Printed circuit board

PCB screen printing stencil production of several steps

I. Instructions.

1. Because the screen frame is used repeatedly, there are residual adhesive, screen yarn and other debris around the screen frame, which must be cleared to avoid affecting the adhesion between the screen yarn and the screen frame.
2. Place the frame on the platform (need to be horizontal) to check whether the frame is deformed, if there is deformation, it should be leveled.
3. Clean the mesh frame and the mesh yarn without deformation and then apply a layer of glue without hardener evenly in order to enhance the bonding force between the mesh yarn and the mesh frame after drawing.
4. After the first application of glue for about 10 minutes, place the frame on the screen pulling table, and adjust the relative position and height.
5. Select the mesh, loosen the clip nozzle around, lay the mesh flat on the frame, then clip the mesh evenly into the clip, no wrinkles, pay attention to the four corners to have a looser balance of mesh, the clip nozzle must be locked tight, there should be no gap between the clip and the clip (automatic lifting frame, manual pulling mesh for example).
6. Tension: the first tension 26, resting 5 minutes tension 24; second tension 28, resting 5 minutes tension 26; third tension 32, resting 5 minutes tension 30; fourth correction 5 points tension 32, resting 20 minutes on the glue tension 30; 15 minutes glue curing under the net tension 28, resting 72 hours before making the screen (to a meter × a meter automatic production line using (take one meter x one meter automatic production line as an example). The longitudinal and lateral synchronous pulling away, has been pulled to the required tension then brush glue, commonly used net mesh tension for (100T, 110T, 120T are 30 ± 2 Newton) (77T, 51T are 35 ± 2 Newton) (24T is 50 ± 2 Newton)
7. The glue has been adjusted with a small brush evenly brushed on the screen frame and screen then above the surface, do not drop the glue into the middle part of the screen, wait for 8 minutes to dry glue, available scraper glue in the glue surface will not completely fit the place pressed tightly paste contract 10 minutes or so after the glue is completely dry (should be open blowing air to strengthen drying) before the network.
8. Use the paper cutter to remove the excess mesh around the screen, and in the frame of the screen, specify the date, mesh and tension when the screen is down (so as to observe the change of tension) In order to prevent the infiltration of the wash water (anti-white water), the inner corner of the screen frame is sealed with red glue, and then sealed with waterproof tape above the screen frame and mesh, also to prevent the infiltration of the water.

II. Tanning

1. Washing net: Use grinding net cream to remove grease (new net), ghost shadow cream to remove graphics (old net), pulp removal powder to remove net pulp and blue oil, wash debris with anti-white water, rinse net with detergent, finally rinse clean with high-pressure water gun, and finally wash clean with pure water.
2. Drying: – Oven setting temperature should be less than 48 degrees Celsius.
3. Use the method of pasting water film: wash the clean net again with pure water. Select the water film according to the engineering film spelling graphics increased by about 20%, use the triangle ruler to press the water film end on the net, then use the triangle ruler to slowly scrape upward, then use the rubber scraper to lightly press the scraper, towel wipe excess water drying.
4. The use of photopolymer (net paste): drying screen plate and then photopolymer, the use of scraping box, will be scraped to the net, which screen printing green oil need to sizing three times, (about once every 10 minutes or more) screen printing other anti-corrosion ink is two times, screen printing can be peeled off the adhesive (orchid glue) first on 50 micron water film to tear the film, and then 2 times on the net paste, each time scraping three times, sizing is completed after drying.
5. The selection of screen yarn general line contains character ink screen printing, and anti-corrosion ink (green oil, base oil, surface oil) with 120T, 100T, 110T screen yarn, carbon paste (carbon oil) 51T, screen printing peelable ink (blue glue) 24T screen printing photographic line and heat-curing ink with 77T.
6. The choice of film line with 18K water film (without photopolymer with photopolymer online easily uneven will produce: such as hairy edge (dog teeth) and other resist ink (green oil, base oil, surface oil) choose photopolymer (net paste), carbon paste (carbon oil) choose 50 micron water film
7. with the required engineering graphics film paste in the position selected by the screen, placed on the burst of light machine for the choice of time (3000W spotlight), the line is generally in 60-80 seconds, green oil in 80-100 seconds, the bottom character oil 40-60 seconds, carbon oil, 350-400 seconds Lan glue
8. Pressurized water rinses the screen and dries.
9. After the screen is made, use the screen sealer (blue oil) to cover the screen not covered by film or photopolymer, scrape on the screen sealer with screen printing scraper and dry.
10. Check, repair the screen, write the date of completion and the corresponding number and record archives, storage.

III. Storage

Storage is generally vertical storage, can be homemade or purchase screen frame, need to be stored in the same environment as the screen printing environment to prevent deformation, while the tension of the screen needs to be tested before screen printing, and can be used to test the graphics photographic negative.


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