Eileen -

The recommendations I received from my fabricator are as follows:

0.013 dia. BGA lands
0.0195 dia. Via lands
0.010 dia. Via drill (through)
All connections to be tear-dropped (filleted)

This will allow for a 5 mil trace and space routing on external layers and 4
mil traces with 5 mil spaces on internal layers.

Good luck with the design.

Jeffrey A. McGlaughlin
Sr. PCB Designer
Battelle Memorial Institute
Columbus Ohio
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        -----Original Message-----
        From:   Eileen Ong [R&D] [SMTP:[log in to unmask]]
        Sent:   Tuesday, 14 March, 2000 05:23
        To:     [log in to unmask]
        Subject:        [DC] BGA

        Hi,
        This is the first time using a micro BGA package (256 lead,pitch
1mm) below
        are some of my questions that anyone help me.
        1) What  pad size to use for a good solder joint?
        2) What is the best way to route and layers needed? Also the most
cost
        saving example microvia,blind/burried via ?
        3) what trace width to use ?
        4) Is it possible to route this BGA without using any via on pads ?
        5) What are the instruction for pcb manufacturer.
        6) Any one who have design this type of bga that can share your
package or
        show me your design. ( I'm a Pads user)
        Tia.

        Best Regards,
        EILEEN ONG (R&D Dept.)
        Paradise Innovations (Asia) Pte Ltd
        25 Serangoon North Ave 5
        6th floor Uraco Building
        Singapore 554914
        Did: (65) 485-6690 (Office)
        Fax: (65) 481-2611
        Email : mailto:[log in to unmask]
        Web: http://www.paradisemmp.com