1. Introduction:
In the electronic manufacturing process, the wave soldering process is indispensable. The structure of the wave soldering equipment and the welding principle determine the process of the soldering process. The liquid tin flows continuously and is exposed to the air to produce oxidation. At the same time, the liquid tin is exposed to high temperatures and Under the friction conditions of the equipment, the oxidation rate of tin is exacerbated. A large amount of tin slag not only seriously affects the welding quality of the product, but also brings huge cost waste. With the popularization of lead-free solder, the oxidation of solder is more serious. How to solve the slag waste of up to 30%-50% is a top priority for the electronics manufacturing industry.

2. Analysis of the current situation
Tin, as the most important material for electronic soldering, and the serious shortage of tin data, it is indisputable to face the status quo of depletion.In fact, according to the proved situation in 1993, the tin reserves are 10 million tons, with an annual output of 180,000 tons, and can be mined for 55. 5 years; of which, China’s reserves can be mined for 29.6 years. In 2008, the world’s proven tin metal reserves were approximately 7.12 million tons! The average annual demand for tin is growing at a rate of at least 5% (conservative estimate). Based on the global tin consumption of 360,000 tons in 2006, if there is no major new discovery of tin resources globally in the future, it will be consumed in about 20 years. Exhausted.ITRI ​​data shows that the global tin consumption in 2007 will be almost flat, reaching a record high of 362,000 tons in 2006. In 2006, solder accounted for about 52% of global tin consumption, higher than 50% of the previous year; statistics and markets Peter Kettle of the research department said: “Asia’s solder consumption for soldering accounts for about 80%, and China alone accounts for 55% of the global solder business.” The severe shortage of tin resources and the increasing demand have led to the rapid growth of tin prices. According to the latest data released by Shanghai Nonferrous Metals, the price of tin ingots increased by 77.8% year-on-year in 2010. At present (February 2011), the ratio of tin ingot prices In 2009, it increased by 222%, exceeding 200,000 yuan / ton. It is expected that tin ingot prices will continue to rise in the future.

The cost of solder has increased exponentially, coupled with the huge waste of tin slag, the cost of the entire electronics manufacturing industry has risen sharply. At the same time, the continuous increase in the price of raw materials and the increase in labor costs in recent years have made electronics manufacturing, which had limited profit margins, worse. !! In addition, the influence of tin oxide slag on soldering quality and reliability has caused headaches for electronics manufacturing engineers; reducing the generation of lead-free solder oxide slag and improving the utilization of lead-free solder can directly and effectively reduce the manufacturing of electronic manufacturing Cost; improve the quality and reliability of electronic products; it is the simplest, most direct and most effective measure for enterprises to improve their own competitiveness! At the same time, the effective and reasonable use of global tin resources will also make a huge contribution!

3. Measures to improve tin slag
In order to reduce the production of tin dross, experts, scholars, institutions and enterprises at home and abroad have carried out a lot of research.
There are the following aspects:
� Nitrogen protection
� Tin slag reduction machine
� Tin slag reducing agent
Nitrogen protection began to rise as early as the 1990s. At that time, it was mainly used from the perspective of improving process quality. In wave soldering, nitrogen protection can reduce the formation of tin slag. It is obvious that tin slag is solder and nitrogen. It is in contact with the product of oxidation reaction, and under the protection of nitrogen (the oxygen content in nitrogen is generally 50 ~ 500ppm at this time), the contact between the solder and oxygen is close to being isolated, the degree of solder oxidation will definitely decrease, however, the nitrogen protection Not all the advantages brought by the process and soldering quality are advantages, but it also has disadvantages. The main manifestation is the increase in solder beads on the surface of the printed circuit board after soldering. In addition, if nitrogen protection is required, a problem must be involved, that is, the purity of nitrogen, and the initial investment of nitrogen protection system equipment is relatively large. In 2002, the introduction of tin slag reduction machine products just relieved the electronics to a certain extent. Manufacturing slag waste issues, the application of tin slag reduction machine also reached a high level:
 It accounts for about 5% of the market, and more than 90% of Japanese companies are using it. In the process of using a tin slag reduction machine, people also found that this equipment is an off-line separation process. Because the physical separation method is used, it is impossible to reduce the oxidized tin slag SnO2 to tin Sn. We see the so-called reduction The tin that comes out is just pure tin mixed in the tin slag when it is fastened. The high temperature, pressurization, and friction of the reducing machine under working conditions will actually mix the pure tin mixed in the tin slag when it is fastened. Oxidation again; the oxide can be partially dissolved in the molten liquid solder according to the distribution law. At the same time, the metal oxide diffuses to the inside due to the dissolution difference. The internal metal contains oxygen gradually increasing and the solder quality is deteriorated. After high temperature separation (or reduction) The anti-oxidation elements in the alloy solder produced have been consumed, so the solder processed by this method is very easy to oxidize, and there are many oxide slags. In addition, the operation is cumbersome and the smoke and odor generated are harmful to the human body and the environment, and equipment maintenance The input costs of maintenance, site, and power personnel are all unacceptable. As a result, after the tin slag reducing agent is on the market, the tin slag reducing machine will be abandoned situation.

The above several methods use the principle of physical separation to separate the pure tin Sn mixed in the oxide slag. Although the generation of tin oxide slag can be reduced to a certain extent, the oxidized SnO2 cannot be reduced by this method The tin comes from Sn, and the tin separated by high temperature heating is more likely to oxidize, resulting in more tin oxide slag. After removing the related costs, the purpose of cost savings will not be achieved at all! Therefore, most electronics manufacturing companies are looking for a chemical product that can resist oxidation and reduce SnO2 to Sn.
At the same time, this product must meet the following conditions:
1. Comply with ROHS requirements
2. Easy to save
3. Easy to use, clean and tidy without second pollution
4. The output is unlimited
5. No impact on wave soldering machine during processing
6. No impact on PCB solder joints and board surface during processing
7. Lower cost
8. Non-toxic, comply with REACH directive, no serious harm to human body
 Use of anti-oxidant solder
Japanese scholar Tadashi Takemoto <3> and others added P and Ge elements to the solder for research. The alloy solder used for the experiments was SnAg and SnAgCu. The specific chemical composition is shown in Table 1. The equipment is a small wave soldering tin furnace that can hold 15KG, and the test temperature is 250 ℃. It is obtained through experiments that the weight of the oxide slag linearly increases with time; adding a small amount of Ge and P can effectively reduce the weight of the oxide slag, where the addition of P can reduce the weight of the oxide slag to about 50% of the original; Analysis shows that in the trace elements contained in the oxide slag, Ge is added in an amount of 2-9%, and phosphorus is 4.5 times more. The main component in the oxide slag is SnO, the oxygen content is about 5at%, and 90% of the oxide slag is composed of metal.

Domestic scholars have also studied and proposed that by adding various trace elements such as TI, Ga, Re, Sb, In, Ni to various lead-free solders of various alloys to reduce the generation of oxide slag, they have received certain Effect. At present, the lead-free solders used in the domestic wave soldering industry are mainly SnCu and SnAgCu. Most solder manufacturers use P element to improve their oxidation resistance, but the oxidation resistance will gradually fail with the extension of time and the consumption of trace elements. . So with the emergence of antioxidants!Fourth, the application of soldering tin slag surfactant

The generation of oxide slag has a great relationship with the flow behavior of molten solder. The more unstable the fluid and the greater the disturbance, the easier it is to absorb oxygen and increase the oxide slag. So far, the formation mechanism of the solder oxide slag mixture in the wave soldering process is not clear enough. For electronic production enterprises using wave soldering, it is best to choose a wave jet system with a reasonable design, less oxide slag generation, and convenient slag extraction Welding equipment, coupled with cost-effective anti-oxidant reducing agent, to ultimately reduce the waste caused by oxide slag (SnO2), so as to obtain higher economic benefits.

 As the anti-oxidation trace elements in the lead-free solder tend to condense to the surface of the molten solder and prior to the combination of Sn elements and oxygen in the air, the trace elements are quickly consumed and the solder loses its antioxidant effect; the fluid is unstable And the waterfall effect, and the phenomenon of oxygen absorption caused by the rolling of the molten solder; the oxide can be partially dissolved in the molten liquid solder according to the distribution law, and the metal oxide diffuses to the inside due to the solubility difference. The oxygen content is gradually increasing; therefore, adding an anti-oxidation reducing agent in the molten solder furnace, so that the generated tin oxide slag is immediately reduced and cannot be accumulated, and at the same time effectively prevents the further generation of oxide slag, is the most practical and effective measure at present ; Therefore, domestic and foreign merchants have successively introduced tin slag (solder oxide slag, which becomes tin slag in the SnO2 industry) as an anti-oxidation reducing agent (powder).

At present, the mainstream tin slag reducing agent products on the market are: WSS- Ⅲ of Xingbo Expo, JR07 of Qiqi Xinhua, P.Kay

Metal’s MS2, especially XSS’s WSS- Ⅲ products, are among the most pampering ones, accounting for about 60% share. WSS- Ⅲ from the original single slag reduction function to today’s slag prevention, reduction and improvement of welders 60% share. WSS- Ⅲ is a comprehensive third-generation mature product that was transformed from the original single tin slag.WSS- Ⅲ series products come into contact with the molten solder to form a fine and dense protective layer on the surface of the molten solder. This effectively prevents the solder from contacting with oxygen in the air, reduces the oxygen content in the solder, and prevents the oxidation of the solder. The element N has a greater affinity for oxygen, and the replacement reaction is used to achieve deoxidation, which further improves the anti-oxidation ability of the solder. Secondly, the element F in the material has strong polar solubility, which can dissolve ionic compounds and Dissociated covalent compounds, combined with solid-liquid suspension gravity sedimentation, rely on natural forces, so the organometallic compound is suspended between the metal oxide particles and the remaining active agent for maximum dissolution and reduction. Due to the large amount of tin slag accumulation in the furnace, the flow and wettability of liquid tin are greatly enhanced under the dual action of N (see Figure 2, solderability test curve of solder), so that Improve welding quality process. As time goes on until the activator is consumed and removed, the cleaning cycle is generally 24 hours. The active agent does not react with the metal, and only reacts with the oxide slag, which is less smoke and tasteless. When the metal oxide in the tin oxide slag is dissolved, the interconnected metal oxide arrangement is open, and any useful metal sandwiched in the slag can be dispersed and flowed back into the molten tin without being affected by the active agent. . Can control the amount of tin slag to less than 1kg (sets / day), and the tin content of tin slag is less than 10%. (See Figures 3 and 4 for the situation of tin slag before and after use)

Conclusion In the current social and economic form, only by providing customers with more high-quality and reliable products while minimizing their own operating costs, can enterprises be established in the face of fierce market competition and cost pressures. Invincible. As an important part of the manufacturing cost, how to reduce the huge waste of tin slag —– soldering surfactant is your best solution!