I'm not with IPC but I have in front of me IPC-SM-782A Amendment 1 which
was recently released ... There was a correction to IPC-SM-782A section
3.6.2.2 stating a width and length for the necked-down area of 0.25mm
(0.010") and 0.50mm (0.020") respectively.

As Gary mentioned, I have also _heard_ "the trace should not be larger than
50% of the pad width" but I don't remember ever seeing that in print by
anyone.

-Jeff-

At 06:37 AM 3/6/97 -0600, Tomas Garman wrote:
>John;
>
>Your reference is correct, but I believe it is a typo in IPC-SM-782.
>.025mm would be .001in the statement in 782 is  "Maximum conductor width
>should be .025mm [.010in]"
>
>Would someone from IPC like to clarify? I believe the .010in figure is
>closer to reality.
>
>Regards
>Tom G.
>
>On Mar 6,  6:16am, john balchunas wrote:
>> Subject: Re: SMTTraces
>> >Date: Wed, 05 Mar 1997 09:02:11
>> >To: [log in to unmask] (Mike Modrzejewski)
>> >From: john balchunas <[log in to unmask]>
>> >Subject: Re: SMTTraces
>> >
>> >Hello Mike, I came across the following info in Surface Mount Design and
>> Land Pattern standard IPC-SM-782A section 3.6.2.2..."Wide conductors
>> connecting to a land area can act as a solder thief...Narrow the conductor
>> as it enters the land area.  Maximum conductor width should be .025
>> mm....The minimum conductor length should be .025 mm."  Hope this helps!
> John
>> >
>> >
>> >At 06:54 AM 3/4/97 CST, you wrote:
>> >>
>> >>
>> >>Hi my name is Michael Modrzejewski
>> >>Iam looking for some information on trace width going into SMT pads.
>> >>Is there any problems with a .025 trace going into a 1206,0805 or 0603
pads
>?
>> >>IS there a rule of thumb for this ?
>> >>
>> >>MOJO
>>-- End of excerpt from john balchunas
>-- 
>Tom Garman KC4WAR
>PCB Designer and Librarian
>Sacred cows make the best hamburger (stolen from a friend)
>Don't force it, get a bigger hammer.
>


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| Jeff Foster                                         [log in to unmask]    |
| Engineering Assistant                                                     |
| Broadcast Electronics, Inc.                         http://www.bdcast.com |
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