Reliability of PCB Solder Joints Assembled with SACm™ Solder Paste

2014 ◽  
Vol 2014 (1) ◽  
pp. 000367-000373 ◽  
Author(s):  
Arnab Dasgupta ◽  
Fengying Zhou ◽  
Christine LaBarbera ◽  
Weiping Liu ◽  
Paul Bachorik ◽  
...  
Keyword(s):  
Solder Joint ◽  
Thermal Aging ◽  
Test Performance ◽  
Solder Joints ◽  
Ductile Failure ◽  
Drop Test ◽  
Bulk Property ◽  
Solder Paste ◽  
Fatigue Reliability ◽  
Sac305 Solder

The solder alloy SACm™0510 has been reported to be a superior alloy when used as BGA balls, exhibiting not only an outstanding drop test performance when compared to SAC105, but also as having high thermal fatigue reliability when compared to high Ag SAC solders. In this study, SACm0510 solder was evaluated as a solder paste. The voiding behavior of SGA solder joints was comparable for SACm0510, SAC105, and SC305. When evaluating SGA assemblies on a customized drop test, SACm0510 outperformed SAC105 considerably, which in turn was much better than SAC305. The drop test performance was found to improve upon thermal aging at 150°C, and the difference between the alloys reduced significantly. This was explained by the speculated grain coarsening which resulted in a softened solder joint, and consequently, a shift of fracture mode from brittle failure toward ductile failure. This model was supported by the observation of the fractured surface moving away from the interface upon thermal aging. The improvement in drop test performance upon thermal aging can be further explained by the large solder joint size of the SGA employed in this study, where the bulk property of solder weighed more than a small solder joint. When the assembled chip resistors were evaluated with a −55°C/+125°C TCT test, no failure was observed after 369 cycles for all three alloys. SAC305 appeared to be the best in maintaining the integrity of the interfacial IMC layer. SACm0510 showed a few crack lines, but less than that of SAC105. SACm0510 solder paste was found to be very compatible with BGAs with SAC305 solder joints, and no abnormal microstructure was observed after thermal aging at 150°C for 1000 hours.

Voiding and Reliability of Assembly of BGA with SAC and 57Bi42Sn1Ag Alloys

2013 ◽  
Vol 2013 (1) ◽  
pp. 000128-000139 ◽  
Author(s):  
Yan Liu ◽  
Joanna Keck ◽  
Erin Page ◽  
Ning-Cheng Lee
Keyword(s):  
Test Performance ◽  
Shear Test ◽  
Solder Joints ◽  
Low Cost ◽  
Drop Test ◽  
Solder Paste ◽  
Weakest Link ◽  
Solder Bumps ◽  
Pasty Range ◽  
Homogenization Temperatures

Low melting 57Bi42Sn1Ag (BiSnAg) was explored for replacing SAC solders as a low-cost solution. In this study, BGAs with SAC105, SAC305, and BiSnAg balls were assembled with SAC105, SAC305 or 57Bi42Sn1Ag solder paste. Joint mechanical strength, drop test performance, and voiding performance were evaluated against the reflow profile. SnPb was included as a control. The findings are as follows: (1) The microstructure of solder joints showed that, among all of the combinations, only BiSnAg-105 LT and BiSnAg-305 LT exhibited well-distinguishable alloy regions. For SAC-BiSnAg systems, Sn-dendrites were noticeable at LT, while Ag3Sn needles developed at HT. The joints were homogeneous for the rest of the combinations. (2) In the shear test, combinations involving BiSnAg solder were brittle, regardless of the Bi alloy location and reflow profile, as evidenced by stress-strain curves and morphology of the ruptured surface. The strong influence of Bi on the rupture site may have been caused by the stiffening effect of solder due to the homogenized presence of Bi in the joint. With the stiffened solder, the brittle IMC interface became the weakest link upon shearing, although the brittle BiSn crystalline structure also contributed to the rupture. (3) In the drop test, all Bi-containing solder joints performed poorly compared with Bi-free systems, which was consistent with shear test results. Drop numbers increased with increasing elongation at break of solder bumps as measured in the shear test. (4) Voiding was affected by flux chemistry and reduced by low alloy homogenization temperatures and solid top factors, but was increased by low surface tension factor, melting sequence factor, overheating factor and wide pasty range factor. Compared to SAC or SnPb systems, the BiSnAg system is low in voiding if reflowed at LT. In this study, voiding had an insignificant effect on shear strength and drop test performance.

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.

scholarly journals Suppression of the Growth of Intermetallic Compound Layers with the Addition of Graphene Nano-Sheets to an Epoxy Sn–Ag–Cu Solder on a Cu Substrate

Materials ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 936 ◽  
Author(s):  
Min-Soo Kang ◽  
Do-Seok Kim ◽  
Young-Eui Shin
Keyword(s):  
Intermetallic Compound ◽  
Isothermal Aging ◽  
Solder Joints ◽  
Solder Paste ◽  
Shear Tests ◽  
Sac305 Solder ◽  
Epoxy Solder ◽  
The Relationship ◽  
Bonding Characteristics ◽  
Preventive Effects

This study investigated the suppression of the growth of the intermetallic compound (IMC) layer that forms between epoxy solder joints and the substrate in electronic packaging by adding graphene nano-sheets (GNSs) to 96.5Sn–3.0Ag–0.5Cu (wt %, SAC305) solder whose bonding characteristics had been strengthened with a polymer. IMC growth was induced in isothermal aging tests at 150 °C, 125 °C and 85 °C for 504 h (21 days). Activation energies were calculated based on the IMC layer thickness, temperature, and time. The activation energy required for the formation of IMCs was 45.5 KJ/mol for the plain epoxy solder, 52.8 KJ/mol for the 0.01%-GNS solder, 62.5 KJ/mol for the 0.05%-GNS solder, and 68.7 KJ/mol for the 0.1%-GNS solder. Thus, the preventive effects were higher for increasing concentrations of GNS in the epoxy solder. In addition, shear tests were employed on the solder joints to analyze the relationship between the addition of GNSs and the bonding characteristics of the solder joints. It was found that the addition of GNSs to epoxy solder weakened the bonding characteristics of the solder, but not critically so because the shear force was higher than for normal solder (i.e., without the addition of epoxy). Thus, the addition of a small amount of GNSs to epoxy solder can suppress the formation of an IMC layer during isothermal aging without significantly weakening the bonding characteristics of the epoxy solder paste.

SAC–xTiO2 nano-reinforced lead-free solder joint characterizations in ultra-fine package assembly

2018 ◽  
Vol 30 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Fakhrozi Che Ani ◽  
Azman Jalar ◽  
Abdullah Aziz Saad ◽  
Chu Yee Khor ◽  
Roslina Ismail ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Solder Joint ◽  
Solder Joints ◽  
Ion Beam ◽  
Lead Free ◽  
Lead Free Solder ◽  
Solder Paste ◽  
Content Type ◽  
X Ray ◽  
Free Solder

Purpose This paper aims to investigate the characteristics of ultra-fine lead-free solder joints reinforced with TiO2 nanoparticles in an electronic assembly. Design/methodology/approach This study focused on the microstructure and quality of solder joints. Various percentages of TiO2 nanoparticles were mixed with a lead-free Sn-3.5Ag-0.7Cu solder paste. This new form of nano-reinforced lead-free solder paste was used to assemble a miniature package consisting of an ultra-fine capacitor on a printed circuit board by means of a reflow soldering process. The microstructure and the fillet height were investigated using a focused ion beam, a high-resolution transmission electron microscope system equipped with an energy dispersive X-ray spectrometer (EDS), and a field emission scanning electron microscope coupled with an EDS and X-ray diffraction machine. Findings The experimental results revealed that the intermetallic compound with the lowest thickness was produced by the nano-reinforced solder with a TiO2 content of 0.05 Wt.%. Increasing the TiO2 content to 0.15 Wt.% led to an improvement in the fillet height. The characteristics of the solder joint fulfilled the reliability requirements of the IPC standards. Practical implications This study provides engineers with a profound understanding of the characteristics of ultra-fine nano-reinforced solder joint packages in the microelectronics industry. Originality/value The findings are expected to provide proper guidelines and references with regard to the manufacture of miniaturized electronic packages. This study also explored the effects of TiO2 on the microstructure and the fillet height of ultra-fine capacitors.

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.

scholarly journals Mechanical Properties and Interface Microstructure of SAC305 Solder Joints Made to a Ag-Pd-Pt Thick Film Metallization: Part 2—Isothermal Aging Effects

2021 ◽  
Vol 18 (3) ◽  
pp. 97-112
Author(s):  
Paul. T. Vianco ◽  
Alice. C. Kilgo ◽  
Bonnie. B. McKenzie ◽  
Shelley Williams ◽  
Robert Ferrizz ◽  
...  
Keyword(s):  
Solder Joint ◽  
Thick Film ◽  
Precipitation Hardening ◽  
Failure Modes ◽  
Solder Joints ◽  
Accelerated Aging ◽  
Process Window ◽  
Aging Effects ◽  
Sac305 Solder ◽  
Hardening Mechanism

Abstract The performance and reliability were documented for solder joints made between the 96.5Sn-3.0Ag-0.5Cu (wt.%, abbreviated SAC305) Pb-free solder and a Ag-Pd-Pt thick film conductor on an alumina substrate. The Sheppard’s hook pull test was used to assess the solder joint strength. The Part 1 study confirmed that the solder joint fabrication process had a wide process window. The current study determined that the SAC305 solder joints maintained that robustness after accelerated aging at temperatures of 70–205°C and time durations of 5–200 d. Short-term aging of 5–10 d caused a peak in the pull strength peak that resulted from precipitation hardening by Ag-Pd and (Pd, Pt)xSny intermetallic compound (IMC) particles. The pull strengths did not decrease significantly after longer aging times at 70°C and 100°C; those conditions were accelerations of typical service lifetimes. Longer aging times at temperatures of 135–205°C resulted in a gradual, albeit not catastrophic, strength decrease when the precipitation hardening mechanism was lost to dissolution of the particle phases and their reprecipitation at the solder/alumina interface. The failure modes were ductile fracture in the solder except for the most severe aging conditions. These findings confirmed that the SAC305 solder/Ag-Pd-Pt thick film interconnections have excellent long-term reliability for hybrid microcircuit and high-temperature electronics applications.

Experimental Evaluation on Solder Joint Reliability of PBGA Assembly Under Mechanical Drop Test

2002 ◽  
Author(s):  
Shi-Wei Ricky Lee ◽  
Yin-Lai Tracy Li ◽  
Hoi-Wai Ben Lui
Keyword(s):  
Solder Joint ◽  
Failure Modes ◽  
Solder Joints ◽  
Drop Test ◽  
Solder Joint Reliability ◽  
Joint Reliability ◽  
Free Solder ◽  
Board Level ◽  
Better Than ◽  
Mechanical Drop Test

The present study is intended to investigate the board level solder joint reliability of PBGA assemblies under mechanical drop test. During the course of this study, a five-leg experiment was designed to investigate various combinations of solder materials and peak reflow temperatures. Two major failure modes, namely, solder cracking and copper trace breakage, were identified. In addition, the critical location of solder joints was characterized. It was found that Sn-Pb eutectic solder joints performed better than Pb-free solder joints under mechanical impact loading.

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.

Superior Drop Test Performance of BGA Assembly Using SAC105Ti Solder Sphere

2012 ◽  
Vol 2012 (1) ◽  
pp. 000829-000843
Author(s):  
Weiping Liu ◽  
Ning-Cheng Lee ◽  
Simin Bagheri ◽  
Polina Snugovesky ◽  
Jason Bragg ◽  
...  
Keyword(s):  
Test Performance ◽  
Electrical Response ◽  
Threshold Value ◽  
Drop Test ◽  
Data Sets ◽  
Solder Paste ◽  
Partial Fracture ◽  
Pasty Range ◽  
Reflow Temperature ◽  
Complete Fracture

Board-level drop test performance was evaluated and compared for the following four different solder combinations in BGA/CSP assembly: 1) SnPb paste with SnPb balls, 2) SnPb paste with SAC105Ti balls, 3) SAC305 paste with SAC105Ti balls, and 4) SAC305 paste with SAC105 balls. Presence of Ti improved the drop test performance significantly, despite the voiding side effect caused by its oxidation tendency. It is anticipated that the voiding can be prevented with the development of a more oxidation resistant flux. The consistently poor drop test performance of 105Ti/SnPb is caused by the wide pasty range resulted from mixing SAC105 with Sn63 solder paste. The effect of Ti in this system is overshadowed by the high voiding outcome due to this wide pasty range material. In view of this, use of SAC105 BGA with SnPb solder paste is not recommended, with or without Ti addition. High reflow temperature drove fracture shift to interface at package side, presumably through building up IMC thickness beyond the threshold value. A lower reflow temperature is recommended. Electrical response is consistent with complete fracture data. But, complete fracture trend is inconsistent with that of partial fracture trend, and neither data can provide a full understanding about the failure mode. By integrating complete fracture and partial fracture into “Virtual Fracture”, the failure mechanism becomes obvious and data sets become consistent with each other.

The Cause Analysis of Pseudo Solder in Surface Mounted Technology

2010 ◽  
Vol 146-147 ◽  
pp. 895-898
Author(s):  
Fu Pei Wu ◽  
Sheng Ping Li
Keyword(s):  
Solder Joint ◽  
Technological Process ◽  
Solder Joints ◽  
Solder Paste ◽  
Cause Analysis ◽  
Solder Material ◽  
Five Factors ◽  
Degree Of Satisfaction ◽  
Solder Paste Printing

Pseudo solder is one kind of familiar solder joint defect, and it is very difficult to be detected in surface mounted technology. Reduce the pseudo solder is viewed as one of effectively way to keep the quality of solder joints. In this manuscript, the quality of component, solder paste printing process, mounting processing, reflowing process, solder material are analyzed to illustrate the cause of pseudo solder in surface mounted technology. Based on the five factors, a pseudo solder model is built for IC component. In the pseudo solder model, its parameters are used corresponding to the cause of pseudo solder, and their values are used to evaluate the degree of satisfaction based on the SMT technological process. Experiments results show that parameters of the pseudo solder model can illustrate the cause of pseudo solder effectively.

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