Ever opened up a phone or a laptop and seen those thin, yellowish, bendable ribbons connecting the screen to the main board? That's a flexible printed circuit board (flex PCB) . Unlike the hard green fiberglass boards you're used to, a flex PCB can bend, twist, and fold without breaking.

Now, what about "drill flexible"? That simply means drilling holes in a flexible circuit board – and believe me, it's not as easy as drilling into a hard board. But you need holes to mount components or create vias, so it's a must-know topic.

In this beginner-friendly guide, I'll walk you through everything: what a flex PCB is, where it's used, how drilling works, and what to watch out for when ordering custom flexible boards. No engineering degree required – just plain talk.

1. Hard Board vs. Flex Board – What's the Difference?

• Hard PCB (FR4) : The base material is fiberglass and epoxy. It's stiff, cheap, and great for most electronics – like a piece of plywood.

• Flex PCB (Polyimide / PET) : The base is a thin, plastic-like film (Kapton). It bends like a thick piece of paper or a plastic card.

Hard boards are strong and cheap. Flex boards are more expensive but can be bent, rolled, or folded into tiny, odd-shaped spaces. Think of a hard board as a wooden plank and a flex board as a leather belt. You can't wrap a plank around your wrist, but a belt – easy.

2. How Do You Drill a Flexible PCB? (The "Drill Flexible" Process)

Drilling holes in a flexible board is trickier than in a hard board. Why? Because the material is soft. When the drill bit pushes down, the board wants to bend and lift up. That gives you rough, fuzzy hole walls – or worse, a torn board.

Manufacturers use three main methods:

• High-speed CNC drilling – They use extremely sharp carbide bits, spin them at 80,000+ RPM, and back the flex board with a solid aluminum or hardboard sheet to keep it flat.

• Laser drilling – For tiny holes (<0.1mm) or high volume, they blast holes with CO2 or UV lasers. No contact means no deformation. Perfect but pricier.

• Punching – For large, simple holes (like connector slots), they use a metal die to punch through, like a paper hole puncher.

So when you order a custom flex PCB, drilling is part of the cost – and not all factories do it well. You want a shop that specializes in flexible board drilling.

3. Where Are Flexible PCBs Used? (Everywhere You'd Never Guess)

You've used them thousands of times without knowing it:

• Smartphones & tablets – display cables, camera cables, button flexes.

• Laptops – hinge cables, trackpad flex.

• Printers – the moving print head rides on a long flex cable that bends constantly.

• Medical devices – hearing aids, pacemakers, endoscopes (tiny and reliable).

• Cars – airbag systems, steering wheel controls, LED headlights.

• Wearables – smartwatches, fitness bands, smart rings.

Basically, anywhere the space is tight, curved, or moving – you'll find a flex PCB.

4. What Info Do You Need to Order a Custom Flex PCB?

If you want to get a flex board made (and hey, we do that), come prepared with these five things:

1. Schematic (circuit diagram) – How should your components be connected? Use free tools like EasyEDA or KiCad.

2. Board outline & dimensions – Length, width, cutouts, corners. A DXF or Gerber file is ideal.

3. Bill of Materials (BOM) – List all the parts: chips, resistors, capacitors, connectors, etc.

4. Bending requirements – Do you need it to bend once (e.g., folded 90° into an enclosure) or constantly (like a printer cable moving back and forth thousands of times)? This changes the material and layer stack.

5. Drilling info – Hole locations, diameters, and whether they need copper plating (vias).

Send these to a fab shop, and they'll quote you a price and send you a sample.

5. Common "Drill Flexible" Mistakes to Avoid

• Holes too small – Minimum recommended hole size for flex is 0.2mm (0.008"). Smaller than that, and drill bits break or hole walls crack.

• Holes too close together – Keep at least 0.3mm of material between holes. Otherwise, drilling will tear the web.

• Holes in the bending area – Never put vias or component holes where the board will flex repeatedly. The copper around the hole will crack after a few bends. Keep holes out of bending zones.

• Forgetting stiffeners – Where you plug in a connector or mount a screw, you need a stiffener (a piece of FR4 or steel glued to the back). Otherwise, the flex board will flop around and break solder joints.

Remember: Drilling a flex PCB is fine – but drilling in the wrong spot will kill your board.

6. How Much Does Custom Flex PCB Cost? And How Long?

Expect to pay 2 to 5 times more than a hard board of the same size. Reasons:

• Material is more expensive (polyimide vs. FR4)

• Process is slower (drilling, laminating coverlay, etc.)

• Lower yield (soft boards wrinkle and get damaged more easily)

Typical turnaround for prototypes: 5–10 business days. Rush service can be 3 days but costs extra.

For your first project, order a small batch (5–10 pieces) to test before committing to hundreds or thousands. It's cheaper to scrap a few test boards than to rework a whole production run.

7. Can You Replace a Flex PCB with a Hard Board + Cables?

Sometimes, yes. If you just need to connect two hard boards that are far apart, a flat flexible cable (FFC) is cheaper. But there are situations where only a flex PCB works:

• Curved space – A bracelet-style wearable needs the board to wrap around the wrist. No cable can do that.

• Folding – Flip phones and foldable screens require the board to fold exactly in half.

• Extreme thinness – Flex PCBs can be as thin as 0.1mm. Hard boards start at 0.4mm.

• Dynamic flexing – Moving printer heads, robot joints – rigid cables break after a few cycles.

Final Takeaway

A flexible PCB is just a circuit board that bends. And drill flexible is the art of putting holes in it without ruining it. If you're designing a product that's small, curved, or moves, you probably need a flex board.

When you're ready to order, remember:

• Tell the factory how and how often it will bend.

• Keep holes away from bend areas.

• Don't make holes too small or too crowded.

• Add stiffeners where connectors attach.

We make custom flexible circuit boards every day – from simple flex cables to complex multi-layer bendable designs. Got an idea? Even a rough sketch? Send it over. We'll help you turn that bendy dream into a real board that works.