The Zero Waste Paste Project: Development of an Energy-Efficient and Automated Process for the Gentle Recovery of Raw Materials from Solder Paste Waste

During the assembly, solder pastes are employed in the mass production of printed circuit boards. However, they possess a restricted shelf life. The solder paste containers and the residues of the (expired) solder paste are classified as hazardous waste. There is no automated process to remove the solder paste from the containers without leaving any residue, thus allowing for the targeted recycling of all components. Instead, the containers are incinerated as hazardous waste, which results in inefficient recovery and high environmental pollution. This paper outlines a research project that aims to develop an environmentally friendly circular economy, with the objective of recovering or recycling all components of solder paste waste. The initial phase of the project will entail the development of a process and construction of an associated system prototype to facilitate the automated, efficient, and gentle recovery of raw materials from solder paste components (solder metal and flux) and the container material (polypropylene and polyethylene). Concurrently, a logistics system is being developed to ensure the efficient collection and presorting of containers according to the paste components they contain. The incorporation of recovered components into the manufacturing process of new solder paste is also being considered, with the development of new recycling options to realize the implementation of a circular economy with the objective of zero waste. The design of the washing process represents the initial stage of the concept phase and serves as a fundamental element. Cleaning and separation tests were conducted to evaluate the suitability of various processes and solvents. The tests encompass a range of technical processes, solvents and liquid nitrogen. The objective is to assess the repeatability and reliability of the cleaning and separation processes, while minimizing the impact on the environment and human health. The initial findings of the project's analyses are presented and discussed in detail.

Keywords: Soldering, Reflow soldering process, Solder paste waste, Circular economy, Zero waste, Recycling, Reliability.