PCB Fabrication
Flexible PCBs: circuits that fold into places boards can't.
Copper on polyimide film, thin enough to bend, fold, and flex for the life of the product — the answer when the enclosure refuses to be rectangular.
What is a flexible PCB?
A flexible PCB replaces rigid glass-epoxy laminate with thin polyimide film, producing a circuit that bends. Flex circuits fold into three-dimensional spaces, survive millions of flex cycles in dynamic applications, and replace entire wire harnesses with a single reliable part.
They also cut weight and assembly labour: one flex replaces connectors, cables, and the failure points that come with them. That's why they're inside nearly every camera, wearable, and slim device you own.
How it's made
01
Polyimide preparation
Copper-clad polyimide film is prepared — adhesiveless laminates for the best flexibility and thermal performance.
02
Imaging & etching
Traces are imaged and etched as on rigid boards, but handled on carriers to manage the thin, flexible material.
03
Coverlay application
Instead of liquid solder mask, a polyimide coverlay film is laminated over the circuit, leaving pads exposed — it flexes with the copper.
04
Stiffener bonding
FR-4 or polyimide stiffeners are bonded under connector and component zones that must stay rigid.
05
Profiling & test
Parts are laser- or die-cut to their final outline and 100% electrically tested.
Where it's used
When to choose it
- The circuit must bend in use (dynamic flex) or fold once to fit the enclosure (flex-to-install)
- You're replacing a cable-and-connector assembly with one reliable part
- Weight and thickness budgets are tight — wearables, drones, aerospace
- Vibration would fatigue rigid boards or connectors
Worth considering: If only a small zone needs to bend and the rest is dense rigid circuitry, ask us about board-to-flex interconnect options or stiffened flex designs — tell us your bend radius and flex-cycle expectations and we'll advise.
| Layer count | 1 – 2 |
|---|---|
| Base material | Polyimide (adhesiveless available) |
| Overall thickness | 0.07 – 0.4 mm (excl. stiffeners) |
| Copper weight | 0.5 oz – 2 oz (rolled-annealed for dynamic flex) |
| Min track / spacing | 0.1 mm / 0.1 mm |
| Coverlay | Yellow polyimide |
| Stiffeners | FR-4, polyimide |
| Surface finish | ENIG (recommended), OSP |
| Typical prototype lead time | 8 – 12 working days |
Frequently asked questions
What's the difference between static and dynamic flex?
Static (flex-to-install) circuits bend once or a handful of times — folded into the enclosure during assembly and left there. Dynamic flex circuits bend continuously in operation, like a printer head cable, and need rolled-annealed copper and a more conservative bend radius. Tell us which yours is; it changes the construction.
What bend radius should I design for?
As a rule of thumb: minimum bend radius of 6× the flex thickness for single-layer static applications and 10–20× for dynamic flexing. Tighter radii are possible with adhesiveless laminates and thinner copper — share your geometry and we'll confirm manufacturability.
Why do flexible PCBs use coverlay instead of solder mask?
Liquid solder mask cracks when flexed repeatedly. Coverlay — a laminated polyimide film with adhesive — flexes with the copper and provides much better mechanical protection, so it's the standard insulation for flex circuits.
Can you assemble components on flex circuits?
Yes. Component zones get bonded stiffeners so they behave like rigid board during SMT placement and reflow, and we handle flex panels on carriers through the assembly line. Pair your flex order with our PCB assembly service for a finished, tested part.
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