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Scraper Types and Characteristics of Fully Automatic Solder

Time:2019/05/15 丨 Source:未知 丨 Browse times:

The wear, pressure and hardness of the scraper determine the printing quality of the automatic solder paste screen printer . HC automation solder paste screen printer here to share with you the type and characteristics of the scraper of the automatic paste printing machine.
SMT solder paste printing should have sharp edges and straight lines for acceptable printing quality. Low scraper pressure causes missing and rough edges, while high or very soft scraper pressure will cause spot printing, and may even damage the scraper and template or screen. Excessive pressure also tends to extract solder paste from wide openings, resulting in inadequate solder fillets.
There are two types of scrapers commonly used in automatic solder paste printers: rubber or polyurethane scrapers and metal blades. When using rubber scraper, use 70-90 rubber hardness tester hardness scraper. When using excessive pressure, solder paste penetrating into the bottom of the template may cause a tin bridge, requiring frequent bottom rubbing. In order to prevent bottom penetration, the opening of the pad must provide sealing during printing. This depends on the roughness of the hole wall of the template.
Metal scrapers are also commonly used in automatic printing presses. With the use of tighter spacing elements, the use of metal scrapers is increasing. They are made of stainless steel or brass with a flat blade shape and a printing angle of 30-45 degrees. Some scrapers are coated with lubricants. They don't dig solder paste out of openings because of lower pressure, and because they are metal, they don't wear as easily as rubber scrapers, so they don't need sharp edges. They are much more expensive than rubber scrapers and may cause template wear. Printed circuit assembly (PCA) using standard components and tightfoot components is differentiated by using different types of scrapers.

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