ILFA design rules for rigid-flex PCBs
General design rules
Max. PCB dimensions420x570mmOn request
Thickness rigid-flexA0.4 - 4.2mmOn request
Metallized holes & milled cut-outs (details refer to the diameter of the drilling tool)
Drilling tool diameterDeviations possible with press-fit technologySpecified end diameter + 100 µmOn request
Through hole 1Aspect ratio 1:8, minimum Ø 100 µmAspect ratio 1:10, minimum Ø 100 µm
Through hole, plugged and capped ¹2Aspect ratio 1:8, minimum Ø 150 µmAspect ratio 1:10, minimum Ø 100 µm
Edge metallizations3min. 2.0 mm distance from the flexible area
Conductive pattern / remnant annular rings
Trace width on inner & outer layers (µm)Depending on copper thicknessBWithout plugging ≥75 with plugging ≥100Without plugging ≥50 with plugging ≥75
Conductor spacing on inner & outer layers (µm)Depending on copper thicknessCWithout plugging ≥75 with plugging ≥100Without plugging ≥50 with plugging ≥75
Annular ring between end-Ø inner and outer layers (µm) D≥150On request
Distance from hole to hole (µm)Based on end- ØE≥300On request
Distance bore to adjacent conductive pattern (µm)Based on end- ØF≥250On request
Overlap of edge metallization on outer layer (µm)On inner layer recommendedG≥300
Distance of conductive pattern to milling contour (µm)H≥250≥100
Distance from hole to milling contour (µm)Based on end- ØI≥400On request
Soldermask fillet width (µm)Depending on solder mask type, colour, copper thicknessJ≥80≥70
Soldermask clearance to copper (µm)K≥50≥25
Soldermask overlap solder mask defined pads (µm)L≥50≥25
Soldermask clearance of edge metallization (µm)M≥100On request
Soldermask clearance via / component bore unplugged (µm)N≥70On request
Special rigid-flex design rules
Distance from bore to flex area (µm)Based on end- ØO≥700
Length of flex area (µm)P≥2000
Overlap of of coverlay with rigid area (µm)Q500500 - 1000
Minimum bending radius² single bend (mm)Without back bendThickness of flexible area X 1On request
Minimum bending radius² 4-12 cycles (mm)Thickness of flexible area X 6On request
Minimum bending radius² dyn. stress (mm)Thickness of flexible area X ≥10On request
¹Plugging is possible from a circuit board thickness of ≥0.3 mm excl. copper thickness. PCBs with external, flexible base materials, or materials without glass fabric cannot be plugged.
² Bending radius: Thickness of the flexible area = addition of all materials (coverlay, adhesive, copper, base material). The information is only valid for a flexible core with maximum two copper layers.

Download design rules for rigid-flex PCB´s here.