Datasheet

15© KEMET Electronics Corporation • KEMET Tower • One East Broward Boulevard A4075_ALS70_71 • 7/15/2020
Fort Lauderdale, FL 33301 USA • 954-766-2800 • www.kemet.com
Screw Terminal Aluminum Electrolytic Capacitors – ALS70/71, High CV, +85°C
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 de ned 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