Document Number: 40025

For technical questions, contact: wettants@vishay.com

www.vishay.com

Revision: 17-Mar-08

23

138D

Hermetically-Sealed with True Glass-to-Tantalum Seal

Vishay

For example, percent dissipation factor of a 30 µF, 6 V

capacitor, which has a maximum ESR of 3.4

Ω at

+ 25 °C and 120 Hz, would be calculated as shown:

7.

Leakage Current: Measurements shall be made at

the applicable rated working voltage at + 25 °C ± 5 °C

through application of a steady source of power, such

as a regulated power supply. The total resistance in

series with each capacitor shall be between 1000

Ω

and 10 000

Ω. The voltage shall be applied to the

capacitor for 5 minutes before making the leakage

current measurement.

7.1

The maximum leakage current for any capacitor shall

not exceed the value in microamperes listed in the

Standard and Extended Ratings Table for each

capacitor.

Note: leakage current varies with applied voltage. See graph

below for the appropriate adjustment factor.

8.

Low Temperature Impedance: The impedance of

any capacitor at - 55 °C at 120 Hz, shall not exceed the

values given in the Standard and Extended Ratings

Tables.

9.

Life Test: Capacitors are capable of withstanding a

2000 h life test at a temperature of + 85 °C or + 125 °C

at the applicable rated DC working voltage.

10.

High Frequency Vibration: Capacitors shall with

stand vibration from 10 Hz to 2000 Hz at 20 g when

tested.

11.

Lead Pull Test: Capacitors shall withstand a lead

tensile stress of 3 pounds (13.2 N) for 30 s, applied

axially.

12.

and/or the Sprague trademark 2, the Sprague type

(138D);

rated

capacitance

and

tolerance

(the

tolerance shall be coded, using the list shown in How

to Order); rated DC working voltage at + 85 °C; the

standard EIA date code of manufacture.

GUIDE TO APPLICATION

1.

Ripple Current: All capacitors will withstand rms

ripple currents as listed for each capacitor.

1.1

The rms ripple current rating is independent of

temperature

or

frequency

within

the

following

limitations:

1.1.1 At frequencies of less than 120 Hz, the rated rms ripple

current must be multiplied by the factors shown:

1.1.2 The sum of the peak AC voltage plus the DC voltage

shall not exceed the DC working voltage of the

capacitor.

1.1.3 The sum of the negative peak AC voltage, plus the

applied DC voltage shall not allow a voltage reversal.

2.

Cleaning wiring boards with Type 138D capacitors:

Customary cleaning solvents used in the electronics

industry at present will not affect Type 138D

capacitors. However, the use of ultrasonic cleaning

techniques

is

not

recommended

under

any

circumstances.

3.

Apparent Capacitance: Note that in timing circuit

applications, the circuit designer must take into

account two important variables which affect any

electrolytic capacitor. These are the internal leakage

resistance

of

the

capacitor

and

its

dielectric

absorption, which will depend on the elapsed time

since the capacitor was last energized. In applications

where electrolytic capacitors are subjected to DC

energy, or in effect, extremely low frequencies, the

value of the apparent capacitance will be somewhat

higher than that which is measured at 120 Hz.

4.

No Reverse Voltage: The application of reverse

voltage to these capacitors will cause internal damage.

The resulting damage will lead to immediate or

delayed failure of the unit. This will take the form of a

catastrophic short circuit with possible expulsion of the

electrolyte.

LEAKAGE AS A FUNCTION OF VOLTAGE

& TEMPERATURE

DF

2

π 120

×

3.4

×

30

×

10

4

--------------------------------------------------

3.4

30

×

13.26

---------------------

7.7 %

==

=

1.0

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0.08

0.07

0.06

0.05

0.04

0.03

0.02

0.01

0.008

0.007

0.006

0.005

0.004

0.003

0.002

0.001

0

PERCENT OF RATED VOLTAGE

10

30

20

90

40

50

60

70

80

100

FREQUENCY IN HERTZ

25

50

60

100

0.36

0.59

0.65

0.88