Archive for January, 2017

Selection and use of high – quality dispenser skills

Friday, January 20th, 2017

Selection and use of high – quality dispenser skills 1, in the purchase of dispensers need to pay attention to the amount of dispensing According to the principle of dispensing operation steel hole punch, the size of the spot diameter should be half of the pad interval, the diameter of the spot after the patch should be 1.5 times the diameter of the glue point. This ensures that there is enough glue to bond the components and avoid too much glue damaging the pads. The amount of dispensing by the screw pump rotation time to choose the length of the actual operation should be based on the production conditions (room temperature, glue viscosity, etc.) a reasonable choice of pump rotation time. 2, the dispensing pressure (back pressure) At that time the use of dispenser use screw pump supply dispensing needle hose selection of a pressure to ensure that meet the glue supply screw pump. If the back pressure when the plastic pressure is too easy to constitute a plastic overflow, glue too much; and the dispensing pressure is too small will show a discontinuous appearance of plastic, leakage, and then constitute shortcomings and other issues. Dispensing should be based on the same quality of glue, operating temperature to choose the pressure. Ambient temperature will make the viscosity of the smaller, better fluidity, then simply reduce the back pressure to ensure that the supply of glue, and vice versa. 3, dispenser needle size Dispenser in the actual work, needle diameter size should be the point of plastic dot diameter 1/2, dispensing process, the PCB should be based on the size of the pad to choose the size of the dispensing needle: pad size difference between the case , You can choose the same needle, the difference between the size of the pad is not the same as the need to choose the same needle, so that both to ensure the quality of plastic points, but also to marching production power. 4, the distance between the needle and PCB board Not the same as the use of different dispensing needle, and some needles have a certain degree of movement.

 

The calibration of the needle-to-PCB spacing should be done prior to the start of each job, ie the Z-axis height is calibrated. 5, glue temperature regulation Commonly used epoxy glue should be stored in 0 – 5 ℃ in the refrigerator, work should be out early 1/2 hours, so that the glue fully consistent with the working temperature angle steel machine. Glue the operating temperature should generally be 22 ℃ – 25 ℃; ambient temperature on the viscosity of a great impact on the glue, the temperature is too low will be smaller gel point, wire drawing machine appears to show. Ambient temperature difference of 5 ℃, will constitute a 50% dispensing volume changes laser cutting machine. Therefore, attention should be paid to the ambient temperature and be properly regulated. Humidity of the general environment also need to be given to ensure that moisture is too small gel point on the easy to dry, affecting the bonding force. 6, the viscosity of the glue The viscosity of dispenser glue will directly affect the quality of dispensing. Viscosity, the plastic dot will become smaller, and even drawing; viscosity is small, the plastic dot will become larger, and then be able to infiltrate the pad. Dispensing process, should not the same as the viscosity of the glue custom metal fabrication, the need to correctly select a reasonable back pressure