MASS SOLDERING SYSTEM PROVIDING AN IMPROVED FLUID BLAST

摘要

An improved hot air knife for use in removing excess solder from a circuit board in a mass soldering system of the type described in U.S. Patent Nos. 4410126 and 4401253 is described. In the present invention the hot air knife comprises a commercially available square tube, one of whose edges has been cut to provide the air knife outlet. Inside this tube, there is provided a second round tube for introducing hot air into the space between the round tube and the square tube. This inner round tube has holes facing away from the outlet slit of the square tube, preferably at least 45 degrees on both sides of a plane extending from the outlet of the square tube to the opposite corner of the square tube. In a preferred embodiment of the invention there is also provided at least one baffle in the volume between the outlet holes from the inner tube and the outlet slot for the air knife. In a preferred invention, this baffle is in the form of a fairly fine screen (about 60 mesh) in the volume between the tube and the rear corner of the square tube. Another such wire mesh can be provided on the other side of the space between the round and square tubes. The "air knife" can also be used as a high pressure water Jet for cleaning surface mounted semiconductor elements carried by printed circuit boards.