Chapter 5
Working with Traces and Copper
5-18
ni.com
Placing SMD Fanouts
The
Fanout SMD
command attaches vias to each pin of either a selected
surface mount device (SMD) or all SMDs on the board.
Complete the following steps to place SMD fanouts:
1.
Optionally, select the part(s) to which you wish to apply fanouts, as in
the example shown in the figure below.
2.
Select
Design»Fanout SMD
. The
Fanout Options
dialog box
appears.
3.
In the
Fanout Type
box, select one of:
•
Fanout Board
—Fanout action will apply to the entire board.
•
Fanout Selected Part
—Fanout action will apply to the selected
part only.
4.
In the
Fanout Via Configuration
box, enter the following as desired:
•
Via Drill Diameter
—The diameter of the placed vias’ holes.
•
Via Pad Diameter
—The diameter of the placed vias’ pads.
•
Via Spacing Factor
—This is for PGA parts only (it does nothing
for non-PGA parts); determines how far apart the vias are placed.
For example, if the distance between the SMT pins is 2mils, and
the
Via Spacing Factor
is 2, then the distance between the vias
will be 2mils × 2 = 4mils. The direction of this distance depends
on where the via is placed, but basically, if the SMT pin is at the
top, the the via will also be at the top, and the distance is the Y
distance between each row of vias will be 4mils. The distance also
depends on the particular part - each part may have different SMT
spacing, so the distance may vary.
