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The IPC Land Pattern Subcommittee has
approved the use of 3 modifiers at the end of Land Pattern names.
The
original IPC-7351 footprint naming convention does not include component
tolerances, thermal pad sizes, BGA Ball sizes or various pin assignments into
account. Therefore, the same component with different tolerances can produce a
different land size and spacing with the same footprint name.
A
footprint name of SOP50P710X120-14N can have version A, B, C, D which do
not indicate the variances.
There
are 3 component features that affect the footprint name –
1. Thermal
Tab Size = SOP50P710X120-14NT300
·
T300 = 3.00 mm
Square Thermal Pad
·
T300X200 = 3.00
mm X 2.00 mm Rectangle Thermal Pad
2. Lead
Length Tolerance = SOP50P710X120-14NL50
·
L50 = 0.50 mm Nominal Terminal Length
3. Ball
Size = BGA121C50P11X11_600X600X100NB23
·
B23 = 0.23 mm Nominal
Ball Diameter
These would be used at the end of the Land Pattern Name
only if a new Land Pattern is added to the user library with an identical Land
Pattern Name but different T, L or B.
Example: Create a BGA chart that has a default Ball
Size for each Pin Pitch.
|
Pin Pitch
|
Nominal Ball Diameter
|
|
1.50
|
0.90
|
|
1.27
|
0.75
|
|
1.00
|
0.60
|
|
0.80
|
0.50
|
|
0.75
|
0.45
|
|
0.65
|
0.40
|
|
0.50
|
0.30
|
|
0.40
|
0.25
|
|
0.35
|
0.22
|
|
0.30
|
0.20
|
For
component mfr. recommended footprint drop the environment level character after
the pin qty. - SOP50P710X120-14
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