Creep Behavior of Lead Free Solder Interconnects in Microelectronic Packages: Impression Creep Testing and Constitutive Modeling

2005 ◽  
Author(s):  
I. Dutta ◽  
D. Pan ◽  
S. Jadhav ◽  
R. Mahajan
Keyword(s):  
Creep Behavior ◽  
Solder Joints ◽  
Ball Grid Array ◽  
Creep Testing ◽  
Lead Free ◽  
Creep Model ◽  
Impression Creep ◽  
Creep Response ◽  
Microelectronic Packages ◽  
Free Solder

The creep behavior of ball grid array (BGA) or flip-chip (FC) solder joints during thermo-mechanical cycling associated with service often limits the reliability of microelectronic packages. In addition, the fine intermetallic precipitates (Ag3Sn and/or Cu6Sn5) in the microstructures of the new lead-free solders (Sn-Ag and Sn-Ag-Cu) can undergo significant in situ strain-enhanced coarsening during TMC, resulting in in-service evolution of the creep behavior of the joints. Since there are significant microstructural/ compositional differences between bulk solder samples and tiny microelectronic solder joints, it is critical to develop accurate creep testing methodologies on tiny life-sized solder joints and microstructurally adaptive constitutive creep models for the emerging Pb-free solder alloys. In this paper, we present creep data obtained from tests conducted on individual Sn4Ag0.5Cu ball grid array (BGA) solder balls attached to a packaging substrate, using a newly developed miniaturized impression creep apparatus, which affords high test throughput with minimal sample preparation. Coarsening of intermetallic particles is demonstrated to influence creep behavior in two ways. At low stresses, the creep rate increases proportionately with precipitate size. At high stresses, precipitate coarsening influences creep response by altering the threshold stress for particle-limited creep. Based on the experimental observations, a microstructurally adaptive creep model, which accounts for the effects of coarsening on the creep response of solder joints, and is capable of adjusting itself as solder joint microstructures evolve during service, is presented, along with experimental determination of the relevant coarsening kinetics parameters.

Creep and Microstructural Evolution in Lead-Free Microelectronic Solder Joints

2003 ◽  
Author(s):  
I. Dutta ◽  
C. Park ◽  
S. Choi
Keyword(s):  
Microstructural Evolution ◽  
Life Prediction ◽  
Solder Joints ◽  
Creep Testing ◽  
Lead Free ◽  
Creep Model ◽  
Second Phase ◽  
Impression Creep ◽  
Microstructural Coarsening ◽  
Lead Free Solders

Microelectronic solder joints are typically exposed to aggressive thermo-mechanical cycling (TMC) conditions, resulting in significant strain-enhanced microstructural coarsening during service. This microstructural evolution produces continuously evolving mechanical properties during extended use. Since solder joint life is dictated largely by the creep strain range, it is necessary to develop microstructurally adaptive creep models for solders to enable accurate prediction of joint life. In this paper, we present (1) a new closed-form creep model incorporating microstructural coarsening in lead-free solders, which can be easily incorporated into life-prediction models; and (2) a methodology for impression creep testing of Sn-3.5Ag solders which can potentially enable creep testing of individual flip chip or BGA balls in a package. The proposed creep model incorporates the effects of both static and strain-enhanced coarsening of second phase intermetallic particles which are present in lead-free solders, and shows that as a joint undergoes TMC, the creep rate increases continuously, adversely impacting life. This inference is supported by the impression creep experiments, which are shown to capture the essential features of creep in Sn-Ag alloys, in accordance with the available literature. It is also shown that the creep resistance of a given alloy composition is strongly dependent on the microstructure, making it important that creep data used for joint life prediction be based on testing of actual joints or very tightly controlled microstructures.

Methodology for Analyzing Slip Behavior in Ball Grid Array Lead-Free Solder Joints After Simple Shear

2009 ◽  
Vol 38 (12) ◽  
pp. 2702-2711 ◽  
Author(s):  
Bite Zhou ◽  
Thomas R. Bieler ◽  
Tae-Kyu Lee ◽  
Kuo-Chuan Liu
Keyword(s):  
Simple Shear ◽  
Solder Joints ◽  
Ball Grid Array ◽  
Lead Free ◽  
Lead Free Solder ◽  
Free Solder

IMC and creep behavior in Lead-free solder joints of Sn-Ag and Sn-Ag-Cu alloy system by SP method

2014 ◽  
Vol 15 (7) ◽  
pp. 1137-1142 ◽  
Author(s):  
Z. J. Yang ◽  
S. M. Yang ◽  
H. S. Yu ◽  
S. J. Kang ◽  
J. H. Song ◽  
...  
Keyword(s):  
Creep Behavior ◽  
Solder Joints ◽  
Alloy System ◽  
Lead Free ◽  
Lead Free Solder ◽  
Cu Alloy ◽  
Free Solder

A Systematic Approach for Determining the Thermal Fatigue-Life of Plastic Ball Grid Array (PBGA) Lead-Free Solder Joints

2005 ◽  
Author(s):  
John Lau ◽  
Ricky Lee ◽  
Walter Dauksher ◽  
Dongkai Shangguan ◽  
Fubin Song ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Thermal Fatigue ◽  
Solder Joints ◽  
Ball Grid Array ◽  
Lead Free ◽  
Lead Free Solder ◽  
Thermal Fatigue Life ◽  
Plastic Ball ◽  
Plastic Ball Grid Array ◽  
Free Solder

Reliability of plastic ball grid array (PBGA) SnAgCu lead-free solder joints is investigated. Emphasis is placed on the design for reliability (DFR) of lead-free solder joints. In particular, the thermal-fatigue life of the lead-free solder joints of a PBGA package assembly is predicted and compared with thermal cycling test results.

scholarly journals Effective Solder for Improved Thermo-Mechanical Reliability of Solder Joints in a Ball Grid Array (BGA) Soldered on Printed Circuit Board (PCB)

2020 ◽  
Vol 50 (1) ◽  
pp. 263-282
Author(s):  
Joshua A. Depiver ◽  
Sabuj Mallik ◽  
Emeka H. Amalu
Keyword(s):  
Thermal Cycling ◽  
Solder Joints ◽  
Ball Grid Array ◽  
Temperature Cycling ◽  
The Other ◽  
Lead Free ◽  
Creep Model ◽  
Mechanical Reliability ◽  
Printed Circuit ◽  
Isothermal Ageing

AbstractBall grid array (BGA) packages have increasing applications in mobile phones, disk drives, LC displays and automotive engine controllers. However, the thermo-mechanical reliability of the BGA solder joints challenges the device functionality amidst component and system miniaturisation as well as wider adoption of lead-free solders. This investigation determines the effective BGA solders for improved thermo-mechanical reliability of the devices. It utilised a conducted study on creep response of a lead-based eutectic Sn63Pb37 and four lead-free Tin–Silver–Copper (SnAgCu) [SAC305, SAC387, SAC396 and SAC405] solders subjected to thermal cycling loadings and isothermal ageing. The solders form the joints between the BGAs and printed circuit boards (PCBs). ANSYS R19.0 package is used to simulate isothermal ageing of some of the assemblies at − 40°C, 25°C, 75°C and 150°C for 45 days and model the thermal cycling history of the other assemblies from 22°C ambient temperature for six cycles. The response of the solders is simulated using the Garofalo-Arrhenius creep model. Under thermal ageing, SAC396 solder joints demonstrate possession of least strain energy density, deformation and von Mises stress in comparison to the other solders. Under thermal cycle loading conditions, SAC405 acquired the lowest amount of the damage parameters in comparison. Lead-free SAC405 and SAC387 joints accumulated the lowest and highest energy dissipation per cycle, respectively. It is concluded that SAC405 and SAC396 are the most effective solders for BGA in devices experiencing isothermal ageing and temperature cycling during operation, respectively. They are proposed as the suitable replacement of eutectic Sn63Pb37 solder for the various conditions.

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