Pinholes produced in screen making (bottom)

5) Direct legal network edition. The post-coating drying of the film/emulsion system screen should be dried in a separate drying oven and cannot be combined with the screen after degreasing and the screen after washing. If put together, the evaporation of moisture on these screens may fall on the surface of the emulsion layer to form fisheyes and pinholes. If possible, two drying ovens should be prepared.
6) Do not expose light until the light is completely dry. The screen is placed in a drying oven. The moisture on the direct screen plate is evaporated from both sides. The moisture on the film/emulsion screen can only evaporate from the scraping surface. The presence of water will reduce the photon activity and hinder the sensitivity of the photosensitizer. Sex. Sometimes it seems that both sides of the screen are dry, and in fact they are not dry inside and must be further dried. For film/emulsion screens, remove the film and dry it for about 2 minutes to ensure sufficient moisture evaporation.
7) Stain on the printing film will have negative consequences on exposure. All the fingerprints and dust traces on the printing film should be wiped clean with cloth and isopropyl alcohol, and electrostatic dust cloth should be used for dust treatment before use. When using screen printing software to paste the screen for exposure, be sure to The film layer of the printing plate is tightly compacted against the surface of the screen.
8) Dust and dirt on the platen glass of the printer also affect the exposure. To wipe the surface with a suitable glass cleaner and a soft fleece, the glass transmittance must be replaced in time.
9) Unclean platemaking environment can also cause defects in the quality of the coating process, and it is the main cause of pinholes. The establishment of equipment should be regularly cleaned; the floor should be painted with protective paint or paving bricks to prevent dust from escaping from the surface. Daily cleaning work regularly, use a damp cloth to wipe the ground or wipe the ground with an electrostatic cloth, conditional equipped electrostatic precipitator in the plate room.
10) Before the photosensitive adhesive is poured into the rubber bucket, the rubber bucket must be wiped clean with an electrostatic cloth, and the gluing machine is used for gluing, and the gluing roller must be cleaned.
11) Pay attention to the coating speed and coating pressure. The speed of moving the glue bucket on the screen surface should be controlled at about 4 seconds/3 inches. If the speed is too slow, it will cause uneven coating; if the coating pressure is too high, the central part of the screen during the coating process will When the edge of the glue bucket is separated from the contact, the coating thickness of the central portion is too thick, and the thickness of the glue layer on both sides of the glue bucket is too thin.
Since the length of the exposure time depends on the thickness of the photosensitive layer, the center portion often suffers from underexposure. Screens with loose mesh are not used in printing because this inevitably causes the glue bucket to be coated with a lower pressure and cannot control the thickness of the coating. Uneven thickness is a potential cause of pinholes.
12) Many sensitized films need to be sensitized before use. Dissolve sensitization in distilled water first, mix well and then pour into emulsion and mix well. Sensitized sensitized adhesive needs to be placed for at least 1 hour, and sometimes it takes 12 hours to allow air bubbles to completely disappear. Then the coating operation is performed. Inhomogeneous mixing is easy to form uneven thickness during coating, and bubbles are the culprit of pinholes.
13) Most sensitized adhesives can be placed for 4-8 weeks after being sensitized. If the sensitized adhesive is stored in a refrigerator, the storage time is significantly prolonged. The use of photoemulsions that are stored for a long time often causes problems.
14) The extremely fine foreign particles in the water source will also form pinholes in the screen. To overcome this problem, 5 micron screens and filters can be installed on the faucet.