y ( tensile / compressive) stress in MPa 12 = Shear stress in MPa SLt = Longitudinal tensile strength in MPa STt = Transverse tensile strength in MPa SLts = in-plane shear strength in MPa
55. 55. 55 Tsai Wu Failure Theory F1 11 + F2 22 + F6 12+ F11 11 2 + F22 22 2 + F66 12 2 +2 F12 1122 = 1 Where, Other parameters / symbols appear on the previous slide, SLc = Longitudinal compressive strength in MPa STc = Transverse compressive strength in MPa.
56. 56. 56 Failure theory for 4x4mm 24L TQLMP Normal conditioning i.e at 25C ambience X stress in MPa = 39.695 Y stress in MPa = 63.794 XY shear stress in MPa = 27.078 Tensile strength in MPa =185 Compressive strength in MPa = 195 Shear strength in MPa = 92.5 Tsai Wu Failure theory: 0.203 < 1 Azzi-Tsai-Hill theory: 0.1757(Tensile) / 0.1675(compressive) < 1 Design is safe.
57. 57. 57 Failure theory for 4x4mm 24L TQLMP Maximum operating temperature i.e at 61.1C X stress in MPa = 39.695 Y stress in MPa = 63.794 XY shear stress in MPa = 27.078 Tensile strength in MPa =145.78 Compressive strength in MPa = 153.66 Shear strength in MPa = 72.86 Tsai Wu Failure theory: 0.318 < 1 Azzi-Tsai-Hill theory: 0.2841(Tensile) / 0.0.27 (compressive) < 1 Design is safe.
58. 58. 58 Failure theory for 4x4mm 24L TQLMP Peak conditioning i.e 125C for 24 hrs X stress in MPa = 70.509 Y stress in MPa = 98.811 XY shear stress in MPa = 45.793 Tensile strength in MPa =27.01 Compressive strength in MPa = 28.47 Shear strength in MPa = 13.5 Tsai Wu Failure theory: 22.29> 1 Azzi-Tsai-Hill theory: 22.047(Tensile) / 21.083(compressive) > 1 Design is unsafe.
59. 59. 59 SAM (Scanning Acoustic Microscopy) Photographs SAM picture for 24L TQLMP before preconditioning, No Plasma* cleaning
60. 60. 60 SAM Picture for 24L TQLMP after preconditioning, No Plasma* Cleaning Red areas show delaminations in IC Packages
61. 61. 61 SAM Picture for 24L TQLMP before Preconditioning, with Plasma* cleaning
62. 62. 62 SAM Picture of 24L TQLMP after preconditioning, with Plasma* cleaning
63. 63. 63 SAM picture of 64L TQLMP Baked at 150C for 24hrs.
64. 64. 64 ASTM STP D 5229 M Rule The MOT ( Maximum Operating Temperature) of the material, device/component should be at least 25 Celsius lower than the lowest Tg ( normally wet) of the material. In this case the mould compound qualify this clause as the maximum temperature developed due to joule heating is 83.3 Celsius in the
65. 65. 65 Coffin-Manson's EquationCoffin-Manson's Equation Fatigue is the most common failure mode in ICFatigue is the most common failure mode in IC packaging,packaging, IC device dissipate heat to its surroundingsIC device dissipate heat to its surroundings during operation, differential thermalduring operation, differential thermal expansion generates stresses in theexpansion generates stresses in the interconnecting structure.interconnecting structure. These stresses produce instantaneous elasticThese stresses produce instantaneous elastic and plastic strain in the material joint.and plastic strain in the material joint. The mechanical properties of material changeThe mechanical properties of material change strongly over the normal temperature range ofstrongly over the normal temperature range of
66. 66. 66 Coffin-Manson Equations Cyclical plastic deformations change theCyclical plastic deformations change the grain structure, weaken the joints and cangrain structure, weaken the joints and can lead to fatigue.lead to fatigue. The time of the joint fracture depends onThe time of the joint fracture depends on relative deformation (strain), temperature andrelative deformation (strain), temperature and frequency of deformation.frequency of deformation. A simplified relationship is given by theA simplified relationship is given by the Coffin-Manson's formula;Coffin-Manson's formula; NN0.50.5 pp = constant= constant WhereWhere
67. 67. 67 Coffin-Manson Fatigue vs CTE MULLITE+SILICA+ALUMINA GLASS-CRAMIC ALUMINUM NITRIDE ALUMINA+BOROSILICATE LOW TCE POLYIMIDE ALUMINA EPOXY-KEVLAR POLYIMIDE-GLASS MALEIMIDE-STYRIL EPOXY-GLASS COEFFICIENT OF THERMAL EXPANSION (E-7/C) FATIGUELIFECYCLESN50 SILICON 40 80 120 160 200 100 1000 10,000 (1 7)**2 COFFIN-MANSON EQUATION INORGANIC MATERIAL ORGANIC MATERIAL
68. 68. 68 Philosophy Pyramidal Substantiation The product ,we hope, is reliable The sub-assemblies and the assemblies are tested the least The subcomponents and components are tested less often The test specimens are tested more often
69. 69. 69 Conclusions Modelling of some Dual and TQLMP IC packages was accomplished. Reliability analysis of IC packages using FEM software was carried out. Die shear tests, Scanning Acoustic Microscopy, Hygrothermal behaviour analysis and Validation through Failure
70. 70. 70 Thank You That one coming being, Was covered with void, That arose through the power of heat -The Rig Veda ( The Existence- 10.129.03)