1、 EIA CB34 93 3234600 0507343 bTb Ropmduced y GLOBAL ENGINEERING DOCUMENTS Nith Thr hmtukn ol EIA d unda RwJtl Almmant EIA ENGINEERING BULLETIN Contact Lubrication CB14 JUNE 1993 ELECTRONIC INDUSTRIES ASSOCIATION ENQINEERINQ DEPARTMENT EIA CB14 93 3234600 0507144 532 m NOTICE EIA Engineering Standard
2、s and Publications are designed to serve the public interest through eliminating misunderstandings beween manufacturers and purchasers, facilitating interchangeability and improvement of products, and assisting the purchaser in selecting and obtaining with minimum delay the proper product for his pa
3、rticular need. Existence of such Standards and Publications shall not in any respect preclude any member or nonmember of EIA from manufacturing or selling products not conforming to such Standards and Publications, nor shall the existence of such Standards and Publications preclude their voluntary u
4、se by those other than EIA members, whether the standard is to be used either domestically or internationally. Recommended Standards and Publications are adopted by EIA in accordance With the American National Standards Institute (ANSI) patent policy. By such action, EIA does not assume any liabilit
5、y to any patent owner, nor does it assume any obligation whatever to parties adopting the Recommended Standard or Publication. Technical Bulletins are distinguished from EIA Recommended Standards or Interim Standards, in that they contain a compilation of engineering data or information useful to th
6、e technical community, and represent approaches to good engineering practices that are suggested by the formulating committee. This Bulletin is not intended to preclude or discourage other approaches that similarly represent good engineering practice, or that may be acceptable to, or have been accep
7、ted by, appropriate bodies. Parties who wish to bring other approaches to the attention of the formulating committee to be considered for inclusion in future revisions of this Bulletin are encouraged to do so. It is the intention of the formulating committee to revise and update this Bulletin from t
8、ime to time as may be occasioned by changes in technology, industry practice, or government regulations, or for other appropriate reasons. (Formulated under the cognizance of the EL4 CE-2.0 Committee on National Connector Standards.) Published by 0 ELECTRONIC INDUSTRIES ASSOCIATION 1993 Engineering
9、Department 2001 Pennsylvania Ave., N.W. Washington, D.C. 20006 PRICE Please refer to the current Catalog of EU & JEDEC STANDARDS & ENGINEERING PUBLICATIONS or call Global Engineering Documents, USA and Canada (1-800-854-7179) In tema tional (303-7!n-2 18 1) All Rights Reserved Printed in U.S.A. EIA
10、CB34 93 3234600 0507345 479 EIA CBL4 93 3234b00 0507L4b 305 = CB14 Page 1 The purpose of this document is to review contact lubricants used in signal contact systems for electronics. Factors affecting the use of lubricants will be discussed including those areas requiring further study. Applicable a
11、dvantages, limitation and cautions are indicated. A bibliography is included if further investigation is desired. It is not the intent of this document to make a conclusion or forward a recommendation. Due to the wide variation of available lubricants (both generic and proprietary), the specific sit
12、uations briefly discussed herein may not be of issue contingent on the lubricant formulation which may have been designed to resolve a specific problem. In considering the use of a lubricant, the reader is advised to assess the specific areas of interest and chose a lubricant which best fits the app
13、lication after proper evaluation techniques have been performed. The information contained herein has been based from various publications and papers as indicated in the bibliography contained at the end of this document. information, these publications should be researched as applicable. For more s
14、pecific EIA CBL4 93 3234600 0507147 241 CB14 Page 2 Two surfaces in contact with each other appear to form a relatively large continuous contact area. area of contact is formed by contact asperities (commonly called la-spots). contact with each other and represent as low as 1% of the apparent contac
15、t area. In reality the real These asperities are actually metallic peaks in When a contact force is applied these peaks contact each other and may actually enlarge dependent on the magnitude of the applied force. This may result in localized cold welding and/or potential galling. d wem is defined as
16、 the solid state bonding between atoms of the metallic surface areas in contact. Contamination free surfaces are required for this to fully occur. of contaminants on the surface can minimize cold welding. The presence u is defined as a wear condition resulting from friction between the asperities of
17、 the contacting surfaces. This can result in localized welding and subsequent metal surface disruption, metal transfer and/or further roughening of the mating surfaces. In addition, when one of the two, or both contacting surfaces are moved relative to each other, any localize cold welding between t
18、he asperities has to be broken or sheared. is a function of a numberof variables such as compressive forces, surface conditions, cleanliness etc. This shearing force , EIA CB34 73 = 3234600 0507348 188 CB14 Page 3 SIC PHENOMENON - ontinuea When a lubricant is applied to a surface, the fluid generall
19、y forms small droplets. When surfaces are brought into contact, these droplets are spread over the entire surfaces in the form of a thin film. The film is thin enough to be penetrated in several areas by the material asperities thus not affecting electrical resistance. welding, reduces shear forces
20、involved and hence reduces wear, galling and frictional forces. The impact of this film results in minimizing cold C. 1. WEAR: The term “wear“ indicates the “forced“ removal of contact material during the sliding action which occurs. This removal may be a result of the transfer phenomena, loss of lo
21、ose particles (debris), pushing material aside, etc. The following are the basic wear mechanisms which exist. a) ABRASIVE: Wear resulting from rough, sharp hard materials or a combination thereof in contact with a softer material. An example of this is a lead-in chamfer of a mating pcb against a gol
22、d or tin (ally) plating of the mating contact. these situations. Lubricants may not be effective in b) BRITTLE FRACTURE: This is the cracking of a plated surface perpendicular to the direction of sliding. strength materials or a poorly controlled plating process. not prevent this type of wear from o
23、ccurring. This type of wear can occur on low Lubrication by itself will EIA CB14 93 W 3234600 0507149 O14 c CB14 Page 4 UTES AFFECTED BY LURRICATION - ontinued Cl 2. 3. ADHESIVE: This is the most common type of wear common to connectors. Basically this type of wear results from cold welding and/or t
24、he transfer phenomena. significantly reduced when a lubricant is used on the surfaces. This type of wear is The rate of wear sharply increases from “mild“ to “severe“ usually when a specific load is achieved. Use of a lubricant will result in this transition to occur at higher force levels with all
25、other factors being equal. Lubrication will also allow thinner gold plating to be used due to the reduction of the wear rate. CORROSION : A lubricant can l*seall* off reactive surfaces from the surrounding atmosphere. It can also significantly reduce pore corrosion as well. mixture of wax and an oil
26、 are effective in this case. Microcrystaline wax or a Fretting corrosion may be inhibited by the use of a fluid lubricant. as well as inhibiting frictional polymers in palladium (alloy) systems. It will reduce fretting wear on of gold platings LOWER MATING FORCES: reduces coefficient of friction and
27、 this decreases the mating force of a connector system. This can be an important feature for high density connector currently evolving. reduction may be as great as 80% contingent on contact configuration (entry geometry) , surface, conditions (eg . roughness, cleanliness, etc.). This reduction may
28、be achieved without reducing normal force and may allow an actual increase in this attribute without adversely affecting the resultant mating force. A lubricant by its inherent nature Said EIA CB14 93 3234600 0507150 836 M CB14 Page 5 Typical coefficient of frictions are as follows: Clean surfaces :
29、 0.3 to 1.0 Lubricated Surfaces : 0.15 to 0.2 There are two basic equations which may be used in understanding frictional forces: a) F = (KN/H)S F = Frictional Force K = Constant, Proportionality N = Normal Force H = Hardness of the soft material S = Shear Strength of the soft material b) F=pN F = F
30、rictional Force p = Coefficient of Friction N = Normal Force In essence, frictional forces is a function of cold welding. Cold Welding is a function of the adhesive bonding of metals in contact relative to the “real“ area contact and the shearing force required. “real“ area of contact. It also exhib
31、its a much lower shear force and as a result of these factors, the frictional forces are reduced. A lubricant will minimize the D. CONDITIONS TO BE EVALUATED 1. COSTS: the manufacturing process and as a result represents additional costs. the technique. The addition of a lubricant is an additional s
32、tep in This cost can greatly vary contingent on EIA CBL4 93 m 3234600 0507L5L 772 m CB14 Page 6 ITIONS TO RE PIvaZsBTEp - 2. 3. 4. 5. 6. E. CLEANING: If a lubricant is applied by the connector manufacturer, cleaning will remove the lubricant and, hence, no advantage will be gained. PARTICULATE RETEN
33、TION: A lubricate can increase the retention of particulates from the environment. This can be in the form of dust and/or fibers. Recent studies have indicated that dust does not adversely affect the function of a lubricant. Further study is required relative to fibers. CONTAMINATION OF ADJACENT SUR
34、FACES: Certain lubricants and the volatile carriers can transfer to adjacent surfaces. Non-spreading, low volatility lubricants are, however, unlikely to transfer. A lubricant reduces mating forces. It will also reduce unmating forces. Thus, to prevent “walk out“, connectors with a lubricant should
35、be “locked“ together by jackscrews or other hardware locking techniques used in its application. Fluid lubricants contingent on their formulation may evaporate. dependent. should be researched prior to using. The rate of evaporation varies and is temperature Lubricants used in applications beyond 65
36、OC ON CONTACT LUBRICANTS The following are typical contact lubricants available: a) Polyphenylethers : 5-PPE and 6-PPE b) Hydrocarbon oils : Mineral Oils c) Perfluroalkylpolyethers d) Polyolef in EIA CBL4 93 323qbOO 0507152 b0 D CB14 Page 7 For additional information relative to generic or proprieta
37、ry contact lubricants, the following companies may be contacted: Moncanto, St. Louis, MO William F. Nye, New Bedford, MA Dow Chemical Corporation, Midland, MI Tenneco Chemicals, Piscataway, NJ Roh & Haas, Philadelphia, PA Electrotube Corporation, Syosset, NY EIA CB14 93 3234600 0507153 5Y5 CB14 Page
38、 8 The following is not a complete listing of all reference work published in the area of contact lubrication. references. Additional references are contained with the publications listed. It does list key 1. 2. 3. 4. 5. 6. 7. 8. * 9. 10. 11. 12. S.J. Knunbein, Mort Antler, “Inhibition of Corrosion
39、and Wear on Gold Plated Contacts“, NEP/CON, 1967. L.P. Solos, “Fundamental Study of Gold Plating and Dry Film Lubricant System for Long Life Sliding Contacts“, Nat. Aerospace Electronics Conf. , NAECON, 1964. G. Steinberg, S. W. Chaikin, “Lubrication of Electrical Contacts with Solid Thin Films of O
40、rganic Compounds“, Holm Conf., 1966. M. Antler, “The Lubrication of Gold“, Wear, 1963. R.V. Chiarenzelli, B.C.Henry, “Lubricating Separable Electric Contacts and Tarnish Prevention“, Lubrication Eng., 1966. R.Geckle, L.Witt, “Graphite as a Sliding Lubricant“ Plating, 1972 W.Abbott, J.H. Whitley, “Th
41、e Lubrication and Environmental Protection of Alternatives to Gold for Electronic Connectors“, Holm Conf. , 1975. F.D. Messina, “Evaluation of Microcrystalline Wax Dispersion Lubricants“, Holm Conf., 1980. Centralen, 1971. P. Villien, “Effect Reliability of Gold Centralen, 1985. M. Antler, “Sliding
42、1981. “Lubricants for Electrical Contacts“, ECR-08Et Electronik- of Lubrication on Environmental Plated Connectors“, SPM-81 , Electronik- Wear of Mettalic Contacts“, IEEE Trans. M. Antler, “Electronic Connector Contact Lubricants: The Polyether Fluids“, Holm Conf. , 1986. . EIA CB14 93 3234bOO 0507i
43、154 481 W CB14 Page 9 BIBLIGm - Continued 13. M. Antler, M.Feder, “Wear and Friction of Electrodeposited Palladium Contacts: Thin Film Lubrication with Fluids and with Gold“, Elec. Comp. Conf. , 1986. 14. C.A.Hague, M.D. Richardson, E.T. Ratlrff, “Effect of Dust on Contact Resistance of Lubricated C
44、onnector Contact Materialstt, Holm Conf., 1985. 15. W .O. Freitag, “Lubricants for Separable Connectors“, Holm Conf., 1976. 16. R.V. Steenstrup, V.M. Fiacco, L.K. Schultz, “A Comparative Study of Inhibited Lubricants for Dry Circuits Sliding Contacts“, IEEE Trans, 1983. 17. M. Antler, “Sliding Studies of New Connector Contact Lubricants . 18. Tech. Staff Airborn, “Surface Conditioning Study“, Tech Bulletin No. 100, 1988. EIA CE39 93 3234b00 0507355 33
