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I'm working on a project which requires the use of a CSP package. The product's datasheet provides ball pitch in each axis as X:710um Y:580um and ball diameter as 250um but nothing about the preferred land pad diameter.

How can the pad diameter be worked out from these figures assuming an NSMD land?

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Well a good place to start for questions like these would be the IPC spec PC-7351B not free but it has all the information you'd need about land patterns for most any part.

Second I like to use the free version of the pcblibraries tool because it automatically generates IPC compliant footprints from your input data, and can then output or create them in your CAD program.

Finally here's a link from mentor describing more than you'd ever want to know about BGA pad size. For instance it shows this IPC table:

enter image description here

With your ball diameter being 0.25mm, that looks like a land pattern of 0.20mm.

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  • \$\begingroup\$ You mean 0.25 and 0.2 \$\endgroup\$ Apr 17, 2015 at 2:02

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