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RTF reverse treated double-side treated copper foil product illustration

Reverse Treated Foil · Double-Side Treated Copper Foil

RTF Reverse Treated Double-Side Treated Copper Foil

Double-side treated copper foil with the shiny side of the electrodeposited foil also roughened. Both sides offer good bonding strength, eliminating the black-oxide step for multilayer inner layers. One of the mainstream choices for high-frequency, high-speed copper clad laminates.

· Product Features

  • Rz 4–6 μm surface roughness
  • Double-side roughened treatment
  • No black oxide, streamlined process
  • Df ≤ 0.015 Mid Loss grade
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Roughness Evolution Roadmap

Surface Roughness Evolution

STD
Standard foil
Rz 7–8μm
HTE
High-temp elongation
Rz 7–8μm
RTF
Reverse treated
Rz 4–6μm
LP
Low profile
Rz 3–4μm
VLP
Very low profile
Rz ≤2μm
HVLP
Hyper very low profile
Rz ≤1.5μm

Product Introduction

Product Introduction

RTF (Reverse Treated Foil), also known as double-side treated copper foil, applies varying degrees of roughening to the drum side (shiny side) of conventional electrodeposited foil, which is normally smooth, so that both sides have good peel strength. Hence the name "reverse": the roughening treatment normally applied to only one side is "reversed" onto the other side.

The treatment level on each side is carefully designed: the side facing the dielectric is rougher (for stronger adhesion), while the roughened layer on the other side is thinner (preserving good etchability). This asymmetric double-side treatment meets two seemingly conflicting needs at once: strong bonding to the insulating substrate and easy etching during subsequent pattern transfer.

When used as inner-layer foil in multilayer boards, RTF's greatest practical value is eliminating the conventional black-oxide pre-treatment. The shiny inner-layer side of ordinary STD foil must be black-oxide treated before lamination to ensure bonding, while RTF has this step already done, directly shortening the process and lowering manufacturing costs. This is the core reason RTF has become the mainstream material for mid- to high-speed PCBs (1–10 Gbps).

Key Process Characteristics

  • Double-side roughening: Both drum side and matte side are roughened to different degrees, giving both sides bonding strength
  • Asymmetric treatment: Bonding side is rougher (strong adhesion), exposed side is thinner (easy etching)
  • No black-oxide step: No additional oxidation treatment needed for inner layers; laminate directly
  • Frequency range: 1–10 Gbps mid- to high-speed digital circuits

RTF double-side treatment structure

Drum side: roughened (bonds to dielectric)Matte side: lightly roughened (exposed etching side)
RTF double-side structure
Both sides treated, no extra black oxide needed
Shiny side: smooth (requires black oxide ❌)Matte side: roughened (bonds ✓)
STD single-side structure
Shiny side needs extra black oxide, adding a process step

Specifications

Available Specifications & Parameters

Multiple thickness and roughness combinations to suit different layer stack-ups and cost budgets.

Model Nominal thickness Areal weight Surface roughness Rz Peel strength Typical applications
RTF-18E-S 18 μm ~161 g/m² 5–6 μm ≥ 1.0 kg/cm Smartphone mainboard inner layers (most common)
RTF-18E-M 18 μm ~161 g/m² 4–5 μm ≥ 0.95 kg/cm Mid-speed digital board inner layers, slightly lower loss
RTF-35E-S 35 μm ~305 g/m² 5–6 μm ≥ 1.1 kg/cm Server mainboard inner layers, network equipment
RTF-35E-M 35 μm ~305 g/m² 4–5 μm ≥ 1.05 kg/cm Inner layers with higher speed requirements
RTF-70E 70 μm ~610 g/m² 5–6 μm ≥ 1.1 kg/cm Heavy-copper power plane inner layers

Supply Format

  • Rolls: width up to 1295 mm
  • Sheets: up to 1295 × 1295 mm
  • Two roughness options: S / M

Core Value

  • Eliminates inner-layer black-oxide (oxidation) pre-treatment
  • Shortens multilayer board production cycle by 10–15%
  • Lowers overall manufacturing cost

Applications

End-Use Applications

Serving every key sector of electronics manufacturing.

Servers & Storage

Rack server mainboard inner layers, storage array controller boards

Network Communications

Gigabit / 10-gigabit switch inner layers, router backplanes, firewall mainboards

HDI Multilayer Boards

Smartphone mainboards (8–12 layers), tablet mainboard inner layers

Automotive Electronics

In-vehicle infotainment systems, ADAS domain controller inner layers

5G Devices

5G phone / module mainboard inner layers, CPE devices

Consumer Electronics

High-performance laptop mainboards, game console mainboards

Core Advantages

Core Product Advantages

Building differentiated competitiveness.

1

Simplified Process

No black-oxide pre-treatment for inner layers; laminate directly and shorten production cycles

2

Balanced Bonding on Both Sides

Double-side roughening ensures sufficient adhesion whichever side faces the dielectric

3

Outstanding Cost-Effectiveness

20–40% cheaper than LP/VLP, meeting high-volume 1–10 Gbps demand

4

Good Etchability

The thin roughened layer on the exposed side makes clean fine lines easier to achieve than with STD

5

Mature Supply Chain

Ample global capacity, stable lead times and smaller price fluctuations than high-end series

6

Flexible Options

Two roughness levels (S/M) at the same thickness, selectable to match your actual loss budget

Get RTF Copper Foil Samples & Technical Data

Our technical team can recommend the optimal thickness grade and matching substrate for your specific application.