Flexible Printed Circuits (FPC): Design Considerations
| FPC Type | Single sided (SS) Double sided (DS) Flex multilayer Rigidflex multilayer |
High volume panel or R2R High volume panel or R2R High volume to 4 layers Low volume |
|---|---|---|
| Base Materials | Polyimide (PI) Polyester (PET) |
Adhesive type and adhesive-less type available |
| Base Materials Thickness | 25 μm + adhesive-less 50 μm + adhesive |
12.5 μm available 25 μm available |
| Available Copper Thickness (Weight) |
12 μm (1/3 oz), 17.5 μm (1/2 oz), 35 μm (1 oz), 70 μm (2 oz) |
|
| Coverlay Materials | Polyimide (PI) Polyester (PET) |
|
| Coverlay Material Thickness | 50 μm and up (25 μm PI / 25 μm adh) |
25 µm possible (12.5 µm PI / 12.5 µm adh) |
| Soldermask Materials | Flexible soldermask | Printed or LPI (Liquid Photo Imageable) |
| Soldermask Thickness | 20 μm – 25 μm typical | |
| Min Line & Space | 80 μm (based on 17 μm cu) | 75µm available |
| Outline Tolerance | ±70 μm Hard tool ±100 µm + ±200 µm Steel Rule Die ±250 μm + |
Outline to outline feature Trace to edge Outline to outline feature Trace to edge |
| Minimum Drilled Hole Size | 80 μm 2 – 3 μm |
Mechanical drill Laser (R2R processing) |
| Available Surface Finish | OSP - Electro-plated Sn Immersion Sn Electro-plated Ni / Au ENIG Immersion Ag |
0.2 μm – 0.5 μm thick 25 μm ± 10 μm thick 0.6 μm – 1.2 μm thick 3-5 μm Ni / 0.05 – 0.125 μm Au 3-5 μm Ni / 0.05 – 1.0 μm Au 0.2 μm – 0.3 μm thick |
| Components | 0402 and up0 SMT Flip chip available |
Conventional Pb free solder or Polysolder™ conductive epoxy |
| Continuous Operating Temp | 40 °C to +125 °C (PI) 20 °C to +85 °C (PET) |
+150 °C available |
| Temperature / Humidity | 1000 hrs 85 °C / 85% RH | Temperature / Humidity |