George,

Sounds like your mfg folk need a new BGA rework station.  A bottom side
heater and controlled profile is a must.  We've had no problem removing
400-600 ball arrays off of .093 boards with multiple 1 & 2 oz copper planes,
with all direct connected vias.

http://www.metcal.com/products/1.2.5.3.htm

Gary Crowell
Micron Technology



-----Original Message-----
From: George Patrick [mailto:[log in to unmask]]
Sent: Wednesday, December 13, 2000 8:51 AM
To: [log in to unmask]
Subject: Re: [DC] Thermal relief for Vias?


Mark:
Our manufacturing folks want thermals on BGA vias.  They say removal of the
part for rework is much harder if all the ground/power vias are connected
directly to the plane.

--
George Patrick
Tektronix, Inc.
Central Engineering,  M/S 39-512
P.O. Box 500
Beaverton, OR 97077-0001
Phone: 503-627-5272    Fax: 503-627-5587



-----Original Message-----
From: Mark Gutierrez [mailto:[log in to unmask]]
Sent: Tuesday, December 12, 2000 09:23
To: [log in to unmask]
Subject: [DC] Thermal relief for Vias?


Someone here suggested that all vias connected to power and ground planes
should have the thermal relief's eliminated. Reason to
minimize inductance to power planes. I recall reading somewhere about
removing thermals could induce reliability problems. Can anyone share their
knowledge and experience with this?. IPC-2221 specifies thermal relief is
only required for holes that are subject to soldering in large conductor
areas. Wouldn't this apply to a via tied to a plane coming off a SMD land?

Mark Gutierrez


Mark Gutierrez

Senior Printed Circuit Designer

Blaze Network Products Inc.

5180 Hacienda Drive

Dublin, CA 94568

email: [log in to unmask] <mailto:[log in to unmask]>

www.blazenp.com <http://www.blazenp.com/>

----------------------------------------------------------------------------
-----
DesignerCouncil Mail List provided as a free service by IPC using LISTSERV
1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF DesignerCouncil.
Search previous postings at: www.ipc.org > On-Line Resources & Databases >
E-mail Archives
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700
ext.5315
----------------------------------------------------------------------------
-----

---------------------------------------------------------------------------------
DesignerCouncil Mail List provided as a free service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF DesignerCouncil.
Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
---------------------------------------------------------------------------------