IPC-4562 Guide: Copper Foil Types, Profiles, and Selection for PCB Applications

As a PCB engineer who has worked with countless laminate specifications over the years, I can tell you that understanding IPC-4562 is fundamental to getting your board designs right the first time. This specification governs everything about the copper foil that ends up on your circuit boards, and making the wrong choice here can mean the difference between a board that performs flawlessly at 10 GHz and one that falls apart during thermal cycling.

In this guide, I’ll walk you through the essential aspects of IPC-4562, including copper foil types, profile classifications, thickness standards, and practical selection criteria. Whether you’re designing consumer electronics or aerospace-grade hardware, this information will help you make informed decisions about your copper foil specifications.

What is IPC-4562 and Why Does It Matter?

IPC-4562, officially titled “Metal Foil for Printed Board Applications,” is the industry standard that defines requirements for metal foils used in printed wiring applications. Developed by the IPC (Association Connecting Electronics Industries), this specification covers both unsupported foils and foils supported by carrier films.

The current revision, IPC-4562B, builds upon previous versions by addressing emerging needs in high-speed digital designs and RF applications. The standard provides quality classes, thickness tolerances, and performance requirements that ensure consistency across the global PCB supply chain.

Key Elements Covered by IPC-4562

The specification addresses several critical parameters that directly impact PCB performance:

Material Designation System: IPC-4562 uses a standardized coding system that specifies foil metal type, manufacturing process, grade, thickness, treatment, and profile. For example, a designation like “IPC-4562/3-CU-E-S-LP” tells manufacturers exactly what copper foil characteristics are required.

Quality Classifications: The standard provides quality classes (Class 1, 2, and 3) that reflect functional performance requirements and testing properties. Class 3 represents the tightest tolerances and is typically specified for high-reliability applications.

Thickness Tolerances: Depending on the class selected, thickness tolerances range from -1/+5% for Class 1 to -2/+3% for Class 3, ensuring consistent copper weight across production batches.

Copper Foil Manufacturing Types Under IPC-4562

IPC-4562 recognizes different manufacturing processes for copper foil, each designated by a letter code. Understanding these distinctions is crucial because the manufacturing method directly affects the foil’s crystalline structure, surface characteristics, and mechanical properties.

Electrodeposited (ED) Copper Foil (Type E)

Electrodeposited copper foil is created when copper ions from an electrolyte solution are deposited onto a rotating titanium drum that serves as the cathode. As the drum rotates, copper accumulates until it reaches the desired thickness, then gets stripped off as a continuous sheet.

The ED process creates a foil with two distinct sides. The drum side (shiny side) has a smoother surface from contact with the polished titanium, while the bath side (matte side) has a rougher, dendritic tooth structure from the electrodeposition process. This tooth structure is actually beneficial for adhesion to laminate materials during pressing.

ED copper foil is the workhorse of the rigid PCB industry. About 70% of all printed circuit boards use ED copper because it offers good performance at reasonable cost and is available in a wide range of thicknesses and treatments.

Wrought (Rolled Annealed) Copper Foil (Type W)

Wrought copper foil, commonly called rolled annealed (RA) copper, is produced by mechanically rolling copper billets between heavy rollers until the desired thickness is achieved. The foil is then annealed (heat-treated) to improve ductility.

RA copper has a horizontal grain structure and naturally smooth surfaces on both sides. This makes it inherently better for high-frequency applications where surface roughness causes signal loss. However, that same smoothness creates challenges for adhesion to dielectric materials, requiring special treatments.

RA copper is preferred for flexible circuits and high-frequency applications because its fine grain structure allows for repeated bending without cracking, and its smooth surface minimizes conductor losses at GHz frequencies.

Comparison: ED vs. RA Copper Foil

IPC-4562 Copper Foil Grade Classifications

Within the ED copper category, IPC-4562 defines several grades based on mechanical properties and intended application. These grade designations appear after the foil type code.

Grade 1: Standard Electrodeposited (STD-Type E)

Standard electrodeposited copper is the baseline grade intended primarily for outer layer applications on rigid boards. It offers good etchability, adequate peel strength, and reliable performance for general-purpose PCBs.

STD copper is available in thicknesses from 12 µm up to 140 µm (including the heavy 105 µm and 140 µm weights often used for power boards and heat sinks). For applications without specific high-frequency or flex requirements, Grade 1 copper provides excellent value.

Grade 2: High Ductility Electrodeposited (HD-Type E)

High ductility copper offers improved elongation properties compared to standard ED foil. This grade is useful when better formability is needed but the full flex capabilities of RA copper aren’t required.

Grade 3: High Temperature Elongation (HTE-Type E)

HTE copper foil maintains its ductility even at elevated temperatures, making it essential for boards that will undergo multiple thermal cycles during assembly (such as multilayer boards requiring several lamination presses) or operate in high-temperature environments.

Grade 3 HTE copper is the most commonly specified ED grade for multilayer PCBs. The IPC-4562 Grade 3 specification ensures the foil can survive the thermal stresses of lamination without cracking or delaminating. Most reputable laminate suppliers bond their cores and prepregs with HTE copper as standard.

Additional Grades

IPC-4562 also defines grades for:

• Annealed Electrodeposited (ANN-Type E): Heat-treated for improved ductility
• Low Temperature Annealable (LTA-Type E/W): Can be annealed at lower temperatures
• As Rolled Wrought (AR-Type W): Non-annealed rolled copper
• Light Cold Rolled Wrought (LCR-Type W): Partially work-hardened rolled copper

Understanding Copper Foil Profile Classifications

While the grade tells you about mechanical properties, the profile classification tells you about surface roughness, which is increasingly critical for high-speed and high-frequency designs. IPC-4562A defines foil profile based on the Rz (mean peak-to-valley height) measurement.

Standard Profile (STD)

Standard profile copper, sometimes called RTF (Reverse Treated Foil) when the shiny side is treated, has a typical roughness of 5.1 µm Rz or greater. This is the traditional copper foil that has been used for decades and works well for applications below 1 GHz.

Typical Roughness: 5-8 µm Rz on the matte side, 7-12 µm Rz after treatment

Low Profile (LP)

Low profile copper has a reduced tooth structure with roughness between 3-5 µm Rz. This profile represents the first step up for designs requiring better high-frequency performance while maintaining reasonable cost.

Typical Roughness: 3-5 µm Rz

Very Low Profile (VLP)

VLP copper foil has significantly reduced surface roughness, typically below 5.1 µm Rz per IPC-4562A definition. In practice, most VLP foils achieve 2.5-4 µm Rz.

Typical Roughness: 2.5-4 µm Rz

VLP copper is recommended for high-speed digital applications operating at 10 Gbps and above, where signal integrity becomes sensitive to conductor losses.

Hyper Very Low Profile (HVLP)

HVLP represents the smoothest electrodeposited copper commonly available, with Rz values below 2 µm. This profile is essential for millimeter-wave RF applications and ultra-high-speed digital designs above 25 Gbps.

Typical Roughness: 1.5-2.5 µm Rz

Copper Foil Profile Summary Table

Copper Foil Thickness and Weight Standards

IPC-4562 defines copper foil thickness using both weight (oz/ft²) and metric thickness (µm). The weight designation comes from a historical convention where one ounce of copper spread over one square foot creates a specific thickness.

Standard Copper Weights per IPC-4562

The 1 oz copper weight (35 µm) is the industry default. Approximately 70% of PCBs use 1 oz copper on outer layers. If your fabrication notes don’t specify otherwise, most fabricators will assume 1 oz finished copper.

Finished Copper Thickness Considerations

It’s important to understand that the starting copper weight may differ from finished copper thickness. Per IPC-6012 and IPC-A-600, acceptable finished copper thickness accounts for:

• Base copper tolerance (up to 10% reduction allowed per IPC-4562)
• Micro-etch during processing
• Plating additions for through-hole boards

For plated boards, copper is typically added during the electroplating process. A 1/2 oz starting copper on outer layers often finishes at 35 µm or more after plating, meeting the same performance as 1 oz base copper.

Bond Enhancement Treatments

The copper foil’s ability to bond with dielectric materials is crucial for long-term reliability. IPC-4562 specifies different bond enhancement treatments using letter codes:

Most copper foil used for lamination receives an S treatment (single-sided matte treatment with stain proofing). This treatment typically includes:

1. Micro-roughening: Fine copper nodules electroplated onto the surface to increase mechanical adhesion
2. Barrier layer: Zinc or brass layer to prevent copper migration
3. Anti-tarnish coating: Chromate or silane treatment to prevent oxidation during storage

How Copper Foil Selection Impacts High-Frequency PCB Performance

For engineers working on high-speed digital or RF designs, copper foil selection becomes one of the most critical material decisions. The physics behind this involves the skin effect and how it interacts with surface roughness.

The Skin Effect and Copper Roughness

At DC and low frequencies, current flows throughout the entire cross-section of a conductor. As frequency increases, current increasingly concentrates near the conductor surface due to the skin effect. The skin depth (δ) decreases with frequency according to:

δ = √(ρ / πfμ)

At 1 GHz, skin depth in copper is approximately 2.1 µm. At 10 GHz, it drops to about 0.66 µm. When this skin depth becomes comparable to or smaller than the copper surface roughness, current must follow the contours of the rough surface, traveling a longer effective path.

Impact on Insertion Loss

Rough copper surfaces increase conductor losses in two ways:

1. Increased effective path length: Current following a rough surface travels further than it would on a smooth surface
2. Scattering losses: Irregular surfaces cause non-specular reflections and phase distortions

Research shows that switching from STD copper (Rz ~7 µm) to HVLP copper (Rz ~2 µm) can improve insertion loss by approximately 5-8% at frequencies above 10 GHz. For a 10-inch trace, this can translate to measurable dB improvements in eye diagram performance.

Copper Foil Selection by Application

Practical Selection Guidelines for PCB Engineers

When specifying copper foil per IPC-4562, consider these practical factors:

Cost vs. Performance Trade-offs

Smoother copper costs more. HVLP foil can cost 2-3 times more than standard profile. Before specifying premium foil, evaluate whether your design truly requires it. Many designs below 5 GHz perform adequately with LP or even STD copper when paired with low-loss dielectrics.

Laminate Compatibility

Copper foil must be compatible with your chosen laminate system. Most laminate datasheets specify which copper profiles are available and recommended. High-performance laminates like Megtron 6 or Rogers materials often offer VLP and HVLP options as standard.

Fabricator Capabilities

Not all fabricators stock all copper foil types. Verify availability before finalizing specifications. Exotic foil types may require minimum order quantities or extended lead times.

Complete Material System Approach

Don’t focus on copper alone. A VLP copper with high-loss FR-4 may perform worse than STD copper with low-loss laminate. Consider the entire material system:

• Dielectric constant (Dk) and loss tangent (Df)
• Copper foil profile
• Surface finish type
• Fiberglass weave style

Read more IPC Standards:

IPC Standards Explained: A Comprehensive Guide to PCB & Electronics Assembly Standards

IPC 2615 Standard Explained: PCB Dimensioning & Tolerancing Requirements

MIL-STD-2000A: Military Soldering Standards for Electronic Assemblies

MIL-STD-1686: ESD Control Program Requirements for Military Electronics

IPC 1791 Standard: Everything You Need to Know About Trusted PCB Certification

MIL-STD-883: Complete Guide to Microelectronics Test Methods

J-STD-048 Explained: Complete Guide to Product Discontinuance Notifications

MIL-STD-750: Semiconductor Device Test Methods Explained

MIL-STD-454: General Requirements for Military Electronic Equipment

IPC 9194: Complete Guide to SPC for PCB Assembly Manufacturing

MIL-STD-202: Electronic Component Testing Methods & Procedures

IPC 4110: Complete Guide to Cellulose Paper Specs for Printed Circuit Boards

Boundary Scan Testing (JTAG) in PCB Design: A Complete DFT Guide

Axiomtek IPC-950 Review: Specs, Features & Performance [2026 Guide]

MIL-PRF-55681: Military Ceramic Chip Capacitor Specification Guide

Useful Resources for PCB Engineers

For additional information on IPC-4562 and copper foil specifications, these resources provide valuable reference material:

Official IPC Standards

• IPC-4562B (Current Revision): Metal Foil for Printed Board Applications available at shop.ipc.org
• IPC-4101: Specification for Base Materials (includes copper-clad laminate requirements)
• IPC-6012: Qualification and Performance Specification for Rigid Printed Boards
• IPC-TM-650: Test Methods Manual (includes copper foil testing procedures)

Industry Technical Resources

• Altium Resources: PCB Design Blog with copper foil selection guides
• Isola Group: Technical papers on material selection including copper profiles
• Rogers Corporation: Application notes for RF materials
• Sierra Circuits Knowledge Base: Practical PCB engineering guides
• Insulectro Copper Foil Line Card: Commercial availability and specifications

Trace Width and Current Calculators

Several online tools help determine appropriate copper thickness for current-carrying requirements:

• Saturn PCB Design Toolkit
• IPC-2152 current capacity guidelines
• Various online trace width calculators

Frequently Asked Questions About IPC-4562

What is the difference between IPC-4562 Grade 1 and Grade 3 copper foil?

Grade 1 (Standard ED) and Grade 3 (HTE) differ primarily in their high-temperature properties. Grade 3 HTE copper maintains better ductility at elevated temperatures, making it essential for multilayer boards that undergo multiple lamination cycles. Grade 3 also has tighter thickness tolerances (-2/+3% vs. -1/+5% for Grade 1). For single-layer or simple double-sided boards, Grade 1 may suffice. For any multilayer construction, especially with more than 4 layers, Grade 3 HTE is strongly recommended to prevent thermal stress cracking.

How do I specify copper foil profile in my fabrication notes?

Include the profile designation explicitly in your fab notes. For example, “Inner layer copper: 1/2 oz HTE VLP per IPC-4562” or “Outer layer copper: 1 oz Grade 3 HVLP.” If your laminate datasheet specifies the copper type (many high-frequency laminates do), you can reference it as “Copper per laminate datasheet specifications.” Always confirm with your fabricator that they can supply the specified copper profile.

Does thicker copper help with high-frequency signal loss?

No, increasing copper thickness does not reduce high-frequency conductor losses. Due to the skin effect, current at GHz frequencies only flows in the top 1-2 µm of the conductor surface. Thicker copper doesn’t help because the signal never reaches the additional material. Instead of thickness, focus on surface roughness (profile) and trace width. Wider traces provide more surface area for current flow, reducing resistive losses without requiring premium copper.

What copper foil should I use for a 10 Gbps design?

For 10 Gbps NRZ signaling, VLP copper paired with mid-loss laminate (Df ~0.005-0.008) typically provides adequate margin. Calculate your total channel loss budget first, then allocate portions to dielectric loss, copper loss, via stubs, and connector losses. If your channel is short (under 6 inches), LP copper may work. For longer channels or stacked via structures, VLP provides better margin. HVLP is usually overkill for 10 Gbps unless you’re pushing very long trace lengths.

How does IPC-4562 relate to IPC-4101 laminate specifications?

IPC-4562 covers the copper foil itself, while IPC-4101 covers the complete copper-clad laminate (dielectric plus bonded copper). When you specify a laminate by its IPC-4101 slash sheet (like IPC-4101/126 for standard FR-4), that specification includes acceptable copper foil types. The two standards work together: IPC-4562 ensures consistent copper foil quality, and IPC-4101 ensures that copper is properly bonded to dielectric materials meeting specific performance requirements.

Conclusion

IPC-4562 provides the foundation for specifying copper foil in PCB applications. Understanding the distinctions between ED and RA copper, the various grades and profiles, and how surface roughness impacts high-frequency performance allows engineers to make informed material selections.

For most applications below 5 GHz, standard or low-profile copper with appropriate Grade 3 HTE classification provides excellent results. As frequencies climb into the 5G and mmWave territory, investing in VLP or HVLP copper becomes necessary to maintain signal integrity. The key is matching your copper specification to actual design requirements while considering the complete material system including dielectric, surface finish, and fabrication capabilities.

When in doubt, consult with your laminate supplier and fabricator early in the design process. They can provide guidance on what copper foil options are readily available and help you optimize the cost-performance balance for your specific application.