[SI-LIST] Re: 0.8mm BGA routing
- From: Dimiter Popoff <dimiter.popoff@xxxxxxxxxxx>
- To: <si-list@xxxxxxxxxxxxx>
- Date: Wed, 24 Dec 2003 17:34:19 +0200
Tayyab Jamil Qureshi,
I have been successfull with these using 5 mil resolution.
This allowed 3 traces between the BGA pads; also, I put a
via on all BGA pads, hole was drilled 0.3mm thus getting
about 0.2mm after plating. This leaves 0.508mm (20 mil)
pad diameter - and allowed me to route the whole mess
without sacrificing any area on two signal layers (and 4
planes).
There is an important detail with the through-holes on
every BGA pad. Sometimes some of the solder balls on the
BGA package are not well attached; this may result into
losing the ball during reflow (it just flows through the hole
to form a bubble on the bottom of the board).
My solution to that was to reflow all BGA packages with
some flux once belly up; this makes sure all balls are
really soldered to the package, and surface tension does
the rest of the job during the final reflow (it does it for
most of the balls either way, the thing is, we want all
of them to connect :-).
Good luck,
Dimiter
--------------------------------------------------------------------
Dimiter Popoff
Transgalactic Instruments, Gourko Str. 25 b, 1000 Sofia, Bulgaria
http://transgalactic.freeyellow.com
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List technical documents are available at:
http://www.si-list.org
List archives are viewable at:
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
Other related posts:
