6LR61 battery.What is lead-free manufacturing technology?

　　What is lead-free manufacturing technology for you electronics enthusiasts? , what is lead-free manufacturing technology? The so-called "lead-free manufacturing" actually means "lead-free manufacturing technology?" The so-called "lead-free manufacturing" is actually "lead-free" production technology. So what is "lead-free" production technology?

　　The chips on current board equipment are connected to the PCB board through small solder joints under the chip package. These small solder joints are traditionally made of lead, but "lead-free" technology uses a combination of tin, silver, and copper to replace the lead. However, switching from lead-based products to lead-free products is a complex process that affects all electronic device suppliers and brings many supply chain, lead-free process and reliability challenges. It requires the use of lead-free-based products. The material replaces lead-rich solders and lead-containing materials used in the assembly process.

　　It should be noted that lead-free technology does not bring about all revolutionary changes, which is something that users should understand. To a certain extent, it is still a "development" technology. In other words, lead-free technology is developed from existing lead-containing SMT technology. Since the beginning of the SMT technology era, the rapidly expanding user market has made the industry realize the harm of "revolutionary" changes, so when researching and developing new technologies, they always try their best to retain a considerable degree of old methods.

　　It is certainly a good thing to have more "evolvability", which means that we can make better use of past experience. However, for lead-free technology, this is not simple. In the development process of SMT, we have experienced several "development" experiences with great impact, such as grid array solder terminal technology (BGA), Flip-Chip, etc. Some users may still be fresh in their minds about the challenges these technologies pose. However, the arrival of lead-free technology is definitely more difficult and challenging than previous technologies.

　　In lead-free processes, soldering material selection is the most challenging. Because for the lead-free soldering process, the selection of lead-free solder, solder paste, flux and other materials is the most critical and difficult. At present, the industry mainly considers several major parts of the material selection standards, including: metal characteristics, melting point, solderability, patents, cost, porosity, and toxicity. Metal properties mainly consider thermal fatigue life, bonding strength, compatibility with lead-containing components and other metal properties. Solderability includes tin dipping properties (or wettability) when soldering to components and solder extension on the PCB soldering pad. sex.

　　While there is currently no solder alloy that is as "good" as lead-containing solder, there are many that can be substituted (to suit the application). At present, there are three main alloy materials that replace tin-lead as lead-free solder - tin/silver/copper, tin/copper and tin/silver/copper/bismuth. American and European manufacturers are optimistic about tin/silver/copper, while Japanese manufacturers tend to use tin/silver/copper/bismuth alloys. There is currently no unified lead-free process standard internationally.

　　Some institutions and organizations are actively formulating standards for the application of lead-free technology. For example, the Japan Welding Society (JIS) is stepping up its efforts to explore standards and evaluation methods for lead-free solder, and hopes to formulate JIS standards as soon as possible. This requirement drives the industry's choice of new solder systems. The new solder system is required not only to provide similar physical, mechanical, temperature and electrical properties to tin/lead eutectic solder (Snpb63), but also to be reliable.

　　In addition to the alloy being a key consideration and selection point in solder, the flux should not be ignored. Different alloys have different densities and weights, different melting surface tensions, different melting temperatures, and different oxidation characteristics. This also tells us that the formula of flux Flux will be different from that containing lead (Note: Flux is a general term. Flux in solder paste contains many ingredients with different functions, such as carriers, solvents, diluents, stabilizers, fluxes, etc. etc. The combination of these multiple ingredients and multiple optional materials result in a variety of different Flux formulas.). Since the flux formula has always been a competitive trade secret among solder paste suppliers, it is not easy for users to know its actual characteristics. However, it is foreseeable that changes in this area will have a greater impact on the welding process.

　　Manufacturer's lead-free plating application projects

　　NECSn-BiQFp, TQFp, LQFp, SOJ, SOp, TSOp

　　Ni-AuLGA

　　FujitsuSn-BiQFp, SOp

　　HITACHISn-BiQFp, SOp

　　panosonicNi-pd-Au, Sn-BiQFp, TQFp, LQFp, HQFp, QFJ, SOJ

　　ASE Su-Cu, Sn-BiQFp, TQFp, LQFp, HQFp, QFJ

　　The compositions of lead-free solder alloys currently available include the following: SnAg, SnCu, SnZn, SnAgCu

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