Ross,

1.  Watch your copper height from your conductors (minimal).
2.  Based on past experience you cannot have 4 - 8mil lines with 
     10mil spacings between land patterns.  The standard max. land to land 
     spacing is 1.4mm (55mils) and the min. is 1.2mm (47mils).  You 
     decreased your X pad but not your Y pad dimension which is critical.
     You would need a min. of 82mils in between lands.  10mils between 
     lands and the conductors with a 5mil soldermask dam.  If you 
    decreased your Y land anymore, you would need to watch your 1206 
    packages very carefully.

    The standard land pattern for a 1206 is outlined in IPC-782, 
    section 8.

Others may disagree.

John Gulley - PE
Compuroute Inc.
Dallas, TX 
214-340-0543





  




> Date:          Wed, 11 Sep 96 10:37 WET DST
> To:            [log in to unmask]
> From:          [log in to unmask] (test)
> Subject:       spacing/design considerations for 1206 packages

> I would like to konw if anyone out there has done a design using 1206 style
> packages and has run four traces underneath the part.  By shrinking the
> standard pad in our default CAD libraries to 52 x 64 I can get four 8 mil
> lines underneath the package.  It works out to 10 mil spacing with 8 mil
> lines.  Anyone out there have problems with doing something like this?
> 
> Thanks in advance.
> 
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