Screaming Circuits: BGA Via in pad


BGA Via in pad

We're starting to see more an more .5mm ball pitch mid-count BGAs here at Screaming Circuits. When you've got 400 - 500 balls on a .5mm pitch BGA, routing becomes a real challenge. One of the solution designers are exploring involves putting vias directly in the ball land pad.

This can be a very helpful technique, both from the perspective of easing layout pain and with ultra high-frequency applications, can get your capacitors even closer to the chip.

If you are going to do this, we strongly recommend that you have your vias filled and plated over at your board house. From an assembly standpoint, this will result in the same reliability that you would expect without vias in pad.

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Comments

I'd follow your PCB fab shop's or the component manufacturer's recommendation for the specific fill materials based on the application. In general though, thermally sensitive applications may need copper plugs and a lot of other applications can use a conductive epoxy.

With any fill material, it should then be plated with copper and the same finish as the rest of the PCB.

If I may clarify, what type of fill and plating materials would you recomend?

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