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© KEMET Electronics Corporation • KEMET Tower • One East Broward Boulevard

A4094_PEG227 • 4/5/2022

Fort Lauderdale, FL 33301 USA • 954-766-2800 • www.kemet.com

Axial Aluminum Electrolytic Capacitors – PEG227, +125°C & +150°C

Anode foil

Cathode foil

Tissues

Foil tab

Extended cathode

Aging

Etching

Forming

Winding

Assembly

Filling (elyt)

Impregnation

Testing

Labeling

Packing

Sealing

Construction Data

The manufacturing process begins with the anode foil being

electrochemically etched to increase the surface area and

then “formed” to produce the aluminum oxide layer. Both the

anode and cathode foils are then interleaved with absorbent

paper and wound into a cylinder. During the winding process,

aluminum tabs are attached to each foil to provide the

electrical contact.

The winding is assembled to the capacitor Al-can and to

theAl-lid.Thecanisfilledwithelectrolyteandthewinding

is impregnated during a vacuum treatment. The capacitor

is sealed. Throughout the process, all materials inside the

housing must be maintained at the highest purity and be

compatible with the electrolyte.

Each capacitor is aged and tested before being packed. The

purpose of aging is to repair any damage in the oxide layer

and thus reduce the leakage current to a very low level. Aging

is carried out at elevated temperature and is accomplished by

applying voltage to the device while carefully controlling the

supply current. The process takes between 2 and 20 hours,

depending on voltage rating.

Damage to the oxide layer can occur due to a variety of

reasons:

• Slitting of the anode foil after forming

• Attaching the tabs to the anode foil

• Minor mechanical damage caused during winding

The following tests are applied for each individual capacitor.

Electrical:

• Leakage current

• Capacitance

• ESR

• Tan Delta

Mechanical/Visual:

• Pull strength test of wire terminals

• Print detail

• Box labels

• Packaging, including packed quantity