ASTM F74-73(1989)

Practice for Determining Hydrolytic Stability of Plastic Encapsulants for Electronic Devices (Withdrawn 1994)

General Information

• Status: Withdrawn
• Withdrawal Date: 14-Dec-1994
• ICS: 31.240 - Mechanical structures for electronic equipment
• Technical Committee: F01 - Electronics

Standards Content (Sample)

ASTM F74 73 m 0757530 0053383 b
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An American NaW Standard
(m Designation: F 74 - 73 (Reapproved 1989)
Standard Practice for
Determining Hydrolytic Stability of Plastic Encapsulants for
Electronic Devices'
This standard is issued under the fix& designation F 74; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicaies the year of last reapproval. A
superrnip: @on (e) indicates an editorial changc since the last revision or reapproval.
E 104 Practice for Maintaining Constant Relative Hu-
1. scope
midity by Means of Aqueous Solutions4
1.1 This practice covers the determination of the changes
2.2 Other Standard:
due to exposure to high humidity (hydrolytic stability) which
IEEE 101 Institute of Electrical and Electronics Engineers
occur in the properties of plastic materials used to encapsu-
Standard Guide for Statistical Analysis of Test Data'
late electronic devices and to estimate the service life of the
encapsulant in such an environment. Procedures are pro-
3. Summary of Practice
vided for exposing plastics to a maximum of 1WC at a high
3.1 This practice describes procedures for the accelerated
humidity to accelerate the changes which would take place
aging of plastic matenais at a high humidity and at a
under humid seMce conditions and for estimating service
minimum of three elevated temperatures, Failure of the
life using the resultant data. Only the proCsdure for humidity
materiais is based on predetermined criteria for the property
exposure and for use of the data are specified, and not the
under investigation. The time of fdure at the various
specimen nor the property to be tested and its test method.
temperatures is plotted as the logarithm of time against the
The effect on a specific property may be determined by
reciprocal of the absolute temperature. If a straight line plot
selection of an appropriate test method and specimen.
results, extrapolation to the failure time corresponding to the
1.2 This practice applies when the degradation may be
actual service temperature provides an estimate of service
accelerated by heat at the same relative humidity according
life. If straight line extrapolation is not possible, the proce-
to Arrhenius' equation?n3 In this case the effit of humidity
dure is not applicable.
at the temperature of operation can be accelerated by aging
3.2 The property to be tested (for 'example, hardness,
at higher temperatures at the same relative humidity.
tensile strength, or tear strength), the test method, the faiiure
1.3 A risk is involved in extrapolation of the results to a
criteria, the type and number of specimens, and the aghg
lower temperature, since it is possible that a reaction may temperatures must be agreed to by the parties concerned.
occur only at high temperatures. However, by selecting the
lowest aging temperature reasonably close to the service 4. Apparatus
temperature to which an extrapolation is desired, the risk of
4.1 Ovens-Forced-circulation air ovens capable of main-
a substantial error is minimized. If possible, the lowest aging
taining the temperature in the test container within f 1°C
temperature should be within 20'C of the service tempera-
over the temperature range from 50 to 100°C. A separate
ture.
oven for each aging temperature is recommended.
1.4 No extrapolation can be made to temperatures above
4.2 Containers-Noncorroding containers with an inte-
the highest aging temperature. rior shelf to support the .test specimens above the solution
1.5 This standard may involve hazardous materials, oper- used for mainfainhg the required humidity. The,containers
shall be capable of being tightiy sealed except for an aperture
ations, and equipment. This standard does not purpori to
to permit insertion of thermocouple leads and release of
address all of the safety problems associated with its use. It is
vapor pressure that might otherwise lift the top off the
the responsibility of the user of this standard to establish
container. A separate container is required for each generic
appropriate safety and health practices and determine the
material in each oven used.
applicability of regulatory limitations prior to use.
4.3 Thermocouple System-Welded thermocouples and
associated continuous recorders having a range suitable for
2. Referenced Documents the temperatures at which the containers are to be main-
tained and a sensitivity of 0.5"C. A separate thermocouple is
2.1 ASTM Standard:
required for each sample container.
5. Reagents and Materiais
This practice is under the jurisdiction of SìM commi#ct F-I on Electronics
and is the dirrct responsibility of subcommitteC Fû1.05 on Encapsulotion.
5.1 Purity ofReagents-Reagent grade chemicals shd be
Current edition spproved March 1, 1973. Published April 1973. onpiaally
used in ali tests. Unless otherwise
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