![]() The heating and cooling length, will be defined by a number of factors like required machine throughput, board dimensions, distance between boards, required board exit temperature and the temperature profile based on solder paste and components specifications.ĭefine process parameters and conduct Taguchi experiments and data analysis: A Taguchi method is used to make the process minimally sensitive to variation, to find the optimum settings, and determine the sensitivity of the control parameters to variations in the process.įigure 2. The wave configuration and contact times will depend on the solder joint quality as a result of solderability of the selected lead-free alloy.ĭefine the reflow machine requirements: The heating method must be determined. The plastics and other component materials should have a higher heat resistance.ĭefine wave solder machine requirements: Fluxer application and preheat configuration must be determined depending on flux specification and required process temperatures. * Components' lead-free finish material is dictated by the lead-free solder alloy/paste materials selection. Board material must be able to withstand higher temperatures. * Eliminate halogenated flame retardants from board materials with lead-free board finishes. The materials and technologies are currently available. * Lead-free solder paste (reflow) and alloy (wave). In the lead elimination route we can differentiate three phases: Select the right materials and equipmentįrom alloy and flux selection to necessary equipment capabilities: This means not only selecting the solder alloys or paste, but also the flux, board materials and finishes as well as the component packaging material and finish. The input and experiences of these companies teaches us more about issues such as solder contamination, yields, parts wear, costs, board warpage and process control aspects, where feasibility and other studies help us with material selections. Most of the companies who have been soldering with lead-free alloys for two years or more are automotive or other (special) applications, where assemblies are subjected to temperatures in excess of 150☌ or higher. ![]() Today, knowledge of lead-free soldering is based upon feasibility studies of several consortia, wetting balance tests, university investigations, and only a small part on real lead-free soldering in the production environment. What must be done and investigated before the first lead-free soldered boards leave the assembly line? How can the new process be controlled and improved after implementation? Many recently published papers discuss legislation, marketing, temperature, and alloy selection issues, but none describe how to actually implement the process. The goal is to continue where most lead-free papers stop, ie, at the point of beginning to actually solder lead-free. Typical SnPb and lead-free reflow profileįollowing these steps will lead to successful lead-free soldering for a robust, repeatable lead-free soldering process that will deliver consistent high yields. The five steps are based upon modern techniques, (eg, problem-solving/process-improvement models (plan do check act) quality engineering, design of experiments, and statistical process control).įigure 1. '5 steps to successful lead-free soldering' is a guide for those who are responsible, interested or confronted with the implementation of lead-free wave and/or reflow soldering. Successful implementation of lead-free soldering requires careful, well thought-out planning, as well as rigorous process monitoring to ensure quality and process control. Why the '5 steps to successful lead-free soldering'? The development of practical lead-free alloys and flux chemistries, as well as more sophisticated soldering equipment, have made lead-free soldering a process whose time has come, and one which can be implemented successfully at the production level. Gerjan Diepstraten, Technology Group, Vitronics SoltecĮlectronics manufacturers worldwide are moving to lead-free solders for a variety of reasons that include environmental concerns and compliance with impending regulatory legislation.
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