Crack Initiation and Growth in Solder Joints Under Cyclic Shear Deformation Using Piezomechanical Actuation

2005 ◽  
Vol 129 (1) ◽  
pp. 19-28 ◽  
Author(s):  
Dong-Jin Shim ◽  
S. Mark Spearing ◽  
Qingda Yang
Keyword(s):  
Crack Initiation ◽  
Solder Joint ◽  
Shear Deformation ◽  
Mechanical Response ◽  
Solder Joints ◽  
Image Correlation ◽  
Cyclic Shear ◽  
Perfectly Plastic ◽  
Lap Shear ◽  
Shear Strains

Crack initiation and growth behavior in solder joints under cyclic shear deformation using piezomechanical actuation have been investigated. Experiments were conducted on specimens that consist of piezo–ceramic plates and eutectic Sn–Pb solder bonded in a double-lap shear configuration. Specimens were tested under various frequencies and ranges of applied electric field at room temperature, and a shear-lag model using elastic–perfectly plastic solder properties was developed to characterize the mechanical response of the solder joint. Nominal plastic shear strain ranges from 0.182% to 2.69% were considered. The applied shear strains measured using digital image correlation showed agreement with shear strains from analyses. The Coffin–Manson relationship was used to characterize crack initiation, and a power law was employed for crack growth. This work shows that the fatigue characteristics of solder joints using piezomechanical actuation exhibit reasonable agreement with those using other types of testing methods and provides the framework for a new accelerated testing methodology for solder joint reliability.

scholarly journals Shear Strength and Aging Characteristics of Sn-3.0Ag-0.5Cu/Cu Solder Joint Reinforced with ZrO2 Nanoparticles

Metals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1295
Author(s):  
Sri Harini Rajendran ◽  
Seung Jun Hwang ◽  
Jae Pil Jung
Keyword(s):  
Shear Strength ◽  
Solder Joint ◽  
Solder Joints ◽  
Solder Matrix ◽  
Fracture Analysis ◽  
Zro2 Nanoparticles ◽  
Solder Paste ◽  
Lap Shear ◽  
Matrix Fracture ◽  
The Matrix

This study investigates the shear strength and aging characteristics of Sn-3.0Ag-0.5Cu (SAC 305)/Cu joints by the addition of ZrO2 nanoparticles (NPs) having two different particle size: 5–15 nm (ZrO2A) and 70–90 nm (ZrO2B). Nanocomposite pastes were fabricated by mechanically mixing ZrO2 NPs and the solder paste. ZrO2 NPs decreased the β-Sn grain size and Ag3Sn intermetallic compound (IMC) in the matrix and reduced the Cu6Sn5 IMC thickness at the interface of lap shear SAC 305/Cu joints. The effect is pronounced for ZrO2A NPs added solder joint. The solder joints were isothermally aged at 175 °C for 24, 48, 144 and 256 h. NPs decreased the diffusion coefficient from 1.74 × 10–16 m/s to 3.83 × 10–17 m/s and 4.99 × 10–17 m/s for ZrO2A and ZrO2B NPs added SAC 305/Cu joints respectively. The shear strength of the solder joints decreased with the aging time due to an increase in the thickness of interfacial IMC and coarsening of Ag3Sn in the solder. However, higher shear strength exhibited by SAC 305-ZrO2A/Cu joints was attributed to the fine Ag3Sn IMC’s dispersed in the solder matrix. Fracture analysis of SAC 305-ZrO2A/Cu joints displayed mixed solder/IMC mode upon 256 h of aging.

Damage Evolution in Lead Free Solder Joints in Isothermal Fatigue

2015 ◽  
Vol 137 (2) ◽  
Author(s):  
Awni Qasaimeh ◽  
Sa’d Hamasha ◽  
Younis Jaradat ◽  
Peter Borgesen
Keyword(s):  
Crack Initiation ◽  
Mechanical Response ◽  
Solder Joints ◽  
Fatigue Testing ◽  
Hysteresis Loops ◽  
Damage Function ◽  
Lead Free ◽  
Lead Free Solder ◽  
Sac305 Solder ◽  
Free Solder

The extrapolation and generalization of accelerated test results for lead free solder joints require the identification of a damage function that can be counted on to apply beyond the region of the test. Individual ball grid array (BGA) scale Sn3Ag0.5Cu (SAC305) solder joints were subjected to isothermal shear fatigue testing at room temperature and 65 °C. The resulting mechanical response degradation and crack behavior, including strain hardening, crack initiation, and propagation, were correlated with the inelastic work and effective stiffness derived from load–displacement hysteresis loops. Crack initiation was found to scale with the accumulated work, independently of cycling amplitude and strain rate. The subsequent damage rate varied slightly with amplitude.

Phase Growth Process of Sn-3.0Ag-0.5Cu Solder Joints Under Mechanical Cyclic Loading at the Same Temperature

2009 ◽  
Author(s):  
Hiroyuki Nakano ◽  
Yasuhiro Ejiri ◽  
Takao Mori ◽  
Toshihiko Sayama ◽  
Takeshi Takayanagi ◽  
...  
Keyword(s):  
Cyclic Loading ◽  
Crack Initiation ◽  
Solder Joint ◽  
Growth Process ◽  
Solder Joints ◽  
Fatigue Crack Initiation ◽  
Growth Parameter ◽  
Lap Joint ◽  
Phase Growth ◽  
Strain Concentration

In order to improve the reliability of electronic devices, it is important to evaluate the thermal fatigue crack initiation lifetime of Sn-3.0Ag-0.5Cu solder joints. The phase growth parameter has been shown to be useful in estimating the thermal fatigue crack initiation lifetime of Sn-3.0Ag-0.5Cu solder joints through thermal cyclic tests. The phase growth parameter is affected by both temperature and the strain induced by the mismatch between the thermal expansion of a chip and substrate. A study of the influence of this strain on the phase growth process is important in estimating lifetime. In a previous paper, mechanical cyclic loading tests using a mini-lap joint type shear specimen at a temperature of 125°C were performed in order to evaluate the influence of the strain in Sn-3.0Ag-0.5Cu solder joints on the phase growth parameter. Moreover, an elastic-plastic-creep analysis of the solder joints under mechanical cyclic loading was carried out using a finite element method. Consequently, it was confirmed that the phase growth parameter of Sn-3.0Ag-0.5Cu solder joints was in good agreement with the creep strain. While the strain distribution in the solder joint of a mini-lap joint type specimen is nearly uniform, strain concentration exists in the actual solder joint. Therefore, in this paper, in order to clarify the phase growth process in the solder joint, which exhibits strain concentration at the joint end, a detailed finite element analysis of a mini-lap joint type specimen was performed, and the strain in the neighborhood of the joint corner was examined. The corrected increment for the phase growth parameter at the strain concentration occurrence zone is in good agreement with the master curve obtained by the thermal cycle tests of the PCB specimen. It is clear that the crack initiation life time can be evaluated using the increment of the phase growth parameter at the strain concentration occurrence zone, as same as for a PCB specimen. The phase growth parameter is considered to be the evaluation parameter corresponding to creep strain.

Fatigue Life of Sn3.0Ag0.5Cu Solder Alloy Under Combined Cyclic Shear and Constant Tensile/Compressive Loads

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Travis Dale ◽  
Yuvraj Singh ◽  
Ian Bernander ◽  
Ganesh Subbarayan ◽  
Carol Handwerker ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Axial Load ◽  
Solder Joints ◽  
Axial Loads ◽  
Cyclic Shear ◽  
Lap Shear ◽  
Shear Loads ◽  
Area Array ◽  
Compressive Loads ◽  
The Impact

Abstract Solder joints in electronic assemblies experience damage due to cyclic thermomechanical loading that eventually leads to fatigue fracture and electrical failure. While solder joints in smaller, die-sized area-array packages largely experience shear fatigue due to thermal expansion mismatch between the component and the substrate, larger area-array packages experience a combination of cyclic shear and axial tensile/compressive loads due to flexure of the substrate. Additionally, on larger processor packages, the attachment of heatsinks further exacerbates the imposed axial loads, as does package warpage. With the increase in size of packages due to 2.5D heterogeneous integration, the above additional axial loads can be significant. Thus, there exists a critical need to understand the impact on fatigue life of solder joints with superposed compressive/tensile loads on the cyclic shear loads. In this paper, we describe a carefully constructed multi-axial microprecision mechanical tester as well as fatigue test results on Sn3.0Ag0.5Cu (SAC305) solder joints subjected to controlled cyclic shear and constant compressive/tensile loads. The tester design allows one to apply cyclic shear loads up to 200 N while maintaining a constant axial load of up to 38 N in tension or compression. The tester is capable of maintaining the axial load to within a tolerance of ±0.5 N during the entirety of fatigue experiment. Carefully constructed test specimens of Sn3.0Ag0.5Cu solder joints were isothermally fatigued under systematically increased compressive and tensile loads imposed on the test specimen subject to repeated loading (R = 0) under lap-shear. In general, the imposition of the superposed compressive load increases the fatigue life of the solder joint compared to application of pure cyclic shear, while the imposition of the superposed tensile load decreases the fatigue life. At larger compressive loads, friction between fractured surfaces is responsible for significant energy dissipation during the cyclic load–unload cycles.

Strain Evolution during Lap Shear Testing of SnCu Solder

2011 ◽  
Vol 70 ◽  
pp. 303-308 ◽  
Author(s):  
Sankara J. Subramanian ◽  
Vijay K. R. Penmetcha
Keyword(s):  
Shear Strain ◽  
Solder Joints ◽  
Simple Calculation ◽  
Axial Displacement ◽  
Ease Of Use ◽  
Image Correlation ◽  
Transverse Displacement ◽  
Full Field ◽  
Lap Shear ◽  
Lap Shear Test

The lap-shear test is frequently used in the microelectronics industry to obtain mechanical properties of solder joints. In these tests, solder joints formed between slender metallic substrates are pulled apart in a simple shear configuration. Although it is known that calculation of stress-strain curves from lap shear tests is not straightforward due to rotation of the joints and strain inhomogeneity within the joint, these tests still find widespread use due to their simplicity and apparent ease of use. Chawla and co-workers [1, 2] show that the state of strain near the solder-substrate interfaces is significantly different from that in the interior of the joint and that this effect is only minimized for large joints. In the present work, we offer experimental evidence for these conclusions by presenting full-field strain measurements on solder joints in double-lap shear configuration, obtained using Digital Image Correlation (DIC). While confirming that significant strain gradients exist within the joint, the present work also indicates that a simple calculation of shear strain as axial displacement of the joint divided by joint thickness is misleading due to the presence of a significant gradient of the transverse displacement along the loading direction. This gradient persists through the course of the deformation and results in the actual average shear strain in the joint being smaller than that computed from the axial displacement alone.

Inhibiting the Re-Deposition of AuSn4 on Au/Ni Metallization Pads by Varying the Accessibility of Cu in Isothermally Aged SAC305 Solder Joints

2013 ◽  
Author(s):  
Subhasis Mukherjee ◽  
Abhijit Dasgupta ◽  
Julie Silk ◽  
Lay-ling Ong
Keyword(s):  
Solid State ◽  
Solder Joint ◽  
Barrier Layer ◽  
Solder Joints ◽  
Circuit Board ◽  
Nickel Layer ◽  
Gold Content ◽  
Sac305 Solder ◽  
Lap Shear ◽  
Sac Solder

Electroplated Ni/Au over Cu is a popular metallization for printed circuit board (PCB) finish as well as for component leads, especially for wire-bondable high frequency packages, where the gold thickness (≥ 20 μinches) requirement is high for wire bonding. Redeposition of bulk AuSn4 intermetallic compound (IMC) at Au/Ni contact pads of isothermally conditioned SnAgCu (SAC) solder joints is a critical reliability concern in these packages because the interfacial layer between redeposited AuSn4 IMC and initially formed IMC during reflow at the contact pad after reflow is brittle in nature. Redeposition of bulk AuSn4 IMC in Pb-free SAC solder joints (most popularly SAC305) is also believed to be dependent on the degree of access to copper. This study examines the effect of varying gold content (2–5 nominal weight-%) in the solder joint and accessibility to copper (by presence or absence of nickel barrier layer on top of Cu plating) on redeposition of AuSn4 IMCs at the interface of isothermally aged SAC305 solder joints for 720 hours at 121°C (0.8*Tmelt). The modified lap shear Iosipescu specimens used for the study are divided into two batches: i] In the first batch, both the copper platens to be soldered are electroplated with Au and Ni. Ni barrier layers are used to completely stop the solder from accessing the Cu in the substrate ii] In the second batch, one Cu platen is electroplated with Au and Ni barrier layer but the other platen is electroplated only with copper (no Nickel layer), to allow accessibility of Cu from the substrate. Representative solder joints from above two batches are then cross-sectioned and analyzed using environmental scanning electron microscopy (ESEM) and energy-dispersive x-ray spectroscopy (EDX) to investigate the composition, thickness and morphology of both bulk and interfacial IMCs. The first phase to form at the interface of the first batch of specimens after initial reflow is Ni3Sn4/(Ni,Cu)3Sn4. During the subsequent solid-state annealing, the redeposition of AuSn4 occurred in systems plated with Au/Ni on both sides. Contrarily, in the second batch when the solder joint has copper access from one side of the joint, the first intermetallic after reflow to form is (Cu,Ni,Au)6Sn5/(Cu,Au)6Sn5 and no redeposition of AuSn4 is observed after solid state annealing except for the solder joint containing nominal 5wt-% of Au.

A Mechanistic Model for Solder Joint Failure Prediction Under Thermal Cycling

1990 ◽  
Vol 112 (2) ◽  
pp. 104-109 ◽  
Author(s):  
Boon Wong ◽  
D. E. Helling
Keyword(s):  
Crack Initiation ◽  
Solder Joint ◽  
Crack Propagation ◽  
Thermal Cycling ◽  
Solder Joints ◽  
Mechanistic Model ◽  
Propagation Model ◽  
Time To Failure ◽  
Surface Mount ◽  
Life Predictions

A mechanistic model for eutectic Pb/Sn solder life predictions has been developed and applied to leadless surface mount solder joints. This model can quantitatively describe both crack initiation and crack propagation processes in the solder. There are four parts to this model: a crack initiation model, a crack propagation model [1], a microstructural coarsening model and an analysis of the deformation in the solder during thermal cycling. By merging these models together, it is possible to predict the time to crack initiation and the time to failure of these solder joints. Solder joint life predictions show good agreement with data obtained on thermally cycled surface mount leadless chip resistors.

Fatigue Life of Sn3.0Ag0.5Cu Solder Alloys Under Combined Shear and Compressive Loads

2019 ◽  
Author(s):  
Travis Dale ◽  
Yuvraj Singh ◽  
Ian Bernander ◽  
Ganesh Subbarayan ◽  
Carol Handwerker ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Solder Joints ◽  
Compressive Load ◽  
Axial Loads ◽  
Cyclic Shear ◽  
Lap Shear ◽  
Shear Loads ◽  
Area Array ◽  
Compressive Loads ◽  
The Impact

Abstract Solder joints in electronic assemblies experience damage due to cyclic thermomechanical loading that eventually leads to fatigue fracture and electrical failure. While solder joints in smaller, die-sized area-array packages largely experience shear fatigue due to thermal expansion mismatch between the component and the substrate, larger area-array packages experience a combination of cyclic shear and axial tensile/compressive loads due to flexure of the substrate. Additionally, on larger processor packages, the attachment of heatsinks further exacerbates the imposed axial loads, as does package warpage. With the increase in size of packages due to 2.5D Heterogeneous integration, the above additional axial loads can be significant. Thus, there exists a critical need to understand the impact on fatigue life of solder joints with superposed compressive/tensile loads on the cyclic shear loads. In this paper, we describe a carefully constructed microscale mechanical tester as well as fatigue test results on Sn3.0Ag0.5Cu (SAC305) solder joints subjected to controlled cyclic shear and constant compressive loads. The tester design allows one to apply cyclic shear loads up to 200 N while maintaining a constant axial load of up to 38 N in tension or compression. The tester is capable of maintaining the compressive load to within a tolerance of +/− 0.5 N during the entirety of fatigue experiment. Carefully constructed samples of Sn3.0Ag0.5Cu solder joints were isothermally fatigued under systematically increased compressive load imposed on the sample subject to repeated loading (R = 0) under lap-shear. In general, the imposition of the superposed compressive load increases the fatigue life of the solder joint compared to application of pure cyclic shear load. At larger compressive loads, friction between fractured surfaces is responsible for significant energy dissipation during the cyclic load-unload cycles.

Construction of plastic contact deformation maps on ceramics: a case study on aluminum nitride

1996 ◽  
Vol 54 ◽  
pp. 636-637
Author(s):  
D. L. Callahan
Keyword(s):  
Plastic Deformation ◽  
Aluminum Nitride ◽  
Mechanical Response ◽  
Three Dimensional ◽  
Bright Field Image ◽  
Perfectly Plastic ◽  
Contrast Analysis ◽  
Deformation Patterns

Modern polishing, precision machining and microindentation techniques allow the processing and mechanical characterization of ceramics at nanometric scales and within entirely plastic deformation regimes. The mechanical response of most ceramics to such highly constrained contact is not predictable from macroscopic properties and the microstructural deformation patterns have proven difficult to characterize by the application of any individual technique. In this study, TEM techniques of contrast analysis and CBED are combined with stereographic analysis to construct a three-dimensional microstructure deformation map of the surface of a perfectly plastic microindentation on macroscopically brittle aluminum nitride.The bright field image in Figure 1 shows a lg Vickers microindentation contained within a single AlN grain far from any boundaries. High densities of dislocations are evident, particularly near facet edges but are not individually resolvable. The prominent bend contours also indicate the severity of plastic deformation. Figure 2 is a selected area diffraction pattern covering the entire indentation area.

scholarly journals Digital Image Correlation for Evaluation of Cracks in Reinforced Concrete Bridge Slabs

2021 ◽  
Vol 6 (7) ◽  
pp. 99
Author(s):  
Christian Overgaard Christensen ◽  
Jacob Wittrup Schmidt ◽  
Philip Skov Halding ◽  
Medha Kapoor ◽  
Per Goltermann
Keyword(s):  
Reinforced Concrete ◽  
Digital Image Correlation ◽  
Crack Initiation ◽  
Laboratory Test ◽  
Digital Image ◽  
Crack Detection ◽  
Image Correlation ◽  
In Situ Tests ◽  
Stop Criterion

In proof-loading of concrete slab bridges, advanced monitoring methods are required for identification of stop criteria. In this study, Two-Dimensional Digital Image Correlation (2D DIC) is investigated as one of the governing measurement methods for crack detection and evaluation. The investigations are deemed to provide valuable information about DIC capabilities under different environmental conditions and to evaluate the capabilities in relation to stop criterion verifications. Three Overturned T-beam (OT) Reinforced Concrete (RC) slabs are used for the assessment. Of these, two are in situ strips (0.55 × 3.6 × 9.0 m) cut from a full-scale OT-slab bridge with a span of 9 m and one is a downscaled slab tested under laboratory conditions (0.37 × 1.7 × 8.4 m). The 2D DIC results includes full-field plots, investigation of the time of crack detection and monitoring of crack widths. Grey-level transformation was used for the in situ tests to ensure sufficient readability and results comparable to the laboratory test. Crack initiation for the laboratory test (with speckle pattern) and in situ tests (plain concrete surface) were detected at intervals of approximately 0.1 mm to 0.3 mm and 0.2 mm to 0.3 mm, respectively. Consequently, the paper evaluates a more qualitative approach to DIC test results, where crack indications and crack detection can be used as a stop criterion. It was furthermore identified that crack initiation was reached at high load levels, implying the importance of a target load.

Sign in / Sign up

Export Citation Format

Share Document