Harmful properties of lead have been known for years. This element is not only hazardous to our health but also poses some problems as far as the subsequent storage of waste is concerned, consequently affecting our environment in an unwanted way. In addition, the need to meet the ROHS and REACH directives forces manufacturers of electronic devices to switch to lead-free technology. How can this technology be characterised and what does its implementation in the electronic devices production look like?
Lead replaced by other materials
Changes take place on the stage of soldering paste application on the PCB. In the past pastes containing lead were used. According to recent directives this alloy is gradually being abandoned in favor of other materials such as silver, copper and zinc. Properly prepared paste combined with modern soldering technology allows to obtain the same results as in the case of lead soldering.
Lead-free alloys differ in terms of thermomechanical reliability parameters. Silver is used for delicate and expensive components. Where possible, costs are reduced through the use of copper and zinc alloys.
Lead-free technology in particular soldering technologies
In the case of surface mounting of SMT, lead-free technologies do not require any changes in the design and production process. Some changes will appear in the case of condensation soldering and THT assembly. The way in which the solder is evenly distributed differs here. Ultimately, it is about reducing the temperature amplitude on the board, for the sake of delicate electronic components.
What should you pay attention to as far as lead-free technology is concerned?
Lead-free alloys have a higher surface tension which is more difficult to fully control than lead alloys. Consequently, manufacturers must pay attention to a number of factors: hole size, type of flux, thermal inertia, and soldering profile. In the case of copper alloys, it is very important to prevent corrosion and other chemical reactions that can shorten the life of the systems. Consequently, other PCB finishes are used which do not react with the lead-free alloy.
Lead-free technology differences in the quality
Originally, many manufacturers feared a significant drop in the quality of electronic products that used lead-free technology. In practice, the fears have proved to be unfounded, provided that the manufacturer takes care of the proper selection of materials and the proper parameters of the assembly process, with particular emphasis on soldering. Zinc and copper can guarantee equal durability, although obtaining the expected results is a bit more difficult than with lead.
An important factor is also the adaptation of devices responsible for the quality control of finished products. The process of creating testers for electrical tests is slightly different, as is the configuration of apparatus for optical tests. Nevertheless, if all stages of production are carried out in accordance with the art, the manufacturer will be guaranteed high-quality products.