Scraper with single
Screen scraper to scrape the ink squeezing so that leakage printed on the printing surface. Scraper from the Squeegee Articles and Scraper Folder combination. Scraper in precision machinery Print Plays an important role, however, technicians are often ignored. "Make bricks without straw his tools", a knife edge with a good quality, suitable blade foot, hardness, printing pressure and speed of the scraper, screen printing will be able to ensure image quality.
Single-sided PCB Screen Printing of all graphics used polyurethane squeegee scraper, its high strength, wear resistance, and resistance Solvent Very good, thickness 8 ~ 10mm, hardness 65 ~ 75 °, the shape of the selected rectangular scraper. Select
hardness Squeegee hardness is usually the situation with the colors, the hardness increases with the color gradually deepened:
60 ~ 65 °: hardness of 60 ~ 65 ° range, now marketed mostly imported material, usually red, to soft scratch, apply to PCB solder graphics and character graphics printing;
70 ~ 75 °: as the hardness of squeegee, on behalf of some green, some with white representatives, are used for corrosion graphics and printing conductive pastes.
Targeted to select the appropriate hardness of the scraper will help to improve print quality, if you choose properly, will cause poor printing fault, such as graphics in the PCB solder printing process, the selected hardness of 75 ° or more scraper and wire spacing when faced more intense when the circuit pattern, such hardness of the scraper is more difficult to screen print on all printed materials to the line, and sometimes in order to be able to screen print on the printed material completely Next, will increase the pressure caused by the printing screen scraper strip damage or to generate small gap, in a later printing in the direction of movement along the scraper would have strip traces.
Installation Scraper installed, you should select the squeegee straight defect-free article, revealing scraper Scraper Clip height 10 ~ 25mm, the more the less soft exposed to some of scraper hard, not easy to bend. If you use gas Network printer print the graphics PCB, some article Xiang squeegee blade folder into the part height, exposed outside the squeegee section over the height of more than 25mm, scraper strip according to the thickness of 1mm or 1.6mm use thickness of scrap copper clad board as a support plate clamping out of the squeegee on the bare, it was rigid state, support the board's height should be high than the squeegee to short 10 ~ 25mm, so not printing due to pressure on the hardness of the scraper over with the printing surface in surface contact, resulting in printing the image blurred, especially in the graphics printing PCB solder process, as pressure increases in face contact, solder plate location easily erosion, the ink layer thickness, affect the curing solder mask ink effect, while minimizing the scraper larger life.
Lengths Scraper length should be chosen as short as possible under applicable principles of more than the entire image on screen length 40 ~ 50mm, if too long, scraper knife edge deformation occurs on both sides, in the screen printing process will naturally increasingly curved uneven, resulting in the uneven ink coating; if scraper too short, corrosion resistance in printing graphics, the graphics easy to cast a shadow on both sides of the phenomenon of printing solder paste graphics and carbon insulation layer and the protective layer graph, sometimes occur at both ends of printed material is not down or side of the printed ink layer of partial thickness and so on. In addition, the cut and the appropriate length of the squeegee to the edge after the sharp corners cut off with knives, and polished with sandpaper, it dull, so as not to screen the coated Sensitive adhesive Photographic film or capillary membrane surface scrapings streak, resulting in the printing process Loumo phenomenon.
Use matters
Order to get good printing effect, in print before the first check whether the flat scraper blade, scraper in the wash after use immediately, especially in the PCB solder screen printing graphics and character graphics, tags, due to strong solvent ink, dip a long time will be soft scraper squeegee speed up the wear, printed in the printing film is very thick, solder plate position was eroded, affecting the quality of the product.
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I think the real question is how to compare and choose web scraping tools?
I recommend reading these series of posts is dedicated to executives taking charge of projects that entail scraping information from one or more websites.
http://www.fornova.net/blog/?p=18