High-quality PCB ink is the comprehensive embodiment of technology advance and environmentally friendly. It is reflected in the following ways:
It is short for dynamic viscosity, generally indicated by the viscosity. That is the shear stress of the fluid flow divided by the velocity gradient in the flow direction; the international unit is Pa.S or mPa.S. In PCB production, it is the mobility promoted by the external force of ink.
It refers to the ink still maintains pre-deformation nature by external force. The plasticity of the ink is conducive to improving the printing accuracy.
Ink is in gelatinous on stand, and a change in nature by the viscosity also known as shaking, anti-sagging.
This means the speed of ink flow around in the external force. The degree of fluidity is the reciprocal of viscosity, and the degree of fluidity is related to the plasticity and thixotropy of the ink. If plasticity and thixotropy is large, then the mobility is large so that link is easy to expand. If liquidity is small, it is prone to resulting in network, ink phenomenon (also known as reticulate).
The dryness speed of ink on the screen is required to be as slowly as possible, while the faster the better when the ink is transferred to the substrate.
As for the pigment and solid material particle size, PCB ink is generally less than 10μm, the size of fineness should be less than one-third of the opening degree of the mesh.
When the ink is used to pick up the ink, the degree of filamentation for filamentous ink is known as spinnability. Ink long, there are many filaments in the ink surface and the printing surface, making the substrate and the printing plate dirty, or even cannot be printed.
Ink transparency and hiding power
For PCB inks, various requirements on the transparency and hiding power will be put forward according to the different requirements of ink. In general, line inks, conductive inks and character inks all require high hiding power, while the solder resist is more flexible.
The chemical resistance of the ink
According to the different purposes, PCB ink has strict standards of requirements on the acid, alkali, salt and solvents and so on.
The physical resistance of the ink
PCB ink must meet the resistance to external scratches, heat shock, mechanical stripping, and to achieve a variety of strict electrical performance requirements.
The safe use of ink and environmentally friendly
PCB ink requires low toxicity, odorless, safe and environmentally friendly.