ASTM F1663-09

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it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation:F 1663–95 (Reapproved 2002) Designation:F 1663–09
Standard Test Method for
1
Determining the Capacitance of a Membrane Switch
This standard is issued under the fixed designation F 1663; 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 indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method covers the determination of capacitance(s) of a membrane switch.
1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
2. Terminology
2.1 Definitions:
2.1.1 membrane switch—a momentary switching device in which at least one contact is on, or made of, a flexible substrate.
2.1.2 test points—two preselected mutually insulated locations on switch assembly.
3. Significance and Use
3.1 Capacitance testing is useful for design verification, quality control of materials, and workmanship.
3.2 High capacitance may interfere with the reliable performance of interface electronics.
3.3 Specific areas of testing are, but not limited to:
3.3.1 Conductor/dielectric/conductor crossing point,
3.3.2 Close proximity of conductors, and
3.3.3 Any other conductive surface such as shielding or metal backing panel.
4. Interferences
4.1 The following parameters may affect the results of this test:
4.1.1 Humidity,
4.1.2 Contamination,
4.1.3 Barometric pressure, and
4.1.4 Temperature.
5. Apparatus
5.1 Electronic Test Instrument , for measuring very small capacitance (pico-farad range).
6. Procedure
6.1 Pretest Setup:
6.1.1 Suspend the switch specimen in air or otherwise isolate it from any interfering affects.
6.1.2 Attach to the capacitance measuring instrument any necessary leads, probes or connectors required to connect the
membrane switch assembly for measurement. Place test leads as close to test points as possible without physical connection. (This
will reduce any variations due to lead positioning).
6.1.3 Record the capacitance reading indicated on the instrument to equal capacitance (C) (this is the capacitance of the test
i
setup).
6.2 In-Process Test:
6.2.1 Connect test leads to the test points.
6.2.2 Record the capacitance reading indicated on the instrument to equal total capacitance (C) (this is the total capacitance of
t
the switch and device.
1
This test method is under the jurisdiction of
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