The mechanical properties degradation of solder joints under thermal cycling

2002 ◽  
Author(s):  
Wang Qian ◽  
S.-W.R. Lee ◽  
Wang Gangqiang ◽  
Chen Guohai ◽  
Hung Le ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Cycling ◽  
Solder Joints

Reliability of Underfill-Encapsulated Flip-Chips With Heat Spreaders

1998 ◽  
Vol 120 (4) ◽  
pp. 322-327 ◽  
Author(s):  
H. Doi ◽  
K. Kawano ◽  
A. Yasukawa ◽  
T. Sato
Keyword(s):  
Mechanical Properties ◽  
Fatigue Life ◽  
Thermal Cycling ◽  
Failure Mode ◽  
Flip Chip ◽  
Solder Joints ◽  
Alumina Substrate ◽  
Heat Spreader ◽  
Flip Chips ◽  
Heat Spreaders

The effect of a heat spreader on the life of the solder joints for underfill-encapsulated, flip-chip packages is investigated through stress analyses and thermal cycling tests. An underfill with suitable mechanical properties is found to be able to prolong the fatigue life of the solder joints even in a package with a heat spreader and an alumina substrate. The delamination of the underfill from the chip is revealed as another critical failure mode for which the shape of the underfill fillet has a large effect.

Nanoindentation Testing of SAC305 Solder Joints Subjected to Thermal Cycling Loading

2019 ◽  
Author(s):  
Abdullah Fahim ◽  
S. M. Kamrul Hasan ◽  
Jeffrey C. Suhling ◽  
Pradeep Lall
Keyword(s):  
Mechanical Properties ◽  
Solder Joint ◽  
Thermal Cycling ◽  
Creep Behavior ◽  
Solder Joints ◽  
Test Results ◽  
Sac305 Solder ◽  
Nanoindentation Testing ◽  
Single Grain ◽  
Cycling Loading

Abstract Solder joints in electronic packages are frequently exposed to thermal cycling environment. Such exposures can occur in real life application as well as in accelerated thermal cycling tests used for the fatigue behavior characterization. Because of temperature variations and CTE mismatches of the assembly materials, cyclic temperature leads to damage accumulation and material property evolution in the solder joints. This eventually results in crack initiation, and subsequent crack growth and failure. In this study, the nanoindentation technique was used to understand the evolution of mechanical properties (modulus, hardness and creep behavior) of SAC305 BGA solder joints and Cu pad subjected to thermal cycling loading for various durations. In addition, microstructural changes in those joints that occur during thermal cycling were observed using both SEM and optical microscopy. BGA solder joint strip specimens were first prepared by cross sectioning BGA assemblies followed by surface polishing to facilitate SEM imaging and nanoindentation testing. The strip specimens were chosen to contain several single grain solder joints. This enabled large regions of solder material with equivalent mechanical behavior, which could then be indented several times after various durations of cycling. After preparation, the solder joint strip samples were thermally cycled from T = −40 to 125 °C in an environmental chamber. At various points in the cycling (e.g. after 0, 50, 100, and 250 cycles), the package was taken out from the chamber, and nanoindentation was performed on each single grain joint and joint Cu pads to obtain the modulus, hardness, and creep behavior at 25 °C. This allowed the evolution of the mechanical properties with the duration of thermal cycling to be determined. Moreover, microstructural changes were also observed after various durations of cycling using optical microscopy. From the nanoindentation test results, it was found that the modulus and hardness of the SAC305 solder joints dropped significantly with thermal cycling. However, the Cu pad did not show any change in the mechanical behavior during cycling. Moreover, the nanoindentation creep test results showed significant increases in the creep deformation for solder joints whereas Cu pad did now show any significant changes in creep behavior when both of them were subjected to thermal cycling up to 250 cycles.

Evolution of Mechanical Properties and Microstructure in SAC Bulk Solder and Solder Joints During Thermal Cycling Exposures

2021 ◽  
Author(s):  
S. M. Kamrul Hasan ◽  
Abdullah Fahim ◽  
Mohammad Al Ahsan ◽  
Jeffrey C. Suhling ◽  
Sa'd Hamasha ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Thermal Cycling ◽  
Mechanical Behavior ◽  
Solder Joints ◽  
Bulk Solder ◽  
Temperature Extreme ◽  
Free Condition ◽  
Elapsed Time ◽  
Solder Balls

Abstract Electronic packages are frequently exposed to thermal cycling during their service life between low to high temperature extreme. Similar phenomena can be observed in solder joints during the characterization of thermal-mechanical fatigue behavior. This variation in temperature causes the evolution of mechanical and microstructural behavior of solder joints. Also, dwelling at high temperature extreme causes the mechanical properties reduction of solder joints due to thermal aging phenomena which eventually leads to the change in microstructure. In literature, the effect of thermal aging on the mechanical behavior evolution has been reported by several research groups, but the evolution of mechanical and microstructural properties under different thermal cycling exposure is limited. In our prior study, reduction of mechanical properties of SAC305 lead-free solder material under different thermal cycling exposures have been reported for up to 5 days of thermal cycling. It was found that thermal cycling with long ramp period and dwell time has severe effect on mechanical properties reduction. In our present study, previous study has been extended up to 100 days along with the mechanical behavior evolution of solder joints under stress free condition at different thermal cyclic loading. Particularly, the evolutions of mechanical behavior in both bulk SAC305 miniature solder bar samples and small SAC305 solder balls under stress free condition have been investigated for several thermal cycling profiles, and then the results were compared. Reflow solidification technique with a controlled temperature profile has been used to prepare bulk solder specimens for uniaxial tensile testing. Optical microscopy has been used to figure out the single grain BGA solder balls after grounding and polishing to avoid grain orientation effect during nanoindentation technique. Then, both bulk solder bars and solder balls were thermally cycled between −40 C to +125 °C under a stress-free condition (no load) in a thermal chamber. Several thermal loading were adopted such as (1) 150 minutes cycles with 45 minutes ramps and 30 minutes dwells, (2) air-to-air thermal shock exposures with 30 minutes dwells and near instantaneous ramps, (3) 90 minute cycles with 45 minutes ramps and 0 minutes dwells (thermal ramp only), and (4) Isothermal aging at high temperature extreme (no cycle). After each thermal cycling exposure, mechanical properties evolution of both solder bars and solder balls were recorded in terms of effective elastic modulus (E), hardness (H), yield strength (YS), and ultimate tensile strength (UTS). For the BGA solder balls, the evolution of mechanical properties was measured using nanoindentation. Moreover, mechanical properties evolution of both specimens was compared in terms of normalized properties with respect to elapsed time under different thermal cycling exposures. Finally, the microstructural evolution of bulk solder bars was observed under slow thermal cycling exposures with elapsed time.

scholarly journals Microstructure and shear properties of ultrasonic-assisted Sn2.5Ag0.7Cu0.1RExNi/Cu solder joints under thermal cycling

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jianguo Cui ◽  
Keke Zhang ◽  
Di Zhao ◽  
Yibo Pan
Keyword(s):  
Shear Strength ◽  
Thermal Cycling ◽  
Solder Joints ◽  
High Reliability ◽  
Sharp Decrease ◽  
Thermal Shock Test ◽  
Shear Properties ◽  
Equivalent Time ◽  
Ultrasonic Assisted ◽  
Reliability Of Solder Joints

AbstractThrough ultrasonic wave assisted Sn2.5Ag0.7Cu0.1RExNi/Cu (x = 0, 0.05, 0.1) soldering test and − 40 to 125 °C thermal shock test, the microstructure and shear properties of Sn2.5Ag0.7Cu0.1RExNi/Cu solder joints under thermal cycling were studied by the SEM, EDS and XRD. The results show that the Sn2.5Ag0.7Cu0.1RExNi/Cu solder joints with high quality and high reliability can be obtained by ultrasonic assistance. When the ultrasonic vibration power is 88 W, the ultrasonic-assisted Sn2.5Ag0.7Cu0.1RE0.05Ni/Cu solder joints exhibits the optimized performance. During the thermal cycling process, the shear strength of ultrasonic-assisted Sn2.5Ag0.7Cu0.1RExNi/Cu solder joints had a linear relationship with the thickness of interfacial intermetallic compound (IMC). Under the thermal cycling, the interfacial IMC layer of ultrasonic-assisted Sn2.5Ag0.7Cu0.1RExNi/Cu solder joints consisted of (Cu,Ni)6Sn5 and Cu3Sn. The thickness of interfacial IMC of ultrasonic-assisted Sn2.5Ag0.7Cu0.1RExNi/Cu solder joints was linearly related to the square root of equivalent time. The growth of interfacial IMC of ultrasonic-assisted Sn2.5Ag0.7Cu0.1RExNi/Cu solder joints had an incubation period, and the growth of IMC was slow within 300 cycles. And after 300 cycles, the IMC grew rapidly, the granular IMC began to merge, and the thickness and roughness of IMC increased obviously, which led to a sharp decrease in the shear strength of the solder joints. The 0.05 wt% Ni could inhibit the excessive growth of IMC, improve the shear strength of solder joints and improve the reliability of solder joints. The fracture mechanism of ultrasonic-assisted Sn2.5Ag0.7Cu0.1RExNi/Cu solder joints changed from the ductile–brittle mixed fracture in the solder/IMC transition zone to the brittle fracture in the interfacial IMC.

scholarly journals Interfacial Reactions and Mechanical Properties of Sn–58Bi Solder Joints with Ag Nanoparticles Prepared Using Ultra-Fast Laser Bonding

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 335
Author(s):  
Gyuwon Jeong ◽  
Dong-Yurl Yu ◽  
Seongju Baek ◽  
Junghwan Bang ◽  
Tae-Ik Lee ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Low Temperature ◽  
Printed Circuit Boards ◽  
Solder Joints ◽  
Interfacial Reactions ◽  
Circuit Boards ◽  
Ag Nps ◽  
Laser Bonding ◽  
Laser Soldering ◽  
Low Temperature Bonding

The effects of Ag nanoparticle (Ag NP) addition on interfacial reaction and mechanical properties of Sn–58Bi solder joints using ultra-fast laser soldering were investigated. Laser-assisted low-temperature bonding was used to solder Sn–58Bi based pastes, with different Ag NP contents, onto organic surface preservative-finished Cu pads of printed circuit boards. The solder joints after laser bonding were examined to determine the effects of Ag NPs on interfacial reactions and intermetallic compounds (IMCs) and high-temperature storage tests performed to investigate its effects on the long-term reliabilities of solder joints. Their mechanical properties were also assessed using shear tests. Although the bonding time of the laser process was shorter than that of a conventional reflow process, Cu–Sn IMCs, such as Cu6Sn5 and Cu3Sn, were well formed at the interface of the solder joint. The addition of Ag NPs also improved the mechanical properties of the solder joints by reducing brittle fracture and suppressing IMC growth. However, excessive addition of Ag NPs degraded the mechanical properties due to coarsened Ag3Sn IMCs. Thus, this research predicts that the laser bonding process can be applied to low-temperature bonding to reduce thermal damage and improve the mechanical properties of Sn–58Bi solders, whose microstructure and related mechanical properties can be improved by adding optimal amounts of Ag NPs.

scholarly journals Study on the Reliability of Sn–Bi Composite Solder Pastes with Thermosetting Epoxy under Thermal Cycling and Humidity Treatment

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 733
Author(s):  
Lu Liu ◽  
Songbai Xue ◽  
Ruiyang Ni ◽  
Peng Zhang ◽  
Jie Wu
Keyword(s):  
Solder Joint ◽  
Thermal Cycling ◽  
Composite Solder ◽  
Solder Joints ◽  
Solder Paste ◽  
Epoxy System ◽  
Mechanical Reinforcement ◽  
Microstructure Observation ◽  
Temperature And Humidity ◽  
Thermosetting Epoxy

In this study, a Sn–Bi composite solder paste with thermosetting epoxy (TSEP Sn–Bi) was prepared by mixing Sn–Bi solder powder, flux, and epoxy system. The melting characteristics of the Sn–Bi solder alloy and the curing reaction of the epoxy system were measured by differential scanning calorimeter (DSC). A reflow profile was optimized based on the Sn–Bi reflow profile, and the Organic Solderability Preservative (OSP) Cu pad mounted 0603 chip resistor was chosen to reflow soldering and to prepare samples of the corresponding joint. The high temperature and humidity reliability of the solder joints at 85 °C/85% RH (Relative Humidity) for 1000 h and the thermal cycle reliability of the solder joints from −40 °C to 125 °C for 1000 cycles were investigated. Compared to the Sn–Bi solder joint, the TSEP Sn–Bi solder joints had increased reliability. The microstructure observation shows that the epoxy resin curing process did not affect the transformation of the microstructure. The shear force of the TSEP Sn–Bi solder joints after 1000 cycles of thermal cycling test was 1.23–1.35 times higher than the Sn–Bi solder joint and after 1000 h of temperature and humidity tests was 1.14–1.27 times higher than the Sn–Bi solder joint. The fracture analysis indicated that the cured cover layer could still have a mechanical reinforcement to the TSEP Sn–Bi solder joints after these reliability tests.

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