I repeat; We use square and rectangular for 0201, 0402, 0603 and etc.
These are used on designs running at a million / month volume and all lead
free.
I work for Flextronics.
I add, over 60M units last year from one division shipped this way from
one division.
------------------------------
*From:* icu-pcb-forum-bounce@xxxxxxxxxxxxx [mailto:
icu-pcb-forum-bounce@xxxxxxxxxxxxx] *On Behalf Of *J Wages
*Sent:* Friday, January 05, 2007 4:36 AM
*To:* icu-pcb-forum@xxxxxxxxxxxxx
*Subject:* [Norton AntiSpam] [PCB_FORUM] Re: 0402, 0603 round pads
Small discrete footprints with rounded or beveled pads (each outside
corner beveled at 45 degrees for 20% of the pad width) on 0402 & 0603's
benefit in the alignment process in both wave soldering and reflow assembly
methods due to the greatest amount of solder being at the center of the
component axis. I have been strictly contracting layout for the last 5 years
and the assembly vendors that have measured this approach have found
approximately 10 to 15% decrease in component misalignment issues. This
yield ratio is, of course, subject to the manufacturers expertise and
equipment. Unfortunately, many companies are not willing to adjust their
"golden library footprints". Why? … and I'm sure you've all heard this
before…"Cuz this is the way we always do it!"
I have also used the beveled 0402 pads for use in placing decoups within a
1mm BGA via fan-out grid. This requires some other pad size/geometry
refinements and are not as reliable, but if you need BGA pin decoupling, as
apposed to area decoupling, it's the way to go. Of course many large
companies are banking on yield savings and designing out decoupling losses,
so are very reluctant to use this approach. We used the 0402 with octagon
pad geometries for 50 mil & 1mm BGA fan-out decoupling at Sanmina-SCI with a
pretty good success ratio, although I don't remember what those numbers
were. I do remember that it definitely creates a yield reduction. The same
old battle; Yield vs signal integrity. A good discussion to initiate with
your assembly house.
*Jim S. Wages / SR. PCB Layout Designer: *
*Cary**, NC** - H: 919-466-1596 Cell: 919-484-2963*
-----Original Message-----
*From:* icu-pcb-forum-bounce@xxxxxxxxxxxxx [mailto:
icu-pcb-forum-bounce@xxxxxxxxxxxxx] *On Behalf Of *Peter
*Sent:* Thursday, January 04, 2007 11:26 PM
*To:* icu-pcb-forum@xxxxxxxxxxxxx
*Subject:* [PCB_FORUM] Re: 0402, 0603 round pads
We use square and rectangular for 0201, 0402, 0603 and etc. These are used
on designs running at a million / month volume and all lead free.
I work for Flextronics.
------------------------------
*From:* icu-pcb-forum-bounce@xxxxxxxxxxxxx [mailto:
icu-pcb-forum-bounce@xxxxxxxxxxxxx] *On Behalf Of *Austin Franklin
*Sent:* Thursday, January 04, 2007 6:53 PM
*To:* icu-pcb-forum@xxxxxxxxxxxxx
*Subject:* [Norton AntiSpam] [PCB_FORUM] Re: 0402, 0603 round pads
Hi Gary,
I use round pads for my 0402s on the opposite side of 1mm BGAs. That way
I can keep the decoupling caps and termination resistors right there. Works
fine, haven't had any yield problem.
Regards,
Austin
-----Original Message-----
*From:* icu-pcb-forum-bounce@xxxxxxxxxxxxx [mailto:
icu-pcb-forum-bounce@xxxxxxxxxxxxx]*On Behalf Of *Macindoe, Gary
*Sent:* Thursday, January 04, 2007 6:05 PM
*To:* icu-pcb-forum@xxxxxxxxxxxxx
*Subject:* [PCB_FORUM] 0402, 0603 round pads
Hey guys,
Man has it been quiet (or am I not receiving forum e-mails?).
So, I've been looking at some designs from a couple of other groups within
the company.
Both of them have their 0402 and 0603 foot prints with round pads (0402 =
rd25).
Is anyone out there also using round pads for 0402s and 0603s, and why?
They have oval pads for their 0805s and 1206s also.
I still have square or rectangular for all of the above. Could it have
something to do
with lead free?
Thanks and Happy New Year!
Gary
**
*Gary E. MacIndoe*
PCB Design Engineer
Longmont, Colorado
amd.com
gary.macindoe@xxxxxxx
