- Distribution of Solder Paste: The thickness of the SMT stencil and the size of the apertures determine the amount of solder paste distributed on the pad pattern. Oversized apertures can lead to excessive solder paste, causing solder bridging during soldering. Conversely, undersized apertures may result in insufficient solder paste, leading to weak solder joints or solder voids.
- Quality of Reflow Soldering: The thickness of the SMT stencil and the size of the apertures influence the soldering quality during reflow soldering of PCBs. The spacing between PCB components and the quality of reflow soldering are closely related, and the aperture size of the SMT stencil is related to the pin spacing of components and the size of PCB pads.
- Ease of Solder Paste Release: The thickness of the SMT stencil and the size of the apertures affect the ease of solder paste release during printing. If the solder paste does not release smoothly from the SMT stencil during printing, it may damage the solder paste shape or even cause solder paste collapse. Additionally, when soldering components with fine pin spacing, solder bridging may occur. Therefore, it is required that the aspect ratio of the SMT stencil size is greater than 1.5 and the area is greater than 0.66, which helps to avoid damage to the solder paste shape due to the adhesive force of the hole wall during release.
In summary, while the thickness and aperture size of the SMT stencil may seem insignificant on the surface, they often determine the quality of our printed electronic circuit boards and should not be overlooked.