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SMT Processing Factory Weld Judgment And Solution
Nov 13, 2017

  In the electronics industry, although the research on lead-free solder has made great progress, it has been widely used in the world, and environmental issues have also attracted people's attention. The soldering technology using Sn-Pb solder alloy is still an electronic The main circuit connection technology. Smd electronic components used in SMT processing plants are also getting smaller. How to ensure the quality of solder joints smd SMD an important issue. Solder pads as SMD components and pcb board welding bridge, its quality and reliability determines the quality of electronic products. In the production process, the quality of SMT eventually shows the quality of solder joints. Its importance is self-evident. Good solder joints should be in the equipment life cycle, its electrical performance will not fail. The appearance of the performance: a complete and smooth and shiny surface; the appropriate amount of solder and solder completely cover the welding pad and lead parts, components, moderate height; good wettability; welding edge should be thinner, solder and pad surface The wetting angle is better than 300, the maximum does not exceed 600.

SMT processing plant Weld Weld Inspection: First of all look at the components with or without missing; whether the wrong components with or without short-circuit; with or without open; with Weld; Weld reason is relatively complex.

Weld judgments, the general use of online testers special equipment for inspection; visual or AOI test. When found solder joints solder too little solder infiltration poor, or solder joints in the middle of broken seam, or solder balls were convex ball, or solder and SMD components do not blend, etc., minor phenomena can also cause hidden dangers, should immediately determine whether there is Weld problem. Judgment is to see if there are more PCB solder joints on the same location has a problem, but the problem on the individual PCB, solder paste may be scratched, pin deformation and other reasons, if it is a common phenomenon, in many PCB There are problems, this time is likely to be bad components or pad problems. How to solve Weld; pad existence of through-hole PCB design is a major defect, of course, except for PCB counterbore. Generally do not use, through holes will lead to solder loss caused by insufficient solder; pad spacing, the area also need to match the standard, or should be re-designed as soon as possible. PCB oxidation phenomenon, the pad is not bright enough. If there is oxidation, eraser can be used eraser to make it light reproduction. PCB board damp, can be placed in the oven drying. PCB board has oil, perspiration and other pollution, to clean with anhydrous ethanol; PCB printed solder paste, solder paste is scraped, rub, solder paste to reduce the amount of solder, insufficient solder. Should promptly make up. Make up the method available dispenser or bamboo pick a little complement; SMD component quality is not good, expired, oxidation, easily lead to Weld. Oxidized components are not bright. The melting point of the oxide will increase, with electricity chrome iron with rosin flux can be welded. Note: Oxidized SMD should not be reflow oven welding. When buying components must see if there is oxidation, and to buy back after the timely use. Oxidized solder paste can not be used; multi-legged surface smd mount components, the legs small, easily deformed under the action of external force, once the deformation, will certainly Weld or lack of welding occurs, so before and after the patch To carefully check the timely repair.