## 2 Materials and Methods
### Analysis of Dross Amount Formed on the Solder Bath Surface  
To verify the effects of the antioxidant SnP2 alloy on reducing the amount of the melt surface oxides in the production of tin solder, the production of solder, SAC305 type, was chosen, and the chemical composition is shown in Table 1. The content of the elements in the table is indicated with the maximum permissible content of the individual elements according to the standard for this type of alloy (J-STD-006C) [7]. This type of alloy is specifically mentioned as a substitute for Sn63 Pb37 (Sn 63%, Pb 37%) lead alloy. The performance characteristics of this alloy are very desirable; e.g., this alloy shows the best-in-class yield, outperforms all SnCu-based materials, has low cross generation, excellent solderability due to fast wetting speed (in back-to-back tests 0.65 s compared to 1.00 s for SnCu-based materials), and delivers excellent performance across a wide range of flux technologies. SAC305 complies with all requirements of RoHS Directive (Article 4.1 of the European Directive 2011/65/EU). Alloy specification for maximum lead (Pb) content = 0.07%. As [PERSON], [PERSON] et al. writes in their article, Micro-structure evolution and growth kinetics of intermetallic compound in SAC305/Ag and SAC305/Cu solder joints during solid-state aging [8], SAC305 is a lead-free alloy that has proven to be a suitable substitute for leaded solder, precisely because of its good mechanical properties and relatively low melting point (melting point is from 217 \({}^{\circ}\)C to 219 \({}^{\circ}\)C). The solder pot temperature for wave soldering applications is from 255 \({}^{\circ}\)C to 265 \({}^{\circ}\)C and, for selective soldering, the recommended solder pot temperature is from 280 \({}^{\circ}\)C to 320 \({}^{\circ}\)C. Due to these temperatures, this type of alloy is also commonly used to stabilize and reduce the copper content in a wave solder bath. The temperature difference in use is also confirmed by [PERSON] in his book _Lead-free Soldering Process Development and Reliability_, chapter Wave/Selective Soldering, where the solder temperatures for selective soldering are slightly higher than for wave soldering (260 \({}^{\circ}\)C). However, they are much lower than lead-free hand soldering temperatures for rework wire (400 \({}^{\circ}\)C). Typically, the solder temperature is between 280 and 300 \({}^{\circ}\)C. The smaller nozzles need more heat to obtain enough energy in the assembly and have complete hole fill. Some engineers do not want to have temperatures above 300 \({}^{\circ}\)C because of fillet/pad lifting or flux activation loss [9]. Also, the results of [PERSON]'s study showed that a Cu\({}_{6}\)Sn\({}_{5}\) scallop-type layer with round grains having a strong texture was formed at the interface of the SAC solders/Cu systems. The addition of Ag decreased the IMC/liquid SAC solder interfacial energy and improved the wettability of the solder on the Cu [10]. Two solder baths (A and B) with the same material content were prepared, and each 300 kg batch of SAC305 consisted of the following parts:  
1. Tin (Sn), with 99.98% purity, in the form of bars--288.45 kg. 2. Silver (Ag), with 99.98% purity in the form of cut wire with 5 mm diameter--9.0 kg. 3. Copper (Cu), with 99.98% purity in the form of thin wire with 0.44 mm\({}^{\bullet}\)--1.5 kg. *This form of material was chosen for better melting of copper at a lower temperature. Deoxidation alloy SnP2 (Sn 98%, P 2%) was used in one of the solder baths (B), in the form of solid waffle-shaped ingots (Figure 4). The amount that was added to the melting was 1.05 kg. All of the above materials were put into an electric industrial furnace with a pot made of cast iron. The heat temperature was set at 300 \({}^{\circ}\)C. After an hour and a half, the temperature was reduced to 255 \({}^{\circ}\)C, and the tin-phosphorus deoxidation alloy was then added to the second melt (B) to bring the phosphorus level up to a range of 0.005-0.007%. Molten alloy was mixed. The first dress began to appear.