Stephen M. Heinrich
Dept. of Civil Engineering
Marquette University
Milwaukee, WI
Updated Literature Summary
November 28, 1995
On the following pages is a summary of several papers that have been published in the area of solder joint geometry modeling. This material represents an updated version of the tables and bibliography that appear in the following reference:
Heinrich, S.M., "Prediction of Solder Joint Geometry," Chapter 5 of Mechanics of Solder Alloy Interconnects, Frear et al. (eds.), Van Nostrand Reinhold, 1994, pp. 158-198.
If you are aware of any relevant publications that are not included in this summary, please send copies to the address below:
Stephen M. Heinrich
Dept. of Civil Engineering
Marquette University
P.O. Box 1881
Milwaukee, WI 53201-1881
Ph.: (414) 288-5466
FAX: (414) 288-7082
E-Mail: [email protected]
Thank you.
Table 1. Literature Involving Models for Predicting 2-D Joint Geometries
Ref. | Applications | Solution Type | Main Results | Restrictions on Results |
Klein Wassink & Verguld 1986 | Reflow of Leadless Chips: Tombstone Prevention | Straight-Line Fillets | Gen'l Guidelines for Preventing Tombstoning | Straight-Line Fillet Assumption is Approximate |
Alexander & Bello 1987 | Reflow of Leadless Chips | Elastica Solution | General Recommendations to Increase Joint Compliance by Controlling Solder Volume | Elastica Solution is Approximate |
Klein Wassink 1989 | Reflow & Wave Soldering of Leadless Chips | Numerical Solution of BVP; Elastica Solution | Samples of Upright & Inverted Fillet Profiles | Numerical Results are Problem- Specific; Perfect Wettability; Infinite Tinning |
Jopek 1989 | Reflow of Leaded Fine-Pitch Components | "Piecemeal" Elastica | General Guidelines for "Optimal" Volume | Elastica is Approximate; Theory Underestimates "Optimal" Volume |
Ellis & Masada 1990 | Reflow of Leadless Chips: Tombstone Prevention & Self- Alignment Enhancement | Numerical Solution of BVP for Fillet Profile; Numerical Solution of Equations of Motion for Chip Dynamics | General Guidelines for Preventing Tombstoning and Promoting Self-Alignment | Specific Contact Angle (12 deg) Assumed at Chip Metallization |
Heinrich et al. 1990a,b | Reflow of Leadless Chips | Explicit Integral Solution of BVP; Circular Arc Approximation (Zero- Gravity Solution) | Fillet Height & Length vs. Solder Area (Volume); Closed-Form Expressions for Small & Large Joint Profiles and for Maximum Fillet Height | Infinite Tinning Assumption; Acute Contact Angles |
Rooks et al. 1991 | Reflow of Leadless Chips | Numerical Solution of BVP; Circular Arc Approximation (Zero-Gravity Solution) | Samples of Fillet Profiles; Comparison of Exact and Zero-Gravity Solutions | Numerical Results are Problem- Specific; Infinite Tinning |
Liedtke et al. 1991; | Wave-Soldering of Leadless Chips | Explicit Integral Solution of BVP | Fillet Size & Shape vs. Pad & Component Sizes (Dimensionless) | Perfect Wettability; Horizontal Conveyor Angle; Joint Size Estimated by "Equivalent Dipping Model" |
Nambisan et al. 1995 | Wave-Soldering of Leadless Chips | Circular-Arc Approximation (Zero-Gravity Solution) | Fillet Size, Shape, Contact Angles as Functions of Metallization Dimensions; Effect of Conveyor Angle Included | Perfect Wettability; Joint Size Estimated by "Equivalent Dipping Model" |
Heinrich et al. 1993 | Reflow of Leadless Chips | Explicit Integral Solution of BVP; Circular Arc Approximation (Zero- Gravity Solution) | Fillet Profiles as Function of Chip & Pad Geometry (Dimensionless Results); Closed-Form Expressions for Small Joints | Perfect Wettability; (Finite Tinning) |
Nigro et al. 1993 | Reflow of Leadless Chips | Energy Minimization by Finite Element Method | Samples of Fillet Profiles for Finite & Infinite Tinning | Numerical Results are Problem-Specific |
Jahsman 1992 | Reflow of Long (Channel-Type) Solder Bumps | Circular Arc Approximation (Zero-Gravity Solution) | Bump Volume and Bump Force vs. Contact Angle and Bump Height (Dim'less Results); Effect of "Count Ratio" of Two Bump Sizes on Dim'less Bump Height | Equal Pad Radii; Count Ratio Results are Problem-Specific |
Table 2. Literature Involving Models for Predicting Axisymmetric Joint Geometries
Table 3. Literature Involving Models for Predicting General 3-D Joint Geometries
REFERENCES
Alexander, P.T., and Bello, D.C., "The Single Key Process Variable in SMT Solder Joint Reliability," Expo SMT '87, Technical Proceedings, Las Vegas, 1987, pp. 85-89.
Chu, T.Y., "A Hydrostatic Model of Solder Fillets," Western Electric Engineer, Vol. 19, No. 2, 1975, pp. 31-42.
Ellis, J.R., and Masada, G.Y., "Dynamic Behavior of SMT Chip Capacitors Durind Solder Reflow," IEEE Trans. on Components, Hybrids, and Mfg. Technology, Vol. 13, No. 3, Sept. 1990, pp. 545-552.
Golachev, S.M., Kudryavtsev, V.S., and Ovseevich, V.L., "The Hydrostatic Model of the Redistribution of the Tin-Lead Alloy in the Melting of the Coating of Printed Circuit Boards," Welding Prod. (Svar. Proiz.), Vol. 27, No. 2, 1980, pp. 19-21.
Goldmann, L.S., "Geometric Optimization of Controlled Collapse Interconnections," IBM J. Res. Develop., Vol. 13, May 1969, pp. 251-265.
Heinrich, S.M., Elkouh, A.F., Nigro, N.J., and Lee, P.S., "Solder Joint Formation in Surface Mount Technology -- Part I: Analysis," Journal of Electronic Packaging, ASME, Vol. 112, No. 3, 1990a, pp. 210-218.
Heinrich, S.M., Nigro, N.J., Elkouh, A.F., and Lee, P.S., "Solder Joint Formation in Surface Mount Technology -- Part II: Design," Journal of Electronic Packaging, ASME, Vol. 112, No. 3, 1990b, pp. 219-222.
Heinrich, S.M., Liedtke, P.E., Nigro, N.J., Elkouh, A.F., and Lee, P.S., "Effect of Chip and Pad Geometry on Solder Joint Formation in SMT," ASME Journal of Electronic Packaging, Vol. 115, No. 4, 1993, pp. 433-439.
Heinrich, S.M., Schroeder, S.A., and Lee, P.S., "Prediction of Solder Joint Geometries in Multiple Bump Arrays," Mechanics and Materials for Electronic Packaging: Volume 1, Design and Process Issues in Electronic Packaging, Chen, Nguyen, and Winterbottom (eds.), ASME AMD- Vol. 195, 1994, pp. 11-22; presented at the 1994 International Mechanical Engineering Congress and Exposition, Chicago, IL, November 6-11, 1994.
Heinrich, S.M., Wang, Y., Shakya, S., Schroeder, S.A., and Lee, P.S., "Selection of Design and Process Parameters for Non-Uniform Ball-Grid Arrays," Advances in Electronic Packaging 1995, Vol. 1, ASME EEP-Vol. 10-1, pp. 273-288; presented at InterPack '95, Lahaina, HI, 1995.
Heinrich, S.M., Shakya, S., Wang, Y., Lee, P.S., and Schroeder, S.A., "Improved Yield and Performance of Ball-Grid Array Packages: Design and Processing Guidelines for Uniform and Non- Uniform Arrays," to appear in Trans., Components, Packaging & Manufacturing Technology Society, Series B, IEEE, February 1996. (Also appearing in Proc., 45th Electronic Components and Technology Conference, Las Vegas, NV, May 1995, pp.793-803.)
Jahsman, W.E., "Channel Solder Bump Shape Analysis," Internal Correspondence, Intel Corporation, 1992.
Jopek, S., "Solder Volume Determination for Fine Pitch Packages," Printed Circuit Assembly, Vol. 3, 1989, pp. 15-20.
Ju, T.-H., Lin, W., Lee, Y.C., and Liu, J.J., "Effects of Ceramic Ball-Grid-Array Package's Manufacturing Variations on Solder Joint Reliability," ASME Journal of Electronic Packaging, Vol. 116, No. 4, December 1994, pp. 242-248.
Katyl, R.H., and Pimbley, W.T., "Shape and Force Relationships for Molten Axisymmetric Solder Connections," Mfg. Processes and Materials Challenges in Microelectronic Packaging, ASME AMD-Vol. 131/EEP-Vol. 1, 1991, pp. 57-63.
Katyl, R.H., "Calculation of Molten Solder Profiles for Rectangular Pad Geometries," Advances in Electronic Packaging 1993, Vol. 2, ASME EEP-Vol. 4-2, 1993, pp. 1095-1101.
Klein Wassink, R.J., "Notes on the Shape of Fused Solder Coatings of Metallised Holes in Printed Boards," Brazing and Soldering, No. 8, Spring 1985, pp. 5-7.
Klein Wassink, R.J., and Verguld, M.M.F., "Drawbridging of Leadless Components," Hybrid Circuits, No. 9, Jan. 1986, pp. 18-24.
Klein Wassink, R.J., Soldering in Electronics, 2nd ed., Electrochemical Publications Limited, 1989.
Kudryavtsev, V.S., Nikiforov, G.D., Dolgov, Yu. S., Golachev, S.M., and Oparin, M.I., "Effect of Design and Technological Factors on the Reduction in Diameter of Metallised Openings in Printed Circuits in Melting the Tin-Lead Coating," Welding Prod. (Svar. Proiz.), Vol. 29, No. 11, 1982, pp. 13-14.
Landry, M., Patra, S.K., and Lee, Y.C., "Experiment and Modeling of the Self-Alignment Mechanism in Flip-Chip Soldering," Manufacturing Processes and Materials Challenges in Microelectronic Packaging, ASME AMD-Vol. 131/EEP-Vol. 1, 1991, pp. 49-56.
Lee, T.S., Choi, T.P., and Yoo, C.D., "Finite Element Modeling of 3-Dimensional Solder Joint Geometry in SMT," Advances in Electronic Packaging 1995, Vol. 2, ASME EEP-Vol. 10-2, pp. 1031-1041; presented at InterPack '95, Lahaina, HI, 1995.
Liedtke, P.E., Heinrich, S.M., Elkouh, A.F., Nigro, N.J., and Lee, P.S., "Prediction of Wave-Soldered Fillet Geometry in SMT Applications," Manufacturing Processes and Materials Challenges in Microelectronic Packaging, ASME Applied Mechanics Division, Vol. 131; Electrical and Electronic Packaging Division, Vol. 1; pp. 65-72; presented at the ASME Winter Annual Meeting, Atlanta, GA, December 1991.
Nambisan, B.U., Heinrich, S.M., Fournelle, R.A., Elkouh, A.F., Nigro, N.J., and Lee, P.S., "An Approximate Model for Predicting the Size and Shape of Wave-Soldered Surface-Mount Joints," Journal of Electronics Manufacturing, Vol. 5, No. 3, September 1995, pp. 217-233. (Also appearing in Advances in Electronic Packaging 1993, Vol. 2, ASME EEP-Vol. 4-2, 1993, pp. 1079-1093.)
Nigro, N.J., Heinrich, S.M., Elkouh, A.F., Zou, X., Fournelle, R.A., and Lee, P.S., "Finite Element Method for Predicting Equilibrium Shapes of Solder Joints," ASME Journal of Electronic Packaging, Vol. 115, No. 2, 1993, pp. 141-146.
Oshima, M., Kenmotsu, A., and Ishi, I., "Optimization of Micro-Solder Reflow Bonding for the LSI Flip Chip," Proc., 2nd Annual Intl. Electronics Packaging Soc. Conf., 1982, pp. 481-488.
Oshima, M., Satoh, R., Hirota, K., and Ishi, I., "New Micro-Soldering Technology and its Application to VLSI," Proc., 1st IEEE CHMT Symposium: CHMT Tokyo '84, published in Aug. 1985, pp. 165- 170.
Patra, S.K., and Lee, Y.C., "Quasi-Static Modeling of Self-Alignment Mechanism in Flip-Chip Soldering. Part I: Single Solder Joint," ASME Journal of Electronic Packaging, Vol. 113, No. 4, Dec. 1991, pp. 337-342.
Patra, S.K., Sritharan, S.S., and Lee, Y.C., "Minimum-Energy Surface Profile of Solder Joints for Non-Circular Pads," Proc., ASME Winter Annual Meeting, Anaheim, CA, 1992.
Patra, S.K., Ma, J., and Lee, S.H., "Alignment Issue Relating to Flip-Chip Bonding Requirement for Holographic Optical Interconnects," Advances in Electronic Packaging 1993, Vol. 2, ASME EEP- Vol. 4-2, 1993, pp. 1191-1196.
Racz, L.M., Szekely, J., and Brakke, K.A., "A General Statement of the Problem and Description of a Proposed Method of Calculation for Some Meniscus Problems in Materials Processing," Trans., Iron and Steel Institute of Japan International, Vol. 33, No. 2, 1993.
Racz, L.M., and Szekely, J., "Determination of Equilibrium Shapes and Optimal Volume of Solder Droplets in the Assembly of Surface Mounted Integrated Circuits," Trans., Iron and Steel Institute of Japan International, Vol. 33, No. 2, 1993a.
Racz, L.M., and Szekely, J., "An Analysis of the Applicability of Wetting Balance Measurements of Components with Dissimilar Surfaces," Advances in Electronic Packaging 1993, Vol. 2, ASME EEP-Vol. 4-2, 1993b, pp. 1103-1111.
Rooks, S., Racz, L.M., Szekely, J., Benhabib, B., and Neumann, A.W., "Evaluation of Two- Dimensional and Three-Dimensional Axisymmetric Fluid Interface Shapes with Boundary Conditions," Langmuir, Vol. 7, 1991, pp. 3222-3228.
Satoh, R., Oshima, M., Komura, H., Ishi, I., and Serizawa, K., "Development of a New Micro-Solder Bonding Method for VLSIs," Proc., 3rd Annual Intl. Electronics Packaging Soc. Conf., 1983, pp. 455-461.
Satoh, R., Oshima, M., Hirota, K., and Ishi, I., "Optimum Bonding Shape Control of Micro-Solder Joint of IC and LSI," J. Japan Inst. Metals, Vol. 51, No. 6, 1987, pp. 553-560.
Singler, T.J., and Zhang, X., "Computer Simulation of Solder Bridging Phenomena," Advances in Electronic Packaging 1995, Vol. 2, ASME EEP-Vol. 10-2, pp. 1117-1127; presented at InterPack '95, Lahaina, HI, 1995.
Singler, T.J., Pitarresi, J.M., Holub, I.R., and Yin, H., "Towards an Optimization Algorithm for Solder Joint Reliability," Advances in Electronic Packaging 1995, Vol. 2, ASME EEP-Vol. 10-2, pp. 1155- 1166; presented at InterPack '95, Lahaina, HI, 1995.
Subbarayan, G., Li, Y., and Mahajan, R.L., "Reliability Simulations for Solder Joints Using Stochastic Finite Element and Artificial Neural Network Models," Advances in Electronic Packaging 1995, Vol. 1, ASME EEP-Vol. 10-1, pp. 459-471; presented at InterPack '95, Lahaina, HI, 1995.
Whalley, D.C., Conway, P.P., Sarvar, F., and Kalantary, M., "The Globule Block Wetting Balance Test," Advances in Electronic Packaging 1995, Vol. 1, ASME EEP-Vol. 10-1, pp. 89-94; presented at InterPack '95, Lahaina, HI, 1995.
Yost, B., McGroarty, J., Borgesen, P. and Li, C.-Y., "Shape of a Nonaxisymmetric Liquid Solder Drop Constrained by Parallel Plates," IEEE Trans. on Components, Hybrids, and Manufacturing Technology, Vol. 16, No. 5, August 1993, pp. 523-526.
Yost, F.G., and Holm, E.A., "Capillary Flow on Narrow Strips and in V-Shaped Grooves," Advances in Electronic Packaging 1995, Vol. 2, ASME EEP-Vol. 10-2, pp. 1265-1271; presented at InterPack '95, Lahaina, HI, 1995.
Ref. Applications Solution Type Main Results Restrictions on Results
Goldmann
1969C4 Joints in Flip-Chip
ApplicationsTruncated Sphere Approximate Analytical Expression
Relating Pad Radii, Bump Height,
and Solder Volume; Optimization of
Joint GeometryTruncated Sphere Assumption
is ApproximateChu 1975 Plated-Through-Hole Fillets
Using Solder PreformsNumerical Solution of BVP Coupled with
Approximate Energy MinimizationSamples of Top & Bottom Fillet
Profiles; Ideal Solder Volume vs.
Board Thickness; Fillet Heights
vs. Solder VolumeNumerical Results are for Specific Pin and Hole
Diameters and Pad Radii;
"Operationally Ideal" Solution
is Arbitrarily Taken to be
Within 0.5% of True Minimum- Energy StateGolachev
et al.
1980Melting of Tin-Lead Coatings
in Plated-Through-Hole
AperturesCircular Arc Approximation for
MeridianChange in Hole Diameter vs. Volume
of Plated Solder Alloy;
Recommended Solder Layer Thickness
vs. Pad and Hole DiametersCircular Arc Approximation is Invalid for Larger Pad
Diameters; Results are Problem-
SpecificKudryavtsev
et al.
1982Melting of Tin-Lead Coatings
in Plated-Through-Hole
AperturesCircular Arc Approximation for
Meridian
Change in Hole Diameter vs. Board &
Plating Thicknesses and Pad & Hole
DiametersCircular Arc Approximation is Invalid for Larger Pad
Diameters; Results are Problem-
SpecificOshima et
al. 1982C4 Joints in Flip-Chip
ApplicationsNumerical Solution of BVP; Truncated Sphere; Circular Arc Meridian Exact Results for Bump Height vs.
Solder Volume; Optimization of
Joint Geometry Using Approximate SolutionsExact Numerical Results Limited
to Equal Pad DiametersSatoh et
al. 1983,
1987;
Oshima et al. 1985C4 Joints in Flip-Chip
Applications Using Self-
Stretching Technique (SST),
i.e., Height-Control Solder
BumpsCircular Arc Meridian Bump Height vs. Volumes of Joint Solder and Control Solder;
Optimization of Joint GeometryResults are Problem-Specific
Klein
Wassink
1985, 1989Melting of Solder Coatings in
Plated-Through-Hole
ApplicationsNumerical Solution of BVP with and without Gravity; Circular Arc Meridian Sample Profiles of Fused Solder
Coatings; Comparisons of Exact and
Approximate ProfilesResults are Problem-Specific
Klein
Wassink
1989Plated-Through-Hole Fillets Numerical Solution of BVP Samples of Top & Bottom Fillet
ProfilesResults are Problem-Specific;
Perfect WettabilityRooks et
al. 1991Top Fillet in Plated-Through-
Hole ApplicationsNumerical Solution of BVP; Elliptic
Integral Solution for Zero GravitySamples of Top Fillet Profiles; Fillet Volume vs. Height (Dimensionless) Results are Problem-Specific;
Contact Angle at Pin is 15 degKatyl &
Pimbley
1991C4 Joints in Flip-Chip
ApplicationsNumerical Solution of BVP; Energy Minimization by Ritz Method; Elliptic
Integral and Approximate Polynomial
Solutions for Zero GravitySample Profiles of Sessile and Pendant
Drops on Finite Pad; Sample Profiles of C4 JointsResults are Problem-Specific
Nigro et
al. 1993C4 Joints in Flip-Chip Applications Energy Minimization by Finite Element Method Sample Profile for C4 Joint;
Bump Force vs. Bump Height Results are Problem-Specific
Ju et al. 1994 C4 Joints in Flip-Chip Applications Approximate Numerical Solution of BVP
Neglecting Solder Self-WeightNo Specific Geometry Results; Geometry Model was Integrated with Reliability Model to Predict Effect of Process Variability on Joint Fatigue Life Numerical Results are Problem- Specific
Heinrich et al. 1994 BGA Joints Circular-Arc Meridian General Results for Joint Height and Mid- Height Width in Terms of Joint Volume, Array Size, Component Weight, Pad Size, and Solder Surface Tension: Upright or Inverted Reflow Equal Pad Sizes; Identical Joint Shapes Throughout Array
Heinrich et al. 1995, 1996 Joints in Non-Uniform BGAs (Joint Shapes Vary Throughout Array) Circular-Arc Meridian Results for Joint Height and Mid-Height Widths in Terms of Joint Volumes and Count Ratio: Upright or Inverted Reflow "Bi-Uniform Array"
with 0.6-mm PadsSubbarayan et al. 1995 BGA Joints Energy Minimization by Finite Element Method No Specific Geometry Results; Geometry Model was Integrated with Stochastic FEM and Neural Network Models to Predict Optimal Joint Shape 72 I/O OMPAC BGA with Stand- Off Spacers
Singler et al. 1995 Bump/Ball-Type Joints Energy Minimization by Finite Element Program (Surface Evolver) Illustrations of Joint Shapes for Different Heights and Volumes; Geometry Model was Integrated with FEM and Fatigue Models to relate Geometry to Reliability Joint Height and Volume Specified Independently; Results are Problem-Specific
Ref. Applications Solution Type Main Results Restrictions on Results
Landry et al. 1991 Realignment of C4 Joints in
Flip-Chip ApplicationsApproximate Numerical Solution of BVP
Neglecting Solder Self-Weight,
Coupled with Curve-Fit of Oscillatory
Realignment MotionSample Profiles of C4 Joints Before
and After Realignment; Restoring Force & Equivalent Stiffness vs.
Misalignment; Verification of Predicted
Oscillatory MotionHorizontal Cross-Sections
Assumed to be Circular;
Numerical Results are Problem-
SpecificPatra & Lee 1991 Realignment of C4 Joints in
Flip-Chip ApplicationsApproximate Numerical Solution of BVP
Neglecting Solder Self-WeightSample Profiles of C4 Joints Before
and After Realignment; Restoring Force
vs. MisalignmentHorizontal Cross-Sections
Assumed to be Circular;
Numerical Results are Problem-
SpecificPatra et
al. 1992Realignment of C4 Joints on Circular or Non-Circular Pads Numerical (Finite-Difference) Solution
of BVP Neglecting Solder Self-Weight3-D Graphical Representations of Joints
on Fully Wetted and Partially Wetted
Circular and Rectangular Pads (Zero
Misalignment); Joint Height vs. Rectangular Pad Aspect Ratio; Joint
Height vs. Wetted % of Circular Pad
AreaNumerical Results are Problem- Specific
Racz & Szekely 1993a; Racz et al. 1993 Prediction of Complex Joint Geometries, such as in Gullwing and J-Lead Fine-Pitch Applications Energy Minimization by Finite Element Program (Surface Evolver) 3-D Graphical Representations of a Variety of Solder Joints; Dimensionless Design Nomographs for Selecting "Optimal" Solder Volume as a Function of Wettable Pad/Lead Area for Gullwing & J-Leads Stand-Off Height Between Lead and Pad is Specified a Priori; Criteria for "Optimal" Joints are Qualitative "Rough Guidelines" Extrapolated from Through-Hole to Surface-Mount Technology
Yost et al. 1993 Realignment of C4 Joints in
Flip-Chip ApplicationsNumerical (Finite-Difference) Solution
of BVP Neglecting Solder Self-WeightHorizontal and Vertical Force-Displacement Curves Stand-Off Spacers Used; Numerical Results are Problem- Specific
Katyl 1993 Sessile Droplets on Circular and Rectangular Pads; Joint Spanning Parallel Rectangular Pads; Joint Connecting TSOP Lead to Rectangular Pad Several Methods of Solution Solution Methods are Compared for Accuracy and Efficiency; 3-D Profiles are Illustrated Numerical Results are Problem- Specific
Racz and Szekely 1993b Wetting Balance Measurements Energy Minimization by FEM Program (Surface Evolver) Relates Wetting Force to % of Sample Perimeter Having Poor Wettability Numerical Results are Problem- Specific
Ju et al. 1993 Realignment of C4 Joints in
Flip-Chip ApplicationsNumerical Solution of Laplace-Young Equation Experimental Verification of Geometry Model for Circular and Square Pads __________
Patra et al. 1993 Realignment of C4 Joints in
Flip-Chip ApplicationsNumerical Solution of Laplace-Young Equation Plots of Lateral Restoring Force vs. Misalignment, Solder Volume, and Surface Tension; Plots of Joint Height vs. Joint Volume and Vertical Loading 40 µm x 40 µm Square Pads
Lee et al. 1995 General Energy Minimization by FEM 3-D Plots of Joints on Gullwing Leads No Gap Between Lead and Pad; Solder Does Not Flow onto Top of Lead
Singler and Zhang 1995 Bridging of Solder Droplets Between Circular and Rectangular Pads Energy Minimization by FEM Program (Surface Evolver) Plots of Critical Solder Volume (at Which Stable Bridges May Form) vs. Pad Spacing for Different Pad Shapes; Plot of Critical Volume vs. Wettability of the Solder Resist Surface; To Minimize Bridges, Use Circular Pads and Solder Resist of Low Wettability Results are for Specific Pad Area and for Mercury
Yost and Holm 1995 Solder Flow on Narrow Strips and in V-Shaped Grooves Energy Minimization by FEM Program (Surface Evolver) 3-D Plots of Droplet Shapes on Circular Pad Connected to Thin Metallized Strip and in V-Groove Droplet Shapes are Problem- Specific
Whalley et al. 1995 Globule Block Wetting Balance Test Energy Minimization by FEM Program (Surface Evolver) Plot of Globule Height vs. Solder Volume; Sensitivity Studies on Test Parameters Numerical Results are Problem- Specific
Nigro et al. 1995 Sessile Droplets on Circular and Rectangular Pads Parametric FEM Droplet Shapes Plotted for Specific Pad Dimensions and Solder Volumes; Droplet height Plotted vs. Aspect Ratio of Rectangular Pad Numerical Results are Problem- Specific
Ju, T.-H., Chan, Y.W., Lin, W., Lee, Y.C., Patra, S.K., and Lee, S.H., "Experimental Verification of a General Purpose Solder Profile Model," Advances in Electronic Packaging 1993, Vol. 2, ASME EEP-Vol. 4-2, 1993, pp. 1163-1168.
Nigro, N.J., Zhou, F.J., Elkouh, A.F., Fournelle, R.A.,Heinrich, S.M., and Lee, P.S., "Parametric Finite Element Method for Predicting Shapes of Three-Dimensional Solder Joints," Advances in Electronic Packaging 1995, Vol. 1, ASME EEP-Vol. 10-1, pp. 435-449; presented at InterPack '95, Lahaina, HI, 1995.