1、ENVIRONMENTAL DESIGN GUIDELINESFOR INTEGRATED MODULAR AVIONICSPACKAGING AND INTERFACESARINC REPORT 654PUBLISHED: DECEMBER 9, 1994AN DOCUMENTPrepared byAIRLINES ELECTRONIC ENGINEERING COMMITTEEPublished byAERONAUTICAL RADIO, INC.2551 RIVA ROAD, ANNAPOLIS, MARYLAND 21401Copyright 1994 byAERONAUTICAL R
2、ADIO, INC.2551 Riva RoadAnnapolis, Maryland 21401-7465 USAARINC REPORT 654ENVIRONMENTAL DESIGN GUIDELINES FORINTEGRATED MODULAR AVIONICS PACKAGING AND INTERFACESPublished: December 9, 1994Prepared by the Airlines Electronic Engineering CommitteeReport 654 Adopted by the Airlines Electronic Engineeri
3、ng Committee: October 21, 1994Report 654 Adopted by the Industry: December 9, 1994FOREWORDActivities of AERONAUTICAL RADIO, INC. (ARINC)and thePurpose of ARINC Reports and SpecificationsAeronautical Radio, Inc. is a corporation in which the United States scheduled airlinesare the principal stockhold
4、ers. Other stockholders include a variety of other air transportcompanies, aircraft manufacturers and foreign flag airlines.Activities of ARINC include the operation of an extensive system of domestic andoverseas aeronautical land radio stations, the fulfillment of systems requirements to accomplish
5、ground and airborne compatibility, the allocation and assignment of frequencies to meet thoseneeds, the coordination incident to standard airborne communications and electronics systems andthe exchange of technical information. ARINC sponsors the Airlines Electronic EngineeringCommittee (AEEC), comp
6、osed of airline technical personnel. The AEEC formulates standardsfor electronic equipment and systems for airlines. The establishment of EquipmentCharacteristics is a principal function of this Committee.It is desirable to reference certain general ARINC Specifications or Reports which areapplicabl
7、e to more than one type of equipment. These general Specifications or Reports may beconsidered as supplementary to the Equipment Characteristics in which they are referenced. Theyare intended to set forth the desires of the airlines pertaining to components or equipment isconcerned.An ARINC Report (
8、Specification or Characteristic) has a twofold purpose which is:(1) To indicate to the prospective manufacturers of airline electronic equipment theconsidered opinion of the airline technical people coordinated on an industry basisconcerning requisites of new equipment, and(2) To channel new equipme
9、nt designed in a direction which can result in the maximumpossible standardization of those physical and electrical characteristics which influenceinterchangeability of equipment without seriously hampering engineering initiative.iiARINC REPORT 654TABLE OF CONTENTSITEM SUBJECT PAGE1.0 INTRODUCTION 1
10、1.1 Objectives 11.2 Scope 11.3 References 12.0 VIBRATION AND SHOCK 62.1 Introduction 62.2 Vibration and Shock Isolation 63.0 THERMAL CONSIDERATIONS 73.1 Thermal Management 73.1.1 Electronic System Thermal Design Objectives 73.1.2 Design Condition Definitions 73.1.3 Air Flow 73.1.4 Fully Enclosed and
11、 Flow-Through Cooling 73.1.5 Thermal Design Conditions 73.1.6 Cooling Hole Sizes - Limit Cases 83.2 Electronic Parts Application 83.3 Ambient Temperatures 83.4 Equipment Sidewall Temperature 93.5 LRM Thermal Appraisal 93.6 Thermal Interface Information 93.7 Materials for Thermal Design 94.0 DESIGN L
12、IFE 144.1 Operational Design Life 144.2 Failure Modes 144.3 Service Life-Cycles/Duration 145.0 INTRINSIC SAFETY/EXPLOSION PROOFNESS 155.1 Introduction 155.2 Explosive Atmosphere - Propagation of Flame 155.2.1 Sealed Enclosure 155.2.2 Unsealed Enclosure 156.0 ELECTROMAGNETIC ENVIRONMENTAL CONSIDERATI
13、ONS 166.1 Introduction 166.2 LRM Considerations 166.3 Cabinet Considerations 166.4 Wire Integration Assembly 176.5 Lightning - Indirect Effects 176.5.1 Design Guidelines 177.0 SHIELDED ENCLOSURES 187.1 Non-Metallic Composite Enclosures 187.2 Metallic Enclosures 187.2.1 Construction 187.2.2 Corrosion
14、 Protection 187.2.2.1 Dissimilar Metals 187.2.2.2 Carbon Fiber-Metal Interface 187.2.2.2.1 Wet Assembly 197.2.2.2.2 Dry Assembly 197.2.2.2.3 Fasteners 197.3 Penetrations 197.3.1 Minimizing Harmful Effects 207.3.2 Waveguide Techniques 207.3.3 Structural Gaps - How They Can Form Slot Antennas 20iiiARI
15、NC REPORT 654TABLE OF CONTENTSITEM SUBJECT PAGE7.4 Surface Treatments 207.4.1 Chromate Conversion Finishes 207.4.2 Steel Surface Treatments 237.5 Metal-to-Metal Contact Interference 247.5.1 Techniques to Minimize Intermodulation Product (IP) Signal Effects 247.6 Measuring Shielding Effectiveness 247
16、.6.1 Characterizing Shielding Effectiveness 247.6.2 Shielding Effectiveness Test Set-Up 247.6.3 Test Methodology 258.0 ENVIRONMENTAL SEALING GASKETS 268.1 Overview of Gasket Forms, Styles and Materials and Required Attributes 268.1.1 Looseleaf Gaskets 268.1.2 Combination Gaskets 268.1.3 Elastomeric
17、Core Gaskets 268.2 Gasket Selection 268.2.1 Major Cost Drivers 268.2.2 Environmental Parameters 268.3 Recommendations 269.0 ELECTRICAL BONDING AND GROUNDING 299.1 Purpose 299.2 Considerations 299.3 Electrical Bonding based on indirectcooling via flat vertical surfaces 8 mm apart. This8 mm separation
18、 is optimum for ambient airtemperatures less than 40oC, with the optimumspacing increasing prohibitively for higher airtemperatures. The dissipation wattage estimate isa lower limit assuming no beneficial inducedturbulence from external agencies.3.1.6 Cooling Hole Sizes - Limit CasesDetermination of
19、 the size of cooling holes to allow flowof cooling air through the LRM is a compromise betweenthe following factors:a. Drip formation and icing - To prevent water dropletshanging in the cooling holes, the hole size should beat least 0.120 inches (3 mm) in diameter. For holesizes less than this, wate
20、r droplets may not clear andfor low temperatures ice formation will block thecooling holes. Under these conditions semiconductordevice junction temperatures have been know to riseto damaging levels before the ice melts and allows thefree passage of cooling air.b. Foreign Object Damage (FOD) - Hole s
21、izes should besmaller than 0.157 inches (4 mm) to prevent entry ofthe smallest fasteners, nuts, screws, washers or rivetsin general aircraft use, i.e., those with a head diameterof 0.2 inches (5 mm).COMMENTARYUse of #0 or smaller hardware is discouraged ascooling hole size cannot be reduced to a poi
22、nt whereentry of small hardware can be prevented (see above).If small screws (such as 2 mm) are used,consideration should be given to reducing the coolinghole size to 0.125 inches to prevent entry of thathardware. While manufacturing costs will be greaterdue to the increased quantity of holes requir
23、ed, allpossible steps should be taken to prevent entry ofstray hardware into the LRM.c. Electro Magnetic Shielding - Standard Honeycombconstruction ventilation panels are generally availablewith a cell size of 0.125 inches (3.2 mm). A one inchsquare of this type of panel provides an insertion lossof
24、 60 dB at 400 MHz.The ventilation and screening construction examplesillustrated in Figures 3-1, 3-2 and 3-3 incorporating an0.125 inch honeycomb cell will allow the droplets to clear,will block passage of the smallest generally used pieceparts, and will provide 60 dB of insertion loss at 400MHz.Alt
25、hough the selection of the style of ventilation panel,illustrated in Figure 7-5, and hole size will be determinedby the designer, these potentially conflicting requirementsshould be taken into consideration.3.2 Electronic Parts ApplicationElectronic parts used in LRMs should be selected forreliable
26、operation over the full range of temperatureconditions which occur at their site in the LRM whensubject to normal operation and the ambient range ofSection 3.3. As a minimum requirement the junctiontemperatures should be less than or equal to the suppliersrating (or de-rating as appropriate), at the
27、 peak functionalload of the particular circuit.Note: This load condition does not necessarily coincidewith the condition of Section 3.1.5.b above andshould be part of an individual component loadrating temperature assessment.3.3 Ambient TemperaturesAmbient temperature is the air temperature immediat
28、elysurrounding the equipment cabinet. For test purposes,ambient temperature is measured three inches in front ofthe LRM.a. Ground survival temperature: -55oCto+85oCNote: These are the lowest and highest groundtemperatures expected to be experienced byequipment during aircraft storage or exposure toc
29、limatic extremes with power off. Equipment isnot expected to be capable of operation at thesetemperatures, but to survive them without damage.These temperature ranges should be taken intoconsideration when calculating the design life ofthe LRM(s), refer to Section 4.0 of this document.ARINC REPORT 6
30、54 - Page 93.0 THERMAL CONSIDERATIONS (contd)b. Short term operating temperature, 30 minutes duration:-40oCto+70oCc. Low and high operating temperature, ground orflight: -15oCto+65oCd. Normal ground operating temperature: +50oCe. Operation from storage within 10 minutesARINC Specification 650 Sectio
31、n 1.5.3 states that theintention for the cabinet is to utilize available floor toceiling space by use of multi-tiered cabinets, whichimplies LRM cabinets may be arranged vertically abovea floor level cabinet.It is implicit that to comply with the local ambient airtemperature limit for any LRM, the s
32、ystem should makeadequate provisions to prevent rising heated air from anycabinet from mixing significantly with the ambient airsupply to a cabinet located above. It is also implicit thatsuch provisions should allow for the affects of naturalconvectively cooled LRMs sharing a cabinet row withLRMs ha
33、ving internal provision for forced cooling. Thereshould be no air flow dynamic effect that will cause anadverse pressure gradient or localized air re-circulation tonaturally cooled LRMs due to the presence of force cooledLRMs.It is recommended that internal air moving devices beused only if the LRM
34、can continue to function with anysuch device failed for an extended period of time, (e.g.,ETOPS) and the failure can be indicated by appropriatemeans.3.4 Equipment Sidewall TemperatureLRM power dissipation is limited to that which restrictsthe LRM external surface temperature to a maximum of15oC abo
35、ve the normal operating ground temperature.There should be no hotspot temperatures of 20oC abovenormal operating ground temperature. The maximumtemperature external surface area should be minimized.3.5 LRM Thermal AppraisalA thermal appraisal should be conducted to show that thedesign objectives hav
36、e been met.3.6 Thermal Interface InformationBefore designing an LRM/cabinet assembly to meet thethermal management requirements, the followinginformation should be available from equipmentinstallation and control drawings:a. Total wattage input and actual heat dissipation for allmodes of electrical
37、operation for which the equipmentwas designed (e.g., standby, receiving, transmitting,etc.).Note: Wattage input and actual heat dissipation shouldbe based on normal operating ground temperatureconditions. If significant increases in powerdissipation (i.e., 10% increase) occur attemperature extreme c
38、onditions (e.g., -40oC and/or+70oC) they should also be identified.b. Estimated in-flight and ground maximum duty cycle(when specified in the applicable ARINCCharacteristics).c. Average temperature of equipment sidewalls for thethermal design condition.d. Effect of dry contamination on unit coolingp
39、erformance and recommended unit service intervalsrequired to maintain cooling performance, ifapplicable.3.7 Materials for Thermal DesignThe range of materials available to facilitate thermaldissipation through the various levels of packagingbetween the base die of semiconductor devices and theLRM is
40、 too wide to allow more than a brief referencehere. A description of generic features in a qualitativefashion is presented in Table 3-2 for guidance only -design engineers will need to contact respective suppliersfor property data on the specific grades of materialappropriate to their application.AR
41、INC REPORT 654 - Page 103.0 THERMAL CONSIDERATIONS (contd)LRM CASE SIZEAMU (width ins)LRM CaseSurface Areain2(m2104)Dissipation Wattsmax enclosed LRM60oC case surfacetempCircuitBoards(Example)Indirect Flow-throughnatural convectionDissipation Watts vs HeatSink Temp+60oC +75oC +100oC1AMU (1.1) 226.7
42、(1463) 7.0 2 8.7 13.6 24.52AMU (1.5) 242.6 (1565) 7.8 4 10.3 17.7 34.03AMU (1.9) 258.5 (1668) 8.6 4 10.9 21.8 43.6*4AMU (2.3) 274.4 (1770) 9.5 6 12.7 26.0 53.25AMU (2.7) 290.4 (1874) 10.3 6 15.4 30.1 62.8*6AMU (3.1) 306.3 (1976) 11.2 8 17.2 34.3 72.47AMU (3.5) 322.2 (2079) 11.8 8 18.6 38.2 81.8*Tabl
43、e 3-1 Examples of Maximum Heat Dissipation for Fully Enclosed LRMNote 1: Ambient Air Temperature +50oC and Sea Level Static.Note 2: Guide value; as LRM width increases beyond 4 AMU, internal module cooling surface configurationsproliferate and greater un-assisted convection values may be achieved.No
44、te 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 ofthis size will probably contain large items which would break up the otherwise uniform module board pairs.Note 5: So
45、me IMA cabinet designs may limit the amount of airflow between LRMs.Material AttributesEMScreeningHigh ThermalConductivityLow ThermalExpansionHighModulusLowDensityHighToughnessLowCostCopper Aluminum Aluminum Oxide Aluminum Nitride Beryllium KovarTM Cu/InvarTM/Cu Molybdenum Cu/Molybdenum/Cu Tungsten/
46、Cu SiC/Al composite(Metal Matrix,HIVOLTM) Table 3-2 Materials for Thermal Design.ARINC REPORT 654 - Page 113.0 THERMAL CONSIDERATIONS (contd)Figure 3-1 Construction Example of a 1 AMU LRM, Top View.ARINC REPORT 654 - Page 123.0 THERMAL CONSIDERATIONS (contd)Figure 3-2 - Construction Example of a 2 A
47、MU LRM, Top View.ARINC REPORT 654 - Page 133.0 THERMAL CONSIDERATIONS (contd)Figure 3-3 - Construction Example of a 3 AMU LRM, Top View.ARINC REPORT 654 - Page 144.0 DESIGN LIFE4.1 Operational Design LifeThe operational design life refers to the combination ofenvironments and stresses that the equip
48、ment is exposedto over its intended service life. These conditions arerepresented by all relevant operating, shipping andstorage conditions.Operating conditions are usually expressed as anumber/classification of operating flights and/or hours(including ground operation) with their associatedtemperat
49、ure cycling (low cycle fatigue) and vibration(high cycle fatigue)/mechanical shock distribution.Non-operational conditions (including movements suchas delivery by transportation) and storage conditionsusually have a long term thermal cycling condition (e.g.,diurnal cycling) associated with them in addition tovarious temperature extremes and handlingvibration/shock.These various environmental factors contributeunfavorably to the fatigue life of electronic componentsin the equipment LRMs such as compone
