[SI-LIST] Re: 0.8mm BGA routing
- From: Steeve Gaudreault <s.gaud@xxxxxxxxxxxx>
- To: si-list@xxxxxxxxxxxxx
- Date: Fri, 26 Dec 2003 11:39:32 -0500
What I did in previous design, was asking the PCB shop of what they are able
to achieve. Some pads like power and gnd can use blind vias to the 1 or 2
layer down and this provide more routing channel using inner layers. They
can also suggest smaller hole size and smaller FHS etc. Try to get a feel
from more than 1 PCB shop. Also, depending of the device that you are using,
the manufacturer sometime have a breakout example in their app note.
Good luck.
Steeve Gaudreault
H/W engineer
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]On
Behalf Of Tayyab Jamil
Sent: December 25, 2003 11:35 PM
To: Stephen Chavez
Cc: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: 0.8mm BGA routing
Hi,
I could not understand your scheme, for me it is not possible what you
suggest as
0.8 mm pitch means there is only about 31 mil distance between via pads of
adjacent pins. 24 mil pad of via leaves only around 7.xx mils space in
between. If we use 5 mil trace this leaves only around 2.xx mils in total on
both sides of the trace, means 1.xx mil clearence on each side of trace.
What i was thinking of is 18mil via pad and 8mil via hole finished, and 4mil
trace and 4mil clearnce. This allows one trace to be escaped between
adjacent pades. Any suggestions about this.
Please let me know if I am wrong.
Regards
Tayyab
-----Original Message-----
From: Stephen Chavez [mailto:stephen.chavez@xxxxxxxxxxxxxxxx]
Sent: Wednesday, December 24, 2003 9:14 PM
To: tayyab@xxxxxxxxxxxxxx
Subject: RE: [SI-LIST] 0.8mm BGA routing
Tayyab,
I just finished a design with a 896 pin BGA (Xilinx) with 0.8mm pitch. I
used 5mil trace width, 5mil spacing and Via: 24mil pad with 12mil hole. I
have done the research and this is what Xilinx recommended. It works fine. I
have designed with this configuration on a 10 layer board. I have even went
down to a Via with 20mil pad and 10mil hole. This worked fine also. I
checked with my board house to confirm this before I started my design. Feel
free to get back to me if you have any questions. Good luck.
Regards,
Stephen V. Chavez
PCB Designer
Vista Systems
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Tayyab Jamil
Sent: Wednesday, December 24, 2003 4:50 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] 0.8mm BGA routing
Hello,
I am currently working on a design where a 0.8 mm pitch BGA package is used.
Can any one suggest me the design configuration i.e trace width/spce and
specially the via size and via hole, which i should follow and manufacturers
can handle this.
Regards
Tayyab Jamil Qureshi
Sr. Design Engineer
CARE Pvt. Ltd.
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