How Silver Powder Metallurgy Affects the Physical Properties of Low Temperature Firing Silver Conductor

2011 ◽  
Vol 2011 (1) ◽  
pp. 000099-000106 ◽  
Author(s):  
Samson Shahbazi ◽  
Mark Challingsworth
Keyword(s):  
Powder Metallurgy ◽  
Thick Film ◽  
Silver Powder ◽  
Lead Free ◽  
Lead Free Solder ◽  
Pure Silver ◽  
Solder Alloys ◽  
Film Conductor ◽  
Free Solder ◽  
Lead Free Solders

With the implementation of RoHS (the Restriction of Hazardous Substance) Directive banning the use of Lead, Cadmium, Mercury and Hexavalent Chromium, hybrid microelectronic manufacturers are globally embracing the lead free movement. These manufacturers must not only understand the implications of their material choice but must be aware of the interaction between lead free solder alloys and their RoHS compliant thick film materials. It is commonly known that lead free solder alloys process at much higher reflow temperatures than lead containing solder which can directly impact the fired film leach resistance and the loss of adhesion. There are also other concerns; lead free solders alloys generally require a different organic flux system to promote wetting and reflow, but this change may cause a fired film conductor to leach more easily than the flux used in the lead containing solders. The use of lead free solders such as SAC305, SAC405 or 95/5 on a low firing (550–570 °C) pure silver conductor has the tendency of leaching the fired film more readily than conductors containing small amounts of palladium or platinum. Many of these situations provide new challenges for the hybrid circuit manufacturer. There is little information available regarding the effects of the lead free solders on low firing silver thick film conductors. This paper discusses the results of a newly developed Pb and Cd free silver thick film conductor paste with a modified silver powder metallurgy to improve the leach resistance, solder acceptance and adhesion using lead free solder. In addition, the pure silver conductor was fired on top of a low temperature dielectric paste. This conductor was evaluated by comparing lead free solder alloys to traditional tin-lead-silver solder alloys. This study included evaluations based on SEM photos, solderability, leach resistance, and initial and long term adhesions. Results are published describing the difference in behavior between the different solder alloys in conjunction with the different silver powder metallurgy.

Solder Joint Reliability of Sn-Cu and Sn-Ag-Cu Lead-Free Solder Alloys Solidified on Copper Substrates with Different Surface Roughnesses

2015 ◽  
Vol 830-831 ◽  
pp. 265-269
Author(s):  
Satyanarayan ◽  
K.N. Prabhu
Keyword(s):  
Solder Joint ◽  
Solder Matrix ◽  
Lead Free ◽  
Lead Free Solder ◽  
Solder Alloys ◽  
Cu Substrate ◽  
Cu Substrates ◽  
Free Solder ◽  
Substrate Surfaces ◽  
Lead Free Solders

In the present work, the bond strength of Sn-0.7Cu, Sn-0.3Ag-0.7Cu, Sn-2.5Ag-0.5Cu and Sn-3Ag-0.5Cu lead free solders solidified on Cu substrates was experimentally determined. The bond shear test was used to assess the integrity of Sn–Cu and Sn–Ag–Cu lead-free solder alloy drops solidified on smooth and rough Cu substrate surfaces. The increase in the surface roughness of Cu substrates improved the wettability of solders. The wettability was not affected by the Ag content of solders. Solder bonds on smooth surfaces yielded higher shear strength compared to rough surfaces. Fractured surfaces revealed the occurrence of ductile mode of failure on smooth Cu surfaces and a transition ridge on rough Cu surfaces. Though rough Cu substrate improved the wettability of solder alloys, solder bonds were sheared at a lower force leading to decreased shear energy density compared to the smooth Cu surface. A smooth surface finish and the presence of minor amounts of Ag in the alloy improved the integrity of the solder joint. Smoother surface is preferable as it favors failure in the solder matrix.

Nanoindentation Characterization of Lead-free Solders and Intermetallic Compounds under Thermal Aging

2010 ◽  
Vol 2010 (1) ◽  
pp. 000314-000318
Author(s):  
Tong Jiang ◽  
Fubin Song ◽  
Chaoran Yang ◽  
S. W. Ricky Lee
Keyword(s):  
Mechanical Properties ◽  
Thermal Aging ◽  
Solder Joints ◽  
Lead Free ◽  
Small Range ◽  
Lead Free Solder ◽  
Solder Alloys ◽  
Aging Test ◽  
Free Solder ◽  
Lead Free Solders

The enforcement of environmental legislation is pushing electronic products to take lead-free solder alloys as the substitute of traditional lead-tin solder alloys. Applications of such alloys require a better understanding of their mechanical behaviors. The mechanical properties of the lead-free solders and IMC layers are affected by the thermal aging. The lead-free solder joints on the pads subject to thermal aging test lead to IMC growth and cause corresponding reliability concerns. In this paper, the mechanical properties of the lead-free solders and IMCs were characterized by nanoindentation. Both the Sn-rich phase and Ag3Sn + β-Sn phase in the lead-free solder joint exhibit strain rate depended and aging soften effect. When lead-free solder joints were subject to thermal aging, Young's modulus of the (Cu, Ni)6Sn5 IMC and Cu6Sn5 IMC changed in very small range. While the hardness value decreased with the increasing of the thermal aging time.

Intermetallic Study on the Modified Sn-3.5Ag-1.0Cu-1.0Zn Lead Free Solder

2016 ◽  
Vol 857 ◽  
pp. 3-7 ◽  
Author(s):  
Ramani Mayappan ◽  
Nur Nadiah Zainal Abidin ◽  
Noor Asikin Ab Ghani ◽  
Iziana Yahya ◽  
Norlin Shuhaime
Keyword(s):  
Electron Microscope ◽  
Powder Metallurgy ◽  
Joint Strength ◽  
Lead Free ◽  
Environmental Concerns ◽  
Lead Free Solder ◽  
Free Solder ◽  
Lead Free Solders ◽  
Powder Metallurgy Route ◽  
Scanning Electron

Due to environmental concerns, lead-free solders were introduced to replace the lead-based solders in microelectronics devices technology. Although there are many lead-free solders available, the Sn-Ag-Cu solders are considered the best replacement due to their good wettability and joint strength. Although the Sn-Ag-Cu solders are accepted widely, but there are still some room for improvement. In this study, 1wt% Zn, which can be considered high percentage for a dopant, was added into the solder via powder metallurgy route. The effects of adding this dopant into the Sn-3.5Ag-1.0Cu solder on the interface intermetallic and thickness were investigated. The intermetallics phases formed were observed under Scanning Electron Microscope (SEM) and their thicknesses were measured. The SEM results showed the presence of Cu6Sn5, Cu3Sn and (Cu,Zn)6Sn5 intermetallics. It can be concluded that Zn behaved as retarding agent and significantly retarded the growth of Cu-Sn intermetallics.

Aging Induced Mechanical Property Degradation and Microstructure Evolution of SAC+X Lead Free Solder Alloys

2013 ◽  
Author(s):  
Zijie Cai ◽  
Jeffrey C. Suhling ◽  
Pradeep Lall ◽  
Michael J. Bozack
Keyword(s):  
Thermal Cycling ◽  
Aging Time ◽  
Aging Temperature ◽  
Lead Free ◽  
Lead Free Solder ◽  
Solder Alloys ◽  
Stress Strain ◽  
Free Solder ◽  
Effects Of Aging ◽  
Lead Free Solders

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 large degradations occur in the material properties (stiffness and strength) and creep behavior of Sn-Ag-Cu (SAC) lead free solders during aging. These effects are universally detrimental to reliability and are exacerbated as the aging temperature and aging time increases. Conversely, changes due to aging are relatively small in conventional Sn-Pb solders. In our current work, we are exploring several doped SAC+X alloys in an attempt to reduce the aging induced degradation of the material behavior of SAC solders. The doped materials are lead free SAC solders that have been modified by the addition of small percentages of one or more additional elements (X). Using dopants (e.g. Bi, In, Ni, La, Mg, Mn, Ce, Co, Ti, Zn, etc.) has become widespread to enhance shock/drop reliability, wetting, and other properties; and we have extended this approach to examine the ability of dopants to reduce the effects of aging and extend thermal cycling reliability. In this paper, we concentrate on presenting the results for SAC+X (X = Zn, Co, Ni). The enhancement of aging resistance for the doped lead free solders was explored. Comparisons were made to the responses of non-doped SAC lead free solder alloys. The effects of aging on mechanical behavior have been examined by performing stress-strain and creep tests on solder samples that were aged for various durations (0–6 months) at elevated temperature (100 °C). Variations of the mechanical and creep properties (elastic modulus, yield stress, ultimate strength, creep compliance, etc.) were observed and modeled as a function of aging time and aging temperature. Our findings show that the doped SAC+X alloys illustrate reduced degradations with aging for all of the aging temperatures considered. Also, the stress-strain and creep mechanical properties of doped solders are better than those of reference solders after short durations of aging. After long term aging, doped solder alloys were found to have more stable behaviors than those of the standard SAC alloys. A parallel microstructure study has shown that less degradation and coarsening of the phases occurs in doped solder materials relative to non-doped solders after severe aging.

Bismuth-Antimony as an Alternative for High Temperature Lead Free Solder

2012 ◽  
Vol 476-478 ◽  
pp. 1163-1168 ◽  
Author(s):  
M.Z. Shahrul Fadzli ◽  
M.A. Azmah Hanim ◽  
T. Sai Hong ◽  
A. Aidy ◽  
R. Rohaizuan
Keyword(s):  
High Temperature ◽  
Solder Alloy ◽  
Lead Free ◽  
Lead Free Solder ◽  
Solder Alloys ◽  
Bulk Analysis ◽  
Rich Phase ◽  
Solder Bulk ◽  
Free Solder ◽  
Lead Free Solders

The development works on high temperature lead free solder are mostly discussed nowadays. To replace the current high temperature lead free solders, further research need to be done. A great deal of effort has been put into the development of lead free solder alloys. Bi (Bismuth) and Sb (Antimony) solder system proved as one of the promising candidates for electronic assembly. Melting temperature of three Bi-Sb solder alloys studied in this research enhanced their potential as the alternative solder candidates for high temperature lead free solder. At interface, Cu3Sb IMC layer was formed for 95Bi-5Sb solder alloy. Spallation of Cu3Sb IMC layer took placed with the results of Cu3Sb IMC also found in the solder bulk. Analysis of 97.5Bi-2.5Sb solder alloy classified as no metallurgical reaction at the interface and only the mechanical joining existed at the interface. The dissolution of Cu from subtrate affected the formation of Cu rich phase and the unstable Bi-Cu rich phase phenomena act as the isothermal product found in solder bulk. Mechanical grain boundary grooving observed in 98.5Bi-1.5Sb solder alloys at interface. Different compositions of Bi-Sb solder alloys resulted in different types of microstructures at interface and in solder bulk after reflow.

Intermetallic Evolution of Sn-3.5Ag-1.0Cu-0.1Zn/Cu Interface under Thermal Aging

2012 ◽  
Vol 620 ◽  
pp. 142-146 ◽  
Author(s):  
Iziana Yahya ◽  
Noor Asikin Ab Ghani ◽  
Nur Nadiah Zainal Abiddin ◽  
Hamidi Abd Hamid ◽  
Ramani Mayappan
Keyword(s):  
Powder Metallurgy ◽  
Lead Free ◽  
Environmental Concerns ◽  
Lead Free Solder ◽  
Intermetallic Formation ◽  
X Ray ◽  
Zn Addition ◽  
Free Solder ◽  
Lead Free Solders ◽  
Powder Metallurgy Route

Due to environmental concerns, lead-free solders were introduced in replacing the lead-based solders in microelectronics devices technology. Although there are many lead-free solder available, the Sn-Ag-Cu is considered the best choice. But the solder has its draw backs in terms of melting temperature and intermetallic formations. To improve the solder, a fourth element Zn was added into the solder. The new composite solders were synthesized via powder metallurgy route. This research studies the effect of 0.1wt% Zn addition on the hardness and intermetallic formation on Cu substrate. For the hardness results, the micro Vickers values were reported. For intermetallic, the solders were melted at 250°C and aged at 150°C until 400 hours. The microhardness value for Zn based composites solder shows higher micro Vickers hardness compared to un-doped counterparts. The phases formed and its growth was studied under SEM and by energy dispensive x-ray (EDX). The SEM results show the presence of Cu6Sn5and Cu3Sn intermetallics and the Cu5Zn8intermetallic was not detected. The addition of 0.1wt% Zn has retarded the growth of the Cu3Sn intermetallic but not the total intermetallic thickness.

Electrodeposition as an Alternative Route to Prepare Nanostructured Lead-Free Solder Alloy: A Short Review

2015 ◽  
Vol 1113 ◽  
pp. 554-559
Author(s):  
Sakinah Mohd Yusof ◽  
Md Amin Hashim ◽  
Junaidah Jai ◽  
Abdul Hadi
Keyword(s):  
Solder Alloy ◽  
Short Review ◽  
Lead Free ◽  
Lead Free Solder ◽  
Solder Alloys ◽  
Electronic Manufacturing ◽  
Melting Temperatures ◽  
Magnetization Density ◽  
Free Solder ◽  
Lead Free Solders

With world-wide strict legislation for reduction or removal of lead from industrial waste, development of a large number of lead-free alternative solder materials had been intensively examined. The drive for lead-free solders development was towards systems that can imitate conventional lead containing solder alloys in terms of melting temperatures and improvement of mechanical properties. Nanostructured solder alloy, with a grain size of typically < 100 nm, was a new class of materials with properties distinct from and frequently distinguished to those of the conventional alloy. In comparison, nanostructured solder alloys exhibit higher strength and hardness, enhanced diffusivity, and excellent soft and hard magnetic properties. Numerous different techniques were performed to synthesize these nanostructured solder alloys. Electrodeposition method has generated huge interest in nanostructured solder preparation, mainly due to its ability to deposit solders selectively and uniformly at nanoscale. These factors bring significant influences on the behaviors of products, such as magnetization, density, ductility, wear resistance, corrosion resistance, porosity, molecular structure, and crystal properties which plays a vital part in the field of electronic manufacturing. In this paper, a short review on the electrodeposition, a useful technique to deposit different metals and alloys, as a method for nanostructured lead-free solder alloys preparation is presented.

Fabrication and Properties of Lead-Free Sn-Ag-Cu-Ga Solder Alloy

2005 ◽  
Vol 475-479 ◽  
pp. 1747-1750 ◽  
Author(s):  
Guohai Chen ◽  
Ju Sheng Ma ◽  
Zhi Ting Geng
Keyword(s):  
Solder Alloy ◽  
Lead Free ◽  
Lead Free Solder ◽  
Electronic Industry ◽  
Solder Alloys ◽  
Cu Alloys ◽  
Lead Free Solder Alloy ◽  
Free Solder ◽  
Lead Free Solders ◽  
Electronic Assemblies

Sn-Pb solder alloys, widely used in electronic industry, will be restricted because of the toxicity of Pb. That is paramount importance that developing viable alternative lead-free solders for electronic assemblies. Sn-Ag-Cu alloys are better alternative because of its good performance. But they have a melting temperature of 217-225°C that is much higher than that of Sn-Pb eutectic alloy, 183°C. It may be very difficulty to realize industrialization. Sn-Ag-Cu-Ga solder alloys have been studied in this paper, including a series of properties tests, such as melting point, hardness, shear strength and solderability. The best composition of Sn-Ag-Cu-Ga lead-free solder alloy has been obtained.

The Effects of Zinc Addition on the Microstructure, Melting Point and Microhardness of Sn-0.7Cu Lead-Free Solder Fabricated via Powder Metallurgy Method

2016 ◽  
Vol 857 ◽  
pp. 13-17 ◽  
Author(s):  
Nisrin Adli ◽  
Nurul Razliana Abdul Razak ◽  
Norainiza Saud
Keyword(s):  
Powder Metallurgy ◽  
Melting Point ◽  
Lead Free ◽  
Powder Metallurgy Method ◽  
Lead Free Solder ◽  
Zn Addition ◽  
The World ◽  
Zinc Addition ◽  
Free Solder ◽  
Lead Free Solders

The attempt to produce various types of lead-free solder has been actively investigated around the world in order to substitute the harmful SnPb solders. The effects of Zn addition on the microstructure, melting point and microhardness of Sn-0.7Cu lead-free solder were investigated with 1 wt% and 5 wt% of Zn additions. Powder metallurgy (PM) method was used to fabricate these Sn-0.7Cu-Zn lead-free solders. The results revealed that the addition of Zn was able to improve the solder properties. The melting point of Sn-0.7Cu-Zn lead-free solder was decreased drastically as the increasing of Zn additions. The Zn particles were distributed homogenously along the grain boundaries and produced refined dendrite β-Sn, which also lead to a superior microhardness values of solders.

Wetting and Intermetallic Study between Sn-3.5Ag-1.0Cu-xZn Lead-Free Solders and Copper Substrate (x = 0, 0.1, 0.4, 0.7)

2012 ◽  
Vol 501 ◽  
pp. 150-154 ◽  
Author(s):  
Ramani Mayappan
Keyword(s):  
Copper Substrate ◽  
Electronics Industry ◽  
Lead Free ◽  
Lead Free Solder ◽  
Solder Alloys ◽  
Spreading Area ◽  
Cu Substrate ◽  
Soldering Time ◽  
Free Solder ◽  
Lead Free Solders

The development of lead-free solders has been an essential task in the electronics industry because of the restriction of lead use by legislation. Among the candidates, Sn-Ag-Cu group of solder alloys have great advantages to replace the conventional Sn-Pb solder. In this study, the wetting and intermetallic study between Sn-3.5Ag-1.0Cu-xZn lead-free solder reacting on copper substrate were investigated under different soldering conditions. The addition of 0.7wt% of Zn improved the wettability on Cu substrate since it has the highest spreading area at 310°C. The Cu6Sn5 and Cu3Sn phases are the main interface intermetallic formed and these intermetallics increased in thickness with time and temperature. At 270°C, the addition of 0.7wt% Zn retarded the growth of Cu3Sn intermetallic until 10 min of the soldering time. Generally the addition of Zn was beneficial in retarding the total intermetallic thickness.

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