Will a Via Fit In Between?

摘要

I don't know that it would be accurate to say that BGAs have ever been easy, but with 0.4mm pitch commonplace and 0.3mm pitch starting to appear, some of the older sizes - like a whole millimeter pitch larger - seem positively spacious. With lmm and larger ball pitch, putting a via between the pads (not in the pads) is a no-brainer. IPC-7095B classifies 0.8mm and smaller pitch as fine-pitch. It really starts to get complicated at around that point. For example, take a 0.5mm pitch BGA. When looking to put a via between the pads, the diagonal pitch is the critical measurement. In this case, it's 0.71mm (17 mils). It might immediately seem like that's plenty of room for a 6 mil via, but upon closer examination, not so much.