What is New in IPC-7351C.pdf - 第25页
PC B L ibr ar i es Pr e s ents : Wh at is N ew i n IPC- 7351C • Th e land p atte r n o r igin is typi c all y l oc ated at th e c e nte r of gr avi ty o f the c ompon e nt, but som e times thi s is dif fi c ul t to c alc…
PCB Libraries Presents:
What is New in IPC-7351C
Assembly Reference Designators
• The default assembly Ref Des height is 2.00 mm
• For miniature components the text height must be scalable to fit
• The default rotation of the assembly reference designator is
associated with the component body length
REFDES
0.6 x 0.3
0201
1.0 x 0.5
0402
REFDES
1.6 x 0.8
0603
2.0 x 1.2
0805
Ref Des Height
1.00 mm
Ref Des Height
0.70 mm
Ref Des Height
0.50 mm
REFDES
Ref Des Height
0.12 mm
REFDES
These Chip assembly Ref Des are scaled down to fit inside assembly outlines
PCB Libraries Presents:
What is New in IPC-7351C
• The land pattern origin is typically located at the center of gravity of the
component, but sometimes this is difficult to calculate with irregular
shaped components, so Pin 1 is used in these cases. Also Pin 1 in most
through-hole connectors.
• The centroid origin marking in the picture below is an unfilled 0.50 mm
diameter circle with a 0.05 line width with a 0.70 crosshair for cursor
alignment.
Land Pattern Origin Guidelines
PCB Libraries Presents:
What is New in IPC-7351C
Snap Grid & Feature Round-off 0.01 mm
Footprint Features in 0.01 mm increments
*Japanese 80% rule
0.01
0.01
0.01
0.005 for 0.65 pitch
0.01
0.01
0.01
0.01
0.01
0.01
0.01
Line Widths
0.01
Corner Radius
0.01