What is New in IPC-7351C.pdf - 第32页

PC B L ibr ar i es Pr e s ents : Wh at is N ew i n IPC- 7351C La nd P a t t er n Na ming Con v e nt i on • Th e e xis ti ng IPC-735 1 lan d p atte r n nam i ng c on ve ntio n doe s n ot tak e into c on s i de r ation co …

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PCB Libraries Presents:
What is New in IPC-7351C
Extended Names Eliminate Duplication I
• The original IPC-7351 footprint naming convention does not include Gull Wing
component lead tolerances, Thermal Pad sizes, BGA Ball sizes or Chip Terminal
Lead Width 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 SOP50P710X120-14Ncan have version A, B, C, D which do
not indicate the variances in Thermal Tab or Lead Length
• There are 3 component features that affect the footprint name
• Square/Rectangle Thermal Tab Size = SOP50P710X120-14T300/T300X500
• Gull Wing Lead Length Tolerance = SOP50P710X120-14L50
• BGA Ball Size = BGA121C50P11X11_600X600X100B23
• Chip Terminal Lead Width = CAP3216X135L45
• For component mfr. recommended footprint drop the environment level
character after the pin qty. - SOP50P710X120-14
Land Pattern Naming Convention
PCB Libraries Presents:
What is New in IPC-7351C
Land Pattern Naming Convention
• The existing IPC-7351 land pattern naming convention does not take into
consideration component package tolerances.
• Package tolerances affect the pad, silkscreen and courtyard sizes
• You can have several packages with the same dimensions but different
tolerances but the IPC-7351 naming convention will name all the parts with
the same land pattern name
• In order to save the IPC-7351 naming convention and eliminate duplicate
land pattern names for parts with different tolerances, we need to add the
component manufacturer abbreviation as a prefix to the IPC-7351 name
• Example: SOP50P710X120-14L50T300X500 will become these names –
• TI_SOP50P710X120-14L50T300X500
• MAXIM_SOP50P710X120-14L50T300X500
• ANALOG_SOP50P710X120-14L50T300X500
Extended Names Eliminate Duplication II
PCB Libraries Presents:
What is New in IPC-7351C
New Land Pattern Naming Convention
Extended Names Eliminate Duplication III
• Component manufacturer’s apply different tolerances on
the package dimensions which creates a different footprint
pattern. So a new Naming Convention must be created for
each mfr. Case Code
• Standard Packages – MfrNameAbr_MfrCaseCode
• Unique Packages – MfrNameAbr_MfrPartNumber
• This new naming convention is exclusive to all footprints,
so instead of having one naming convention for Standard
Packages and a different naming convention for Unique
packages, a universal naming convention is needed