1、II 3 MIL-T-81955 PlF I 97779Ob 0460550 5 = MILJTARY SPECIFICATION MIL-T-81955 (AS) 15 November 1973 SUPERSEDING AS 1131 A 26 February1968 TIN PLATING; IMMERSION FOR COPPER AND COPPER ALLOYS This specification is approved for use by the Nava Air Systems Command, Department of the Navy. 1. SCOPE 1.1 S
2、cope. This specification covers the requirements for tin plating deposited by immersion, without an external potential, on copper and copper alloys. 1.2 Classification, 12.1 Classes, Deposited tin plating shall be of the following classes as specified (see 6.2): Class 1 - 0.000076 to 0.0001 inch thi
3、ck Class 2 - 0.000051 to 0.000075 inch thick Class 3 - O. 000026 to O. 000050 inch thick Class 4 - 0.000025 inch or less thick 2. APPLICABLE DOCUMENTS 2.1 tion for bids or request for proposal, forni a part of this specification to the extent specified herein. The following documents of the issue in
4、 effect on date of invita- SPECIFIC ATIONS Federal 0-T-634 QQ-S-57 1 Trichloroethylene, Technical Solder, Tin-Alloy : Tin-Lead Alloy; and Lead Alloy Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-_- I_- MIL-T-3755 MF 777770b 0460553 7 W MTL-T-81.955
5、 (AS) SPECIFICATIONS Military I MIL-T-81533 STANDARDS Feder al I 1, 1, 1 Trichloroethane (Methyl Chloroform) Inhibited, Vapor Dogreasing Fed. Test Method Std. No, 151 Metals; Test Methods Military MIL-STD-10 5 Sampling Procedures and Tables for inspection by Attributes t F MI L-STD- 13 1 2 Fasteners
6、, Test Methods (Copies of specifications, standards, and publications required by supplie 1:s in connection with specific procurement functions should be obtained from the procuring activity or as directed by the contracting officer. ) 2.2 Other publications. The following documents form a part of t
7、his specification to the extent specified herein. Unless otherwise indicated, the issue in effect on date of invitation for bids or request f.or proposal shall apply. American Society for Testing and Materials (ASTM) Standards Determination of Tin Coating Weights for Hot-Dip and Electrolytic Tin Pla
8、te A 630 B 487 B 499 B 504 Measuring Metal and Oxide Coating Thickness by Microscopical Examination of a Cross Section Method for Measurement of Coating Thickness by the Magnetic Method: Nonmagnetic Coatings on Magnetic Basis Metals Measuring the Thickness of Metallic Coatings by the Coulometric Met
9、hod 2 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-T-81755 MF m 9779706 0460552 9 H i American Society for Testing and Materials (ASTM) Standards (Continued) B 567 Test for Coating Thickness by the Beta Backscatter Principle B 568 Test for Coa
10、ting Thickness by X-Ray Spectrometry (Application for copies should be addressed to the American Society for Testing and Materials, 1916 Race Street, Philadelphia, PA 19103.) 3. REQULREMENTS 3.1 Materials. The materials used shall be such as to produce tin plating which meets the requirements of thi
11、s specification. - 3.2 Composition. The composition of the plating, deposited on the CleaninP. The basis metd shall be cleaned, pickled or other- basis metal surface, shall not be less than 99 percent tin. 3.3 wise pretreated by methods which shall not damage the substrate and shall not interfere wi
12、th the adhesion of the deposit (see 6.3). 3.4 Plating application, Unless otherwise specified (see 6.2), the plating shall be applied after all basis metal heat treatments and mechanical opera- tions, such as machining, soldering, brazing, welding, forming and perforating of the article have been co
13、mpleted. The tin plating shall be deposited from a bath solution onto the copper or copper alloy surface under the influence of the potential that exists between the solution and the immersed basis metal. 3.5 Coverwe. Unless otherwise specified, the plating shall cover all surfaces including roots o
14、f threads, corners and recesses (see 6.2). 3.6 Thickness. Unless otherwise specified (see 6.2), the thickness range of tin, as specified in- the contract, purchase order or applicable drawing, on significant surfaces for eaih class of plating shall be as detailed in Table I. Significant surfaces sha
15、ll be all surfaces of the article which can be tuched by a sphere O. 75 inch (19 mm) in diameter pius additional functional surfaces specified (see 6.2). Sur- faces on which the specified thickness cannot readily be controlled, such as holes, deep recesses, bases of angles, and internal threads from
16、 which the external environ- ment is completely excluded and where a controlled deposit cannot be normally obtained, shaii not be subjected to a thickness requirement. However, the plating on such sur- faces shall be of sufficient thickness to ensure coating continuity and uniform appear- ance. 3 Pr
17、ovided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-VIL-T-BL755 VF W 7777906 O460553 O MIL-T-819 5 5 ( AS) Microinches (millionths of an inch) Class 3 Micromctrcs (approx. ) equivalent thickness I/ TABLE I THICKNESS Inch O, 00007G to O, O00100 O, O00051 to
18、 O. 000075 O. 000026 to O. 000050 0.000025 or less 76 to 100 51 to75 26 to 50 25 or less 1.92 - 2.54 1.28 - 1.91 0.64 - I. 27 0.63 or less I/ O. 0001 inch = O. 1 mil = 100 microinches = 2.54 3.7 Adhesion. The adhesion of the plating shall be such that when examined at a magnification of approximatel
19、y 10 diameters, the plating shall not show separation from the basis metal at the interface when subject to the tests described in 4.5.3. The ,interface between the tin plating and the basis metal is the surface of the basis metal before plating. The formation of cracks in the plating caused by rupt
20、Ure of the basis metal which does not result in flaking, peeling, or blistering of the coating shall not be considered as nonconformance to this require- ment. 3, a Solderability. Plated specimens or parts shall be easily and completed coated with solder when tested as specified in 4.5.4. The solder
21、 shall be deposited uniformly without lumps or peaks and shall be essentially free from evidence of bubbling, foaming, voids and other defects. The solder shall firmly adhere to the plating and the plating shall be firmly adherent to the basis metal. There shall be no separation at the solder-platin
22、g interface or at the plating-basis metal interface, so that they cannot be lifted when a sharp-edge instrument is applied. 3.9 W or kmans hip. 3.9.1 Basis metal, The basis metal shall be free from visible defects which will be detrimental to the appearance or protective value of the plating. 3.9.2
23、Plating. The tin plating shall be smooth, adherent, continuous, free from visible blisters, pits, nodules, porosity, excessive build-up, staining and other defects. The size and number of contact marks shall be at a minimum consistent witl. qoAd practice. The location of contact marks shall be in ar
24、eas of minimum exposure to service environmental conditions where important to the function of the part. t 4 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-4 MIL-T-1755 MF U 747730b 04b0554 2 Superficial staining which has been demonstratedas result
25、ing from any drying or bak- ing operation shall not be cause for rejection, The plating shall show no indication of contamination or improper operation of equipment used to produce the plating. All details of workmanship shall conform to the best practice for high quality coating, 4. QUAUTY ASSURANC
26、E PROVISIONS 4.1 Responsibility for inspection. Unless otherwise specified in the contract or purchase order, the supplier is responsible for the performance of all inspection requirements as specified herein. Except as otherwise specified in the contract or order, the supplier may use his own or an
27、y other facilities suitable for the performance of the inspection requirements specified herein, unless disapproved by the Government. tions set forth in the specification where such inspections are deemed necessary to assure supplies and services conform to prescribed requirements. The Government r
28、eserves .the right to perform any of the inspec- 4.2 - Lot. A lot shall consist of plated articles of the same material, class, plated and treated under the same conditions and approximately of the same size and shape, submitted for inspection at one time. In no case shall the lot size exceed produc
29、tion for one normal work period, an 8-hour shift. 4.3 Qualitv conformance samplinq. 4.3.1 For visual examination and nondestructive tests. Sampling for visual examination and nondestructive tests shall be conducted as directed by the procuring activity (see 6.2) in accordanqe with MIL-STD-105 or usi
30、ng Table II. A sample of coated parts or articles shall be drawn by taking at random from each lot the nuniber of articles in accordance with MIL-STD-105, Level II, Acceptable Quality Level (AQL) O, 25-percent defective, or as indicated in Table LI. The lot shall be accepted or rejected according to
31、 the procedures in 4.3.1.1 for visual examination and 4.3.1.2 for plating thickness (nondestructive tests). 4.3 1.1 Visual examination. Samples selected in accordance with 4.3.1 shall be examined for compliance with the requirements of 3.9.2 after plating. If the number of nonconforming articles exc
32、eeds the acceptance number for the sample, the lot represented by the sample shall be rejected. 4.3.1.2 Thickness of plating (nondestructive tes tsL. Samples selected in accordance with 4.3.1 shall be inspected and the plating thickness measured by the applicable tests detailed in 4.5.2 at several l
33、ocations on each article as defined in 3.6, as applicable, for compliance with the requirements. Measurements on fastener hardware shall be made at locations defined in MIGSTD-1312, Test 12. The part or article shall be considered nonconforming if one or more measurements fail to meet the specified
34、minimum thickness. L the number of defective items in any sample exceeds the acceptance number for the specified sample, the lot represented by the 5 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-T-81755 MF = 3777706 Oq60555 q sample shall be r
35、ejected, Separate specimens (see 4.4.1) shall not be used for thick- ness measurerncnts unless a need has been demonstrated. TABU II SAMPLING FOR VISUAL EXAMINATION AND NONDESTRUCTIVE TESTS Nimibers of items in lot iiispections 15 or less 16 t3 40 41 to 110 111 to 300 301 to 500 501 aiid over Nunibe
36、r of items Acceptance number in samples (maximum number of (randomly selected) sample items noncon- forming to any test) 7 I/. 10 15 25 35 50 If the number of items in the inspection lot is less than 7, the number of items in the sample shall equal the number of items in the inspection lot. 4.3.2 Fo
37、r destructive tests. A random sample of four plated parts or articles shall be taken from each lot for each destructive test or separately plated specimens shall be prepared in accordance witK 4.4 and 4.4.1 to represent each lot, If the nimber of articles in the lot is four or less, the number of ar
38、ticles in the sample shall be specified by the procuring activity (see 6.2). 4.3.2.1 Composition. When specified in the contract or order, compliance with the requirements for composition shall be determined (see 6.2). Samples selected in accordance with 4.3.2 shall be testecl in accordance with 4.6
39、.1 to determine com- pliance wi tli 3. 2. 4.3.2.2 Thickness of platina (destructive tests). If sampling and testing for thickness of plating by nndestructive testing is not the option of the supplier, samples selected in accordance with 4.3.2 shall be measured for plating thickness by the applicable
40、 tests detailed in 4.5.2 at several locations as defined in 3.6 for com- pliance with the requirements, Measurements on fastener hardware shall be made at locations defined in MIL-STD-1312, Test 12. if the plating thickness on any place on any article or specimen is less than the specified minimum t
41、hickness, the lot shall be rejested. Separate specimens (see 4.4.1) shall not be used for thickness measure- menL5 unless a need has been demonstrated. 6 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-* MIL-T-81755 MF 9797706 04b055b b M d MIL-T-819
42、55( AS) 4.3.2.3 Adhesion (destructive testsl. The articles or specimens used for the destructive thickness test (see 4.5.2), if of suitable size and form, may be used as the test pieces for the adhesion tests to determine compliance with the requirements of 3.7. Failure of one or more of the test pi
43、eces shali constitute failure of the lot. 4.3.2.4 Solderability (destructive tests). Unless otherwise specified (see G.2), compliance with the requirements for solderability shall be determined. The articles or specimens used for the destructive thickness test (see 4.5.2) o suitable size and form, m
44、ay be usecl as the specimens for the solderability test (see 4.5.4) to determine compliance with the requirements of 3.8. Failure of one or more of the test specimens shall constitute failure of the lot. 4.4 Quality conformance specimen preparation, When the plated articles are of such form, shape,
45、size or value as to prohibit use thereof, or are not readily adaptable to a test specified herein, or when destructive tests of small lot sizes are required the test shall be made by the use cf separate specimens plated concurrently with the articles represented. The separate specimens shall be of a
46、 basis metal equivalent to that of the articles represented. Equivalent basis metal includes chemical composition, grade, condition and finish of surface prior to plating. For example, a colcl-worked copper surface should not be used to represcnt an annealed surface. Due to the impracticaiity of for
47、ging or casting separate test specimens, hot-worked specimens mny be used to represent forged and cast articles. The separate specimens may be also cut from scrap castings when castings are being plated. These separate specimens shall be introduced into a lot at regular intervals prior to the cleani
48、ng operations, preliminary to plating, and shali not be separated therefrom until after completion of plating. Conditions affecting the plating of specimens including the spacing, Glating media, residual air pressure, temperature, etc. in respect to other objects being plated shall correspond as nea
49、rly as possible to those affecting the significant surfaces of the articles represented. Separate specimens shall not be used for thickness measurements, however, unless the necessity for their use has been demonstrated. 4.4.1 Specimens for composition, thickness, adhesion, and solderability - tests. If separate specimens for composition, thickness, adhesion, and solderability tests are required, they shall be strips approximately 1 inch wide, 4 inches long
