Ipc-7093a: Pdf [top]

No legitimate free version exists. However, IPC occasionally offers "standards previews" or limited excerpts. For the complete document, you must purchase it.

The standard recommends a stepped or multi-level stencil for BTCs with a large central pad. For the thermal pad, use an array of smaller apertures (e.g., 4 to 16 squares) instead of one large opening. This reduces voiding by providing escape paths for flux gases. Typical aperture area ratio should be >0.66 for good paste transfer. ipc-7093a pdf

Since BTC solder joints are hidden, the dedicates extensive sections to automated X-ray inspection (AXI) and 2D/3D X-ray techniques. It explains how to set up inspection algorithms to detect non-wets, head-in-pillow defects, and voiding percentages. No legitimate free version exists