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Provide information on the effects of flux residues from surface mount assembly on radio frequency (RF) performance.

A series of test vehicles designed to evaluate the RF performance on various test patterns and some simple circuits. Empirical testing is used in determining the data.

Provides a methodology for checking the performance of flux residues as well as information on the performance of a few different flux residue types.

This is not an all encompassing project and the results may not extrapolate out to higher frequency ranges.

A good source of reference that can be used to understand the impacts of the assembly process on RF performance.

This paper shows the effect of assembly materials (flux residues) on a real circuit and not just test patterns. It can give a basic understanding to process engineers of the potential impact of the assembly process on a RF circuit.

The dissolution rates of iron and alloyed steels in molten lead‐free solders were investigated in order to clarify the effect of erosion of iron plating on soldering iron tips. The dissolution rates of iron‐based alloys in lead‐free solders were found to be about three times greater than in conventional Sn‐Pb eutectics, indicating that the iron plating of a soldering iron tip is subjected to heavier damage when used with lead‐free rather than eutectic Sn‐Pb. Several steel alloys showed dissolution rates similar to that of pure iron, suggesting that compositional changes in the iron plating may have little influence on the erosion depth. Decreases in the reaction temperature and time, and a small addition of iron into the solder was found to be effective in suppressing both dissolution of iron wire and erosion of iron plating.

The High Density Packaging Users Group conducted a substantial study of the solder joint reliability of high‐density packages using lead‐free solder. The design, material, and assembly process aspects of the project are addressed in this paper. The components studied include many surface mount technology package types, various lead, and printed circuit board finishes and paste‐in‐hole assembly.

This paper describes the different thickness measurement techniques that enable reliable thickness assessments, and the determination of the recommended immersion tin thickness for lead‐free soldering.

Immersion tin layers were prepared with systematically varying layer thicknesses. The samples were annealed at different reflow profiles, used in assembly for tin/silver/copper (SAC‐alloy) soldering. The layers were characterized with X‐ray fluorescence, electrochemical stripping coulometry, and by examining the cross sections using a scanning electron microscope. The solderability of the samples was determined with a solder balance (Solderability Tester Menisco ST60) using a SAC‐alloy (melting point 217°C) with T(max) at ΔT=28°C and ΔT=43°C above melting.

If all pure tin is converted into the Sn/Cu IMC, so that no pure tin is left as solderable layer, the wetting behaviour will decrease dramatically. Especially for multiple soldering processes, two times reflow followed by wave soldering, it is essential to have a pure tin layer covering the Sn/Cu IMC before going to the final soldering process. The required amount of residual pure tin over the Sn/Cu IMC is detailed in several papers. It is stated that a minimum of 0.2 μm of pure tin over the Sn/Cu IMC is absolutely necessary to ensure reliable wetting and solder joint formation. With the current immersion tin thickness recommendation of 1 μm, based on the needs of lead containing solder pastes, a residual pure tin layer will not be evident or thick enough to ensure reliable assembly for multiple soldering with lead‐free temperature profiles.

Helps to enable reliable thickness assessments, and the determination of the recommended immersion tin thickness for lead‐free soldering.

The purpose of this paper is to characterize the motivations used into migrating to lead‐free solder by providing examples and directions for those making the material change.

This work achieves its objective of identifying which electronic industry actions towards lead‐free soldering have been successful and why. The research reported the various motivating factors considered in adopting lead‐free electronics. To that end, the authors researched industry literature and discussed approaches with various companies and agencies. The scope of this paper is largely the board‐component level soldering process and companies involved in the international electronics industry.

The motivation to migrate to lead‐free solder has been and continues to be multi‐faceted. Issues include regulatory, commercial, and technical. Processing with lead‐free solder is successful, so the electronics industry's move towards environmentally compatible processes will meet regulated dates for change.

A company can learn how to incorporate environmental improvement principles resulting from the migration to lead‐free solder. Using that migration as a case study, the company can realize additional benefits by applying these principles to other product lines. Those interested in developing environmentally friendly products and processes can adopt the lessons that this paper identifies. Incorporation of lead‐free techniques, rather than resistance to change, is the result of adopting the lessons.

The paper presents a synopsis of the electronic industry's migration to lead‐free products and processes. It compares motivations for change that other studies have not compared. Manufacturers searching for direction and example to meet waste minimization goals will find the paper useful in providing such.