Squeegee blades printing

Usually, for good printing, the tip of the squeegee blade should be arranged opposite the centre of the counter-pressure roller—where contact is made with the screen. Its vertical adjustment should be checked carefully on both sides of the screen to ensure an even alignment across the width. If coating with PVC, so as to raise the application weight, the tip can be placed above the centre of the counter-pressure roller. 

The screen-printed approach for depositing thin films of metal has become popular in recent years. This approach is especially useful for producing multiple electrodes on a substrate or electrode array structures. Patterns are photolithographicaUy formed on a screen, whose mesh contains open and blocked zones. An ink containing the metal of interest is applied to the screen and forced through the open zones onto the substrate using a squeegee blade. Once the solvent has been evaporated (air dry or an oven cure), the electrode is ready for use. In the CVD approach, molecules of a volatile precursor are transported in a carrier gas to a heated substrate. The compounds reach the substrate and react to form the desired metal film. 

In printed-circuit board production, stencil printing is the most common process for applying solder paste. A metal stencil is positioned on the blank circuit carrier. The holes in the stencil correspond to the spots where the solder depots will be applied to the board. A squeegee blade passes over the stencil, filling the holes with solder paste. When the stencil is lifted clear, the solder depots are left on the board (Fig. 4.6). All solder-paste depots on the board are applied in a single process step, permitting a high rate of productivity. 

Application of controlled amounts of foam to the substrate is by knife-on-roller, knife-on-blanket, floating knife, horizontal pad or furnishing roller with doctor blade, or by squeegee across a printing screen. 

Squeegee A soft, flexible blade or roller used in wiping operations, particularly in screen printing and lay-up molding. 

Squeegees A basic piece of equipment (mbber-like blade in a handle) used for flooding the screen with the ink and printing. Blades have varying degrees of hardness (durom-eter) for different printing jobs. 

Squeegee Pressure, Speed and Downstop Level. Blade and material determine squeegee pressure. For urethane or polyethylene blades, starting pressure should be around 1.6 to 3.01 Ib./in. of squeegee. For metal blades, starting pressure should be 1 Ib./in. of squeegee. Based on the quality of the print, pressure should be adjusted to give complete aperture fills and clean stencil wipes. 

A screen (a woven mesh or a thin metal foil) with a stencil reflecting the patterns to be printed is put as a mask on the support a filling blade (squeegee) moves the precursor solution ( ink ) over the screen and fills the openings of the stencil, thus printing on the support. ... 

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