Novel Solder Alloy: Wide Service Temperature Capability for Automotive Applications (original) (raw)
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Sn3.2Ag0.7Cu5.5Sb Solder Alloy with High Reliability Performance up to 175C
International Symposium on Microelectronics, 2018
A novel lead-free solder alloy 90.6Sn3.2Ag0.7Cu5.5Sb, designated as Indalloy276, was developed targeting for high reliability with a wide service temperature capability. The alloy exhibited a melting temperature range of 223 to 232°C, reflowable at profile with peak temperature 245°C and 255°C, with ambient temperature Yield Stress 60MPa, UTS 77 MPa, and ductility 28%, and a higher stress than both SAC305 and SACBSbN, the latter two alloys were used as controls. When tested at 140°C and 165°C, the die shear stress of 276 was comparable with SACBSbN but higher than SAC305, and the ductility was higher than both SACBSbN and SAC305, with SACBSbN exhibited distinct brittle behavior. When aged at 125°C and 175°C, the die shear strength of 276 was comparable or higher than both controls. When pretreated with a harsh condition, TST (−55°C/155°C) for 3000 cycles, the die shear strength of 276 was 8 times of that of SACBSbN and SAC305. When pre-conditioned at TCT (−40°C/175°C) for 3000 cycle...
Unveiling High Performance Solder Alloys for Automotive Applications
IMAPSource Proceedings
Vehicle electrification and advances in autonomous driving technologies are creating unique opportunities and challenges in the automotive electronics assembly industry. The ever-increasing demand of reliability at higher temperatures and longer service life, especially for automotive electronics, is leading to the evolution of high reliability solder alloy design in the electronics assembly industry. The combination of harsh operating conditions, increasing power densities, and miniaturization has added to the complexity of assembly designs in the automotive electronics market for which traditional surface mount solders are no longer applicable. Thermo-mechanical reliability of solder alloys under harsh operating conditions has been a primary factor for defining suitability and selection of solder alloy for next generation designs. A next generation high reliability alloy for automotive electronics is introduced herein. The microstructure of this novel alloy consists of a well-dist...
Reliability of New SAC-Bi Solder Alloys in Thermal Cycling with Aging
2020
Drive towards lead-free electronics began in the early 2000s. Solder pastes based on tin (Sn), copper (Cu), and silver (Ag) were the initial replacement for the traditional SnPb solder. With the SAC alloys, several researches reported that one year of aging consumed more than 50% of the component life. Once the detrimental effects of aging were discovered, the industry started the search for better solder paste materials. The SAC based pastes were made better by adding elements such as Bismuth (Bi), Antimony (Sb), Nickel (Ni). Recently, all the leading manufacturers have introduced new solder materials that claim to have high reliability in harsh environments. Extensive tests are required to filter the best solder pastes. In the study, three high reliability solder materials from leading manufacturers have been selected and used for the test vehicle assembly. SAC305 paste is also included for comparison with the new materials. The test vehicle is a printed circuit board (PCB) of FR-...
Thermal Cycling Reliability of Alternative Low-Silver Tin-based Solders
International Symposium on Microelectronics, 2013
Sn-3.0Ag-0.5Cu (SAC305) alloy is the most widely used solder in electronic assemblies. However, issues associated with cost and drop/shock durability have resulted in a continued search for alternative solder alloys. One approach to improve the drop/shock reliability has been to reduce the silver content in Sn-Ag-Cu alloys. Another approach is doping Sn-Ag-Cu solder with additional elements. Moreover, conflicting results have been reported in literature on the effects of aging on Sn-Ag-Cu alloys. In 2008, International Electronics Manufacturing Initiative (iNEMI) started the “Characterization of Pb-Free Alloy Alternatives” project to provide a comprehensive study of fifteen tin-based solder interconnect compositions benchmarked against the eutectic tin-lead solder. For this study, temperature cycle durability was the primary focus and solders were selected to study the effect of varying silver content, microalloy additions, and aging. This paper reports the preliminary findings from...
IEEE Transactions on Device and Materials Reliability, 2011
Applications with temperatures higher than the melting point of eutectic tin-lead solder (183°C) require high-melting-point solders. However, they are expensive and not widely available. With the adoption of lead-free legislation, first in Europe and then in many other countries, the electronics industry has transitioned from eutectic tin-lead to lead-free solders that have higher melting points. This higher melting point presents an opportunity for the manufacturers of high-temperature electronics to shift to mainstream lead-free solders. In this paper, ball grid arrays (BGAs), quad flat packages, and surface mount resistors assembled with SAC305 (96.5%Sn+3.0%Ag+0.5Cu) and Sn3.5Ag (96.5%Sn+3.5%Ag) solder pastes were subjected to thermal cycling from -40°C to 185°C. Commercially available electroless nickel immersion gold board finish was compared to custom Sn-based board finish designed for high temperatures. The data analysis showed that the type of solder paste and board finish used did not have an impact on the reliability of BGA solder joints. The failure analysis revealed the failure site to be on the package side of the solder joint. The evolution of intermetallic compounds after thermal cycling was analyzed.
High-Reliability Low-Ag-Content Sn-Ag-Cu Solder Joints for Electronics Applications
Journal of Electronic Materials, 2012
SnAg -Cu (SAC) alloy is currently recognized as the standard lead-free solder alloy for packaging of interconnects in the electronics industry, and high-Ag-content SAC alloys are the most popular choice. However, this choice has been encumbered by the fragility of the solder joints that has been observed in drop testing as well as the high cost of the Ag itself. Therefore, low-Ag-content SAC alloy was considered as a solution for both issues. However, this approach may compromise the thermal-cycling performance of the solders. Therefore, to enhance the thermal-cycling reliability of low-Ag-content SAC alloys without sacrificing their drop-impact performance, alloying elements such as Mn, Ce, Ti, Bi, In, Sb, Ni, Zn, Al, Fe, and Co were selected as additions to these alloys. However, research reports related to these modified SAC alloys are limited. To address this paucity, the present study reviews the effect of these minor alloying elements on the solder joint reliability of low-Ag-content SAC alloys in terms of thermal cycling and drop impact. Addition of Mn, Ce, Bi, and Ni to low-Ag-content SAC solder effectively improves the thermal-cycling reliability of joints without sacrificing the drop-impact performance. Taking into consideration the improvement in the bulk alloy microstructure and mechanical properties, wetting properties, and growth suppression of the interface intermetallic compound (IMC) layers, addition of Ti, In, Sb, Zn, Al, Fe, and Co to low-Ag-content SAC solder has the potential to improve the thermal-cycling reliability of joints without sacrificing the drop-impact performance. Consequently, further investigations of both thermal-cycling and drop reliability of these modified solder joints must be carried out in future work.
The influence of aging on the stress-strain and creep behavior of sac solder alloys
2010
The microstructure, mechanical response, and failure behavior of lead free solder joints in electronic assemblies are constantly evolving when exposed to isothermal aging and/or thermal cycling environments. In our prior work on aging effects, we have demonstrated that the observed material behavior variations of Sn-Ag-Cu (SAC) lead free solders during room temperature aging (25 o C) and elevated temperature aging (125 o C) were unexpectedly large and universally detrimental to reliability. Such effects for lead free solder materials are especially important for the harsh applications environments present in high performance computing and in automotive, aerospace, and defense applications. However, there has been little work in the literature, and the work that has been done has concentrated on the degradation of solder ball shear strength (e.g. Dage Shear Tester). Current finite element models for solder joint reliability during thermal cycling accelerated life testing are based on traditional solder constitutive and failure models that do not evolve with material aging. Thus, there will be significant errors in the calculations with the new lead free SAC alloys that illustrate dramatic aging phenomena.
Low Temperature Soldering : Thermal Cycling Reliability Performance
2019
The technical and economic benefits derived from lowering the reflow temperatures have motivated the evaluation of new SnBi low temperature alloys for soldering. Eutectic Sn-Bi alloy is usually described as having a brittle nature, not being able to sustain mechanical shock and thermal cycling stresses as well as Sn3Ag30.5Cu (SAC305) solder. A new non-eutectic Sn-Bi solder with 2 wt.% additives (generally called here as alloy A) is evaluated here and compared with other eutectic Sn-Bi alloys and SAC305.Tensile tests at -55 oC, -25 oC, +25 oC, +75 oC and +125oC were performed to provide insights on their relative mechanical properties. Mechanical drop shock tests of BGA84 and LGA84 were performed as per the JESD22-B111 standard, while thermal cycling tests were performed from -40oC (10 min) to +125oC (10 min) as per the IPC 9701 standard. The BGA84 was used for thermal cycling in situ monitoring, while BGA169, SOT223, QFP44 and 1206 chip resistors were also used for evaluating the ef...
Thermal cycling reliability of lead free solders for automotive applications
2004
The solder joint reliability of ceramic chip resistors assembled to laminate substrates has been a long time concern for systems exposed to hush environments such as those found in automotive and aerospace applications. This is due to a combination of the extreme t e m p e r a m excursions experienced by the assemblies along with the large coefficient of thermal expansion mismatches between the alumina bodies of the chip resistors and the glass-epoxy composites of the printed circuit boards (PCBs). These reliability challenges are exacerbated for components with larger physical size (distance to neutral point) such as the 2512 resistors used in situations where higher voltages and/or currents lead to power dissipations up to 1 Wan. In this work the thermal cycling reliability of several 2512 chip resistor lead free solder joint configurations has been investigated. In an initial study, a comparison has been made between the solder joint reliabilities obtained with components fabricated with both tin-lead and pure tin solder terminations. In the main portion of the reliability testing, two temperature ranges (-40 to 125 "C and -40 to 150 "C) and five different solder alloys have been examined. The investigated solders include the normal eutectic SnAgCu (SAC) alloy recommended by earlier studies (95.5Sn-3.8Ag-O.7Cu), and three variations of the lead free ternary SAC alloy that include small quaternary additions of bismuth and indium to enhance fatigue resistance. For each configuration, thermal cycling failure data has been gathered and analysed using two-parameter Weibull models to rank the relative material performances. The obtained lead free results have been compared lo data for standard 63Sn-37Pb joints. In addition, a second set of thermally cycled samples was used for microscopy studies to examine crack propagation, changes in the microstructure of the solders, and intermetallic growth at the solder to PCB pad interfaces.
Design and Properties of New Lead-Free Solder Joints Using Sn-3.5Ag-Cu Solder
Silicon, 2018
This article aims to reduce the melting temperature of lead-free solder alloy and promote its mechanical properties. Eutectic tin-silver lead-free solder has a high melting temperature 221 • C used for electronic component soldering. This melting temperature, higher than that of lead-tin conventional eutectic solder, is about 183 • C. The effect of the melt spinning process and copper additions into eutectic SnAg solder enhances the crystallite size to about 47.92 nm which leads to a decrease in the melting point to about 214.70 • C, where the reflow process for low heat-resistant components on print circuit boards needs lower melting point solder. The results showed the presence of intermetallic compound Ag 3 Sn formed in nano-scale at the Sn-3.5Ag alloy due to short time solidification. The presence of new intermetallic compound, IMC from Ag 0.8 Sn 0.2 and Ag phase improves the mechanical properties, and then enhances the micro-creep resistance especially at Sn-3.5Ag-0.7Cu. The higher Young's modulus of Sn-3.5Ag-0.5Cu alloy 55.356 GPa could be attributed to uniform distribution of eutectic phases. Disappearance of tin whiskers in most of the lead-free melt-spun alloys indicates reduction of the internal stresses. The stress exponent (n) values for all prepared alloys were from 4.6 to 5.9, this indicates to climb deformation mechanism. We recommend that the Sn 95.7-Ag 3.5-Cu 0.7 alloy has suitable mechanical properties, low internal friction 0.069, low pasty range 21.7 • C and low melting point 214.70 • C suitable for step soldering applications.