During the processing and production of PCBA patches in Changsha, due to some processing techniques and other reasons, some tin beads and slag often remain on the surface of PCBA. These tin beads and slag will cause some hidden dangers for the use of products, such as short circuit of circuit boards after loosening. Here, Pate Technology, a professional PCBA chip processing factory in Guangzhou, briefly introduces the causes and solutions of some tin beads and slag.
First, the causes
1. The amount of tin printed on the PCBA SMD pad is too much, and tin beads are extruded by melting tin in the process of reflow soldering.
2. PCBA board or components are affected with damp, and the water will burst during reflow soldering, and the splashed tin beads will be scattered on the board surface.
3. During the post-welding process of DIP plug-in, when tin is added and thrown manually, the tin beads splashed by welding head are scattered on the surface of PCBA.
Second, the solution
1. In the manufacturing process of steel mesh, it is necessary to appropriately adjust the opening size in combination with the layout of specific components, so as to control the printing amount of solder paste.
2. The bare PCBA board with BGA, QFN and close-pin components on the board surface shall be baked strictly according to the processing requirements, so as to ensure that the moisture on the pad surface is removed.
3. Strengthen the visual inspection of SMD components around manually welded components by QC after welding, focusing on whether the solder joints of SMD components are inadvertently touched and dissolved or the solder beads and slag are scattered between the components pins.