scholarly journals Performance of Sn-3.0Ag-0.5Cu Composite Solder with Kaolin Geopolymer Ceramic Reinforcement on Microstructure and Mechanical Properties under Isothermal Ageing

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 776
Author(s):  
Nur Syahirah Mohamad Zaimi ◽  
Mohd Arif Anuar Mohd Salleh ◽  
Andrei Victor Sandu ◽  
Mohd Mustafa Al Bakri Abdullah ◽  
Norainiza Saud ◽  
...  
Keyword(s):  
Shear Strength ◽  
Composite Solder ◽  
Printed Circuit Board ◽  
Microwave Sintering ◽  
Copper Substrate ◽  
Bulk Diffusion ◽  
Circuit Board ◽  
Sac305 Solder ◽  
Lap Shear ◽  
Isothermal Ageing

This paper elucidates the effect of isothermal ageing at temperature of 85 °C, 125 °C and 150 °C for 100, 500 and 1000 h on Sn-3.0Ag-0.5Cu (SAC305) lead-free solder with the addition of 1 wt% kaolin geopolymer ceramic (KGC) reinforcement particles. SAC305-KGC composite solders were fabricated through powder metallurgy using a hybrid microwave sintering method and reflowed on copper substrate printed circuit board with an organic solderability preservative surface finish. The results revealed that, the addition of KGC was beneficial in improving the total thickness of interfacial intermetallic compound (IMC) layer. At higher isothermal ageing of 150 °C and 1000 h, the IMC layer in SAC305-KGC composite solder was towards a planar-type morphology. Moreover, the growth of total interfacial IMC layer and Cu3Sn layer during isothermal ageing was found to be controlled by bulk diffusion and grain-boundary process, respectively. The activation energy possessed by SAC305-KGC composite solder for total interfacial IMC layer and Cu3Sn IMC was 74 kJ/mol and 104 kJ/mol, respectively. Based on a lap shear test, the shear strength of SAC305-KGC composite solder exhibited higher shear strength than non-reinforced SAC305 solder. Meanwhile, the solder joints failure mode after shear testing was a combination of brittle and ductile modes at higher ageing temperature and time for SAC305-KGC composite solder.

scholarly journals Shear Strength Degradation Modeling of Lead-Free Solder Joints at Different Isothermal Aging Conditions

2021 ◽  
Vol 18 (3) ◽  
pp. 137-144
Author(s):  
Dania Bani Hani ◽  
Raed Al Athamneh ◽  
Mohammed Aljarrah ◽  
Sa’d Hamasha
Keyword(s):  
Mechanical Properties ◽  
Shear Strength ◽  
Printed Circuit Board ◽  
Solder Joints ◽  
Constant Strain Rate ◽  
Circuit Board ◽  
Sac305 Solder ◽  
Aging Conditions ◽  
Osp Surface Finish ◽  
Shear Strength Degradation

Abstract SAC-based alloys are one of the most common solder materials that are utilized to provide mechanical support and electrical connection between electronic components and the printed circuit board. Enhancing the mechanical properties of solder joints can improve the life of the components. One of the mechanical properties that define the solder joint structure integrity is the shear strength. The main objective of this study is to assess the shear strength behavior of SAC305 solder joints under different aging conditions. Instron 5948 Micromechanical Tester with a customized fixture is used to perform accelerated shear tests on individual solder joints. The shear strength of SAC305 solder joints with organic solderability preservative (OSP) surface finish is investigated at constant strain rate under different aging times (2, 10, 100, and 1,000 h) and different aging temperatures (50, 100, and 150°C). The nonaged solder joints are examined as well for comparison purposes. Analysis of variance (ANOVA) is accomplished to identify the contribution of each parameter on the shear strength. A general empirical model is developed to estimate the shear strength as a function of aging conditions using the Arrhenius term. Microstructure analysis is performed at different aging conditions using scanning electron microscope (SEM). The results revealed a significant reduction in the shear strength when the aging level is increased. An increase in the precipitates coarsening and intermetallic compound (IMC) layer thickness are observed with increased aging time and temperature.

Performance of 96.5Sn–3Ag–0.5Cu/fullerene composite solder under isothermal ageing and high-current stressing

2020 ◽  
Vol 33 (1) ◽  
pp. 35-46 ◽  
Author(s):  
Guang Chen ◽  
Xinzhan Cui ◽  
Yaofeng Wu ◽  
Wei Li ◽  
Fengshun Wu
Keyword(s):  
Solder Joint ◽  
Composite Solder ◽  
Solder Joints ◽  
Experimental Results ◽  
High Current ◽  
Sac305 Solder ◽  
Content Type ◽  
Interfacial Imcs ◽  
Current Stressing ◽  
Isothermal Ageing

Purpose The purpose of this paper is to investigate the effect of fullerene (FNS) reinforcements on the microstructure and mechanical properties of 96.5Sn3Ag0.5Cu (SAC305) lead-free solder joints under isothermal ageing and electrical-migration (EM) stressing. Design/methodology/approach In this paper, SAC305 solder alloy doped with 0.1 Wt.% FNS was prepared via the powder metallurgy method. A sandwich-like sample and a U-shaped sample were designed and prepared to conduct an isothermal ageing test and an EM test. The isothermal ageing test was implemented under vacuum atmosphere at 150°C, whereas the EM experiment was carried out with a current density of 1.5 × 104 A/cm2. The microstructural and mechanical evolutions of both plain and composite solder joints after thermal ageing and EM stressing were comparatively studied. Findings A growth of Ag3Sn intermetallic compounds (IMCs) in solder matrix and Cu-Sn interfacial IMCs in composite solder joints was notably suppressed under isothermal ageing condition, whereas the hardness and shear strength of composite solder joints significantly outperformed those of non-reinforced solder joints throughout the ageing period. The EM experimental results showed that for the SAC305 solder, the interfacial IMCs formulated a protrusion at the anode after 360 h of EM stressing, whereas the surface of the composite solder joint was relatively smooth. During the stressing period, the interfacial IMC on the anode side of the plain SAC305 solder showed a continuous increasing trend, whereas the IMC at the cathode presented a decreasing trend for its thickness as the stressing time increased; after 360 h of stressing, some cracks and voids had formed on the cathode side. For the SAC305/FNS composite solder, a continuous increase in the thickness of the interfacial IMC was found on both the anode and cathode sides; the growth rate of the interfacial IMC at the anode was higher than that at the cathode. The nanoindentation results showed that the hardness of the SAC305 solder joint presented a gradient distribution after EM stressing, whereas the hardness data showed a relatively homogeneous distribution in the SAC305/FNS solder joint. Originality/value The experimental results showed that the FNS reinforcement could effectively mitigate the failure risk in solder joints under isothermal ageing and high-current stressing. Specifically, the FNS particles in solder joints can work as a barrier to suppress the diffusion and migration of Sn and Cu atoms. In addition, the nanoidentation results also indicated that the addition of the FNS reinforcement was very helpful in maintaining the mechanical stability of the solder joint. These findings have provided a theoretical and experimental basis for the practical application of this novel composite solder with high-current densities.

Effects of Corner/Edge Bonding and Underfill Properties on the Thermal Cycling Performance of Lead Free Ball Grid Array Assemblies

2012 ◽  
Vol 134 (1) ◽  
Author(s):  
P. Borgesen ◽  
D. Blass ◽  
M. Meilunas
Keyword(s):  
Thermal Cycling ◽  
Flip Chip ◽  
Printed Circuit Board ◽  
Ball Grid Array ◽  
Cycling Performance ◽  
Circuit Board ◽  
Lead Free ◽  
Sac305 Solder ◽  
Solder Balls ◽  
Selection Of

Underfilling will almost certainly improve the performance of an area array assembly in drop, vibration, etc. However, depending on the selection of materials, the thermal fatigue life may easily end up worse than without an underfill. This is even more true for lead free than for eutectic SnPb soldered assemblies. If reworkability is required, the bonding of the corners or a larger part of the component edges to the printed circuit board (PCB), without making contact with the solder joints, may offer a more attractive materials selection. A 30 mm flip chip ball grid array (FCBGA) component with SAC305 solder balls was attached to a PCB and tested in thermal cycling with underfills and corner/edge bonding reinforcements. Two corner bond materials and six reworkable and nonreworkable underfills with a variety of mechanical properties were considered. All of the present underfills reduced the thermal cycling performance, while edge bonding improved it by up to 50%. One set of the FCBGAs was assembled with a SnPb paste and underfilled with a soft reworkable underfill. Surprisingly, this improved the thermal cycling performance slightly beyond that of the nonunderfilled assemblies, providing up to three times better life than for those assembled with a SAC305 paste.

The Relationship between XRD Peak Intensity and Mechanical Properties of Irradiated Lead-Free Solder

2017 ◽  
Vol 888 ◽  
pp. 423-427 ◽  
Author(s):  
Wilfred Paulus ◽  
Irman Abdul Rahman ◽  
Azman Jalar ◽  
Norinsan Kamil Othman ◽  
Roslina Ismail ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Printed Circuit Board ◽  
Copper Substrate ◽  
Circuit Board ◽  
Lead Free ◽  
Lead Free Solder ◽  
Peak Intensity ◽  
Free Solder ◽  
Gamma Irradiated ◽  
Xrd Techniques

The variation on mechanical properties and crystalline structure of gamma-irradiated Sn-rich lead-free solder (SAC) were intensively investigated using nanoindentation and X-ray diffraction (XRD) techniques. Samples of solder on a printed circuit board (PCB) with copper substrate were irradiated at low dose (5 Gray) of gamma from Co-60 source. The nanoindentation hardness for β-Sn phase of the solder was found to increase from 0.1935 GPa to 0.2210 GPa after the irradiation. Furthermore XRD peak intensity was also observed to increase as well indicating the occurrence of defect in β-Sn crystal structure due to gamma radiation. The defect contributes to the increment of the hardness by indicating the change in crystallite size of the grains. Microstructure analysis by FESEM-EDAX has also confirmed the indentation was performed with no cracks in subsurface on β-Sn area.

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.

Analysis of the Micro-Mechanical Properties in Aged Lead-Free, Fine Pitch Flip Chip Joints

2003 ◽  
Author(s):  
Changqing Liu ◽  
Paul Conway ◽  
Dezhi Li ◽  
Michael Hendriksen
Keyword(s):  
Shear Strength ◽  
Flip Chip ◽  
Printed Circuit Board ◽  
Initial Period ◽  
Electroless Nickel ◽  
Circuit Board ◽  
Solder Paste ◽  
Soldering Process ◽  
Joint Reliability ◽  
Solder Bumps

This research seeks to characterize the micro-mechanical behavior of Sn-Ag-Cu solder bumps/joints generated by fine feature flip chip fabrication and assembly processes. The bumps used for characterization were produced by stencil deposition of solder paste onto an electroless Nickel UBM, followed by a bump-forming reflow soldering process and the final assembly joints were then achieved by a subsequent reflow of die onto a fine feature Printed Circuit Board (PCB). The bumps and joints were aged at either 80°C or 150°C for up to 1.5 months and then analyzed by means of micro-shear testing and nano-indentation techniques. The shear test of the aged bumps showed a slight increase in shear strength after an initial period of aging (∼ 50h) as compared to as-manufactured bumps, but a decrease after longer aging (e.g. 440 h). A brittle Ag3Sn phase formed as large lamellae in the solder and along the interface between the Cu on the PCB during the initial aging, and is attributed to the increase of shear strength, along with the refinement of the bump microstructure. However, as the time of aging extended, the solder bumps were softened due to grain growth and re-crystallization. It was found that the formation of brittle phases in the solder and along the interfaces caused localized stress concentration, which can significantly affect joint reliability. In addition, Nano-testing identified a lamellar Au-rich structure, formed in the solder and interface of the solder/PCB in the joints after the aging process. These are believed to be detrimental to joint reliability.

Effect on Shear Strength and Hardness Properties of Tin Based Solder Alloy, Sn-50Bi, Sn-50Bi+2%TiO2 Nanoparticles

2020 ◽  
Vol 1159 ◽  
pp. 54-59
Author(s):  
Singh Amares ◽  
Bandar Tchari
Keyword(s):  
Shear Strength ◽  
Melting Temperature ◽  
Solder Alloy ◽  
Vickers Hardness ◽  
Printed Circuit Board ◽  
Circuit Board ◽  
Lead Free ◽  
The European Union ◽  
Solder Alloys ◽  
Free Solder

Solder alloys are important joining medium widely used in the electronics industry to connect components to printed circuit board PCB. The Sn-Pb solder alloys have been the cornerstone medium used for a long time. Unfortunately, the use of Pb was banned by the European Union due to the harmful environmental and health issues with Pb. Therefore, in this study, the Sn-50Bi and Sn-50Bi+2%TiO2 nanoparticles lead-free solder alloy is investigated based on their shear strength, Vickers hardness, and melting temperature. The investigation shows that the hypo eutectic Sn-50Bi has a low melting temperature of approximately 145°C, and the 2%TiO2 nanoparticles reinforced Sn-50Bi has a melting temperature of around 182°C, which is lower than the traditional Sn-Pb (Tm=183 °C) and Sn-Ag-Cu (Tm=227°C). Furthermore, the developed Sn-50Bi had a Vickers hardness and shear strength of 26.81 HV and 40.78 MPa respectively, higher than the other leaded and lead-free solders. However, after the reinforcement, the hardness increased by 12% (30 HV) and a slight increase of 2.5% (42.4MPa) in shear strength. Overall, the addition of the TiO2 nanoparticles showed a clear influence on the Sn-Bi properties. The results obtained from this study seem satisfactory to the electronic industry and the environment.

Influence of Intermetallic Characteristics on the Solder Joint Strength of Halogen-Free Printed Circuit Board Assembly

2011 ◽  
Vol 133 (2) ◽  
Author(s):  
Hung-Jen Chang ◽  
Jung-Hua Chou ◽  
Tao-Chih Chang ◽  
Chau-Jie Zhan ◽  
Min-Hsiung Hon ◽  
...  
Keyword(s):  
Solder Joint ◽  
Printed Circuit Board ◽  
Circuit Board ◽  
Solder Paste ◽  
Sac305 Solder ◽  
Printed Circuit ◽  
Pull Strength ◽  
Free Solder ◽  
Halogen Free ◽  
Electroless Ni

Five halogen-free (HF) dummy plastic ball grid array (PBGA) components with daisy-chains and Sn4.0Ag0.5Cu (SAC405) Pb-free solder balls were assembled on a HF high density interconnection (HDI) printed circuit board (PCB) using Sn1.0Ag0.5Cu (SAC105) and Sn3.0Ag0.5Cu (SAC305) Pb-free solder pastes, respectively. The above compositions were in weight percent. The assemblies were then experienced to moisture sensitive level testing with three times reflow at a peak temperature of 260 °C; no delamination was found present in both the component and PCB laminates. The microstructure showed that the utilization of SAC105 solder paste was beneficial in refining the Ag3Sn intermetallic compound (IMC) within the solder joint and the intermetallic layers formed at various interfaces with different Ni contents and thicknesses due to different metal finishes. The IMC spalling was found at the BGA-side interface within the solder joints formed with SAC105 solder paste but not discovered within the ones made of SAC305 solder paste. The pull strength of the solder joint formed with SAC305 solder paste was always higher than that made from SAC105 no matter on Cu or electroless Ni. Moreover, the fracture was found at the interface between the Cu foil and epoxy in the halogen-free test device. Numerical analysis showed that the thickness of IMC layer dominated the pull strength of the solder joint because the Z-axial normal stress applied to the solder joints formed with Cu and electroless Ni were 752.0 and 816.6 MPa, respectively, and a thicker IMC layer was beneficial to provide a higher pull strength of solder joint.

Development of Embedded High Power Electronics Modules for Automotive Applications

2013 ◽  
Vol 2013 (DPC) ◽  
pp. 001717-001743
Author(s):  
Lars Boettcher ◽  
S. Karaszkiewicz ◽  
D. Manessis ◽  
A. Ostmann
Keyword(s):  
Power Electronics ◽  
High Power ◽  
Printed Circuit Board ◽  
Copper Substrate ◽  
Circuit Board ◽  
Installation Space ◽  
Temperature Sinter ◽  
Die Attach ◽  
Power Modules ◽  
Power Switches

The automotive industry has a strong demand for highly reliable and cost-efficient electronics. Especially the upcoming generations of hybrid cars and fully electrical vehicles need compact and efficient 400 V power modules. Within the engine compartment installation space is of major concern. Therefore small size and high integration level of the modules are needed. Conventionally IGBTs and diodes are soldered to DCB (Direct Copper Bond) ceramics substrates and their top contacts are connected by heavy Al wire bonds. These ceramic modules are vacuum soldered to water-cooled base plates. Embedding of power switches, and controller into compact modules using PCB (Printed Circuit Board) technologies offers the potential to further improve the thermal management by double-sided cooling and to reduce the thickness of the module. In the recently started “HI-LEVEL” (Integration of Power Electronics in in High Current PCBs for Electric Vehicle Application) project, partners from automotive, automotive supplier, material supplier, PCB manufacturer and research teamed up to develop the technology, components and materials to realize high power modules. The following topics of the development will be addressed in detail in this paper:Assemble of power dies (IGBT and diode) using new sinter die attach materials:The deployment of new no pressure, low temperature sinter paste for the assembly of the power dies is a mayor development goal. Here the development of a reliable process to realize a defect free bonding of large IGBT dies (up to 10x14mm2) is essentially. These pastes are applied by stencil printing or dispensing and the sintering will take place after die placement at temperatures of around 200 °C.Thick copper substrate technology:To handle the high switching current, suitable copper tracks in the PCB are required. The realization of such thick copper lines (up to 1mm thickness) requires advanced processing, compared to conventional multilayer PCB production. In this paper the essential development steps towards a 10 kW inverter module with embedded components will be described. The process steps and reliability investigations of the different interconnect levels will be described in detail.

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