Reference symbols and dimension examples

Terminology Reference Symbol Description
Nominal dimensions D x E Combination of package length D and package width E
Package length D Largest dimension of the package length excluding terminals
Package width E Largest dimension of the package width excluding terminals
Overall length HD
or
HD
Length from the tip of the terminal to another tip of the terminal on the opposite side
Overall width HE
or
HE
Width from the tip of the terminal to another tip of the terminal on the opposite side
Seating plane S The surface determined when the package is placed on a horizontal surface
Seated height A Height from the seating plane to the highest point of the package ( including package warp )
1st standoff height A1 Distance from the seating plane to the base plane
Package height A2 Height from base plane to top edge of package body
Standard height of soldered point A3 Standard height 0.25mm from seating plane
Terminal pitch e Terminal pitch. This represents theoretical reference dimension.
Terminal width b or bp Width of terminal with plating
Terminal width b1 Width of terminal before plating
Terminal thickness c Thickness of each terminal(including plating)
Terminal thickness c1 Thickness of terminal before plating
Length of flat part of terminal L Projection length of flat part of terminal
Length of soldered part Lp Effective projected length of terminal attachment defined by standard height of soldered part
Terminal length L1 Projection length of terminal
Tolerance value of terminal center position Positional tolerance for center axis of the terminal on seating plane. Using the maximum material principle, show the tolerance for maximum terminal width. When terminal width is narrow, allowable tolerance is increased by the difference with the maximum width.
Coplanarity y Uniformity of the bottom-most surface of the terminal relative to the datum S (seating plane)
Angle of terminal flat portions θ
Angle between flat part of terminal and seating plane
Package overhang ZD
or
ZD
Distance from the true position of the outer-most terminal to the package edge
Widthwise overhang
Package overhang
ZE
or
ZE
Distance from the true position of the outer-most terminal to the package edge