scholarly journals Electrical resistivity of Sn–3.0Ag–0.5Cu solder joint with the incorporation of carbon nanotubes

2021 ◽  
Vol 11 ◽  
pp. 184798042199653
Author(s):  
Norliza Ismail ◽  
Azman Jalar ◽  
Atiqah Afdzaluddin ◽  
Maria Abu Bakar
Keyword(s):  
Electrical Resistivity ◽  
Carbon Nanotube ◽  
Solder Joint ◽  
Solder Matrix ◽  
Optical Microscope ◽  
Eutectic Phase ◽  
Circuit Board ◽  
Distribution Area ◽  
Solder Paste ◽  
Mechanical Mixing

The main objective of this study is to investigate the electrical properties of Sn–3.0Ag–0.5Cu solder joint with the incorporation of carbon nanotube instead of solder bulk. Sn–3.0Ag–0.5Cu solder paste with the incorporation of carbon nanotube up to 0.04 wt% was fabricated by using mechanical mixing method. Fabricated solder pastes were then soldered on printed circuit board via reflow soldering at 260°C peak temperature. Electrical resistivity of Sn–3.0Ag–0.5Cu-carbon nanotube solder joints was measured by the four-point probe method at room temperature. Microstructure properties were observed by optical microscope and field emission scanning electron microscope. Electrical resistivity of Sn–3.0Ag–0.5Cu solder joint was found to increase with the incorporation carbon nanotube up to 0.03 wt% and slightly decrease at 0.04 wt%. Incorporation of carbon nanotube in the solder matrix apparently changes the microstructure of Sn–Ag–Cu solder alloys. Microstructural observation found that electrical resistivity correlated with the distribution area of eutectic phase in the solder matrix due to the existence of carbon nanotube. It was revealed that eutectic phase area increases with the increasing of carbon nanotube wt% up to 0.03 and then slightly decreases at the incorporation of 0.04 wt% carbon nanotube as parallel with the trend of electrical resistivity values.

The Benefits of Flux-Coated Solder Preforms in a QFN Assembly Process

2015 ◽  
Vol 2015 (1) ◽  
pp. 000827-000832
Author(s):  
Brandon Judd ◽  
Maria Durham
Keyword(s):  
Mechanical Properties ◽  
Form Factor ◽  
Solder Joint ◽  
Circuit Board ◽  
Electrical Performance ◽  
Solder Paste ◽  
Assembly Process ◽  
Circuit Board Assembly ◽  
Difficult Challenge ◽  
Small Form Factor

The use of bottom terminated components (BTCs) such as quad-flat no-leads (QFNs) has become commonplace in the circuit board assembly world. This package offers several benefits including its small form factor, its excellent thermal and electrical performance, easy PCB trace routing, and reduced lead inductance. These components are generally attached to PWBs PCBs via solder paste. The design of these components with the large thermal pad, along with the tendency of solder paste to outgas during reflow from the volatiles in the flux, creates a difficult challenge in terms of voiding control within the solder joint. Voiding can have a serious effect on the performance of these components, including the mechanical properties of the joint as well as spot overheating. Solder preforms with a flux coating can be added to the solder paste to help reduce voiding. This study will focus on the benefits of utilizing solder preforms with modern flux coatings in conjunction with solder paste to help reduce voiding under QFNs, as well as the design and process parameters which provide optimal results.

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.

Pb-Free Thin Small Outline Package (TSOP) Board Level Reliability Study

2009 ◽  
Author(s):  
Weidong Xie ◽  
Kuo-Chuan Liu ◽  
Mark Brillhart
Keyword(s):  
Solder Joint ◽  
Coefficient Of Thermal Expansion ◽  
Circuit Board ◽  
Solder Paste ◽  
Eutectic Solder ◽  
Qualification Testing ◽  
Free Solder ◽  
Board Level ◽  
The Impact

Thin Small Outline Package (TSOP) are one of the most commonly used surface mount components due to its low overall cost. Traditionally leadframe packages such as TSOP or Quad Flat Package (QFP) are less of a concern (if assembled with SnPb eutectic solder paste) about their long term reliability and often exempted from board level qualification testing as the mechanical compliance of metal leads mitigate the stresses due to the Coefficient of Thermal Expansion (CTE) mismatch between the package and Print Circuit Board (PCB). Therefore more attention has been put on the solder joint reliability of Pb-free Ball Grid Array (BGA) packages over leadframe packages while the industry is moving away from SnPb eutectic solder materials to meet RoHS regulatory requirements. The authors have observed that TSOPs if assembled with Pb-free solder materials could fail at very early stages during qualification testing (in some case as early as 300 cycles under standard 0°C to 100°C thermal cycling). Since most Pb-free solder materials such as SnAgCu are mechanically more rigid than SnPb eutectic solder material, higher stresses are expected be induced in solder joints during temperature excursions. Pb-free solder materials’ wicking behavior may also contribute to the early failures. In this study, long term reliability of a flash memory TSOP has been investigated. These tested TSOPs, assembled on 93mil-thick PCBs with SAC305 paste, are of two configurations: one with single die and the other with stacked quadruple dies. Some test vehicles have been thermally aged under four different thermal aging conditions to study the aging effect on Pb-free solder joint life. Finite element analysis (FEA) modeling has also been employed to further investigate the impact of other parameters such as die size, package size, and the number of dies that being stacked inside one package.

scholarly journals The Effect of Epoxy Polymer Addition in Sn-Ag-Cu and Sn-Bi Solder Joints

Materials ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 960 ◽  
Author(s):  
Min-Soo Kang ◽  
Do-Seok Kim ◽  
Young-Eui Shin
Keyword(s):  
Solder Joint ◽  
Strain Energy ◽  
Printed Circuit Board ◽  
Solder Joints ◽  
Circuit Board ◽  
Solder Paste ◽  
Element Analysis ◽  
Printed Circuit ◽  
Shock Testing ◽  
Polymer Addition

To analyze the reinforcement effect of adding polymer to solder paste, epoxies were mixed with two currently available Sn-3.0Ag-0.5Cu (wt.% SAC305) and Sn-59Bi (wt.%) solder pastes and specimens prepared by bonding chip resistors to a printed circuit board. The effect of repetitive thermal stress on the solder joints was then analyzed experimentally using thermal shock testing (−40 °C to 125 °C) over 2000 cycles. The viscoplastic stress–strain curves generated in the solder were simulated using finite element analysis, and the hysteresis loop was calculated. The growth and propagation of cracks in the solder were also predicted using strain energy formulas. It was confirmed that the epoxy paste dispersed the stress inside the solder joint by externally supporting the solder fillet, and crack formation was suppressed, improving the lifetime of the solder joint.

CONTROLLING AND OPTIMIZATION OF THERMAL PROFILE IN REFLOW SOLDERING

2009 ◽  
Vol 23 (06n07) ◽  
pp. 1949-1955
Author(s):  
JIANWEI SHI ◽  
PENG HE ◽  
XIAOCHUN LV
Keyword(s):  
Solder Joint ◽  
Circuit Board ◽  
Solder Paste ◽  
Thermal Profile ◽  
Reflow Soldering ◽  
Soldering Process ◽  
Joint Reliability ◽  
Controlling Parameter ◽  
Technical Evaluation ◽  
Reliability Of Solder Joints

Heating factor, Q is a quantitative parameter describing a process of reflow soldering. It can be used to evaluate a reflow soldering process and the reliability of solder joints. The value of Q is directly related to the energy absorbed by solder joint during heating and the morphology of Intermetallic Compound formed at the interface between solder and pad. Electronic product manufacturers use heating factor as a technical evaluation parameter to guide the adjustment of reflow soldering process and the optimization of reflow soldering curve, to ensure the best reliability of the circuit board. Solder paste manufacturers use heating factor to represent characteristics of their reflow soldering products, and to customize products according to consumer's requests. Equipment manufacturers for reflow soldering use heating factor as an important controlling parameter to establish automatic system for managing solder joint reliability. A reliable soldering result can be achieved using the automatic reflow management system, to control and optimize thermal profile, which leads to the adjustment of the heating factor.

Experimental approach to thermal conductivity of macro solder joints with voids

2019 ◽  
Vol 31 (3) ◽  
pp. 181-191 ◽  
Author(s):  
Maciej Sobolewski ◽  
Barbara Dziurdzia
Keyword(s):  
Thermal Conductivity ◽  
Solder Joint ◽  
Solder Joints ◽  
Copper Plate ◽  
Circuit Board ◽  
Solder Paste ◽  
Reflow Soldering ◽  
Content Type ◽  
Copper Cylinder ◽  
The Impact

Purpose The purpose of the paper is to experimentally evaluate the impact of voids on thermal conductivity of a macro solder joint formed between a copper cylinder and a copper plate by using reflow soldering. Design/methodology/approach A model of a surface mount device (SMD) was developed in the shape of a cylinder. A copper plate works as a printed circuit board (PCB). The resistor was connected to a power supply and the plate was cooled by a heat sink and a powerful fan. A macro solder joint was formed between a copper cylinder and a copper plate using reflow soldering and a lead-free solder paste SAC305. The solder paste was printed on a plate through stencils of various apertures. It was expected that various apertures of stencils will moderate the various void contents in solder joints. K-type thermocouples mounted inside cylinders and at the bottom of a plate underneath the cylinders measured the temperature gradient on both sides of the solder joint. After finishing the temperature measurements, the cylinders were thinned by milling to thickness of about 2 mm and then X-ray images were taken to evaluate the void contents. Finally the tablets were cross-sectioned to enable scanning electron microscopy (SEM) observations. Findings There was no clear dependence between thermal conductivity of solder joints and void contents. The authors state that other factors such as intermetallic layers, microcracks, crystal grain morfologyof the interface between the solder and the substrate influence on thermal conductivity. To support this observation, further investigations using metallographic methods are required. Originality/value Results allow us to assume that the use of SAC305 alloy for soldering of components with high thermal loads is risky. The common method for thermal balance calculation is based on the sum of serial thermal resistances of mechanical compounds. For these calculations, solder joints are represented with bulk SAC305 thermal conductivity parameters. Thermal conductivity of solder joints for high density of thermal energy is much lower than expected. Solder joints’ structure is not fully comparable with bulk SAC305 alloy. In experiments, the average value of the solder joint conductivity was found to be 8.1 W/m·K, which is about 14 per cent of the nominal value of SAC305 thermal conductivity.

Microstructural evolution and micromechanical properties of SAC305/CNT/CU solder joint under blast wave condition

2020 ◽  
Vol 33 (1) ◽  
pp. 47-56
Author(s):  
Norliza Ismail ◽  
Azman Jalar ◽  
Maria Abu Bakar ◽  
Nur Shafiqa Safee ◽  
Wan Yusmawati Wan Yusoff ◽  
...  
Keyword(s):  
Solder Joint ◽  
Blast Wave ◽  
Microstructural Evolution ◽  
Circuit Board ◽  
Solder Paste ◽  
Sac305 Solder ◽  
Wave Condition ◽  
Content Type ◽  
Micromechanical Properties ◽  
Sac Solder

Purpose The purpose of this paper is to investigate the effect of carbon nanotube (CNT) addition on microstructure, interfacial intermetallic compound (IMC) layer and micromechanical properties of Sn-3.0Ag-0.5Cu (SAC305)/CNT/Cu solder joint under blast wave condition. This work is an extension from the previous study of microstructural evolution and hardness properties of Sn-Ag-Cu (SAC) solder under blast wave condition. Design/methodology/approach SAC/CNT solder pastes were manufactured by mixing of SAC solder powder, fluxes and CNT with 0.02 and 0.04 by weight percentage (Wt.%) separately. This solder paste then printed on the printed circuit board (PCB) with the copper surface finish. Printed samples underwent reflow soldering to form the solder joint. Soldered samples then exposed to the open field air blast test with different weight charges of explosives. Microstructure, interfacial IMC layer and micromechanical behavior of SAC/CNT solder joints after blast test were observed and analyzed via optical microscope, field emission scanning microscope and nanoindentation. Findings Exposure to the blast wave induced the microstructure instability of SAC305/Cu and SAC/CNT/Cu solder joint. Interfacial IMC layer thickness and hardness properties increases with increase in explosive weight. The existence of CNT in the SAC305 solder system is increasing the resistance of solder joint to the blast wave. Originality/value Response of micromechanical properties of SAC305/CNT/Cu solder joint has been identified and provided a fundamental understanding of reliability solder joint, especially in extreme conditions such as for military applications.

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.

Materials Characterization of Lead Free Compositions for Minimum Temperature SMT Processes at the SLI-Second Level Interconnect Solder Joint

2004 ◽  
Author(s):  
Norman J. Armendariz ◽  
Prawin Paulraj
Keyword(s):  
Solder Joint ◽  
Printed Circuit Board ◽  
Gold Surface ◽  
Circuit Board ◽  
Lead Free ◽  
Processing Temperature ◽  
The European Union ◽  
Printed Circuit ◽  
Higher Temperature ◽  
Tin Silver Copper

Abstract The European Union is banning the use of Pb in electronic products starting July 1st, 2006. Printed circuit board assemblies or “motherboards” require that planned CPU sockets and BGA chipsets use lead-free solder ball compositions at the second level interconnections (SLI) to attach to a printed circuit board (PCB) and survive various assembly and reliability test conditions for end-use deployment. Intel is pro-actively preparing for this anticipated Pb ban, by evaluating a new lead free (LF) solder alloy in the ternary Tin- Silver-Copper (Sn4.0Ag0.5Cu) system and developing higher temperature board assembly processes. This will be pursued with a focus on achieving the lowest process temperature required to avoid deleterious higher temperature effects and still achieve a metallurgically compatible solder joint. One primary factor is the elevated peak reflow temperature required for surface mount technology (SMT) LF assembly, which is approximately 250 °C compared to present eutectic tin/lead (Sn37Pb) reflow temperatures of around 220 °C. In addition, extended SMT time-above-liquidus (TAL) and subsequent cooling rates are also a concern not only for the critical BGA chipsets and CPU BGA sockets but to other components similarly attached to the same PCB substrate. PCBs used were conventional FR-4 substrates with organic solder preservative on the copper pads and mechanical daisychanged FCBGA components with direct immersion gold surface finish on their copper pads. However, a materials analysis method and approach is also required to characterize and evaluate the effect of low peak temperature LF SMT processing on the PBA SLI to identify the absolute limits or “cliffs” and determine if the minimum processing temperature and TAL could be further lowered. The SLI system is characterized using various microanalytical techniques, such as, conventional optical microscopy, scanning electron microscopy, energy dispersive spectroscopy and microhardness testing. In addition, the SLI is further characterized using macroanalytical techniques such as dye penetrant testing (DPT) with controlled tensile testing for mechanical strength in addition to disbond and crack area mapping to complete the analysis.

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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