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0.65mm BGA constraint management ??

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kabaleevisu

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Hi everyone,

In my board has 0.65mm pitch BGA.via pad size is 14 and drill is 8 (in mil) used between 2 ball .when i send the gerber file to manufacturer side ,i got some issue in design.

the manufacturer need via pad is 0.5mm and annual ring is must be .125m .if i change the via size in BGA i get error in design

i felt if via pad size is increase air gap(clearance ) will change , so design well affect .please anyone help for how to set the constraint in 0.65 mm pitch BGA.....
 

samym

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yes we cant increase the pad size
 

swendy

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I'm not sure if you can try Via In Pad.
 

robertferanec

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I see two options:
- uVIA in PAD and then buried VIA at the same place as are your current VIAs (connected together on Layer 2). This will increase PCB price, but it is fastest solution.
- Reroute it. For this bga (0.65mm pitch) VIA can be placed between pins if all four are on the same net (for example GND). From my experience, I wouldn't use VIAs below 0.45um pad / 0.2 um drill ( PCB stackup example )
 

samym

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I see two options:
- uVIA in PAD and then buried VIA at the same place as are your current VIAs (connected together on Layer 2). This will increase PCB price, but it is fastest solution.
- Reroute it. For this bga (0.65mm pitch) VIA can be placed between pins if all four are on the same net (for example GND). From my experience, I wouldn't use VIAs below 0.45um pad / 0.2 um drill ( PCB stackup example )

hi,

we have done many jobs using via on pad for 0.4mm,0.5mm and 0.65mm pitch bga

in this case we need to callout for silver fill for those vias in via in pad section.

this will increse the cost but not more than buried vias.
 

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