When the stencil's stainless steel foil and the surrounding screen are improperly tensioned to make the tension unbalanced, the stencil will be displaced during printing, causing the solder paste to deviate from the land pattern. This offset will be more as the squeegee pressure increases. Obviously prominent. The selection of the stencil frame should be appropriate so that the ratio of the printed area to the entire stencil area is 1/9, and the edge of the printed graphic to the frame margin is required to be at least 10 cm. When the stencil frame area is too small and the printing area is too large, When the contact printing is performed, the amount of solder paste deposited on the edge of the printed pattern is uneven.
The cleaning methods of the stencil include dry cleaning, wet washing, ultrasonic and vacuum washing. If the template is not cleaned in time, the solder paste will remain on the opening and the inclined surface of the hole wall. After drying and solidifying, the opening is blocked, and the cleaning frequency is insufficient or the cleaning method is improper, which may cause poor printing.
It is usually first wet-washed with alcohol, then rubbed with a non-woven fabric or blown with a wind gun. It can also be cleaned by ultrasonic machine and special solvent, but when the whole stencil is immersed in cleaning, pay attention to the solvent resistance of the adhesive and the impact force on the stencil, and also consider the influence of heating on the thermal expansion coefficient of aluminum frame, wire mesh and stainless steel to avoid Degumming and graphic deformation.
The stencil should be properly stored after cleaning and placed on a special formwork to prevent collision, damage and distortion.
Pe Cosmetic Bags,Clear Pe Cosmetic Bag ,Cheap Pe Cosmetic Bag ,Best Pe Cosmetic Bag
Dongguan City Diadia Industry Co.,Ltd , https://www.diadiabag.com