Screen Printing is a printing technique where tool, like a mesh or a stencil, is used to transfer ink and solder paste onto a PCB surface or into PCB vias and microvias. A blade or squeeze is moved across the screen to fill the tool apertures with ink, and a reverse stroke then causes the screen to touch the substrate momentarily along a line of contact. This causes the ink to wet the substrate and be pulled out of the tool apertures as the screen springs back after the blade has passed. Screen printing is a process in PCB manufacturing and PCB assembly.
Screen Printing Technique Are Widely Applied in PCB and Assembly Process, Including:
- Silkscreen printing: Silkscreen is a layer of ink traces used to identify components, test points, parts of the PCB, warning symbols, logos and marks etc.
- Solder mask printing: Solder mask is a thin lacquer-like layer of polymer that is usually applied to the copper traces of a printed circuit board (PCB) for protection against oxidation and to prevent solder bridges from forming between closely spaced solder pads.
- Conductive carbon ink: the carbon printed layer forms a protective thick film or thin film with some resistances or sheet resistance.
- Conductive silver ink: similar to carbon ink but with very low resistances.
- Epoxy resin printing: mostly used for buried vias filling, blind microvias filling in multilayer boards. In double-sided metal core PCB manufacturing, the cured epoxy resin will insulate the metal and copper layers, and accepts the 2nd drilling to form plated through holes (PTH).
- Peelable solder mask printing: sometimes used to protect specific areas on the PCB during the reflow soldering, wave soldering, or surface finish process.