| Pitch of the holes
should be 2x the hole diameter (i.e. for .020" holes,
center-to-center spacing should be .040").
The idea of the tab is that it may be snapped off
manually, either by hand or by flexing the tab with
a pair of needle nose pliers.
The weakest part of the tab is along the diameter
of the row of holes.
To help minimize the cost in drilling you might use
the smallest via hole size already used on the board
so the fabricator will not have to add additional
drill sizes. Typical : .030" holes on .050"-.060"
centers.
To minimize tab residue, drill the breakaway holes
with their diameter or hole center along the board
outline. When the tab is broken off, part of the drilled
hole will be on the inside of the board outline, and
the tab residue outside the outline will be negligible.
Tab location: tabs should be as far as possible from
small SMD components as practical because the flexing
of the board during singulation could fracture adjacent
solder joints or the component body itself. No component
within .300" radius of the tab should be mounted perpendicular
to the edge of the board.
Specifications Perforated Breakaway Tabs:
Location -- Board Edge:
Perforations shall be located tangent to the board
edge and inside the image to produce a smooth finished
edge.
Location -- Orientation:
Tabs should be located in straight lines along the
x and y axes of the board.
Location -- Overhanging Connectors:
Breakaway tabs shall be outside an overhanging connector
by a distance of no less than 0.100” Inch [2.540
mm].
Tab-To-Tab Clearance:
Breakaway tabs shall be separated by a maximum distance
of 2.00” Inch [50.80 mm].
Tab-To-Corner Clearance:
The maximum distance from a tab to a corner shall
be no less than 0.250” Inch [6.350 mm].
Breakaway Width:
The minimum breakaway width excluding the route shall
be no less than 0.250” Inch [6.350mm].
Tab Width:
For 0.031” thick boards and smaller, the maximum
tab width shall be no more than 0.120” Inch
[3.048 mm].
For 0.062” thick boards, the maximum tab width
shall be no more than 0.120” Inch [3.048 mm].
For 0.093” thick boards, the maximum tab width
shall be no more than 0.110” Inch [2.794 mm].
Perforation Diameter:
For 0.031” thick boards or smaller, the maximum
perforation hole diameter (non-plated holes) shall
be no more than 0.030” Inch [0.762 mm].
For 0.062” thick boards, the maximum perforation
hole diameter, Design For Manufacturability, (non-plated
holes) shall be no more than 0.030” Inch [0.762
mm].
For 0.093” thick boards, the maximum perforation
hole diameter (non-plated holes) shall be no more
than 0.040” Inch [1.016mm].
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