High-quality screen printing application technology (below)

The cause of moiré changes:

1. Mismatching of halftone printing screens and screen meshes (the number of screen meshes should be 2.5, 3.75 or 6.25 times of the screen).

2. There is an error in the angle between the halftone printing screen and the screen line.

3, RZ value is too high (should be less than 8).

4, the template is too thick or too thin.

5, compared with the wire diameter, too small and network points will be lost (outlets in the range of 5-95%).

The reason for the color change:

1. Change in ink consistency due to evaporation of the solvent (different viscosities).

2. Change the squeegee angle during printing.

3. Change the hardness of the squeegee during the printing process.

4, change the speed during the printing process.

5. Damaged stencil caused by scratches.

Reasons for premature damage:

1, lack of fat.

2. Insufficient drying before exposure.

3, lack of exposure time.

4, network distance is too high.

5, the ink blade is too sharp and the pressure is too great.

6, using the wrong cleaning solvent for cleaning (including a small amount of water).

In order to avoid all problems, we suggest that, as mentioned before, the operating specifications and various parameters necessary for the work should be indicated by the work flow diagram, and the work flow should be performed according to this flow chart. Silk screen printing is a process that can be controlled and predicted.

There are several effective measuring instruments that can control different steps and are now briefly introduced to you.

Tension For screen printers, a tensiometer is an instrument that measures and monitors the screen level during the stretching stage or when it is re-used. The unit of measurement is Newton per cm. It is reduced to N/CM. The 1 kg weight of material accelerates the force measured on a square meter of area.

Thickness gauge

In the industry, this instrument is commonly used to measure the thickness of a stencil.

It is one of the most important instruments in the screen printing industry. The thickness of the paste determines the thickness of the ink layer on the print. The device is mainly used in the following areas: printed circuit board (PCB); glass decorations; ceramic ornaments; ceramic decals. The print quality will depend on the control of the process conditions during actual printing. Thickness gauges are increasingly being used by all screen printers certified by quality standards certification bodies.

Surface Roughness Tester Although the instrument has been used in the engineering field for many years, it entered the silk screen industry but it was in the late 80s. It is not used in a wide range and is limited to those large companies with R&D or QC departments. The tester can show the flatness of the stencil surface. The sign of the surface roughness value is RZ, and an RZ value of 0 indicates that the template is very smooth.

Surface moisture meter

For best results, the reticle needs to be fully dried before exposure. If not completely dried, the water contained in the light will cause the photosensitizer to be insufficiently sensitive, resulting in poor exposure of the template, and even worse, there will be a phenomenon of release. The dryness of the screen is not easy to judge. The contact humidity meter is an ideal test instrument. It can eliminate people's concerns about whether the template to be exposed contains moisture.

In the stencil exposure process, the ray detector needs to control two important parameters: the energy of the UV light and the distribution of light in the stencil area. Although most high-quality exposure machines are now equipped with an optical integrator as compensation for the UV output of the wave, it is not easy to measure the value of the incident light distribution and the UV light radiation density. The detector is a portable, battery-mounted device that shows a separate reading of the light source's radiation.

In addition, Yi used some well-known parameters to perform the correct screen exposure test on the sensitivity of the specific photosensitive adhesive produced by the photosensitive adhesive manufacturer. The instrument can be used to record the light radiation density of the new printing lamp, conduct periodic inspections on a monthly basis, and record the date, density reading of the control process, distance and location of the sensor. The readings made by contacting the sensor with the screen glass. If the distance between the side of the screen that is in contact with the glass and the exposure lamp is properly set, one-time measurements can also be made.

When the center of the exposure frame and the density of the furthest corner are at the same level, the ideal distance is indicated. When using this measurement, wear UV-proof glasses and do not prolong unnecessary exposure.