[ Date Time : 2010-8-23 ] [ Comments : 0
PCB ink quality is excellent , in principle, more than likely from a combination of several components . Ink quality is excellent , is a scientific formula , advanced and comprehensive reflection of environmental protection . It is reflected in :
Is the dynamic viscosity (dynamicviscosity) for short. General with viscosity , ie shear stress divided by fluid flow direction of the velocity gradient flow layer , the international unit of Pa / sec (Pa. S) or mPa / sec (mPa. S). PCB production in the ink is produced by the external force to promote mobility .
Viscosity units conversion relationship:
1Pa. S = 10P = 1000mPa. S = 1000CP = 10dpa.s
Deformed by external force that ink , even after the nature of the deformation front . Help to improve the plasticity of ink print Accuracy ;
When the ink was standing gel , and be shocked when a change in the nature of viscosity , also known as rock degeneration , anti- sag resistance ;
( leveling ) ink in the external force , to the extent carried around . Fluidity is the reciprocal of viscosity , fluidity and thixotropy of the ink and plastic . Plastic and thixotropic large liquidity on large ; mobility of the blot easily expanded . Mobility of small, easy to appear webs , resulting in end -Mexican phenomenon, also known as textured ;
India ink scraper scratch that , after the ink is shear fracture rapid rebound performance. Required deformation speed ink , ink printing rebound quickly to help ;
Asked ink dry on the screen the slower the better , and hope that ink after transfer to substrates , requires the sooner the better ;
Pigment particle size and solid materials ,PCB ink is generally smaller than 10μm, the size of the fineness of the mesh opening should be less than one-third ;
Shovel with ink ink stirred up , the filament tensile ink drawing is not known the extent of fracture . Mexico wire length , in the ink and printing side face a lot of filaments , so that substrates and plates soiled dirty , not even printing;
Transparency and opacity ink
For PCB ink , according to the different purposes and requirements of transparency and opacity inks also put forward various demands . In general, the line ink , conductive ink printing ink and character , are required to have high hiding power . The solder is more flexible.
Ink chemical resistance
PCB ink according to the different purpose of use , the corresponding requirements of the acid , alkali , salt and solvent requirements are stringent standards;
Physical properties of resistant ink
PCB inks must meet the external scratch resistant , thermal shock , mechanical stripping , and to achieve a variety of stringent electrical performance requirements ;
The use of ink security and environmental protection
PCB ink requirements have low toxicity, no smell , safety and environmental protection .
We summarized more than 12 basic performance of PCB ink , of which the actual operation in the screen printing process, and the operator is closely related to the viscosity problem . High and low viscosity , on the screen of the deed or not, a great relationship . Therefore, technical papers and inks in thePCB QC report, the viscosity is too clearly marked to indicate under what conditions , what types of viscosity of test instruments. In the actual printing process, if the high viscosity ink can cause difficulties were missing , graphics, jagged edges serious , in order to improve the printing results, will join the diluent to achieve the required viscosity . But not difficult to find , in many occasions , in order to get a good resolution ( Resolving power ), no matter what viscosity you use are always impossible. Why? After extensive research, I discovered that ink viscosity is an important factor, but not unique. There is another very important factor - thixotropy . Is it also affects the printing accuracy .