1. Strictly control the temperature of the wave soldering furnace

For Sn63-Pb37 tin bar, its normal use temperature is 240 ~ 250 ℃. The user should often use the thermometer to measure the temperature in the furnace and evalsuate the uniformity of the furnace temperature, that is, whether the temperature in the four corners of the furnace and the center of the furnace are the same. It should be pointed out that you cannot just look at the wave furnace .The display temperature of the meter, because in fact the display temperature of the meter and the actual furnace temperature usually have a deviation. This deviation is related to the equipment manufacturer and the equipment life.

2.Control the wave height of wave soldering

Control of wave height of wave soldering is not only important for welding quality, but also helpful for reducing tin slag. First, the wave crest should not be too high, and generally should not exceed 1/3 of the thickness direction of the printed circuit board, that is, the wave crest end should exceed the soldering surface of the printed circuit board, but cannot exceed the component surface. At the same time, the stability of the peak height is also very important, which mainly depends on the equipment manufacturer. In principle, the higher the crest, the larger the solder surface in contact with the air, the more severe the oxidation, and the more tin slag. On the other hand, if the wave peak is unstable, the liquid solder will easily bring air into the molten solder when it falls back from the peak, and accelerate the oxidation of the solder.

3.cleaning of wave soldering furnace

It is necessary to clean the surface of the wave soldering furnace frequently. Otherwise, the solder falling from the peak falls on the surface of the tin slag and enters a semi-solidified state due to lack of good heat transfer. Such a malicious cycle will also cause excessive tin slag.

4.Control of the addition of wave soldering strips

For wave soldering, the height of the lower surface should be checked every day / each time before starting. Do not open the wave first, but add tin bars to make the solder in the tin furnace reach a full state. Then turn on the heating device to melt the tin. Because the melting of the tin bars will absorb heat, the temperature inside the furnace is very uneven at this time, and the peaks should not be opened until the tin bars have completely melted and the temperature in the furnace has reached a uniform state. Replenishing tin strips in time can help reduce the height difference between the soldering surface and the soldering surface, that is, reduce the contact area between the solder wave and the air, and also reduce the generation of tin slag.

5.Cleaning of Tofu Sn-Cu Compound Semioxide

pear tofu-like floating on the surface of liquid solder. Of course, some compounds may enter the solder due to the wave band action. Therefore, copper removal is very important. The method is as follows: stop the wave peak, the heating device of the tin furnace operates normally, first clean up the various residues on the surface of the tin furnace, and expose the mercury-like mirror surface state. Then reduce the temperature of the tin furnace by 190 ～ 200 ℃(At this time, the solder is still in the liquid state), then use a tool such as an iron spoon to stir the solder for 1 to 2 minutes (to help the Cu-Sn co,During the wave soldering process, the copper on the surface of the printed circuit board and the copper on the pins of the electronic components will continue to dissolve into the molten solder.

. A Cu6Sn5 intermetallic compound is formed between Cu and Sn, and the melting point of the compound is above 500 ° C, so it exists in a solid form. At the same time, because the density of this compound is 8.28g / cm3, and the density of Sn63-Pb37 solder is 8.80 g / cm3, the compound will apmpound inside the solder float), and then let it stand for 3 to 5 hours. Because the density of the Cu-Sn compound is relatively small, the Cu-Sn compound will naturally float on the surface of the solder after standing. At this time, the surface of the Cu-Sn compound can be cleaned with a tool such as an iron spoon.The above method can exclude a part of copper. However, if the copper content in the solder is too high, the furnace cleaning must be considered. According to production conditions, approximately.The furnaces should be cleaned every six months or every year.

6.Use Antioxidant Oil

Antioxidant oil is a kind of hydrocarbon with high flash point. It can float on the surface of liquid solder and isolate the liquid solder from the air, thereby reducing the chance of solder oxidation and thus reducing tin slag. In general, the use of antioxidant oils can reduce tin slag by about 70%. However, the sludge produced after the use of anti-oxidant oil will pollute the tin furnace and generate some fumes. It has certain requirements on the production environment, especially the exhaust system, and the tin sludge-like tin slag produced also has some utilization value.