pcb design for bga grounding.

I am currently involved with designing a pcb which will use 225 pin bga,s The problem with this design is that the components will dissipate a lot of heat and the design we have come up with is use the middle 6 or 7 rows of balls as the grounding,these would go through micro vias via a teardrop to the next layer of board where these balls would all join up together as one area of copper, which would then come back up to the top layer through vias. Has anyone tried this before, and if so was it successful,or as anyone overcome this problem any other way ?

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| I am currently involved with designing a pcb which will use 225 pin bga,s | The problem with this design is that the components will dissipate a lot of heat and the design we have come up with is | use the middle 6 or 7 rows of balls as the grounding,these would go through micro vias via a teardrop to the next layer of board where these balls would all join up together as one area of copper, which would then come back up to the top layer through vias. | Has anyone tried this before, and if so was it successful,or as anyone overcome this problem any other way ? | Ray- If I understand what you are saying it does not sound like the right solution. You are putting a plane under the BGA that ties to the inner 6 or 7 rows, then a via comes back to the top. A couple of questions. 1) Is the plane you are tying to a ground plane or just local under the BGA? 2) What kind of BGA are you using, a TBGA? 3) Can you not cool off thru the lid or is it a cavity up package? Jim

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| | I am currently involved with designing a pcb which will use 225 pin bga,s | | The problem with this design is that the components will dissipate a lot of heat and the design we have come up with is | | use the middle 6 or 7 rows of balls as the grounding,these would go through micro vias via a teardrop to the next layer of board where these balls would all join up together as one area of copper, which would then come back up to the top layer through vias. | | Has anyone tried this before, and if so was it successful,or as anyone overcome this problem any other way ? | | | Ray- | If I understand what you are saying it does not sound like the right solution. You are putting a plane under the BGA that ties to the inner 6 or 7 rows, then a via comes back to the top. A couple of questions. 1) Is the plane you are tying to a ground plane or just local under the BGA? 2) What kind of BGA are you using, a TBGA? 3) Can you not cool off thru the lid or is it a cavity up package? | Jim, Thanks for the reply, i have sent you an e mail with more info in it. thanks ray hare | |

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Ray,

what about allowing everybody else to know about the "more info" ???? This is supposed to be a forum, isn't it?

Bye, SB

| Thanks for the reply, | i have sent you an e mail with more info in it. | thanks ray hare

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