In the field of copper foil manufacturing, roughening post-treatment is the key process for unlocking the material’s interface bonding strength. This article analyzes the necessity of roughening treatment from three perspectives: mechanical anchoring effect, process implementation paths, and end-use adaptability. It also explores the application value of this technology in fields like 5G communication and new energy batteries, based on CIVEN METAL‘s technical breakthroughs.
1. Roughening Treatment: From “Smooth Trap” to “Anchored Interface”
1.1 The Fatal Flaws of a Smooth Surface
The original roughness (Ra) of copper foil surfaces is typically less than 0.3μm, which leads to the following issues due to its mirror-like characteristics:
- Insufficient Physical Bonding: The contact area with resin is only 60-70% of the theoretical value.
- Chemical Bonding Barriers: A dense oxide layer (Cu₂O thickness about 3-5nm) hinders the exposure of active groups.
- Thermal Stress Sensitivity: Differences in CTE (Coefficient of Thermal Expansion) can cause interface delamination (ΔCTE = 12ppm/°C).
1.2 Three Key Technical Breakthroughs in Roughening Processes
|
Process Parameter |
Traditional Copper Foil |
Roughened Copper Foil |
Improvement |
| Surface Roughness Ra (μm) | 0.1-0.3 | 0.8-2.0 | 700-900% |
| Specific Surface Area (m²/g) | 0.05-0.08 | 0.15-0.25 | 200-300% |
| Peel Strength (N/cm) | 0.5-0.7 | 1.2-1.8 | 140-257% |
By creating a micron-level three-dimensional structure (see Figure 1), the roughened layer achieves:
- Mechanical Interlocking: Resin penetration forms “barbed” anchoring (depth > 5μm).
- Chemical Activation: Exposing (111) high-activity crystal planes increases bonding site density to 10⁵ sites/μm².
- Thermal Stress Buffering: The porous structure absorbs over 60% of thermal stress.
- Process Route: Acidic copper plating solution (CuSO₄ 80g/L, H₂SO₄ 100g/L) + Pulse Electro-deposition (duty cycle 30%, frequency 100Hz)
- Structural Features:
- Copper dendrite height 1.2-1.8μm, diameter 0.5-1.2μm.
- Surface oxygen content ≤200ppm (XPS analysis).
- Contact resistance < 0.8mΩ·cm².
- Process Route: Cobalt-nickel alloy plating solution (Co²+ 15g/L, Ni²+ 10g/L) + Chemical Displacement Reaction (pH 2.5-3.0)
- Structural Features:
- CoNi alloy particle size 0.3-0.8μm, stacking density > 8×10⁴ particles/mm².
- Surface oxygen content ≤150ppm.
- Contact resistance < 0.5mΩ·cm².
2. Red Oxidation vs. Black Oxidation: The Process Secrets Behind the Colors
2.1 Red Oxidation: Copper’s “Armor”
2.2 Black Oxidation: The Alloy “Armor”
2.3 Commercial Logic Behind Color Selection
Although the key performance indicators (adhesion and conductivity) of red and black oxidation differ by less than 10%, the market shows a clear differentiation:
- Red Oxidized Copper Foil: Accounts for 60% of the market share due to its significant cost advantage (12 CNY/m² vs. black 18 CNY/m²).
- Black Oxidized Copper Foil: Dominates the high-end market (car-mounted FPC, millimeter-wave PCBs) with a 75% market share due to:
- 15% reduction in high-frequency losses (Df = 0.008 vs. red oxidation 0.0095 at 10GHz).
- 30% improved CAF (Conductive Anodic Filament) resistance.
3. CIVEN METAL: “Nano-Level Masters” of Roughening Technology
3.1 Innovative “Gradient Roughening” Technology
Through a three-stage process control, CIVEN METAL optimizes surface structure (see Figure 2):
- Nano-Crystalline Seed Layer: Electro-deposition of copper cores 5-10nm in size, density > 1×10¹¹ particles/cm².
- Micron Dendrite Growth: Pulse current controls dendrite orientation (prioritizing the (110) direction).
- Surface Passivation: Organic silane coupling agent (APTES) coating improves oxidation resistance.
3.2 Performance Exceeding Industry Standards
|
Test Item |
IPC-4562 Standard |
CIVEN METAL Measured Data |
Advantage |
| Peel Strength (N/cm) | ≥0.8 | 1.5-1.8 | +87-125% |
| Surface Roughness CV Value | ≤15% | ≤8% | -47% |
| Powder Loss (mg/m²) | ≤0.5 | ≤0.1 | -80% |
| Humidity Resistance (h) | 96 (85°C/85%RH) | 240 | +150% |
3.3 End-Use Applications Matrix
- 5G Base Station PCB: Uses black oxidized copper foil (Ra = 1.5μm) to achieve < 0.15dB/cm insertion loss at 28GHz.
- Power Battery Collectors: Red oxidized copper foil (tensile strength 380MPa) provides a cycle life > 2000 cycles (national standard 1500 cycles).
- Aerospace FPCs: The roughened layer withstands thermal shock from -196°C to +200°C for 100 cycles without delamination.
4. The Future Battlefield for Roughened Copper Foil
4.1 Ultra-Roughening Technology
For 6G terahertz communication demands, a serrated structure with Ra = 3-5μm is being developed:
- Dielectric Constant Stability: Improved to ΔDk < 0.01 (1-100GHz).
- Thermal Resistance: Reduced by 40% (achieving 15W/m·K).
4.2 Smart Roughening Systems
Integrated AI vision detection + dynamic process adjustment:
- Real-Time Surface Monitoring: Sampling frequency 100 frames per second.
- Adaptive Current Density Adjustment: Precision ±0.5A/dm².
Copper foil roughening post-treatment has evolved from a “optional process” to a “performance multiplier.” Through process innovation and extreme quality control, CIVEN METAL has pushed roughening technology to atomic-level precision, providing foundational material support for the upgrade of the electronics industry. In the future, in the race for smarter, higher frequency, and more reliable technologies, whoever masters the “micro-level code” of roughening technology will dominate the strategic high ground of the copper foil industry.
(Data Source: CIVEN METAL 2023 Annual Technical Report, IPC-4562A-2020, IEC 61249-2-21)
Post time: Apr-01-2025