Hi,

We have received a design from a customer (we are a fab shop)
which utilizes a 560pin socket, customer claims for a BGA device.
The parameters of the existing design are;

- 560 pin device
-23mil hole on 30mil pad on 50mil grid, each side is 5 rows deep
-6 layer board with 4 routing layers and 2 plane layers
-currently routing out with 8 and 10mil traces

We have told him that with only 3.5mil annular ring that we are
unable to manufacture this design reliably.  He says this is the
best he can do.

We would like to suggest the following options to him;
-smaller hole size
-5/5 design
-more layers if required

... but would like to pass on some info from seasoned designers.
He may be more receptive to this.

Can anyone suggest a set of manufacturable parameters for this
device and how many layers he can expect to need.

Regards
John Parsons
Circuit Graphics Ltd.