The pricing for Solder Paste and solder dross recycling is not a simple flat rate per kilogram, but is comprehensively determined based on factors such as the actual metal content of the waste solder paste, the thickness of the surface oxide film, and whether impurities such as PCB residue or wiping cloth fibers are mixed in. For example, the recycling unit price of low-temperature solder paste residue with a tin content below 62% is usually 35% to 45% lower than that of high-lead solder paste of the same weight. If more than 5% of residual adhesive from tape is mixed in, the entire batch will be rejected or processed with a 70% discount. This has become a hard standard in the production lines of the 327 customers served by JiajinYuan.

On-site packaging must be sealed using double-layer thickened anti-static PE bags. After the inner bag is filled with material, it must be vacuumed and heat-sealed. The outer bag must be marked with the batch number, production line number, date, and the type of contamination determined by preliminary visual inspection, such as 'SMT-A Line-20240521-Suspected Rosin Residue Contamination'. For any packaging that is unmarked or has illegible writing, the recycler has the right to reject it without further notice, because if subsequent XRF testing finds that the tin content deviation exceeds ±2.3%, the basis for traceability relies entirely on the original label information.

During transportation, mixing with domestic waste, acid, or alkaline waste liquid is strictly prohibited. Independent temperature-controlled box trucks must be used, and the internal temperature of the carriage must be maintained between 18°C and 25°C. This prevents high temperatures from accelerating the decomposition of the organic carrier in the solder paste and producing volatile acid gases, and also prevents low temperatures from causing the Flux to precipitate and cake, which would affect the efficiency of subsequent centrifugal separation. Last year, two customers used ordinary logistics vehicles for mixed transportation, which caused the entire batch of waste solder paste to harden and turn black in the transit warehouse. In the end, it could only be disposed of as hazardous waste, and the cost exceeded the recycling revenue.

The factory inspection adopts a three-stage process. First, it passes through a metal detector to remove foreign objects such as tweezers and screws. Then, samples are taken from 3 different points for rapid XRF scanning. Finally, the mixed sample is sent to the laboratory for ICP-OES full element analysis. Only when the data of the three main components, tin, silver, and copper, have an error ≤1.8% with the contract agreement can settlement proceed. Other trace elements such as lead, bismuth, and antimony are not involved in pricing, but must meet the requirements of the exemption list in 'GB 34330-2017', otherwise the entire batch will be returned.

The settlement cycle is strictly implemented according to the contract. Monthly settlement customers must submit the 'Waste Solder Paste Handover Form' stamped with the official seal before the 5th of each month. The weight on the form must be consistent with the weighbridge receipt, electronic scale screenshot, and video archive. If any one item is missing, it will be postponed to the next month. During automatic verification by the JiajinYuan system, 17 instances were found where the scanned weight differed from the actual weighed weight by more than 0.45kg, and all were voided and re-signed. Because the essence of solder dross recycling is not buying and selling, but a key link in the closed-loop management of production line materials.