5 Layer PCB Stackup: Design Guide, Benefits & When to Use It

If you’ve been designing PCBs for any length of time, you’ve probably noticed something: most Multilayer PCB configurations come in even numbers. Four layers, six layers, eight layers. So when someone mentions a 5 layer PCB, it tends to raise eyebrows.

I’ve been working with multilayer boards for over a decade, and I’ll be honest—odd-layer PCBs like the 5 layer PCB used to make me nervous. The warping concerns, the limited manufacturer support, the questions from production teams. But here’s the thing: there are legitimate scenarios where a 5 layer PCB makes perfect sense.

This guide covers everything you need to know about 5 layer PCB design, from stackup configurations to real-world applications. Whether you’re considering an odd-layer board for the first time or trying to optimize an existing design, you’ll find practical insights here.

What is a 5 Layer PCB?

A 5 layer PCB is exactly what it sounds like—a printed circuit board with five conductive copper layers separated by insulating dielectric materials. Each layer serves a specific purpose in the circuit, whether that’s signal routing, power distribution, or ground reference.

The basic structure alternates between conductive and non-conductive materials:

• Two outer copper layers (top and bottom)
• Three inner copper layers
• Four layers of prepreg/core insulating material

What makes this configuration interesting is its position between 4-layer and 6-layer boards. You get more routing density than a 4 layer PCB without the full cost jump to 6 layers. But this comes with manufacturing complexities that you need to understand before committing to this design approach.

The materials used in a 5 layer PCB typically include FR-4 (fiberglass-reinforced epoxy laminate) as the base material, copper foil ranging from 0.5oz to 2oz depending on current requirements, and prepreg sheets that bond the layers together during lamination.

5 Layer PCB Stackup Configuration

The stackup is where 5 layer PCB design gets interesting. Unlike even-layer boards that naturally balance during lamination, odd-layer stackups require more careful planning to avoid warpage and maintain signal integrity.

Standard 5 Layer PCB Stackup Arrangement

A typical 5 layer PCB stackup looks like this:

Layer	Function	Typical Thickness	Material
Layer 1 (Top)	Signal/Component	1.4 mil (35µm)	Copper
Prepreg	Insulation	3-5 mil	FR-4 Prepreg
Layer 2	Ground Plane	0.7 mil (18µm)	Copper
Core	Insulation	8-12 mil	FR-4 Core
Layer 3	Signal	0.7 mil (18µm)	Copper
Core	Insulation	8-12 mil	FR-4 Core
Layer 4	Power Plane	0.7 mil (18µm)	Copper
Prepreg	Insulation	3-5 mil	FR-4 Prepreg
Layer 5 (Bottom)	Signal/Component	1.4 mil (35µm)	Copper

Recommended Layer Assignment for 5 Layer PCB

When I design a 5 layer PCB, I typically assign layers as follows:

Configuration 1: Signal-Ground-Signal-Power-Signal

• Layer 1: High-speed signals, component placement
• Layer 2: Ground plane (reference for Layer 1 and Layer 3)
• Layer 3: Low-speed signals, routing
• Layer 4: Power plane
• Layer 5: Signals, component placement

Configuration 2: Signal-Power-Ground-Signal-Signal

• Layer 1: High-speed signals
• Layer 2: Power plane
• Layer 3: Ground plane (central reference)
• Layer 4: Signal routing
• Layer 5: Signal routing, components

The first configuration works better for most applications because it places ground adjacent to the primary signal layers, improving impedance control and reducing EMI.

Read more PCB layers:

5 Layer PCB Thickness Specifications

Standard 5 layer PCB thickness typically falls around 1.6mm (0.063″), matching the industry standard for compatibility with connectors and enclosures. However, depending on your design requirements, you can achieve various thicknesses:

Total Thickness	Application
0.8mm (0.031″)	Space-constrained designs
1.0mm (0.039″)	Compact electronics
1.2mm (0.047″)	Standard applications
1.6mm (0.063″)	Most common, industry standard
2.0mm (0.079″)	High-current, rugged applications

Why Manufacturers Avoid Odd-Layer PCBs

Before diving deeper into 5 layer PCB design, it’s worth understanding why most PCB manufacturing facilities prefer even-layer boards. This isn’t arbitrary—there are real technical and economic reasons.

The Warpage Problem

When a multilayer PCB cools after lamination, the different layers contract at slightly different rates. In an even-layer board, this stress is balanced because the stackup is symmetric around the center. A 4-layer board with identical outer layers and identical inner layers experiences equal stress on both sides.

A 5 layer PCB doesn’t have this natural symmetry. The odd layer in the center creates an imbalance that can cause the board to bow or twist. According to IPC standards, warpage should stay below 0.7% for reliable SMT assembly. Achieving this with odd-layer boards requires careful material selection and process control.

Manufacturing Cost Implications

Here’s something that surprises many designers: even though a 5 layer PCB uses less material than a 6-layer board, it often costs the same or more. Why?

Cost Factor	4 Layer	5 Layer	6 Layer
Raw Material	Lower	Medium	Higher
Processing Complexity	Standard	Non-standard	Standard
Lamination Setup	Standard	Custom	Standard
Yield Rate	Higher	Lower	Higher
Overall Cost	$-$	$$

The processing complexity kills any material savings. Most manufacturers quote 5-layer boards at 6-layer prices because they have to use non-standard processes anyway.

The Pseudo-6-Layer Solution

Many experienced designers handle the “I need more than 4 layers but 6 seems excessive” problem differently: they design a 6-layer board and leave one layer mostly empty or use it as an additional ground plane. This approach:

• Costs about the same as a true 5-layer board
• Avoids warpage issues
• Gets better manufacturer support
• Improves EMI performance with extra shielding

That said, there are legitimate cases where a true 5 layer PCB makes sense, which I’ll cover shortly.

Benefits of 5 Layer PCB Design

Despite the challenges, 5 layer PCB configurations offer genuine advantages in specific applications.

Improved Signal Integrity

With five layers, you can dedicate planes to ground and power while still having three signal layers. This means:

• Better impedance control for high-speed traces
• Cleaner return paths for signals
• Reduced crosstalk between signal layers
• More consistent characteristic impedance

The ground plane adjacent to your primary signal layer provides a solid reference plane that significantly improves signal quality compared to routing everything on outer layers.

Enhanced EMI Performance

Electromagnetic interference management becomes easier with a 5 layer PCB. The internal planes act as shields, containing electromagnetic fields that would otherwise radiate from the board. For products that must pass FCC or CE emissions testing, this can be the difference between passing and failing.

Design Flexibility

Five layers give you more routing options than four without the complexity of six. This middle ground works well for:

• Moderately complex digital circuits
• Mixed analog/digital designs where isolation matters
• Designs with moderate power requirements
• Products where size constraints prevent using 4 layers

Thermal Management

The additional copper layer provides extra thermal mass and more paths for heat dissipation. Power planes distribute heat more evenly across the board, reducing hot spots around high-power components.

When to Use a 5 Layer PCB

Based on my experience, here are the scenarios where a 5 layer PCB genuinely makes sense:

Scenario 1: Routing Density Requires More Than 4 Layers

You’ve completed your schematic, started layout, and realized that 4 layers simply won’t provide enough routing channels. Before jumping to 6 layers, evaluate whether 5 will work. If your design has:

• 60-70% routing completion on 4 layers before hitting bottlenecks
• Moderate BGA density (0.8mm pitch or larger)
• Mixed signal requirements that need plane separation

A 5 layer PCB might be the sweet spot.

Scenario 2: Cost-Sensitive High-Performance Applications

When performance matters but budget is tight, five layers can provide better signal integrity than four without the full cost of six. Consider this for:

• Consumer electronics with moderate complexity
• Industrial control boards
• IoT gateway devices
• Audio equipment requiring low noise floors

Scenario 3: Specific Impedance Requirements

Some designs require specific impedance values that are difficult to achieve with standard 4-layer stackups. The additional flexibility of five layers allows fine-tuning of dielectric thickness and trace geometry to hit exact impedance targets.

Scenario 4: Legacy Design Constraints

Sometimes you’re working with an existing enclosure or connector system that dictates board thickness. If your design needs more than four layers but must fit a specific profile, five layers might solve the puzzle.

5 Layer PCB Design Guidelines

If you’ve decided a 5 layer PCB is right for your application, here are practical design guidelines to follow.

Ground and Power Plane Placement

Keep ground planes adjacent to your critical signal layers. This provides the best return path for high-frequency signals. A common mistake is placing the power plane next to a high-speed signal layer—this increases noise coupling and degrades signal quality.

Good practice: Signal → Ground → Signal → Power → Signal

Avoid: Signal → Power → Signal → Ground → Signal

Via Strategy for 5 Layer PCB

Vias in a 5 layer PCB need careful planning:

• Through-hole vias connect all five layers but consume routing real estate on every layer
• Blind vias (Layer 1-2 or 4-5) save inner layer space but add cost
• Buried vias (Layer 2-4) maximize routing density but significantly increase manufacturing complexity

For most 5 layer designs, through-hole vias work fine. Reserve blind and buried vias for high-density applications where through-holes create routing bottlenecks.

Impedance Control Considerations

Calculating impedance in a 5 layer PCB requires attention to which reference plane you’re using. Signals on Layer 1 reference Layer 2 (ground), while signals on Layer 3 might reference either Layer 2 or Layer 4 depending on the stackup.

Signal Layer	Reference Plane	Typical Dielectric	Resulting Impedance Range
Layer 1	Layer 2 (GND)	4-5 mil prepreg	50-60Ω (microstrip)
Layer 3	Layer 2 & 4	8-12 mil core	45-55Ω (stripline)
Layer 5	Layer 4 (PWR)	4-5 mil prepreg	50-60Ω (microstrip)

Managing Asymmetric Stackup

Since a 5 layer PCB is inherently asymmetric, you need strategies to minimize warpage:

1. Balance copper distribution – Keep copper coverage similar on opposite sides of the board
2. Use symmetric prepreg – Same prepreg type and thickness above and below the center layer
3. Consider a dummy layer – Adding a non-functional copper pour can help balance the stackup
4. Work with your fabricator – They may have preferred stackup configurations that minimize warpage

5 Layer PCB Applications

Five-layer PCBs find use across various industries where the balance of performance and cost makes sense.

Consumer Electronics

Smartphones, tablets, and wearables often use 5+ layer boards to achieve the routing density needed for modern processors. While flagship devices might use 8-10 layers, mid-range products can sometimes achieve similar functionality with five layers through careful design optimization.

Automotive Electronics

Engine control units (ECUs), infotainment systems, and advanced driver assistance systems (ADAS) frequently employ 5 layer PCBs. The automotive environment demands good EMI performance and thermal management—both strengths of the 5 layer configuration.

Medical Devices

Medical equipment requires high reliability and often needs to pass strict EMC requirements. Patient monitors, diagnostic equipment, and portable medical devices can benefit from the improved noise immunity that dedicated ground planes provide.

Industrial Control Systems

PLCs, motor drives, and automation controllers often use 5 layer PCBs to achieve the necessary isolation between power and signal circuits while keeping costs reasonable for industrial market pricing.

Telecommunications Equipment

Network switches, routers, and base station equipment frequently use multilayer boards. For lower-density applications within these systems, five layers can provide adequate routing while controlling costs.

Aerospace and Defense Applications

Military and aerospace electronics demand exceptional reliability under extreme conditions. The 5 layer PCB configuration offers several advantages for these applications: the additional ground plane improves radiation hardness, multiple signal layers allow for redundant routing paths, and the compact form factor suits weight-sensitive aerospace applications. Defense contractors often specify odd-layer boards when specific impedance or thermal requirements fall between standard 4 and 6 layer specifications.

Computer and Server Hardware

Computer motherboards, graphics cards, and server boards represent some of the most demanding 5 layer PCB applications. These designs require high-speed signal routing for memory interfaces, careful power distribution for processors, and excellent thermal management. While flagship products often use 8-12 layers, cost-optimized versions targeting the mainstream market can achieve similar functionality with fewer layers through careful design.

Test and Measurement Equipment

Oscilloscopes, spectrum analyzers, and other test instruments require excellent signal integrity and low noise floors. The dedicated ground plane in a 5 layer PCB provides the reference stability these instruments need. Additionally, the separation between analog and digital circuits that five layers enables helps maintain measurement accuracy.

5 Layer PCB Manufacturing Process

Understanding how your 5 layer PCB gets built helps you design for manufacturability.

Inner Layer Fabrication

Manufacturing starts with the inner layers. Copper-clad laminates get coated with photoresist, exposed through a photomask, developed, and etched to create the circuit patterns. For a 5 layer board, this process creates Layers 2, 3, and 4.

Lamination Process

The critical step for any multilayer board. Your fabricator stacks the layers:

1. Outer copper foil
2. Prepreg sheet
3. Inner layer cores with Layers 2-4
4. Prepreg sheet
5. Outer copper foil

Heat and pressure bond everything together. For 5 layer boards, achieving proper alignment and avoiding warpage requires precise control.

Drilling and Plating

After lamination, through-holes are drilled and plated with copper to create electrical connections between layers. The plating process also adds copper to the outer layers.

Outer Layer Processing

The outer layers (1 and 5) get patterned similar to inner layers—photoresist, exposure, development, and etching. Surface finishes like HASL, ENIG, or OSP protect the exposed copper.

Quality Control

Testing includes:

• Automated optical inspection (AOI) for defects
• Electrical testing for continuity and isolation
• Impedance testing for controlled-impedance designs
• Warpage measurement to verify flatness

5 Layer PCB Cost Factors

Several factors influence what you’ll pay for 5 layer PCB fabrication:

Factor	Impact on Cost
Board Size	Larger boards = higher cost
Quantity	Higher volume = lower per-unit cost
Copper Weight	Heavier copper = higher cost
Surface Finish	ENIG > HASL > OSP
Impedance Control	Adds 15-30% to base cost
Tight Tolerances	Via size, trace width specs add cost
Lead Time	Rush orders cost significantly more

Getting Competitive Quotes

When requesting quotes for 5 layer PCB production:

1. Provide complete specifications – Ambiguity leads to conservative (expensive) quotes
2. Ask about standard stackups – Using a fab’s preferred stackup saves money
3. Consider 6 layers – Often costs the same with better performance
4. Volume matters – 5-layer pricing improves significantly at 100+ units

5 Layer PCB vs Other Layer Configurations

Understanding how 5 layer PCBs compare to alternatives helps you make the right choice for your project.

5 Layer PCB vs 4 Layer PCB Comparison

The jump from 4 to 5 layers provides meaningful improvements in several areas:

Characteristic	4 Layer PCB	5 Layer PCB	Advantage
Signal Layers	2	3	5 Layer (+50% routing)
Plane Layers	2	2	Equal
EMI Shielding	Good	Better	5 Layer
Cost	Lower	Higher	4 Layer
Manufacturer Support	Universal	Limited	4 Layer
Warpage Risk	Low	Medium	4 Layer
Routing Density	Moderate	Higher	5 Layer

Choose 4 layers when your routing fits comfortably with margin. Choose 5 layers when you’re struggling to complete routes or need better signal isolation.

5 Layer PCB vs 6 Layer PCB Comparison

This comparison often surprises designers because 6 layers frequently offer better value:

Characteristic	5 Layer PCB	6 Layer PCB	Advantage
Signal Layers	3	4	6 Layer
Plane Layers	2	2-4	6 Layer
Manufacturing Cost-$	$$	6 Layer (often)
Stackup Symmetry	Asymmetric	Symmetric	6 Layer
Yield Rate	Lower	Higher	6 Layer
EMI Performance	Good	Excellent	6 Layer
Design Flexibility	Moderate	High	6 Layer

The counterintuitive result: 6 layers often cost less per board due to higher yields and standard processes. Always get quotes for both before committing to 5 layers.

Signal Integrity in 5 Layer PCB Design

Signal integrity deserves special attention in 5 layer PCB layouts because the odd-layer configuration affects reference planes and return paths differently than even-layer boards.

Reference Plane Selection

Each signal trace needs a solid reference plane for proper impedance control. In a 5 layer stackup:

• Layer 1 signals should reference Layer 2 (ideally ground)
• Layer 3 signals can reference either Layer 2 or Layer 4
• Layer 5 signals should reference Layer 4

When Layer 3 is sandwiched between two planes, it forms a stripline configuration with excellent shielding but tighter impedance tolerances. Design your critical signals accordingly.

Return Path Continuity

High-frequency signals take the path of least impedance for their return current. This path runs directly beneath (or above) the signal trace on the reference plane. Problems occur when:

• Return current must cross a plane split
• Vias transition signals between layers with different reference planes
• Ground plane coverage has gaps under signal routes

In a 5 layer design, carefully plan transitions between Layer 1 and Layer 5 to ensure return currents don’t have to find long paths around plane discontinuities.

Crosstalk Management

With three signal layers, crosstalk management becomes more complex. Key strategies:

1. Maintain adequate spacing between parallel traces on the same layer
2. Avoid running traces on adjacent layers in parallel for long distances
3. Use ground planes to isolate signal layers from each other
4. Route sensitive signals on Layer 3 where they’re shielded by planes above and below

5 Layer PCB Design Software Support

Modern PCB design tools handle 5 layer stackups without issues:

Stackup Definition

All major EDA tools let you define custom stackups:

• Altium Designer – Layer Stack Manager with impedance calculator
• KiCad – Board Setup → Board Stackup
• Eagle – Layer Setup in design rules
• OrCAD/Allegro – Cross-section editor

Design Rule Checks

Configure your DRC to account for layer-specific constraints:

• Different clearances for inner vs. outer layers
• Via-to-plane clearances
• Impedance-matched trace widths per layer

Common 5 Layer PCB Design Mistakes

Learn from others’ mistakes:

Mistake 1: Ignoring Return Paths

Every signal needs a return path. On a 5 layer board, signals on Layer 3 need a clear return path through either Layer 2 or Layer 4. Splitting planes without considering signal routing creates impedance discontinuities.

Mistake 2: Unbalanced Copper Distribution

Heavy copper on one side of the board with minimal copper on the other causes warpage. Even if your design doesn’t need it, adding copper pours helps balance the stackup.

Mistake 3: Not Consulting Your Fabricator

Different fabs have different capabilities and preferences for odd-layer boards. Designing a stackup that your chosen manufacturer can’t build efficiently leads to delays and cost overruns.

Mistake 4: Treating It Like a 4-Layer Design

A 5 layer PCB isn’t just a 4-layer with an extra signal layer. The additional layer changes impedance relationships, thermal characteristics, and manufacturing requirements.

Useful Resources for 5 Layer PCB Design

Here are resources I’ve found helpful when working on multilayer designs:

Stackup Calculators and Tools

• Saturn PCB Design Toolkit (Free impedance calculator)
• Sierra Circuits Stackup Designer (Online tool)
• JLCPCB Impedance Calculator

IPC Standards

• IPC-2221: Generic Standard on PCB Design
• IPC-4101: Specification for Base Materials
• IPC-6012: Qualification and Performance Spec for Rigid PCBs

Manufacturer Resources

• PCBWay Stackup Library (298+ configurations)
• JLCPCB Design Guidelines
• Sierra Circuits Technical Resources

Frequently Asked Questions About 5 Layer PCB

What is the standard thickness of a 5 layer PCB?

The standard thickness is 1.6mm (0.063″), which matches the industry standard for most multilayer boards. However, you can specify thinner options (0.8mm, 1.0mm, 1.2mm) or thicker options (2.0mm) depending on your application requirements. The actual achievable thickness depends on your stackup configuration and the copper weights used.

Is a 5 layer PCB more expensive than a 6 layer PCB?

Surprisingly, a 5 layer PCB often costs the same as or more than a 6-layer board. While raw materials cost slightly less, the non-standard manufacturing process for odd-layer boards increases processing costs. Most fabricators quote 5-layer boards at 6-layer prices. For budget-conscious projects, consider whether a 6-layer board might provide better value through improved manufacturability.

Why do most PCB manufacturers prefer even-layer boards?

Even-layer boards are symmetric, which naturally balances stress during the lamination cooling process. This symmetry prevents warpage and improves yield rates. Odd-layer boards like 5 layer PCBs require custom processes to achieve acceptable flatness, reducing efficiency and increasing cost. Most standard manufacturing lines are optimized for even-layer production.

Can any PCB manufacturer produce 5 layer boards?

Not all manufacturers offer 5-layer options. Many smaller fabs only produce standard 2, 4, 6, and 8-layer boards. Before designing a 5 layer PCB, confirm your chosen manufacturer supports odd-layer production and ask about their specific stackup recommendations. Larger manufacturers typically have more flexibility for non-standard configurations.

When should I choose a 5 layer PCB over a 4 or 6 layer board?

Choose a 5 layer PCB when you’ve maxed out a 4-layer design’s routing capacity but don’t need the full capability of 6 layers. Good candidates include moderately complex digital designs, mixed-signal boards needing plane separation, or designs with specific impedance requirements that 4 layers can’t achieve. If cost is a primary concern, compare quotes for both 5 and 6 layers—you might find 6 layers offers better value.

Conclusion

The 5 layer PCB occupies a unique position in multilayer board design. It’s not the most common choice, and there are good reasons why even-layer boards dominate the market. But for the right application—where 4 layers aren’t quite enough and 6 seem excessive—a 5 layer PCB can deliver the performance you need.

The key to success with 5 layer designs is working closely with your fabricator, understanding the manufacturing implications, and designing with the odd-layer constraints in mind. Balance your stackup, plan your layer assignments carefully, and don’t assume that saving one layer automatically saves money.

If you’re on the fence about layer count, get quotes for both 5 and 6 layers. The pricing often surprises designers, and you might find that the extra layer provides better overall value through improved yield and easier manufacturing.

Whatever you decide, remember that layer count is a means to an end. The goal is a working, reliable product. Sometimes that means a 5 layer PCB. Sometimes it means stepping up to 6 layers or optimizing harder to fit into 4. The best design is the one that meets your requirements while remaining manufacturable at your target cost.