1235 vs 8079 Aluminum Foil for Capacitors

When selecting electrode materials for capacitors, the alloy grade of aluminum foil is far from a trivial number—it directly affects capacitance, leakage current, voltage withstand capability, mechanical reliability, and overall cost. Among the most widely used grades, 1235 vs 8079 Aluminum Foil for Capacitors represents a fundamental trade-off between purity and strength. Many procurement professionals and design engineers struggle to distinguish the two. This article compares them from five dimensions—chemical composition, mechanical properties, electrical performance, typical applications, and cost—to help you make an informed decision.

Chemical Composition: Purity vs. Strengthening Elements

1235 alloy belongs to the high-purity category:

- Al ≥ 99.35%

- Fe ≤ 0.45%, Si ≤ 0.15%

- Extremely low total impurities

The advantage of high purity: more uniform etch tunnels after corrosion, lower leakage current—ideal for demanding electrical performance.

8079 alloy intentionally adds strengthening elements:

- Fe 0.7–1.3%

- Si 0.05–0.3%

- Al approx. 98.5%

The addition of iron and silicon significantly boosts strength, but at the cost of lower purity, slightly reduced conductivity, and less uniform etching.

> One sentence summary: 1235 is “purity first,” 8079 is “strength first.”

Mechanical Properties: The Limit of Thinning and Winding

In the H18 temper, the mechanical property comparison is as follows:

8079 is about 20% stronger, which brings two practical benefits:

- Lower breakage rate during high-speed slitting and automatic winding

- Higher yield and less machine downtime

Even more critical is the thickness limit:

- 8079 can be stably mass-produced as thin as 6μm or even 5μm

- 1235 faces significantly increased breakage risk below 8μm

Therefore, for extreme miniaturization in smartphones and wearables, 8079 is nearly the only choice.

Electrical Performance: Specific Capacitance vs. Leakage Current

Volume resistivity:

- 1235: approx. 2.65 μΩ·cm

- 8079: approx. 2.80 μΩ·cm

The difference is small and has limited impact in practical use. What truly matters is the performance after etching.

Specific capacitance (under identical etching conditions):

- Due to higher purity, 1235 forms denser and more uniform etch tunnels, delivering 5–10% higher specific capacitance than 8079.

- Example for 10μm foil: 1235 ~0.55 μF/cm², 8079 ~0.50 μF/cm².

Leakage current:

- 1235 can be controlled below 0.15 μA/cm², suitable for high-voltage and long-life applications.

- 8079 is typically 20–40% higher, but with optimized etching and forming processes, it can meet most medium/low voltage (≤250V) requirements.

Application Scenarios: Quick Match Table

Cost and Supply: A Real but Manageable Gap

- Raw material cost: 1235 requires A199.7 or higher purity aluminum ingots, which are 5–8% more expensive than standard ingots. 8079 uses standard ingots with Fe-Si master alloy, costing hundreds to over a thousand RMB less per ton.

- Supply stability: Both are mature mass-production grades. However, 8079 has a broader raw material base and smaller price fluctuations.

For customers with monthly consumption of tens of tons, the alloy choice can affect annual costs by hundreds of thousands of RMB—well worth careful calculation.

Selection Summary: Stop Hesitating

Choose 8079 if:

- Required thickness ≤8μm, the thinner the better

- Mechanical strength is a priority (high-speed winding, vibration resistance)

- Medium/low voltage application (≤250V)

- Cost-sensitive

Choose 1235 if:

- Strict leakage current limit (≤0.2 μA/cm²)

- High voltage withstand (≥400V)

- Maximizing specific capacitance is critical

- Precision or long-life scenario

There is no absolute “better” between 1235 vs 8079 Aluminum Foil for Capacitors—only which one matches your design goals. Before purchasing, it is highly recommended to share your etching and forming process parameters with the foil supplier for the most accurate match.

> Whether you need 1235 or 8079 aluminum foil for capacitors, Mingtai Aluminum offers reliable and consistent product solutions. Contact our technical team for sample testing.

Short FAQ

Q1: How thin can 8079 aluminum foil go?  

A: Mass production reaches 5–6μm, while 1235 is typically stable only above 8μm.

Q2: Is 1235 always lower in leakage current than 8079?  

A: Yes under the same etching/forming process, but 8079 can be optimized to approach 1235 levels.

Q3: Can the two alloys be interchanged without process changes?  

A: No. Etchant chemistry and forming voltage must be re‑optimized.

Q4: Which alloy gives higher specific capacitance?  

A: 1235 is usually 5–10% higher.

Q5: Is 8079 much worse in voltage withstand than 1235?  

A: The gap is about 10–15%. Ignorable for medium/low voltage, but choose 1235 for high voltage.