Printing of SMT Adhesives

SMT adhesives are applied to printed circuit boards by the following techniques: dispensing (c. 90% of all manufacturers use this technique at present), printing and pin transfer. The conventional dispensing method of applying adhesive utilises variations in dispense time, pressure and temperature combined with needle diameter to form deposits of varying volume and geometry. Recently, the printing technique has attracted a lot of interest. This technique is well known from solder paste printing. The major driving force is the higher throughput of this application method. moreover, a new printing technique with thick stencils allows the deposition of glue dots with different diameters and different heights. Two printing methods will be discussed: conventional printing technology and printing with thicker stencils.