Stencil manufacturing is crucial for SMT technology, which will directly determine whether the tin on each solder pad is uniform and full, thus affecting the welding reliability of SMT components after reflow welding. Generally speaking, the opening of steel mesh needs to carefully analyze the characteristics of each PCB, for some high precision and quality requirements of the circuit board, laser steel mesh must be used, and SMT engineers need to discuss and confirm the process flow after the meeting, appropriately adjust the aperture of the opening, to ensure the tin effect.
When making SMT steel mesh, it should be noted that:
1.ME requires the supplier to make steel mesh according to relevant documents and materials provided by the engineering department.
2. Frame size requirements of steel mesh (550MM*650MM 370MM*470MM, etc., mainly according to the structure of the printing machine and the specifications of the product)
3. Label on steel mesh (product model, thickness, production date, etc.). 4. Thickness of steel mesh (scraping glue is generally 0.18mm-0.2mm, scraping tin 0.1mm-0.15mm)
5. The opening mode and size of the steel mesh (the tin ball is generally v-shaped, U-shaped, concave, etc., which shall be determined according to the type of each component).
6. The feeding direction and the placement machine should be unified
Note for SMT steel mesh acceptance:
1. Check whether the opening mode and size of steel mesh meet the requirements
2. Check whether the thickness of steel mesh meets the product requirements
3. Check whether the frame size of steel mesh is correct
4. Check whether the marking of steel mesh is complete
5. Check whether the flatness of the steel mesh is level
6. Check whether the tension of the steel mesh is OK
7. Check whether the location and quantity of stencil openings are consistent with GERBER documents
The production of steel mesh is an important part of the quality control of the whole SMT processing process. The engineers must pay full attention to it. Customers should not deliberately reduce the cost, resulting in poor tin effect after the use of steel mesh, which will affect the entire production schedule.