Weld is only a small amount of solder joints, causing poor contact, when the broken. Weld refers to the weldment surface is not fully plated tin layer, between welding pieces is not Sn solid live, is due to the weldment surface without clear clean or flux too little and too short a time caused by the welding. The so-called "spot of late failure is seems on the surface of solder joint quality is acceptable, does not exist" lap welding, "the slightest welding" and "pull Jian" and "copper exposed" welding defects, in the production workshop, loaded into the machine there is nothing wrong with, but to the user using a period of time, due to poor welding, electrical conductivity difference generated fault has occurred, resulting in one of the reasons for the high rate of early repair, this is the "weld". Good joint will seriously affect the overall quality of the potentiometer, must be careful not to produce. Here we will discuss how to control the production in the production process of Xuhan phenomenon.
1, regular cleaning, and keep the head clean iron. Because the electricity of automatic soldering machine soldering iron heads for a long time in high temperature, the surface is very easy to oxidation or burned, iron head thermal conductivity variation affect welding quality. Therefore, can be used wet or wet sponge iron head of impurities, temperature is too high, can be temporarily pulled the plug or dipped in Rosin cooling, ready to make on the soldering iron head hanging tin good.
2, tin note: if the welding and welding surface with rust, dirt or oxides, should be cleaned before welding, welding or welding surface to tin plating.
3, the welding temperature should be appropriate, not too high, not too low. In order to make the temperature appropriate, should be based on the size of the power electronic components automatic soldering machine suitable for automatic soldering machine, when the power of the will, we should control the length of heating time. When the soldering iron head automatically from scattered to be welded when the heating time has enough. This quickly remove the iron head, by welding place leave a sleek. If after remove the auto soldering machine, welding tin not staying or leaving very little, the heating time is too short, temperature is not enough or is welded is too dirty; if remove automatic soldering machine, solder will flow down, it indicates that the heating time is too long, the temperature is too high. General iron head temperature control of welding temperature is the best in the flux melting faster do not smoke when.
4, the amount of tin should be moderate. You can decide the amount of tin in automatic soldering machine according to the required size of the solder joints, wrapped by tough enough welding, forming a suitable size and smooth joints. Also not tin solder, tin as well. On the contrary, more the possibility of the solder joints weld, may be solder stacked on top instead of welding in the above. If a tin not again repair welding, but should be until the previous tin together are melt to remove the auto soldering machine; if a tin content too much, the soldering iron head can be used to take the right amount.
5, to control the welding time, not too long. The welding time is also an important link to the appropriate use of welding technology. If the welding of the printed circuit board, generally 2 ~ 3S is appropriate. Welding time is too long, solder flux completely volatile, loss of solder, solder joint surface oxidation, resulting in defects of solder joint surface rough, black, light, burr or flow etc.. At the same time, the welding time is too long, the temperature is too high, but also easy to burn the components or printed circuit board copper foil. If the welding time is too short, can not reach the welding temperature, solder can‘t be fully melted, wetting effect of flux, easy to cause the weld.
6, welding point of solidification process, remember not to use the hand to touch the welding point. The welding point is not solidified completely before, even if there is a small vibration may cause deformation caused by weld joints. Therefore, in the soldering iron head before the withdrawal of welding parts to be fixed, such as tweezers clamping, or the welding head after the evacuation quickly by blowing nozzle, take these practices, is to shorten the time of solidification of the solder joint.
7, when a welding point welding, selection of welding head angle is also particularly important to evacuate. When the soldering iron head along the upper inclined evacuation. On the soldering iron head away a small amount of solder ball, it can form a smooth solder joint; when the soldering iron head vertical to the evacuation, forming a sharp burr of the solder joint; when soldering iron head to the direction of the level of the evacuation, the soldering iron head can be take away most of the solder ball.
In summary, avoid weld the most direct, the most fundamental method, or to do the cleanup work before welding and cleaning is best not to use solder paste, because it contains acidic materials that might later will corrode electronic element pin, caused by weld. Clean up after welding to surface oxide, the first tin welding is easy, not easy to produce. Should hang on the tin in the pins of the electronic component, and a good grasp of welding time, so as to ensure soldering quality. In order to protect the quality of the circuit board.