Co to jest Aperture

Co to jest Aperture

W branży PCB apertura odnosi się do konkretnego elementu używanego w procesie produkcji płytek drukowanych. Jest to otwór w szablonie, który umożliwia dokładne nałożenie pasty lutowniczej na PCB podczas procesu drukowania pasty lutowniczej. Rozmiar i kształt apertury odgrywają kluczową rolę w określaniu jakości druku pasty lutowniczej i ogólnego sukcesu procesu montażu powierzchniowego (SMT).

To ensure precise solder paste deposition, the dimensions of the aperture are carefully designed. The IPC7525 industry standard provides guidelines for determining stencil print performance, including parameters such as the Aspect Ratio and Area Ratio. The Aspect Ratio is defined as the width of the aperture divided by the thickness of the stencil, while the Area Ratio is the surface area of the aperture divided by the surface area of the aperture walls. These ratios help maintain proper solder paste deposition and minimize defects during the soldering process.

Different types of components require specific considerations when designing the apertures. For example, components with fine pitches, such as AFP, QFN, and CSP, may require electric polishing of the stencil to achieve the necessary precision. The pitch of components like BGA, QFN/QFP ICs, and SOPs also influences the aperture size. For instance, larger BGA pitches may require a 1:1 scale opening, while smaller pitches may require the aperture size to be 95% of the pad’s size. Similar considerations apply to other component types, such as QFP, SOT, and SOT89.