What is New in IPC-7351C.pdf - 第3页

PC B L ibr ar i es Pr e s ents : Wh at is N ew i n IPC- 7351C T he origina l IPC-7 25 1 C oncept f or 3-Tier P ad S t ack Jo i nt Ch a r a cter i s ti cs M axi m u m (Mo s t) Den s i ty Level A M edi a n (No m i na l ) D…

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PCB Libraries Presents:
What is New in IPC-7351C
Through-Hole Technology
PCB Libraries Presents:
What is New in IPC-7351C
The original IPC-7251 Concept for 3-Tier Pad Stack
Joint Characteristics
Maximum
(Most)
Density
Level A
Median
(Nominal)
Density
Level B
Minimum
(Least)
Density
Level C
Hole Diameter Factor (over max lead)
0.25 0.20 0.15
Int. & Ext. Annular Ring Excess
(added to hole dia.)
0.50 0.35 0.30
Anti-pad Excess (added to hole dia.)
1.00 0.70 0.50
Courtyard Excess from Component
Body and/or Pads
(which ever is greater)
0.50 0.25 0.12
Courtyard Round-off factor
Round up to the nearest even two place decimal,
i.e., 1.00, 1.01, 1.02, 1.03 etc.
3-Tier IMD (Inserted Mount Device)
PCB Libraries Presents:
What is New in IPC-7351C
3-Tier Pad Stack Concept
Proportional Pad Stack
Small Hole
Large
Hole
Same Annular Ring
Proportional
Annular Ring