SuZhou Tonkida Electromechanical Technology Co., Ltd Professional SMT whole line supplier

First, the components are correct

The type, model, nominal value and other characteristics of each component with assembly position number are required to mark the assembly drawing and specification requirements, and can not be affixed to the misalignment.

Second, the mounting pressure of the placement machine.

The mounting pressure of the SMT machine, the welding end or pin of the component shall not be less than half of the thickness to be immersed in the solder paste. The solder paste extrusion amount for general component patches should be less than 0.2 mm, and the solder paste extrusion amount for narrow spacing component patches should be less than 0.1 mm. The mounting pressure of the mounter is too small, the welding end or pin of the component is floating on the surface of the solder paste, the solder paste cannot stick to the component, and the position is easy to move during transfer and reflow welding. The mounter patch pressure is too large, and the extrusion of the solder paste is too much, which is easy to cause bonding of the solder paste, which is easy to bridge during reflow welding, and will damage the component in serious cases.

Third, the position is accurate, the end or pin of the component and the welding pad graphics should be aligned and centered as far as possible

The mounting position of the Chip components is required, because the role of the self-positioning effect of the two end CHIP components is relatively large, the length direction of the component when mounting the two ends as long as they are connected to the corresponding pad, and the width direction is one-half of the lap on the pad, and the reflow can be self-positioned, but if one of the end heads is not connected to the pad, the reflow will produce displacement. The self-positioning effect on SOP, SOJ, QFP, PLCC and other devices is relatively small, and the mounting deviation cannot be corrected by reflow welding. Therefore, three-fourths of the pin width should be on the pad when mounting, and the toe and heel of the pin should also be on the pad. If the mounting position allows the deviation range, it must be manually corrected before entering the reflow furnace welding. Otherwise, it is necessary to repair after reflow welding, which will cause waste of working hours and materials. When the allowable deviation range of mounting position is found in the production process, the mounting coordinates should be corrected in time.