Solder paste printing is a crucial step in the SMT process, and its importance cannot be overstated. It is considered one of the main processes in the entire SMT process chain. During production, more than 70% of abnormalities in the SMT placement process are more or less related to solder paste printing, especially on multi-layer PCB boards. Common anomalies in solder paste printing processes include insufficient solder paste, solder paste bridging, solder paste collapse, uneven thickness, solder paste penetration, and solder paste misalignment, leading to component bridging, voids, solder paste deficiency, and open circuits.
There are many factors directly influencing solder paste printing quality, including printing equipment, stencil quality and cleanliness, solder paste, squeegee, PCB board, printing process parameters, and operating environment. In actual SMT production operations, this article will mainly analyze the reasons directly affecting solder paste printing from the perspective of the stencil.
The most important control parameters in stencil design are the opening size and thickness. Considering that the opening size and stencil thickness directly affect the solder paste release rate, with the continuous development of electronic component integration and the reduction in lead pitch, the corresponding pad size and stencil opening size are also getting smaller. The manufacturing method of the stencil directly affects the smoothness and accuracy of the sidewalls of the stencil. Additionally, the cleanliness of the stencil after use is also one of the key factors directly affecting solder paste printing quality. It is recommended to use professional stencil cleaning equipment, such as the Silman Tech stencil cleaning machine DEZ-C730, which provides 360-degree comprehensive spray cleaning without dead angles. For more information about stencil cleaning machines, please contact the website’s online customer service representatives.
