MIL-PRF-22710 Switches, Code Indicating Wheel \(Printed Circuit\), Thumbwheel And Push-Button, General Specification ForThis specification covers the general requirements for illuminated and non-illuminated, thumbwheel \(see 6.4.1\), and push-button, printed circuit rotary switches having unsealed and sealed modules and the associated hardware. These switches are designed for low power alternating current \(ac\) and direct current \(dc\) switching applications for use in electronic and communication equipment. Procurement of switches and mounting hardware will require additional data, giving detailed electrical and mechanical requirements, tolerances, and applicable additions and exceptions to the general requirements and tests specified herein \(see 6.2\).

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MIL-PRF-22710H

f. Final measurements: After the conclusion of the test, while the switches are still in the humidity chamber,

insulation resistance shall be measured within 15 minutes after opening of the chamber and while switches

are still in the humidity chamber as specified in 4.5.12, unless otherwise specified (see 3.1). At the end of the

drying period, insulation resistance shall again be measured as specified in 4.5.12, unless otherwise specified

(see 3.1 and 6.2.2). At the end of the drying period, the switch section or modules, so placed that their

printed circuit boards are in horizontal position with printed circuit contacts and brushes on top, shall be

subjected to the dielectric withstanding voltage test (see 4.5.15).

g. Examination of finish: For switches utilizing a painting process to obtain the black matte or lusterless finish on

that portion of the switch visible from the front of the panel: After completion of the moisture-resistance test

and immediately after opening the chamber, the painted portion of the switch shall be wiped dry and, within 1

minute, several sets of lines shall be scratched to a minimum depth of .003 inch (0.08 mm) with a sharp

pointed stylus. Two parallel lines at least .250 inch (6.35 mm) long and .125 inch (3.18 mm) apart, and two

other parallel lines intersecting the first two at right angles shall be scratched on smooth surfaces in several

places. A .500 inch (12.70 mm) wide strip of waterproof tape, of sufficient length to cover the lines, shall be

firmly pressed over the scratched lines with the adhesive side against the scratched lines. The tape shall

then be abruptly pulled off in one continuous motion. The surface shall be examined for any sign of peeling

or chipping of the finish beyond .005 inch (0.13 mm) from the scratch lines.

After the test, switches shall be examined for evidence of measling, corrosion, breaking, cracking, spalling, or

loosening of terminals. A movement of the terminals within the confines of the terminal-anchoring device shall be

permitted provided continuity of electrical contact is not impaired. Mounting hardware shall be removed.

4.5.16.2 Method II. Switches shall be tested in accordance with method 106 of MIL-STD-202. The following

details and exceptions shall apply:

a. Mounting: As specified in 4.5.16.1a.

b. Initial measurement: Not applicable.

c. Polarization: As specified in 4.5.16.1c.

d. Step 7a and step 7b shall not apply.

e. Loading voltage: Not applicable.

f. Final measurements: After the conclusion of the test, a switch shall be removed from the chamber and the

insulation resistance read within 15 minutes. Each individual switch shall be so removed and tested. The

chamber door shall be closed after each switch removal. At the end of the drying period, insulation

resistance shall again be measured as specified in 4.5.12, unless otherwise specified (see 3.1 and 6.2.2). At

the end of the drying period, the switch section or modules, so placed that their printed circuit boards are in

horizontal position with printed circuit contacts and brushes on top, shall be subjected to the dielectric

withstanding voltage test (see 4.5.15).