Pressed Pad vs Open Pad in Flexible PCB Design

In flexible PCB design, one small detail can quietly determine whether your product survives real-world use or fails after assembly: pad coverage.

At the same time, this is also one of the most common issues we help customers optimize during flexible PCB prototyping and manufacturing—especially in applications involving bending and high reliability requirements.

The choice between pressed pad (coverlay overlap) and open pad (non-covered pad) directly affects solderability, peel strength, and long-term reliability—especially in applications involving bending, vibration, or repeated insertion.

What Is a Pressed Pad in Flexible PCB?

A pressed pad refers to a structure where the coverlay partially overlaps the copper pad edge.

Instead of fully exposing the pad, the coverlay opening is equal to or slightly smaller than the pad, allowing the adhesive and film to “anchor” the copper.

Key Characteristics:

• Coverlay overlaps pad edges

• Smaller or tight opening window

• Often used with reinforcement or stiffeners

Engineers select it because it improves peel strength, prevents pad lifting, and enhances reliability in dynamic flex areas.

What Is an Open Pad (Non-Covered Pad)?

An open pad means the coverlay opening is larger than the pad, leaving the copper fully exposed.

This is closer to standard rigid PCB solder pad design.

Key Characteristics:

• Pad fully exposed

• Larger opening than copper

• No mechanical anchoring from coverlay

Features such as maximized solder wettability, easier assembly and rework, and higher manufacturing yields lead engineers to select it.

Pressed Pad vs Open Pad

Factor	Pressed Pad	Open Pad
Solderability	Moderate	Excellent
Mechanical Strength	High	Low
Peel Resistance	Strong	Weak
Risk of Pad Lifting	Low	High
Process Complexity	Higher	Lower
Rework Difficulty	Harder	Easier

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The Real Engineering Trade-Off

This is not just a design preference—it’s a physics problem:

• Open pads favor soldering

• Pressed pads favor reliability

If your flexible PCB never bends, open pads are fine. 

If your flex PCB moves, flexes, or gets stressed, open pads can become a failure point.

When to Use Pressed Pads

Use pressed pads when mechanical stress is a concern:

Typical Applications:

• Connector interfaces

• Repeated bending areas

• Wearables and medical devices

• Automotive and aerospace electronics

• Long, thin pad geometries

Why It Matters:

In flex applications, copper adhesion becomes critical. Without support, pads can delaminate under stress, even if soldering looks perfect.

When to Use Open Pads

Use open pads when assembly performance is the priority:

Typical Applications:

• SMT component pads (ICs, resistors, capacitors)

• Test points

• Static, non-flex zones

• High-volume production lines

Why It Works:

Open pads help improve solder flow and reduce the risks of cold joints, insufficient wetting, and assembly defects.

Common Design Mistake (and Why It Fails)

Many designers apply rigid PCB logic to flexible PCB: “Fully open pads = best soldering = best design”

That assumption ignores one key difference: Flexible PCBs move. Rigid PCBs don’t.

In flexible environments, this practice often leads to pad lifting after bending, solder joint cracking, or field failures following deployment.

In real projects, we often see these issues caused by incorrect pad design or improper coverlay opening settings. Our engineering team typically reviews Gerber files and suggests optimized pad structures before production to prevent these risks.

Best Practice: Hybrid Pad Design Strategy

Experienced flexible PCB manufacturers rarely use a single approach across the entire board.

Instead, they apply a hybrid design strategy:

Optimized Approach:

• Open pads → for SMT areas

• Pressed pads → for stress zones

• Reinforcement → where needed

Advanced Techniques:

• Teardrop pad transitions

• Local coverlay optimization

• Stiffener + pressed pad combinations

This strategy strikes a balance between assembly efficiency, mechanical durability, and long-term reliability.

Design Recommendations (From Manufacturing Perspective)

To avoid costly redesigns, consider these guidelines early:

• Define dynamic vs static zones in your layout

• Avoid open pads in bend areas

• Use pressed pads for elongated or thin pads

• Coordinate coverlay opening tolerances with your manufacturer

• Validate with peel strength and bend testing

Final Thoughts

If you're working on a flexible PCB project and are unsure whether to use pressed pads or open pads, it's worth validating the design before production.

You can share your Gerber files or design requirements with our team—we’ll provide manufacturability feedback and optimization suggestions based on real production experience.

We support both flex PCB prototyping and mass production, including complex structures like partial coverlay overlap, stiffener integration, and high-reliability applications.