Flex PCB Manufacturing Capabilities
Flexible PCBs require different design rules than rigid boards. The polyimide substrate, adhesive layers, and coverlay all affect what’s achievable. Here’s what we can manufacture.
Layer Count and Thickness
| Parameter | Standard | Advanced |
|---|---|---|
| Layer count | 1–4 layers | 5–8 layers |
| Board thickness (without stiffener) | 0.05–0.5mm | 0.5–0.8mm |
| Thickness tolerance (single layer) | ±0.05mm | ±0.03mm |
| Thickness tolerance (multilayer <0.3mm) | ±0.05mm | ±0.03mm |
| Thickness tolerance (multilayer 0.3–0.8mm) | ±0.1mm | ±10% |
Bend Radius Requirements
The minimum bend radius depends on your layer count and whether the flex will bend repeatedly:
| Configuration | Minimum Bend Radius |
|---|---|
| Single layer (static bend) | 3–6× board thickness |
| Double layer (static bend) | 6–10× board thickness |
| Multilayer (static bend) | 10–15× board thickness |
| Dynamic bend (repeated flexing) | 20–40× board thickness |
Dynamic bend applications require single-layer construction for reliability.
Line Width and Spacing
Achievable trace geometries depend on copper weight:
| Copper Weight | Standard (width/space) | Advanced (width/space) |
|---|---|---|
| 12–18μm (⅓–½oz) | 3.0/3.2 mil | 2.8/2.7 mil |
| 35μm (1oz) | 4.0/4.0 mil | 3.5/3.5 mil |
| 70μm (2oz) | 6.0/6.5 mil | 5.0/6.0 mil |
| 105μm (3oz) | 10/13 mil | 9.5/12.5 mil |
Note: Loop lines (traces that return to the same point) require approximately double the width/space.
Materials
Base Materials (FCCL)
Adhesive-based:
- Shengyi SF305: PI 0.5–2 mil, Cu ⅓–1oz
- Panasonic R-F775: PI 1–3 mil, Cu ½–1oz
- Taiflex MHK: PI 1–2 mil, Cu ⅓–1oz
Adhesiveless:
- DuPont Pyralux AP: PI 1–3 mil (standard), 4 mil (advanced), Cu ½–2oz
- Taiflex MHK: PI 1–2 mil, Cu ⅓–1oz
Coverlay
- Shengyi SF305C
- Taiflex FHK
Stiffeners
- PI stiffener: 3–9 mil thickness
- FR4 stiffener: Available with ±0.1mm tolerance
Drilling and Holes
| Parameter | Standard | Advanced |
|---|---|---|
| Minimum mechanical drill | 6 mil (0.15mm) | 4 mil (0.1mm) |
| Via-to-conductor clearance (<4 layer) | 6 mil | 5 mil |
| Via-to-conductor clearance (4–6 layer) | 8 mil | 7 mil |
| Via-to-conductor clearance (7–8 layer) | 12 mil | 10 mil |
Surface Finishes
Available finishes for flex PCBs:
- HASL – Hot air solder leveling
- ENIG – Electroless nickel immersion gold (Ni: 3–6μm, Au: 0.05–0.1μm)
- ENEPIG – Electroless nickel electroless palladium immersion gold
- Electrolytic gold – Soft or hard gold options
- Immersion silver – 0.2–0.4μm thickness
- OSP – Organic solderability preservative
- Immersion tin – Advanced capability only
Mixed finishes (ENIG+OSP, ENIG+gold finger) are also available.
Board Size
| Parameter | Standard | Advanced |
|---|---|---|
| Minimum size (without bridge) | 5×10mm | 4×8mm |
| Minimum size (with bridge) | 10×10mm | 8×8mm |
| Maximum size | 9×14 inch | 9×23 inch |
Impedance Control
| Type | Standard Tolerance | Advanced Tolerance |
|---|---|---|
| Single-ended ≤50Ω | ±5Ω | ±3Ω |
| Single-ended >50Ω | ±10% | ±8% |
| Differential ≤50Ω | ±5Ω | ±4Ω |
| Differential >50Ω | ±10% | ±8% |
Solder Mask
- Colors: Green standard, others available
- Minimum solder dam: 4 mil (green), 8 mil on large copper areas
- Minimum clearance: 3 mil (2.5 mil for specific areas)
- Coverlay bridge minimum: 8 mil
Related Articles
- Multilayer PCB Capabilities – Rigid PCB specifications for comparison
- PCB Materials and Laminates Guide – Material properties and selection
- PCB Designer’s Tips – Design guidelines for manufacturability
Need help with a flex PCB design? Request a quote – our engineers can review your design for manufacturability and recommend the best construction.