MIL-PRF-87819B
6.4 Environmentally preferable material. Environmentally preferable materials should be used to the
maximum extent possible to meet the requirements of this specification. As of the dating of this
document, the U.S. Environmental Protection Agency (EPA) is focusing efforts on reducing 31 priority
chemicals. The list of chemicals and additional information is available on their website
https://www.epa.gov/osw/hazard/wastemin/priority.htm. Included in the list of 31 priority chemicals are
cadmium, lead, and mercury. Use of these materials should be minimized or eliminated unless needed to
meet the requirements specified herein (see 3).
6.5 Subject term (key word) listing.
Acoustic quality
Attenuation
Speech intelligibility
6.6 Fungus (see 3.5.6). Refer to Guideline 4 of MIL-HDBK-454 for more information on soldering.
This document is available from the Document Automation and Production Service (DAPS)
Standardization Document Order Desk, 700 Robbins Avenue, Building 4D, Philadelphia, PA 19111-
5094.)
6.7 Tin whisker growth (see 3.3.1). The use of alloys with tin content greater than 97 percent, by
mass, may exhibit tin whisker growth problems after manufacture. Tin whiskers may occur anytime from
a day to years after manufacture and can develop under typical operating conditions, on products that
use such materials. Conformal coatings applied over top of a whisker-prone surface will not prevent the
formation of tin whiskers. Alloys of 3 percent lead, by mass, have shown to inhibit the growth of tin
whiskers. For additional information on this matter, refer to https://www.astm.org/ASTM B 545 (Standard
Specification for Electrodeposited Coatings of Tin). Copies of this document are available from
https://www.astm.org or ASTM International, P.O. Box C700, 100 Barr Harbor Drive, West Conshohocken,
PA 19428-2959.
6.8 Definitions.
6.8.1 Pink noise (see 4.7.4). Noise with a spectral intensity that is inversely proportional to frequency
over a specified range.
6.8.2 White noise (see 4.7.3.2). Random noise (e.g., shot and thermal noise) whose constant energy
per unit bandwidth is independent of the central frequency at the band.
a. Electromagnetic isolation (coupling) is the amount of mutual relationship, measured in decibels,
between two separate but adjacent wires, when the magnetic field of one induces a voltage in the
other.
b. Electrostatic isolation (coupling) is a method of coupling by which charges on one surface
influence those on another through capacitive action, measured in decibels.
6.8.4 Occlude (see 4.7.3.2). To close up or block off.
6.9 Changes from previous issue. The margins of this specification are marked with vertical lines to
indicate where changes from the previous issue were made. This was done as a convenience only and
the Government assumes no liability whatsoever for any inaccuracies in these notations. Bidders and
contractors are cautioned to evaluate the requirements of this document based on the entire content
irrespective of the marginal notations and relationship to the last previous issue.
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