MIL- STD-883F 2004 TEST METHOD STANDARD MICROCIRCUITS - 第30页

MIL-STD-883F METHOD 1003 1 May 1968 2 4. SUMMARY . The fol lowing detai ls mus t be spec ifi ed in the appl icabl e acquis iti on document: a. Test condit ion let ter, or other test potential , if speci fied ( see 3). b.…

MIL-STD-883F

METHOD 1003

1 May 1968

METHOD 1003

INSULATION RESISTANCE

1. PURPOSE

. This test is to measure the resistance offered by the insulating members of a component part to an

impressed direct voltage tending to produce a leakage of current through or on the surface of these members. Insulation-

resistance measurements should not be considered the equivalent of dielectric withstanding voltage or electric breakdown

tests. A clean, dry insulation may have a high insulation resistance, and yet possess a mechanical fault that would cause

failure in the dielectric withstanding voltage test. Since insulating members composed of different materials or combinations

of materials may have inherently different insulation resistances, the numerical value of measured insulation resistance

cannot properly be taken as a direct measure of the degree of cleanliness or absence of deterioration.

1.1 Factors affecting use

. Factors affecting insulation-resistance measurements include temperature, humidity, residual

charges, charging currents or time constant of instrument and measured circuit, test voltage, previous conditioning, and

duration of uninterrupted test voltage application (electrification time). In connection with this last-named factor, it is

characteristic of certain components (for example, capacitors and cables) for the current to usually fall from an

instantaneous high value to a steady lower value at a rate of decay which depends on such factors as test voltage,

temperature, insulating materials, capacitance, and external circuit resistance. Consequently, the measured insulation

resistance will increase for an appreciable time as test voltage is applied uninterruptedly. Because of this phenomenon, it

may take many minutes to approach maximum insulation-resistance readings, but specifications usually require that

readings be made after a specified time. This shortens the testing time considerably while still permitting significant test

results, provided the insulation resistance is reasonably close to steady-state value, the current versus time curve is known,

or suitable correction factors are applied to these measurements. For certain components, a steady instrument reading may

be obtained in a matter of seconds. When insulation-resistance measurements are made before and after a test, both

measurements should be made under the same conditions.

2. APPARATUS

. Insulation-resistance measurements shall be made on an apparatus suitable for the characteristics of

the component to be measured such as a megohm bridge, megohmmeter, insulation-resistance test set, or other suitable

apparatus.

3. PROCEDURE. When special preparations or conditions such as special test fixtures, reconnections, grounding,

isolation, low atmospheric pressure, humidity, or immersion in water are required, they shall be specified. Insulation-

resistance measurements shall be made between the mutually insulated points or between insulated points and

ground, as specified. When electrification time is a factor, the insulation-resistance measurements shall be made

immediately after the specified time (see 4) of uninterrupted test voltage application, unless otherwise specified.

However, if the instrument-reading indicates that an insulation resistance meets the specified limit, and is steady or

increasing, the test may be terminated before the end of the specified period. When more than one measurement is

specified, subsequent measurements of insulation resistance shall be made using the same polarity as the initial

measurements. Unless otherwise specified, the direct potential applied to the specimen shall be that indicated by

one of the test condition letters, as specified below, and insulation resistance measurements shall be made with both

polarities of the applied voltage:

Test condition

Test potential

A 10 volts ±10%

B 25 volts ±10%

C 50 volts ±10%

D 100 volts ±10%

E 500 volts ±10%

F 1,000 volts ±10%

For inplant quality conformance testing, any voltage may be used provided it is equal to or greater than the minimum

potential allowed by the applicable test condition. Unless otherwise specified, the measurement error at the

insulation-resistance value shall not exceed 10 percent. Proper guarding techniques shall be used to prevent erroneous

readings due to leakage along undesired paths.

MIL-STD-883F

METHOD 1003

1 May 1968

4. SUMMARY

. The following details must be specified in the applicable acquisition document:

a. Test condition letter, or other test potential, if specified (see 3).

b. Special preparations or conditions, if required (see 3).

c. Points of measurement (see 3). Unless otherwise specified, insulation resistance shall be measured between the

device leads (all leads electrically connected to each other or to a common point) and the device case, and the

measured resistance shall be no less than 15 megohms.

d. Electrification time, if critical (see 1.1).

e. Insulation resistance in terms of maximum leakage current at a specified test voltage. Unless otherwise specified,

the maximum leakage between any adjacent disconnected leads shall not exceed 100 nanoampere at 100 volts

dc.

MIL-STD-883F

METHOD 1004.7

17 August 1987

METHOD 1004.7

MOISTURE RESISTANCE

1. PURPOSE

. The moisture resistance test is performed for the purpose of evaluating, in an accelerated manner, the

resistance of component parts and constituent materials to the deteriorative effects of the high-humidity and heat conditions

typical of tropical environments. Most tropical degradation results directly or indirectly from absorption of moisture vapor

and films by vulnerable insulating materials, and from surface wetting of metals and insulation. These phenomena produce

many types of deterioration, including corrosion of metals; constituents of materials; and detrimental changes in electrical

properties. This test differs from the steady-state humidity test and derives its added effectiveness in its employment of

temperature cycling, which provides alternate periods of condensation and drying essential to the development of the

corrosion processes and, in addition, produces a "breathing" action of moisture into partially sealed containers. Increased

effectiveness is also obtained by use of a higher temperature, which intensifies the effects of humidity. The test includes a

low-temperature subcycle that acts as an accelerant to reveal otherwise indiscernible evidences of deterioration since

stresses caused by freezing moisture tend to widen cracks and fissures. As a result, the deterioration can be detected by

the measurement of electrical characteristics (including such tests as voltage breakdown and insulation resistance) or by

performance of a test for sealing. Provision is made for the application of a polarizing voltage across insulation to

investigate the possibility of electrolysis, which can promote eventual dielectric breakdown. This test also provides for

electrical loading of certain components, if desired, in order to determine the resistance of current-carrying components,

especially fine wires and contacts, to electrochemical corrosion. Results obtained with this test are reproducible and have

been confirmed by investigations of field failures. This test has proved reliable for indicating those parts which are unsuited

for tropical field use.

2. APPARATUS

. The apparatus used for the moisture resistance test shall include temperature-humidity chambers

capable of maintaining the cycles and tolerance described on figure 1004-1 and electrical test equipment capable of

performing the measurements in 3.6 and 4.

3. PROCEDURE

. Specimens shall be tested in accordance with 3.2 through 3.7 inclusive, and figure 1004-1.

Specimens shall be mounted in a manner that will expose them to the test environment.

3.1 Initial conditioning

. Unless otherwise specified, prior to mounting specimens for the moisture resistance test, the

device leads shall be subjected to a bending stress, initial conditioning in accordance with test condition B

of method 2004.

Where the specific sample devices being subjected to the moisture resistance test have already been subjected to the

required initial conditioning, as part of another test employing the same sample devices, the lead bend need not be

repeated.

3.2 Initial measurements

. Prior to step 1 of the first cycle, the specified initial measurements shall be made at room

ambient conditions, or as specified. When specified, the initial conditioning in a dry oven (see figure 1004-1) shall precede

initial measurements and the initial measurements shall be completed within 8 hours after removal from the drying oven.

3.3 Number of cycles

. Specimens shall be subjected to 10 continuous cycles, each as shown on figure 1004-1. In the

event of no more than one unintentional test interruption (power interruption or equipment failure) prior to the completion of

the specified number of cycles (except for the last cycle) the cycle shall be repeated and the test may continue.

Unintentional interruptions occurring during the last cycle require a repeat of the cycle plus an additional uninterrupted cycle.

Any intentional interruption, or any unintentional interruption of greater than 24 hours requires a complete retest.