1、I INCH-POUND I MI L-A- 2474 1 19 JANUARY I990 M P L ITARY SPEC I F I CAT I ON ASSEMBLIES, METAL ELECTRICAL BACKPLANE, ONE AND TWO LAYER, GENERAL SPECIFICATION FOR Thls specification is approved for use by all Departments and Agencies of the Department of Defense. 1. SCOPE 1.1 Scope. This specificati
2、on covers the general requirements for metal electrical backpiane assemblies consisting of one and two layers on which separately manufactured component parts have been added. Beneficial comments (recommendations, additions, deletions) and any pertinent data which may be of use in improving this doc
3、ument should be addressed to: Commander, Naval Sea Systems Command, SEA 55t3, Department of the Navy, Washington, D.C. 20362-5101, by using the self-addressed Standardization Document Improvement Proposal (DD Form 1426) appearing at the end of this document or by letter. AMSC N/A FSC 5998 DISTRIBUTI
4、ON STATEMENT A. Approved for pub1 ic release; distribution is un1 imited. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,- MIL-A-24791 57 W 7777906 0413747 7 MI L-A-24741 1.2 Classification. 1.2.1 Types. Metal electrical backplane assemblies shall be
5、 of the fol 1 owing types : a) Type 1: one layer. (b) Type 2: two layer. 2. APPLICABLE DOCUMENTS 2.1 Government documents 2.1 1 Specifications and standards. The following specifications and standards form a part of this document to the extent specified herein. Unless otherwise specified, the issues
6、 of these documents are those listed in the issue of the Department of Defense Index of Specifications and Standards (DoDISS) and supplement thereto, cited in the solicitation (see 6.2). SPEC IF ICATIONS FEDERAL L-P-509 QQ-A-250 QQ-A-250/8 QQ-A-250/11 MILITARY MI L-C-5541 MI L -A-8625 MIL-C-28754 -
7、Plastic Sheet, Rod and Tube, Laminated, - Aluminum and Aluminum Alloy Plate and Sheet, General - Aluminum Alloy 5052, Plate and Sheet. - Aluminum Alloy 6061, Plate and Sheet. Thermosetting, Specification for. - Chemical Conversion Coatings on Aluminum and - Anodic Coatings, for Aluminum and Aluminum
8、 Alloys. - Connectors, El ectri cal , Modul ar, and Component Parts, Al umi num Al 1 oys . General Specification for. MIL-C-28754/39- Connectors, Electrical, Modular, Connector, Type III, MIL-1-43553 - Ink, Marking, Epoxy Base. Keying Pegs. a MIL-C-55330 - Connectors, Electrical and Fiber Optic, Pac
9、kaging of. 2 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,- MIL-A-24741 59 7999906 0433748 O MIL-A-24741 STANDARDS MI L ITAR DOD-STD-100 - Engineering Drawing Practices, MIL-STD-105 - Sampling Procedures and Tables for Inspection by MIL-STD-I29 - M
10、arking for Shipment and Storage. MIL-STD-202 - Test Methods for Electronic and Electrical Component Part s. MIL-STD-1344 - Test Methods for Electrical Connectors. MIL-STD-45662 - Cal i bration Systems Requirements. MIL-STD-2198 - Design Requirements for Metal Electrical Backplane Assembl iea e Attri
11、butes (Unless otherwise indicated, copies of federal and military specifications and standards are available from the Naval Publications and Forms Center, (ATTN: NPODS) , 5801 Tabor Avenue, Philadelphia, PA 19120-5099.) 2.2 Non-Government publications. The following documents form a part of this doc
12、ument to the extent specified herein. Unless otherwise specified, the issues of the documents which are DOD adopted are those listed in the issue of the DODISS cited in the solicitation. Unless otherwise specified, the issues of documents not listed in the DODISS are the Issues of the documents cite
13、d in the solicitation (see 6,2), AMERICAN NATIONAL STANDARDS INSTITUTE (ANSI) O ANSI 846.1 - Surface Texture (Surface Roughness, Waviness, and Lay 1 (Application for copies should be addressed to the American National Standards Insti tute, 1430 Broadway, New York, NY 10018-3308.) AMERICAN SOCIETY FO
14、R TESTING AND MATERIALS (ASTM) ASTM 5209 - Standard Specification for Aluminum and Aluminum-Alloy Sheet and Plate, 3 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-_._ MIL-A-24741 59 979970b 0413747 2 i- MI L-A- 24741 (Application for copies should
15、be addressed to the American Society for Testing and Materials, 1916 Race Street, Philadelphia, PA 19103-1187.) (Non-Government standards and other pub1 ications are normally available from the organizations that prepare or distribute the documents. documents also may be available in or through libr
16、aries or other i nformat i onal servi ces. ) These 2.3 Order of precedence. In the event of a conflict between the text of this document and the references cited herein (except for related specification sheets), the text of this document takes precedence. Nothing in this document, however, supersede
17、s applicable laws and regulations unless a specific exemption has been obtained. 3. REQUIREMENTS 3.1 Requirements, One layer and two layer metal electrical backplane assemblies furnished under this specification shall be products which meet the requirements of MIL-STD-2198 and the backplane assembly
18、 drawing. The one layer or two layer metal electrical backplane assembly drawings shall be in accordance with DOD-STD-100. In the event of a conflict between MIL-STD-2198 and the backplane assembly drawing, the latter shall govern. O 3.2 Qualification. One layer and two layer metal electrical backpl
19、ane assembl les furnished under this specification shall be products which are authorized by the qualifying activity for listing on the applicable Qualified Manufacturers List (QML) at the time of award (see 4.6 and 6.4). 3.3 Material. The type of material shall be as specified in MIL-STD-2198 and t
20、he backplane assembly drawing. Acceptance or approval of any constituent material shall not be construed as a guarantee of the acceptance of the fini shed product. 3.3.1 Contact and bushing sets. The contact and bushing sets shall be as specified in MIL-C-28754, 3.3.2 Keying pegs. The keying pegs sh
21、all be as specified in MIL-C-28754/39, 4 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MI L-A- 24741 3.3.3 Marking ink. Marking ink shall be an epoxy base ink conforming to MIL-1-43553, 3.4 Design and construction. One layer and two layer metal ele
22、ctrical backplanes shall conform to the design, construction and physical dimensions specified in MIL-STD-2198 and in the assembly drawing. 3.4.1 Wrappost tail tip position, Unless otherwise specified on the backplane assembly drawing, all wrappost tail tip positions shall be within a positional tol
23、erance of 0,020 inch (0,508 mm) diameter to datums Specified on the backplane assembly drawing. 3.4.2 Holes. The mounting holes -in either the one or the two layer metal electrical backplane shall meet the following requirements. 3.4.21 Contact and bushing set holes. Holes for the contact and bushin
24、g sets shall be 0,0725 k0.0015 inch (1.8415 I0.0381 mm) diameter on a grid of 0.100 inch (2.540 mm). This requirement shall be met for a minimum of 50 percent of the backplane thtcknesi. 3.4.2.2 Mounting and other holes. Holes for mounting and other purposes in the assembly are optional. 3.4.3 Assem
25、bly of contact and bushing sets. The assembly of the contact and bushing sets shall satisfy the workmanship standards established by figure 1 when vlsually inspected at a magnification of 10 power. Contacta shall be installed in the insulator bushing in such a manner that the contacts are flush or b
26、elow the top surface of the bushing a maximum of 0.020 inch (0.508 mm). The bushing shall be free of damage on the top surface. Figure 1A is a preferred condition. Figures 1B and 1C are unacceptable conditions. any condition depicted in figures 1D through 11, the backplane is unacceptabl e. If more
27、than 5 percent of the contact and bushing sets display 3.5 El ectrical requi rement s. 3.5.1 Insulation resistance. When the metal backplanes are tested in f accordance with 4.9.1, the insulation resistance shall be 100,000 megohms minimum before humidity test for the one layer backplane, and 100 me
28、gohms minimum before humidity test for the two 1 ayer backplane. 5 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,- - -. - -_ MIL-A-24741 57 W 7777706 0413751 O W MIL-A-24741 FIGURE 1A. Idealized condition. I FIGURE 1B. Either tine broken. I FIGURE 1
29、C. Both contact tines twisted. FIGURE 1. Contact and bushing set workmanship standards. 6 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-A-2LI74L 57 U 7777906 0433752 2 I MIL-A-24741 0 FIGURE ID. Sinqle contact tine twisted. FIGURE 1E. Contact t
30、ines against bushing. I FLGURE 1F. Bust-tinq rotated and contact tines twisted. FIGURE I 1G. Contact orientation not central to cruciform and contact tines bridqinq buchinq. FIGURE 1, Contact and bushing set workmanship standards - Continued. 7 Provided by IHSNot for ResaleNo reproduction or network
31、ing permitted without license from IHS-,-,-_- -_l_l_ MIL-A-247q3 59 = 9779906 0433753 4 W MIL-A-24741 L FIGURE 1H. Bushina and contccts with one set improperly criented. FIGURE 11. Bushina and contacts randomlv oriented in pattern. FIGURE 1. Contact and bushing set workmanship standards - Continued.
32、 8 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MI L -A-2474 1 3.5.2 Dielectric withstanding voltage. When tested in accordance with 4.9.2, there shall be no evidence of arcing, breakdown, or damage, 3.5.3 Mounting plate to contact resistance (i a
33、nd 2 layer),. When the mounting plate to contact resistance is tested in accordance with 4.9.3, the voltage drop between the mounting plate and the contact in a two layer backplane shali not exceed 5.0 millivolts (my) tn the ground plane and 12.0 mV in the power plane. The voltage drop in a one laye
34、r backplane shall not exceed 2Q.O mV. 3.5.4 Capacitance between the 1 ayers. When the capacitance between the layers of a two layer metal electrical backplane is tested in accordance with . 4.9.4, the capacitance value between the layers shall be 30 picofarads maximum per square inch of the Vcc (pow
35、er) plane. 3.6 Mechanical requirements. 3.6.1 Bow and twist. Unless otherwise specified on the-approved assembly drawing (see 4.10.1), the maximum allowable bow and twist shall be. 1.5 percent. D 3.6.2 Contact and bushing retention. When the connectors are tested in accordance with 4.10.2, no contac
36、t shall have been pushed out of its bushing, nor shall any bushing have been pushed out of the base plate. There shall be no movement of the contact or bushings. 3.6.3 Contact torque. When tested in accordance with 4,10.3, the contact shall withstand a minimum torque of 3.0 ounce-inches (0.02 newton
37、- meter). No displacement or deformation of the contact or. bushing shall be visible following removal of the applied torque. 3,6.4 Keying peg retention. When tested in accordance with 4.10.4, the keying pegs installed in the housing shall withstand a removal force of 5 pounds (22 newtons) minimum.
38、I. 3.6.5 Engaging and separating forces. The paragraphs below outline I 1 mechanical requirements for both standard insertion force and low insertion force contacts. 9 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-A-24743 57 7977706 0433755 MI
39、L-A-24741 3.6.5.1 Standard insertion force, When tested in accordance with 4,10.5, the force to engage the tuning fork shall be 6.0 ounces (1.66 newtons) maximum, and the force to separate shall be 2.0 ounces (0.56 newtons) mi ni mu m. 3.6.5.2 Low Insertion Force (LIFL, When tested in accordance wit
40、h 4.10,5, the average force to engage shall be 2.25 ounces (0,63 newtons) maximum with random readings at 4.00 ounces (1.11 newtons) maximum. Separation force shall be 4.0 ounces (1.12 newtons) maximum. 3.6,6 LIF normal force. The average normal force shall be greater than 3.5 ounces (0.98 newtons)
41、with random readings of no less than 3.00 ounces (0,84 newtons) allowed when tested as specified in 4.10.6. 3.7 Environmental requirements. 3.7.1 Durability. When the qualification inspection sample is tested in accordance with 4.11.1, there shall be no evidence of wear that would adversely affect t
42、he operation of the assembly. shall meet th requirements of 3,6.3 and 3,6,5. In addition, the contacts 3.7.2 Salt spray, When the qualification inspection sample is tested in accordance with 4,11.2, there shall be no visible signs of corrosion or corrosive salts on the base metal, contacts, or backp
43、lanes. 3.7.3 Shock (specified pulse). When the qualification inspection sample is tested in accordance with 4.11.3, there shall be no breakage or loosening of contacts, cracking of inserts, nor other visible or dimensional damage which could cause electrical or mechanical breakdown. There shall be n
44、o loss of electrical continuity of any of the contact circuits of more than 100 nanoseconds during test. 3.7.4 Humidity. When the qualification inspection sample is tested in accordance with 4.11.4, the backplanes shall meet the requirements of 3.5.1, 3.5.3 and 3.6.2. , 3,7,5 Temperature cycling. Wh
45、en tested in accordance with 4.11.5, the qualification inspection sample shall show no evidence of cracking, fracturing, or other damage detrimental to the operation of the assembly. 10 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-A-Zq743 57 7
46、73770b 0433756 T W MIL-A-24741 3.7.6 Vibration. When the qualification inspection sample is tested in There shall be no accordance with 4.11.6, there shall be no cracking or breaking, nor shall there be any loosening of parts, or other visible damage. loss of electrical continuity of any of the cont
47、act circuits af more than 100 nanoseconds during the test. After testing, the assemblies shall meet the requirements of 3.5.1, 3.6.2 and 3.6,5, 3.8 Marking. The backplane assemblies shall be marked in accordance with MIL-STD-2198, using the marking ink as specified herein and on the indvldual assemb
48、ly drawing. 3.9 Workmanship. All metal backplane assemblies shall be uniform in quality and appearance. They shall be clean and free of dirt, conductive debris, foreign matters, oil, fingerprints, corrosion, salts, burrs, sharp edges and contaminants. Workmanship qual itiea for two layer metal backp
49、lanes shall also include:. (a) There shall be no voids, cracks, or loose edges along the bond lines. (b) An adhesive bead around the periphery of the joint is acceptable. (c) All adhesive shall be fully cured. 4. QUALITY ASSURANCE PROVISIONS 4.1 Responsibility for inspection, Unless otherwise specified in the contract or purchase order, the contractor is r
