The factors that determine the accuracy of SMT solder paste printing in addition to the quality of the solder paste printing machine itself, the use of its operation will also affect the accuracy of the solder paste printing. For example, the cleaning of the stencil, image positioning, stencil demolding, etc. These can affect the printing accuracy of the solder paste printing machine. The following gives you a specific analysis of the key factors that determine the accuracy of SMT solder paste printing:
I. SMT automatic solder paste printer cleaning
All automatic solder paste printing machine is used to dry cleaning, wet cleaning and vacuum cleaning of these three ways, automatic solder paste printing machine to take up the role of automatic cleaning stencil, to ensure the role of printing quality. With the development of SMT, the gap is small, fast, PCB on the many pull the tip, even tin and cleaning have a lot to do. Automatic cleaning is directly related to the quality of the product is good or bad, cleaning function of the perfect party can realize the speed that the production of high efficiency.
II. Automatic solder paste printing machine image positioning section
Automatic solder paste printing machine image positioning depends on the positioning algorithm, positioning algorithm is also one of the core algorithms of automatic solder paste printing machine. With the PCB board production efficiency is getting higher and higher, the electronic components on the board is getting smaller and smaller, the positioning accuracy and speed also put forward higher requirements. Currently, the positioning algorithms of most automatic solder paste printers on the market are based on image gray scale and realized by autocorrelation matching. For copper-plated boards with good surface uniformity, the grayscale algorithm can complete the function of automatic positioning very well. However, the emergence of more and more tin-plated boards, gold-plated boards, and flexible PCB boards has brought great challenges to grayscale localization. Because the surface uniformity of tin-plated, gold-plated boards is not very good, the reflection rate is high, so that the Mark points on the PCB board has a great difference in the brightness of the imaging, increasing the false detection rate of grayscale localization and the rate of missed detection. Flexible board due to the surface flatness is not good, PCB Mark points on the imaging will also have a large difference in brightness, but also make the Mark point size, shape changes, these problems are based on grayscale positioning algorithms are difficult to overcome. Geometry-based positioning algorithms can be well adapted to appeal to these issues.
III. The whole tin paste printing machine demolding (Snap-off) mode
Good or bad demolding directly affects the printing effect, the general fully automatic solder paste printing machine has two ways of demolding
1. “first up scraper after demolding”, the use of more common, mainly more simple PCB board.
2. “First take off the mold after the scraper”, the use of thin PCB boards and so on.
Solder paste printing machine for different types of PCB mold release requirements specially designed for three kinds of mold release mode, applicable to different tin requirements of the PCB board:
1. Start scraper first and then demold.
2. First release the mold after starting the squeegee.
3. “Squeegee detach first, keep the pre-pressure value, then release the mold”.
Post time: May-31-2024