Lead-Free Soldering (original) (raw)
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IAEME, 2019
Overview of the current advances in lead-free solder, with highlighting the effects of various alloying elements is discussed in this paper. Also discussed is nanoparticle additions in solder alloy, as new prospects for innovative ways to enhance solder strength and reliability. Developing a high strength solder not containing lead is a challenging task, and we still needs to advance our knowledge of ternary and quaternary lead-free solder systems, from physical metallurgy. This paper discusses various alternative lead-free solders.
Lead-free solder materials-state of art and perspectives for the future
Lead was until recently a widely used element in many components of the electronics industry. It appears in the solder material, coatings soldered on printed circuit boards, pins and ends of boards. On one hand, the commonness of the electronic equipment which accompanies almost every aspect of our lives (~ 8 million tones of waste per year in EU countries) and on the other hand, great dispersion of lead within it, made Pb recovery and recycling impossible. As a result of wastes, corrosion toxic lead compounds were passing into groundwater and contributing to environmental pollution. Harmful effect of lead on human health is well known -its accumulation in the body causes disorders in the nervous and reproductive systems, the delays in neurological and physical development, anemia and hypertension. In the 90's of the last century Japan and the U.S. began research on the replacements of typical PbSn solders. Among the countries of the European Union breakthrough came about 10 yea...
A novel lead-free solder replacement
1994
Environmental and toxicity concerns related to the use of lead have initiated the search for acceptable, alternate joining materials for electronics assembly. This paper describes a novel lead-free solder designed as a ``drop in`` replacement for common tin/lead eutectic ...
Reliability of solder joints assembled with lead-free solder
2002
To protect the natural environment, we will introduce the use of lead-free solder instead of the current tin-lead solder in the assembly of printed circuit boards in electronics equipment. During the transition to lead-free soldering, these two types of solders will be used in combination in joints. After the transition, a new element, bismuth, from components will contaminate the lead-free solder joints. We investigated the two types of solder through dynamic mechanical examination and concluded that lead-free solder can be used in combination with the current tin-lead solder and on its own to form sufficiently reliable joints.
Lead-free soldering processes in the electronic industry: industrial implementation at SMES
2007
Following the implementation of the new European environmental directives, Restriction of the Use of Certain Hazardous Substances (RoHS) and Waste Electrical and Electronic Equipment (WEEE), which involve the ban of lead from electronic and electrical products, this work presents process development work, production and reliability testing of real products from several electric and electronic assemblers using lead-free commercial solders that have been tested and monitored to ensure the reliability of the final products. The results were compared with the ones using tin/lead solders, in terms of performance and reliability of the joints obtained. This work aims to help the implementation of the lead-free solders in the soldering processes and supply the SMEs more information about real products and conditions that might be compared with theirs. The reliability tests and characterisation of the real products from several companies showed that the lead-free boards demonstrated a good performance under testing, being equivalent or better than the tin/lead ones. The defects or anomalies found in most of the joints (voiding and pad lifting) result from the manufacturing process. Most of the defects were found in through-hole devices and were due to component failures and not from the joint integrity. The degradation after the reliability tests of both types of solders is similar. The SMEs are engaged in taking this opportunity to reach a higher quality performance level in their processes. Some of the companies embraced this "forced" transition to upgrade and improve their process and facilities, bringing better capabilities and opportunities to their businesses. The objective of this work aims to be a tool of information to the SMEs of the electrical and electronic sector, in order to help them in the transition to lead-free soldering.
Aspects of the structural evolution of lead-free solder joints
JOM, 2002
Studies of the formation of intermetallic compounds at some lead-free solder/metallization interfaces are briefl y reviewed in this article. SnAgCu/Ni and SnAgCu/Cu interfaces are examined in particular. It has been found that (Cu,Ni) 6 Sn 5 forms at SnAgCu/Ni interfaces until copper is depleted from the solder matrix. This article also contrasts the formation of (Au,Ni)Sn 4 and related compounds in PbSn/Ni and lead-free solder/nickel solder joints is compared and contrasted.
Results of comparative reliability tests on lead-free solder alloys
52nd Electronic Components and Technology Conference 2002. (Cat. No.02CH37345)
The use of lead-free solder brings up concerns regarding the reliability of the new alloys to be used. In a European project (LEADFREE) SnAg, SnAgCu, SnAgCuSb, SnZn and SnPbAg have been tested in order to evaluate comparative data of the growth of cracks in solder joints. Reliability tests performed in other projects use accelerated tests proposed for tin-lead solders and showed a superior reliability of lead free solder over tin-lead alloys. The validity of these tests has to be questioned since they do not allow full relaxation of the stresses in solder joints. Thus each alloy is subject to another amount of strain. In LEADFREE tests are run with slow temperature ramps and long dwell times to account for this fact. As a result a faster growth of cracks has been observed in lead free solder joints compared to Sn62Pb36Ag2.
High temperature lead-free solder for microelectronics
Jom, 2001
This paper reports results of a four-year industrial consortium effort to develop lead-free solders for high-temperature applications (up to 160°C). Work included preliminary evaluations of 32 tin-based alloys, a screening of the thermomechanical fatigue performance of 13 promising alloys, and a full manufacturability and fatigue testing of the seven most promising of those alloys, namely Sn-3.5Ag, Sn-4Ag-1Cu, Sn-4Ag-0.5Cu, Sn-2.5Ag-0.8Cu-0.5Sb, Sn-4.6Ag-1.6Cu-1Sb-1Bi, Sn-3.3Ag-1Cu-3.3Bi, and Sn-3.5Ag-1.5In (compositions in weight percent). Eight different components were used on the reliability test vehicle, and the alloys were compared through Weibull analysis. In addition, the same seven experimental alloys were tested with ball grid array packages cycled up to 100°C or 125°C. All the lead-free alloys performed well, but those containing bismuth showed especially outstanding performance. In general, the ternary and higher alloys performed as well or better than the industry standard tin-silver eutectic, suggesting that solders other than the tin-silver eutectic should be considered for high-reliability, high-temperature applications.