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© KEMET Electronics Corporation • P.O. Box 5928 • Greenville, SC 29606 (864) 963-6300 • www.kemet.com

A4018_ELH • 2/10/2016

Snap-In Aluminum Electrolytic Capacitors – ELH Series, +85ºC

Extended cathode

Anode foil

Cathode foil

Tissues

Foil tabs

Aging

Etching

Forming

Winding

Decking

Impregnation

Assembly

Testing

Sleeving

Packing

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 deck, complete with terminals, is attached to the tabs and then

folded down to rest on top of the winding. The complete winding

is impregnated with electrolyte before being housed in a suitable

container, usually an aluminum can, and 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 sleeved and

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 normally carried out at the rated temperature of the capacitor and

is accomplished by applying voltage to the device while carefully

controlling the supply current. The process may take several hours

to complete.

Damage to the oxide layer can occur due to variety of reasons:

• Slitting of the anode foil after forming

• Attaching the tabs to the anode foil

• Minor mechanical damage caused during winding

A sample from each batch is taken by the quality department after

completion of the production process. This sample size is controlled

by the use of recognized sampling tables defined in BS 6001.

The following tests are applied and may be varied at the request

of the customer. In this case the batch, or special procedure, will

determine the course of action.

Electrical:

• Leakage current

• Capacitance

• ESR

• Impedance

• Tan Delta

Mechanical/Visual:

• Overall dimensions

• Torque test of mounting stud

• Print detail

• Box labels

• Packaging, including packed

quantity