You need some expensive 3D x-ray equipment to see these kinds of defects, but x-ray isn't the only way you can identify them. Boundary scan testing can detect opens.
Yeap, to see or identify the head in pillow its necessary to use an xray equipment. And you're right, you can catch an open on the boundary test, but the cause of a open could be oxidation, contamination or missing solder paste over the pad..... Regards
When you started to notice this head in pillow defect is present, you also need to take a view on your oven profile. Is not soldered because the metal does not licuify on the pcb nor the ball down the component.
Why there is silicone in your solder pastes? It´s almost impossible to clean stencils and flux residues although information in TDS speaks differently. Thank you.
