There are some specific requirements for smt patch glue in different coating processes. For example, when using dispenser dispensing and needle transfer technology to apply patches, both require that the patch glue can smoothly leave the needle or needle end without forming "strings", inaccurate or random For the coating phenomenon, the wetting force and surface tension of the patch adhesive are required to have stable properties, a wide range of application, and its performance is not affected by changes in the PCB material being knotted. This is because, when using dispenser dispensing and pin transfer process, if the patch adhesive has a low wetting force on the PCB surface, it is difficult to apply; if it has strong cohesion, it will form a "string" "Coating phenomenon; if there is no stable performance and a certain range of adaptation, its coating process will be very poor.
Regardless of the coating process used, contaminants in the patch glue and on the PCB and SMC / SMD should be avoided when the patch glue is applied; the patch glue cannot interfere with good solder joints, that is, can not pollute the pad and smt component terminals ; Poorly applied patch glue can be clear and clean from the PCB in time; the selected packaging form should be compatible with the coating equipment and storage conditions. When applying patch glue, performance testing should be performed according to the coating method and bonding requirements in order to correctly select the patch glue.
