1070-O and 1060-O
Best for small, deep cans with high draw ratios, such as radial and SMD electrolytic capacitors. The softest option, with the lowest risk of splitting.
Deep-drawing strip
Aluminium Strip for Capacitor Cases (Capacitor Crust)
The aluminium can that houses an electrolytic, film or supercapacitor is deep drawn from thin strip, usually 0.26 – 0.50 mm thick in 1050, 1060, 1070, 1100 or 3004. The strip must draw without tearing, with low earing, a clean oil-free surface and tight thickness tolerance. Metline supplies capacitor case strip in coil to can makers worldwide.
- Alloys
- 1050 · 1060 · 1070 · 1100 · 3004
- Thickness
- 0.26 – 0.50 mm
- Width
- 300 – 600 mm
- Earing
- ≤ 3 – 6 % by grade
What capacitor case strip is used for
An aluminium electrolytic capacitor is a wound roll of anode foil, separator paper and cathode foil soaked in electrolyte. That roll is sealed inside a seamless aluminium can, called the case, shell or crust, closed with a rubber bung or a terminal disc. The can is made from strip in a multi-stage transfer press that blanks a disc, draws it into a cup and redraws it to the final diameter and height.
Aluminium is used because it is the same metal as the electrodes, so there is no galvanic reaction with the electrolyte, and because it draws into deep, thin-walled cans easily. The can wall often doubles as the negative connection, and many cans carry a scored safety vent in the base that opens if internal pressure rises.
The same strip is used for supercapacitor (EDLC) cans, film capacitor housings, motor-run capacitor cans and small battery cases. Can diameters run from about 4 mm for SMD chip capacitors to more than 90 mm for screw-terminal power capacitors, and the strip grade is chosen to suit the draw ratio and wall strength each one needs.
Capacitor case strip specification
| Alloy | Tempers | Thickness (mm) | Width (mm) | Coil ID (mm) |
|---|---|---|---|---|
| 1050, 1060, 1070 | O | 0.26 – 0.50 | 300 – 600 | 150, 200, 300 |
| 1100 | O, H12, H22, H14, H24 | 0.26 – 0.50 | 300 – 600 | 150, 200, 300 |
| 3004 | O | 0.26 – 0.50 | 300 – 600 | 150, 200, 300 |
Tolerances
- Thickness
- +0.02 / 0 mm (one-sided plus tolerance keeps wall thickness above the minimum)
- Width, normal grade
- ±1.0 mm
- Width, high precision
- ±0.5 mm
- Surface
- Clean, degreased, free of oil stains, scratches, inclusions and roll marks
- Other widths and thicknesses
- Slit or rolled to order
Chemical composition (wt %, maximum unless a range)
Limits follow the Aluminum Association registrations used by ASTM B209 and EN 573-3. Higher-purity 1070 gives the softest, most ductile strip; 3004 adds manganese and magnesium for a stronger, stiffer can.
| Element | 1050 | 1060 | 1070 | 1100 | 3004 |
|---|---|---|---|---|---|
| Si | 0.25 | 0.25 | 0.20 | Si + Fe 0.95 | 0.30 |
| Fe | 0.40 | 0.35 | 0.25 | (with Si) | 0.70 |
| Cu | 0.05 | 0.05 | 0.04 | 0.05 – 0.20 | 0.25 |
| Mn | 0.05 | 0.03 | 0.03 | 0.05 | 1.0 – 1.5 |
| Mg | 0.05 | 0.03 | 0.03 | — | 0.8 – 1.3 |
| Zn | 0.05 | 0.05 | 0.04 | 0.10 | 0.25 |
| V | 0.05 | 0.05 | 0.05 | — | — |
| Ti | 0.03 | 0.03 | 0.03 | — | — |
| Others each / total | 0.03 | 0.03 | 0.03 | 0.05 / 0.15 | 0.05 / 0.15 |
| Al (min) | 99.50 | 99.60 | 99.70 | 99.00 | Remainder |
Mechanical properties and earing
Standard tensile ranges for thin strip are shown below. Can makers often agree a narrower band with the supplier so that every coil behaves the same in the press.
| Alloy and temper | Tensile strength (MPa) | Elongation, min (%) | Notes |
|---|---|---|---|
| 1070-O | about 60 – 90 | ≈ 25 (strip > 0.2 mm) | Softest, for the deepest draws |
| 1060-O | about 55 – 95 | ≈ 25 | High purity, very ductile |
| 1050-O | about 65 – 95 | ≈ 22 – 25 | Most common general grade |
| 1100-O | about 75 – 105 | ≈ 20 – 25 | Slightly stronger than 1050 |
| 1100-H12 / H22 | about 95 – 130 | ≈ 3 – 5 | Stiffer cans, shallow draws |
| 1100-H14 / H24 | about 110 – 145 | ≈ 1 – 2 | High rigidity, limited draw |
| 3004-O | about 150 – 200 | ≈ 15 | Strongest; large or thin-wall cans |
Ranges summarised from ASTM B209 and EN 485-2 for thin gauges; actual limits depend on thickness band and the agreed purchase specification.
Earing is the wavy rim that forms when a round blank is drawn into a cup, caused by directional (anisotropic) grain texture in the rolled strip. Ears must be trimmed off, so high earing wastes metal and causes uneven wall thickness. It is measured by drawing a test cup and comparing peak and valley heights, as described in EN 1669.
| Alloy and temper | Earing, ordinary (%) | Earing, high precision (%) |
|---|---|---|
| 1050, 1060, 1070 – O | ≤ 6.0 | ≤ 5.0 |
| 1100 – O, H12, H22 | ≤ 6.0 | ≤ 5.0 |
| 1100 – H14, H24 | ≤ 5.0 | ≤ 3.0 |
| 3004 – O | ≤ 5.0 | ≤ 3.0 |
Which alloy and temper to choose
1050-O
The general-purpose choice for radial and snap-in cans, balancing drawability and cost.
1100-O and H22
A little more strength for cans that must resist denting or that are grooved and crimped hard during sealing.
1100-H14 / H24
Shallow housings and lids where stiffness matters more than draw depth.
3004-O
Large-diameter screw-terminal, motor-run and supercapacitor cans, or thinner walls for the same strength.
Pre-coated or sleeved
Cans are normally insulated with a PVC or PET sleeve after drawing; ask if you need lacquer-coated strip instead.
- Match grain size to the draw: coarse grains cause orange-peel on the can wall
- Keep thickness at the top of tolerance rather than the bottom to protect vent scoring depth
- Specify oil-free or lightly lubricated surface according to your press lubricant system
- Ask for earing results per coil when trim allowance is tight
Strip weight per metre
Weight in kilograms per metre of strip for common thicknesses and widths (density 2.70 g/cm³). Use it to estimate metres per coil: coil weight divided by kg/m.
| Thickness (mm) | 300 mm wide | 400 mm wide | 500 mm wide | 600 mm wide |
|---|---|---|---|---|
| 0.26 | 0.211 | 0.281 | 0.351 | 0.421 |
| 0.30 | 0.243 | 0.324 | 0.405 | 0.486 |
| 0.35 | 0.283 | 0.378 | 0.473 | 0.567 |
| 0.40 | 0.324 | 0.432 | 0.540 | 0.648 |
| 0.45 | 0.364 | 0.486 | 0.608 | 0.729 |
| 0.50 | 0.405 | 0.540 | 0.675 | 0.810 |
Inspection and documentation
Checks per lot
- Chemistry
- Spectrometer analysis against the grade limits
- Tensile and elongation
- Per ASTM B557 or EN ISO 6892-1
- Earing
- Cup test to EN 1669 when specified
- Dimensions
- Thickness across width, slit width, burr height, coil ID and OD
- Surface
- Visual inspection for scratches, oil marks, dents and inclusions
- Certificate
- EN 10204 3.1 mill test certificate
How to order
- SpecifyAlloy and temper, thickness and tolerance, slit width, coil ID, maximum coil OD or weight, and earing limit.
- ConfirmWe confirm mechanical range, surface condition, certification and delivery terms (EXW, FOB, CIF or DAP).
- PackCoils wrapped in film with desiccant, on eye-to-sky or eye-to-wall wooden pallets.
- ShipBy sea or air with mill certificate and packing list.
References and standards
- ASTM B209 – Standard Specification for Aluminum and Aluminum-Alloy Sheet and Plate
- EN 485-2 – Aluminium and aluminium alloys: sheet, strip and plate, mechanical properties
- EN 573-3 – Chemical composition and form of wrought products
- EN 1669 – Aluminium and aluminium alloys: test methods, earing test for sheet and strip
- The Aluminum Association – International Alloy Designations and Chemical Composition Limits
Capacitor case aluminium (aluminum) strip: FAQ
Why are capacitor cases made of aluminium?
The electrodes of an electrolytic capacitor are aluminium, so an aluminium can avoids galvanic reactions with the electrolyte. Aluminium also draws easily into seamless cans, is light and conducts heat away from the winding.
What thickness of strip is used for capacitor cans?
Most cans are drawn from 0.26 – 0.50 mm strip. Small radial and SMD cans use the thinner end; large snap-in and screw-terminal cans use the thicker end or 3004 for extra strength.
What is earing and why does it matter?
Earing is the uneven, scalloped rim on a drawn cup caused by grain texture in the strip. Lower earing means less trim scrap and more uniform walls. It is measured with the EN 1669 cup test.
Should I use 1050 or 1100 for capacitor cases?
1050-O is softer and suits deep draws; 1100 contains a little copper and is slightly stronger, which helps cans resist denting and grooving forces. Either works for most radial cans.
Can you slit strip to my width and coil ID?
Yes. Strip is slit to the width your press feeds, with 150, 200 or 300 mm coil IDs and coil weights to suit your decoiler.
Making capacitor or supercapacitor cans?
Send your alloy, gauge, width and earing limits. We will reply with availability, certification and a delivered price.
