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TMS320C6678 - layout question

Viktorija Cecil
Mastermind 18501 points

Other Parts Discussed in Thread: TMS320C6678

I have a layout footprint design question for 0.8mm pitch BGA.

I use TMS320C6678 in my project, 0.8mm pitch BGA; I checked the recommend footprint NSMD Pad size is 0.45mm; but my PCB board thickness is 93 mil; so if I want use via hole size is 10 mil; via capture pad size is 20 mil; I put via diagonally center; the pad size is too big and it'll make via to pad space =3.25mil; trace and gap =4.5mil; Question: if I reduce pad size from .45mm to .4mm, is it ok? it'll effect realibility or something else..?

Thanks

Viktorija

  • 0
    TI__Mastermind 46460 points

    Viktorija,

    The NSMD pad size is ideally equal to the pad on the BGA.  0.45 mm is 18 mils.  We often see designs using 16 mil pads but 18 mil pads should fit without problem.  Using 0.8 mm (31.5 mils) pitch and 0.45 mm (18 mils) BGA pads, I get 26.5 mils of space diagonally pad to pad.  Using 4 mil spacing will allow only an 18 mil via pad.  If you require a 20 mil via pad then you will be restricted to 16 mil BGA pads.

    Tom