To achieve the high precision non contact dispensing in the technology of electronic packaging and SMT,a piezoelectric jetting valve was designed, which utilizes the hydraulic amplifier principle to amplifying the output displacement of piezo-stack.Firstly,jetting dispensing model was set up, and the factors affecting the velocity and pressure distribution generated by the needle crashing into the nozzle were analyzed by FLUENT software.Then,the relations among the jetting dispensing precision and striking velocity,adhesive viscosity and pressure of supplying adhesive can be obtained by changing different boundary conditions.Finally,the experiment test system was set up, and the result showed that the jetting dispensing precision is closely relative to above factors.Choosing the epoxy viscosity ranges from 500 to 3 500 MPa·s,dispensing properties were tested, and the test results showed that when the pressure of supplying adhesive is 0.2 MPa,square-wave driving voltage 110 V (up level 5 ms, low level 5 ms), the adhesive viscosity 3 500 MPa·s,droplets of minimum volume 0.24 μL could be obtained using the jetting valve system and conformity error is about 6.62%.
