using unused pin on BGA for other tracks

[Via]

I working on BGA component that has a bunch of unused pins by the manufacturer, the BGA pin distance is 0.5 mm, can I use unused pins for other tracks? connecting them together as track actually?

[mohsin_qau]

can I use unused pins for other tracks???? Wots that mean? Please more elaborate.

[robertferanec]

If they do not specifically say in datasheet that these pins are NC (Not Connected) I would not connect these pins. Even if they would say the pins are NC, some manufactures they use NC even for pins which should be mark as DNC (Do Not Connect - this means the pins are connected internally and may be used for example for testing during manufacturing - this means you should not connect these pins).

So even if manufacturer would mark these pins as NC in datasheet, I am not sure if I would connect them - probably rather not. In future the may use these pins for something (e.g. new improved version of the chip) and then you may be limited with your design.