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SMT electronics assembly manufacturing forum.


IPC Class 3 Annular Ring and Fine Pitch BGA Challenges

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#78850

IPC Class 3 Annular Ring and Fine Pitch BGA Challenges | 8 September, 2017

Hello,

I have a few PCB boards i am trying to be manufactured that are miniaturized medical devices. Thus they require IPC Class 3 Specs.

However as miniature devices they have limited space, including a 0.4mm pitch BGA socket, which currently has several via-in-pads at 4/10mil sizing. They are designed currently as through holes for a mechanical drill. 4 Layer 31mil thick board.

One PCB house has informed me that due to the IPC Class 3 annular ring restriction these vias are impossible to manufacture. Hole cannot me smaller and pad cannot be larger. laser drill micro-via design are an option, at a significant cost increase and possible design adjustments on other layers.

Another PCB house has told me as they are Via-in-Pads they can be simply filled with nonconductive epoxy, and plated over. Then they are treated as typical BGA pads and the annular ring restriction will not not apply.

Which is correct?

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#78873

IPC Class 3 Annular Ring and Fine Pitch BGA Challenges | 13 September, 2017

Any insight appreciated!

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