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1、ENVIRONMENTAL DESIGN GUIDELINES FOR INTEGRATED MODULAR AVIONICS PACKAGING AND INTERFACES ARINC REPORT 654 PUBLISHED: DECEMBER 9, 1994 ANDOCUMENT Prepared by AIRLINES ELECTRONIC ENGINEERING COMMITTEE Published by AERONAUTICAL RADIO, INC. 2551 RIVA ROAD, ANNAPOLIS, MARYLAND 21401 Copyright 1994 by AER
2、ONAUTICAL RADIO, INC. 2551 Riva Road Annapolis, Maryland 21401-7465 USA ARINC REPORT 654 ENVIRONMENTAL DESIGN GUIDELINES FOR INTEGRATED MODULAR AVIONICS PACKAGING AND INTERFACES Published: December 9, 1994 Prepared by the Airlines Electronic Engineering Committee Report 654Adopted by the Airlines El
3、ectronic Engineering Committee:October 21, 1994 Report 654Adopted by the Industry:December 9, 1994 FOREWORD Activities of AERONAUTICAL RADIO, INC. (ARINC) and the Purpose of ARINC Reports and Specifications Aeronautical Radio, Inc. is a corporation in which the United States scheduled airlines are t
4、he principal stockholders.Other stockholders include a variety of other air transport companies, aircraft manufacturers and foreign flag airlines. Activities of ARINC include the operation of an extensive system of domestic and overseas aeronautical land radio stations, the fulfillment of systems re
5、quirements to accomplish ground and airborne compatibility, the allocation and assignment of frequencies to meet those needs, the coordination incident to standard airborne communications and electronics systems and the exchange of technical information.ARINC sponsors the Airlines Electronic Enginee
6、ring Committee (AEEC), composed of airline technical personnel. The AEEC formulates standards for electronic equipment and systems for airlines.The establishment of Equipment Characteristics is a principal function of this Committee. It is desirable to reference certain general ARINC Specifications
7、or Reports which are applicable to more than one type of equipment. These general Specifications or Reports may be considered as supplementary to the Equipment Characteristics in which they are referenced. They are intended to set forth the desires of the airlines pertaining to components or equipme
8、nt is concerned. An ARINC Report (Specification or Characteristic) has a twofold purpose which is: (1)To indicate to the prospective manufacturers of airline electronic equipment the considered opinion of the airline technical people coordinated on an industry basis concerning requisites of new equi
9、pment, and (2)To channel new equipment designed in a direction which can result in the maximum possible standardization of those physical and electrical characteristics which influence interchangeability of equipment without seriously hampering engineering initiative. ii ARINC REPORT 654 TABLE OF CO
10、NTENTS ITEMSUBJECTPAGE 1.0INTRODUCTION1 1.1Objectives1 1.2Scope1 1.3References1 2.0VIBRATION AND SHOCK6 2.1Introduction6 2.2Vibration and Shock Isolation6 3.0THERMAL CONSIDERATIONS7 3.1Thermal Management7 3.1.1Electronic System Thermal Design Objectives7 3.1.2Design Condition Definitions7 3.1.3Air F
11、low7 3.1.4Fully Enclosed and Flow-Through Cooling7 3.1.5Thermal Design Conditions7 3.1.6Cooling Hole Sizes - Limit Cases8 3.2Electronic Parts Application8 3.3Ambient Temperatures8 3.4Equipment Sidewall Temperature9 3.5LRM Thermal Appraisal9 3.6Thermal Interface Information9 3.7Materials for Thermal
12、Design9 4.0DESIGN LIFE14 4.1Operational Design Life14 4.2Failure Modes14 4.3Service Life-Cycles/Duration14 5.0INTRINSIC SAFETY/EXPLOSION PROOFNESS15 5.1Introduction15 5.2Explosive Atmosphere - Propagation of Flame15 5.2.1Sealed Enclosure15 5.2.2Unsealed Enclosure15 6.0ELECTROMAGNETIC ENVIRONMENTAL C
13、ONSIDERATIONS16 6.1Introduction16 6.2LRM Considerations16 6.3Cabinet Considerations16 6.4Wire Integration Assembly17 6.5Lightning - Indirect Effects17 6.5.1Design Guidelines17 7.0SHIELDED ENCLOSURES18 7.1Non-Metallic Composite Enclosures18 7.2Metallic Enclosures18 7.2.1Construction18 7.2.2Corrosion
14、Protection18 7.2.2.1Dissimilar Metals18 7.2.2.2Carbon Fiber-Metal Interface18 7.2.2.2.1Wet Assembly19 7.2.2.2.2Dry Assembly19 7.2.2.2.3Fasteners19 7.3Penetrations19 7.3.1Minimizing Harmful Effects20 7.3.2Waveguide Techniques20 7.3.3Structural Gaps - How They Can Form Slot Antennas20 iii ARINC REPORT
15、 654 TABLE OF CONTENTS ITEMSUBJECTPAGE 7.4Surface Treatments20 7.4.1Chromate Conversion Finishes20 7.4.2Steel Surface Treatments23 7.5Metal-to-Metal Contact Interference24 7.5.1Techniques to Minimize Intermodulation Product (IP) Signal Effects24 7.6Measuring Shielding Effectiveness24 7.6.1Characteri
16、zing Shielding Effectiveness24 7.6.2Shielding Effectiveness Test Set-Up24 7.6.3Test Methodology25 8.0ENVIRONMENTAL SEALING GASKETS26 8.1Overview of Gasket Forms, Styles and Materials and Required Attributes26 8.1.1Looseleaf Gaskets26 8.1.2Combination Gaskets26 8.1.3Elastomeric Core Gaskets26 8.2Gask
17、et Selection26 8.2.1Major Cost Drivers26 8.2.2Environmental Parameters26 8.3Recommendations26 9.0ELECTRICAL BONDING AND GROUNDING29 9.1Purpose29 9.2Considerations29 9.3Electrical Bonding based on indirect cooling via flat vertical surfaces 8 mm apart. This 8 mm separation is optimum for ambient air
18、temperatures less than 40oC, with the optimum spacing increasing prohibitively for higher air temperatures. The dissipation wattage estimate is a lower limit assuming no beneficial induced turbulence from external agencies. 3.1.6Cooling Hole Sizes - Limit Cases Determination of the size of cooling h
19、oles to allow flow of cooling air through the LRM is a compromise between the following factors: a.Drip formation and icing - To prevent water droplets hanging in the cooling holes, the hole size should be at least 0.120 inches (3 mm) in diameter.For hole sizes less than this, water droplets may not
20、 clear and for low temperatures ice formation will block the cooling holes. Under these conditions semiconductor device junction temperatures have been know to rise to damaging levels before the ice melts and allows the free passage of cooling air. b.Foreign Object Damage (FOD) - Hole sizes should b
21、e smaller than 0.157 inches (4 mm) to prevent entry of the smallest fasteners, nuts, screws, washers or rivets in general aircraft use, i.e., those with a head diameter of 0.2 inches (5 mm). COMMENTARY Use of #0 or smaller hardware is discouraged as cooling hole size cannot be reduced to a point whe
22、re entry of small hardware can be prevented (see above). Ifsmallscrews(suchas2mm)areused, consideration should be given to reducing the cooling hole size to 0.125 inches to prevent entry of that hardware. While manufacturing costs will be greater due to the increased quantity of holes required, all
23、possible steps should be taken to prevent entry of stray hardware into the LRM. c.Electro Magnetic Shielding - Standard Honeycomb construction ventilation panels are generally available with a cell size of 0.125 inches (3.2 mm). A one inch square of this type of panel provides an insertion loss of 6
24、0 dB at 400 MHz. The ventilation and screening construction examples illustrated in Figures 3-1, 3-2 and 3-3 incorporating an 0.125 inch honeycomb cell will allow the droplets to clear, will block passage of the smallest generally used piece parts, and will provide 60 dB of insertion loss at 400 MHz
25、. Although the selection of the style of ventilation panel, illustrated in Figure 7-5, and hole size will be determined by the designer, these potentially conflicting requirements should be taken into consideration. 3.2 Electronic Parts Application Electronic parts used in LRMs should be selected fo
26、r reliable operation over the full range of temperature conditions which occur at their site in the LRM when subject to normal operation and the ambient range of Section 3.3.As a minimum requirement the junction temperatures should be less than or equal to the suppliers rating (or de-rating as appro
27、priate), at the peak functional load of the particular circuit. Note:This load condition does not necessarily coincide with the condition of Section 3.1.5.b above and should be part of an individual component load rating temperature assessment. 3.3 Ambient Temperatures Ambient temperature is the air
28、 temperature immediately surrounding the equipment cabinet.For test purposes, ambient temperature is measured three inches in front of the LRM. a.Ground survival temperature: -55oC to +85oC Note:Thesearethelowestandhighestground temperatures expected to be experienced by equipment during aircraft st
29、orage or exposure to climatic extremes with power off. Equipment is not expected to be capable of operation at these temperatures, but to survive them without damage. These temperature ranges should be taken into consideration when calculating the design life of the LRM(s), refer to Section 4.0 of t
30、his document. ARINC REPORT 654 - Page 9 3.0 THERMAL CONSIDERATIONS (contd) b.Shorttermoperatingtemperature,30minutesduration: -40oC to +70oC c.Low and high operating temperature, ground or flight:-15oC to +65oC d.Normal ground operating temperature: +50oC e.Operation from storage within 10 minutes A
31、RINC Specification 650 Section 1.5.3 states that the intention for the cabinet is to utilize available floor to ceiling space by use of multi-tiered cabinets, which implies LRM cabinets may be arranged vertically above a floor level cabinet. It is implicit that to comply with the local ambient air t
32、emperature limit for any LRM, the system should make adequate provisions to prevent rising heated air from any cabinet from mixing significantly with the ambient air supply to a cabinet located above. It is also implicit that such provisions should allow for the affects of natural convectively coole
33、d LRMs sharing a cabinet row with LRMs having internal provision for forced cooling. There should be no air flow dynamic effect that will cause an adverse pressure gradient or localized air re-circulation to naturally cooled LRMs due to the presence of force cooled LRMs. It is recommended that inter
34、nal air moving devices be used only if the LRM can continue to function with any such device failed for an extended period of time, (e.g., ETOPS) and the failure can be indicated by appropriate means. 3.4 Equipment Sidewall Temperature LRM power dissipation is limited to that which restricts the LRM
35、 external surface temperature to a maximum of 15oC above the normal operating ground temperature. There should be no hotspot temperatures of 20oC above normal operating ground temperature.The maximum temperature external surface area should be minimized. 3.5 LRM Thermal Appraisal A thermal appraisal
36、 should be conducted to show that the design objectives have been met. 3.6 Thermal Interface Information Before designing an LRM/cabinet assembly to meet the thermalmanagementrequirements,thefollowing informationshouldbeavailablefromequipment installation and control drawings: a.Total wattage input
37、and actual heat dissipation for all modes of electrical operation for which the equipment was designed (e.g., standby, receiving, transmitting, etc.). Note:Wattage input and actual heat dissipation should be based on normal operating ground temperature conditions.If significant increases in power di
38、ssipation(i.e.,10%increase)occurat temperature extreme conditions (e.g., -40oC and/or +70oC) they should also be identified. b.Estimated in-flight and ground maximum duty cycle (whenspecifiedintheapplicableARINC Characteristics). c.Average temperature of equipment sidewalls for the thermal design co
39、ndition. d.Effectofdrycontaminationonunitcooling performance and recommended unit service intervals requiredtomaintaincoolingperformance,if applicable. 3.7 Materials for Thermal Design The range of materials available to facilitate thermal dissipation through the various levels of packaging between
40、the base die of semiconductor devices and the LRM is too wide to allow more than a brief reference here. A description of generic features in a qualitative fashion is presented in Table 3-2 for guidance only - design engineers will need to contact respective suppliers for property data on the specif
41、ic grades of material appropriate to their application. -,-,- ARINC REPORT 654 - Page 10 3.0 THERMAL CONSIDERATIONS (contd) LRM CASE SIZE AMU (width ins) LRM Case Surface Area in2(m2 104) Dissipation Watts max enclosed LRM 60oC case surface temp Circuit Boards (Example) Indirect Flow-through natural
42、 convection Dissipation Watts vs Heat Sink Temp +60oC+75oC+100oC 1AMU (1.1)226.7 (1463)7.028.713.624.5 2AMU (1.5)242.6 (1565)7.8410.317.734.0 3AMU (1.9)258.5 (1668)8.6410.921.843.6* 4AMU (2.3)274.4 (1770)9.5612.726.053.2 5AMU (2.7)290.4 (1874)10.3615.430.162.8* 6AMU (3.1)306.3 (1976)11.2817.234.372.
43、4 7AMU (3.5)322.2 (2079)11.8818.638.281.8* Table 3-1 Examples of Maximum Heat Dissipation for Fully Enclosed LRM Note 1:Ambient Air Temperature +50oC and Sea Level Static. Note 2:Guide value; as LRM width increases beyond 4 AMU, internal module cooling surface configurations proliferate and greater
44、un-assisted convection values may be achieved. Note 3:Values marked * assume internal configuration is multiple of 1 AMU. Note 4:Extrapolation of the watts dissipation values of this table for larger LRMs is not recommended. LRMs of this size will probably contain large items which would break up th
45、e otherwise uniform module board pairs. Note 5:Some IMA cabinet designs may limit the amount of airflow between LRMs. MaterialAttributes EM Screening High Thermal Conductivity Low Thermal Expansion High Modulus Low Density High Toughness Low Cost Copper Aluminum Aluminum Oxide Aluminum Nitride Beryl
46、lium KovarTM Cu/InvarTM/Cu Molybdenum Cu/Molybdenum/Cu Tungsten/Cu SiC/Al composite (Metal Matrix, HIVOLTM) Table 3-2 Materials for Thermal Design. ARINC REPORT 654 - Page 11 3.0 THERMAL CONSIDERATIONS (contd) Figure 3-1 Construction Example of a 1 AMU LRM, Top View. -,-,- ARINC REPORT 654 - Page 12
47、 3.0 THERMAL CONSIDERATIONS (contd) Figure 3-2 - Construction Example of a 2 AMU LRM, Top View. -,-,- ARINC REPORT 654 - Page 13 3.0 THERMAL CONSIDERATIONS (contd) Figure 3-3 - Construction Example of a 3 AMU LRM, Top View. ARINC REPORT 654 - Page 14 4.0 DESIGN LIFE 4.1 Operational Design Life The o
48、perational design life refers to the combination of environments and stresses that the equipment is exposed to over its intended service life. These conditions are represented by all relevant operating, shipping and storage conditions. Operatingconditionsareusuallyexpressedasa number/classification
49、of operating flights and/or hours (including ground operation) with their associated temperature cycling (low cycle fatigue) and vibration (high cycle fatigue)/mechanical shock distribution. Non-operational conditions (including movements such as delivery by transportation) and storage conditions usually have a long term thermal cycling condition (e.g., diurnal cycling) associated with them in addition