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Solder Fatigue
Solder fatigue is the mechanical degradation of solder due to deformation under cyclic loading. This can often occur at stress levels below the yield stress of solder as a result of repeated temperature fluctuations, mechanical vibrations, or mechanical loads. Techniques to evaluate solder fatigue behavior include finite element analysis and semi-analytical closed-form equations. Overview Solder is a metal alloy used to form electrical, thermal, and mechanical interconnections between the component and printed circuit board (PCB) substrate in an electronic assembly. Although other forms of cyclic loading are known to cause solder fatigue, it has been estimated that the largest portion of electronic failures are thermomechanically driven due to temperature cycling. Under thermal cycling, stresses are generated in the solder due to coefficient of thermal expansion (CTE) mismatches. This causes the solder joints to experience non-recoverable deformation via creep and plasticity tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solder
Solder (; NA: ) is a fusible metal alloy used to create a permanent bond between metal workpieces. Solder is melted in order to wet the parts of the joint, where it adheres to and connects the pieces after cooling. Metals or alloys suitable for use as solder should have a lower melting point than the pieces to be joined. The solder should also be resistant to oxidative and corrosive effects that would degrade the joint over time. Solder used in making electrical connections also needs to have favorable electrical characteristics. Soft solder typically has a melting point range of , and is commonly used in electronics, plumbing, and sheet metal work. Alloys that melt between are the most commonly used. Soldering performed using alloys with a melting point above is called "hard soldering", "silver soldering", or brazing. In specific proportions, some alloys are eutectic — that is, the alloy's melting point is the lowest possible for a mixture of those components, and co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Restriction Of Hazardous Substances Directive
The Restriction of Hazardous Substances Directive 2002/95/EC (RoHS 1), short for Directive on the restriction of the use of certain hazardous substances in electrical and electronic equipment, was adopted in February 2003 by the European Union. The initiative was to prevent an overabundance of chemicals in electronics. Thus, as a result electronics were restricted. The RoHS 1 directive took effect on 1 July 2006, and is required to be enforced and became a law in each member state. This directive restricts (with exceptions) the use of ten hazardous materials in the manufacture of various types of electronic and electrical equipment. In addition to the exceptions, there are exclusions for products such as solar panels. It is closely linked with the Waste Electrical and Electronic Equipment Directive (WEEE) 2002/96/EC (now superseded) which sets collection, recycling and recovery targets for electrical goods and is part of a legislative initiative to solve the problem of h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Low Cycle Fatigue
Low cycle fatigue (LCF) has two fundamental characteristics: plastic deformation in each cycle; and low cycle phenomenon, in which the materials have finite endurance for this type of load. The term ''cycle'' refers to repeated applications of stress that lead to eventual fatigue and failure; ''low-cycle'' pertains to a long period between applications. Study in fatigue has been focusing on mainly two fields: size design in aeronautics and energy production using advanced calculation methods. The LCF result allows us to study the behavior of the material in greater depth to better understand the complex mechanical and metallurgical phenomena (crack propagation, work softening, strain concentration, work hardening, etc.). History Common factors that have been attributed to low-cycle fatigue (LCF) are high stress levels and a low number of cycles to failure. Many studies have been carried out, particularly in the last 50 years on metals and the relationship between temperature, st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
