Method and apparatus for improving selective soldering

摘要

A method of assessing a discrepancy between a target value and a measured value of a parameter of a contact area produced between a flow of solder ejected from a nozzle and a surface comprises the steps of: (a) providing a surface of material through which the contact area between the solder and the surface can be visually detected, for example using a camera; (b) flowing solder through the nozzle and then bringing the solder into contact with a side of the surface, thereby creating a contact area between the solder and the side of the surface; (c) detecting the contact area from the other side of the surface so that a value of the parameter of the contact area can then be measured; and (d) assessing any discrepancy between the target value and the measured value so that any necessary compensation in order to achieve the target value can be programmed. A general method of observing the contact area from the side opposite the solder wave contact with the surface is also claimed. A further aspect relates to a method for determining the height of a nozzles tip below a PCB workstation in a soldering apparatus using a vertical displacement measuring apparatus (figures 11-13). A still further aspect relates to a method for calibrating a positional control system for a soldering nozzle using a test plate with a marked target area on its contact surface with the solder, so that calibration about the x and y axes can be effected (figures 14 and 15).