GB2069005A - Intermetallic connector contact finishes - Google Patents
Intermetallic connector contact finishes Download PDFInfo
- Publication number
- GB2069005A GB2069005A GB8102987A GB8102987A GB2069005A GB 2069005 A GB2069005 A GB 2069005A GB 8102987 A GB8102987 A GB 8102987A GB 8102987 A GB8102987 A GB 8102987A GB 2069005 A GB2069005 A GB 2069005A
- Authority
- GB
- United Kingdom
- Prior art keywords
- silver
- tin
- connectors
- intermetallic
- layer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 229910052709 silver Inorganic materials 0.000 claims description 41
- 239000004332 silver Substances 0.000 claims description 40
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 claims description 35
- 238000009792 diffusion process Methods 0.000 claims description 18
- 239000000758 substrate Substances 0.000 claims description 18
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 16
- 230000004888 barrier function Effects 0.000 claims description 10
- 238000000034 method Methods 0.000 claims description 10
- 239000000203 mixture Substances 0.000 claims description 10
- 150000001875 compounds Chemical class 0.000 claims description 9
- 229910052742 iron Inorganic materials 0.000 claims description 8
- 238000004070 electrodeposition Methods 0.000 claims description 7
- QCEUXSAXTBNJGO-UHFFFAOYSA-N [Ag].[Sn] Chemical compound [Ag].[Sn] QCEUXSAXTBNJGO-UHFFFAOYSA-N 0.000 claims description 6
- 238000010438 heat treatment Methods 0.000 claims description 5
- 238000000151 deposition Methods 0.000 claims description 3
- 230000008021 deposition Effects 0.000 claims description 3
- 229910001432 tin ion Inorganic materials 0.000 claims description 2
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 33
- 229910052718 tin Inorganic materials 0.000 description 30
- 239000000463 material Substances 0.000 description 14
- 238000012360 testing method Methods 0.000 description 10
- 229910017692 Ag3Sn Inorganic materials 0.000 description 9
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 9
- 229910052737 gold Inorganic materials 0.000 description 9
- 239000010931 gold Substances 0.000 description 9
- 239000000243 solution Substances 0.000 description 9
- 238000000576 coating method Methods 0.000 description 7
- 229910000906 Bronze Inorganic materials 0.000 description 6
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 6
- 239000010974 bronze Substances 0.000 description 6
- KUNSUQLRTQLHQQ-UHFFFAOYSA-N copper tin Chemical compound [Cu].[Sn] KUNSUQLRTQLHQQ-UHFFFAOYSA-N 0.000 description 6
- 229910000765 intermetallic Inorganic materials 0.000 description 6
- 230000008018 melting Effects 0.000 description 6
- 238000002844 melting Methods 0.000 description 6
- 230000005012 migration Effects 0.000 description 6
- 238000013508 migration Methods 0.000 description 6
- 239000011248 coating agent Substances 0.000 description 5
- 229910000881 Cu alloy Inorganic materials 0.000 description 4
- 230000007797 corrosion Effects 0.000 description 4
- 238000005260 corrosion Methods 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 3
- 229910052802 copper Inorganic materials 0.000 description 3
- 239000010949 copper Substances 0.000 description 3
- 230000003993 interaction Effects 0.000 description 3
- 239000012071 phase Substances 0.000 description 3
- 239000006104 solid solution Substances 0.000 description 3
- 238000011282 treatment Methods 0.000 description 3
- 229910017980 Ag—Sn Inorganic materials 0.000 description 2
- 229910001128 Sn alloy Inorganic materials 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 239000004020 conductor Substances 0.000 description 2
- IOUCSUBTZWXKTA-UHFFFAOYSA-N dipotassium;dioxido(oxo)tin Chemical compound [K+].[K+].[O-][Sn]([O-])=O IOUCSUBTZWXKTA-UHFFFAOYSA-N 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000010587 phase diagram Methods 0.000 description 2
- NNFCIKHAZHQZJG-UHFFFAOYSA-N potassium cyanide Chemical compound [K+].N#[C-] NNFCIKHAZHQZJG-UHFFFAOYSA-N 0.000 description 2
- LFAGQMCIGQNPJG-UHFFFAOYSA-N silver cyanide Chemical compound [Ag+].N#[C-] LFAGQMCIGQNPJG-UHFFFAOYSA-N 0.000 description 2
- RYCLIXPGLDDLTM-UHFFFAOYSA-J tetrapotassium;phosphonato phosphate Chemical compound [K+].[K+].[K+].[K+].[O-]P([O-])(=O)OP([O-])([O-])=O RYCLIXPGLDDLTM-UHFFFAOYSA-J 0.000 description 2
- GEZAUFNYMZVOFV-UHFFFAOYSA-J 2-[(2-oxo-1,3,2$l^{5},4$l^{2}-dioxaphosphastannetan-2-yl)oxy]-1,3,2$l^{5},4$l^{2}-dioxaphosphastannetane 2-oxide Chemical compound [Sn+2].[Sn+2].[O-]P([O-])(=O)OP([O-])([O-])=O GEZAUFNYMZVOFV-UHFFFAOYSA-J 0.000 description 1
- 229910001316 Ag alloy Inorganic materials 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 239000010953 base metal Substances 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000002659 electrodeposit Substances 0.000 description 1
- 238000004453 electron probe microanalysis Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- LQBJWKCYZGMFEV-UHFFFAOYSA-N lead tin Chemical compound [Sn].[Pb] LQBJWKCYZGMFEV-UHFFFAOYSA-N 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 238000005272 metallurgy Methods 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 229910000510 noble metal Inorganic materials 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- HKSGQTYSSZOJOA-UHFFFAOYSA-N potassium argentocyanide Chemical compound [K+].[Ag+].N#[C-].N#[C-] HKSGQTYSSZOJOA-UHFFFAOYSA-N 0.000 description 1
- 239000000276 potassium ferrocyanide Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000004626 scanning electron microscopy Methods 0.000 description 1
- 229940098221 silver cyanide Drugs 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000005494 tarnishing Methods 0.000 description 1
- XOGGUFAVLNCTRS-UHFFFAOYSA-N tetrapotassium;iron(2+);hexacyanide Chemical compound [K+].[K+].[K+].[K+].[Fe+2].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-] XOGGUFAVLNCTRS-UHFFFAOYSA-N 0.000 description 1
- 230000001052 transient effect Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D7/00—Electroplating characterised by the article coated
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
- C25D5/10—Electroplating with more than one layer of the same or of different metals
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
- C25D5/48—After-treatment of electroplated surfaces
- C25D5/50—After-treatment of electroplated surfaces by heat-treatment
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
- H01B1/02—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors mainly consisting of metals or alloys
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
- H01R13/00—Details of coupling devices of the kinds covered by groups H01R12/70 or H01R24/00 - H01R33/00
- H01R13/02—Contact members
- H01R13/03—Contact members characterised by the material, e.g. plating, or coating materials
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D3/00—Electroplating: Baths therefor
- C25D3/02—Electroplating: Baths therefor from solutions
- C25D3/56—Electroplating: Baths therefor from solutions of alloys
- C25D3/60—Electroplating: Baths therefor from solutions of alloys containing more than 50% by weight of tin
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D3/00—Electroplating: Baths therefor
- C25D3/02—Electroplating: Baths therefor from solutions
- C25D3/56—Electroplating: Baths therefor from solutions of alloys
- C25D3/64—Electroplating: Baths therefor from solutions of alloys containing more than 50% by weight of silver
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Contacts (AREA)
- Electroplating Methods And Accessories (AREA)
- Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
Description
1
GB 2 069 005 A 1
SPECIFICATION
Intermetallic connector finishes
The present invention relates to connectors and more particularly to metallic finishes for the contacts of such connectors.
5 Electrodeposited gold has been traditionally used as a connector material because of its unique 5 combination of properties including low wear rate and excellent corrosion resistance. However, the utilization of gold as a contact material has come under close scrutiny since the marked increase in gold prices during recent years and it has become evident that the connector industry must consider alternative cheaper coatings.
10 Several connector manufacturers are now using cheaper tin contact finishes on commercial 10
connectors but the poor wear rate as opposed to that achieved with gold finishes limits the use of the base metal to connectors which require only a 'short' operational lifetime.
Tin also suffers from the disadvantage that electrodeposited tin is prone to the formation of whiskers and is therefore not suitable for use on miniature connectors where the contact pitch is small 1 5 and shorting could readily occur. 15
Silver is also used as an alternative contact finish on commercial connectors but is prone to silver migration and is susceptible to tarnishing in sulphurous atmospheres and has relatively poor wear resistance.
It is an object of the present invention to provide an intermetallic connector finish which is 20 considerably cheaper than finishes containing large percentages of gold but which gives an acceptable 20 wear rate and good corrosion resistance comparable to the previous gold finishes.
The present invention therefore provides a metallic finish for connectors including a mixture of silver and tin in which the silver and tin are combined in part or in whole to form an intermetallic or intermediate compound. Intermediate and Intermetallic compounds are defined in Physical Metallurgy 25 2nd Edition edited by R. W. Cahn, North Holland, 1970 page 229. 25
In a preferred embodiment the final finish contains from 25 to 100% by volume of the intermetallic or intermediate compound.
In a more specific embodiment a layer of silver is deposited on connector contacts, a layer of tin is deposited on the silver and the resultant layers are diffused to produce a combined silver-tin 30 intermetallic connector finish. Alternatively the layer of tin may be deposited first the layer of silver 30 deposited onto the tin with subsequent diffusion to produce the intermetallic connector finish.
Alternatively multiple layers of tin and silver may be deposited to the desired total thickness and composition. This would increase the rate of conversion to the intermetallic phase during diffusion.
In a preferred embodiment a layer of iron is deposited onto the connector contact prior to the 35 deposition of the silver and tin to form a barrier between the contact material and the intermetallic or 35 intermediate compound. The intermetallic or intermediate compound may be directly deposited from a carefully selected solution containing ions of silver and tin providing temperature and rate of deposition is carefully controlled.
Embodiments of the present invention will now be described by way of example.
40 According to the present invention a practical method for the preparation of the intermetallic 40 containing contact finishes involves the successive electrodeposition of a layer of one pure metal over another followed by subsequent diffusion treatment.
In this work the diffusion may be achieved by heat treatment in a 90N2/10H2 atmosphere, but glow discharge assisted diffusion is an alternative method which might be considered for production 45 purposes. The resultant diffused structure consists of varying proportions of solid solution and hard 45 intermetallic compounds depending upon the alloy composition, the heat treatment employed and the presence or absence of interaction with the substrate. Alternatively the finish may be directly deposited by electrodeposition with or without a subsequent diffusion process.
The choice of constituent elements is based upon the material cost, the ease of electrodeposition 50 from commercially available solutions and the melting points of both the original metals the nature of 50 the phase diagram and the melting point of the resultant intermetallic phases. Silver has been selected because it is a semi-noble metal. The combination with a low melting point material such as tin enables the use of relatively low diffusion temperatures if a diffusion process is to be used which should not cause any deterioration of the mechanical properties of the underlying substrate material. Diffusion may 55 be conducted wholly in the solid state; or involving a transient liquid phase if the melting point of the 55 lower melting point metal is exceeded. It is possible for the substrate material to diffuse into the above electroplated layers during the heat treatment; this may or may not have adverse effects upon the performance. A diffusion barrier may be employed to prevent this.
The intermetallics achieved by suitable diffusion treatments or electrodeposition have several 60 properties which are required by contact finishes. The atomic ordering which is very common in 60
intermetallic compounds gives them intrinsically greater hardness than a pure metal or solid solution thereby imparting improved wear resistance. The strong chemical bonding of such phases indicated low reactivity and therefore good corrosion resistance. In addition the relatively high melting points of the intermetallic compounds result in improved ambient temperature mechanical properties (in particular
2
GB 2 069 005 A 2
creep resistance) which is essential when contact finishes are mated under stress.
A preferred intermetallic contact finish is obtained using diffused layers in the Ag-Sn system.
Utilization of different relative plating thickness, diffusion temperatures and diffusion times enables the formation of varying proportions of Ag3Sn intermetallic and silver or tin (Ag or Sn) solid solution as 5 determined form the phase diagram. A range of these materials have been tested on model connector 5 contacts. In the simplest case these materials were prepared by the diffusion of tin and silver layers deposited directly onto a copper based alloy substrate without an intermediate barrier layer. The best of these finishes exhibit consistent low contact resistance (<5 mfi) and low friction (60 grams per contact) during 500 operations with 100 and 150 gram contact loads. Furthermore, the wear rate of these 10 diffused coatings was similar to that of a hard gold finish; in the above tests only 3—4 fim of the 10 jum 10 coating has worn through after 500 operations. Tin-lead finishes of similar thickness were worn through to the substrate after 50 to 250 operations depending upon the deposit lead content.
A first example within this type of intermetallic connector finishes is as follows;—
A layer of 5 microns of tin is electrodeposited over a 5 micron layer of electrodeposited silver on a 15 bronze substrate, and the layers interdiffused for 1 hour at 250°C in a mildly reducing atmosphere. The 15 composition homogeneity and microstructure of the diffused layer were examined by standard metallographic sectioning and by X-ray diffraction scanning electron microscopy and electron microprobe analysis. The resulting layer consisted of the Ag3Sn intermetallic and a smaller proportion of pure tin. The intermetallic Ag3Sn comprised the major proportion of the surface regions of the diffused 20 layers. On testing in a model connector between a 1.5 mm radius coated bronze cone and a flat coated 20 bronze plate at 100 and 150 gram contact load the finishes exhibited consistent low contact resistance (<5 mS) and low friction (<60 grams) during 500 sliding operations. The wear rate of the coating was similar to that of a hard gold coating, only 3—4 microns has worn through after the 500 operations.
A second preferred example within this type of intermetallic connector finish is as follows:— 25 A layer of 2.5 microns of tin is electrodeposited over a 7.5 micron layer of electrodeposited silver 25 on a bronze substrate and the layers interdiffused for one hour at 250°C in a mildly reducing atmosphere. The resulting layer consisted of the Ag3Sn intermetallic and a proportion of pure silver. The intermetallic Ag3Sn comprised the major proportion of the surface regions of the diffused layers. On testing in a similar fashion in a model connector, consistent low contact resistance and low friction were 30 obtained. In addition low contact resistance (<5 mfi) was maintained after exposure to the standard 30 S02/C02 industrial atmosphere as specified for BS 9000 qualified components in both mated and unmated states for a 100 gram contact load for static conditions. Low contact resistance (<5 mfi) was also maintained upon subsequent wiping.
In the above two examples the electrodepositions of the silver and tin layers may be in the reverse 35 order with the silver being deposited on top of the layer of tin which is initially deposited on the bronze 35 substrate. The quantities of silver and tin will be the same.
Although the above samples possess favourable contact properties interaction with the substrate can give rise to variability in contact resistance behaviour. This variability is attributed to the non-planar diffusion of copper from the copper alloy substrate into the Sn/Ag regions during the diffusion 40 treatments and the consumption of liquid tin by reaction with the copper alloy substrate. The use of an 40 iron barrier layer between the Sn/Ag and copper alloy substrates has proved effective in preventing this interaction and diffusion of copper and has permitted the production of contacts with more reproducible properties.
Samples of 2-J- ,«m Sn electrodeposited over /um Ag, electrodeposited over a 3 /xm iron barrier 45 layer and deposited onto a copper alloy substrate had been diffused for 30 minutes at 250°C. The 45
material largely comprises a layer of Ag3Sn whilst a small amount of tin rich material remains at the surface and some silver rich material remains beneath the Ag3Sn layer. The contact resistance of these samples is consistent over 1,000 wipes under 100 g contact load, the values being <8 mfi. The corresponding friction is also consistent and below 100 g force/contact. The wear of 10 fim coating is '50 4—6 ^m after 500 wipes and 7—8 ^m after 1,000 wipes. 50
When an iron barrier is employed optimum contact properties are achieved for a heat treatment of 30 minutes at 250°C. It has also been found that tin to silver thickness ratios should not be in excess of 1:3.
The corrosion resistance of samples of 2\ fim tin electroplated over 7\ fim silver electroplated 55 over a 3 fim iron barrier layer on a bronze substrate and diffused for 30 minutes at 250°C has been 55 examined. The material shows no increase in contact resistance after 10 days exposure to the BS 2011 part 2.1 Db cyclic damp heat test in the mated and unmated states under loads of 100 and 200 grammes. No increase in resistance was observed after 56 days exposure to the BS 2011 part 2.1 Ca 1977 steady state damp heat test in the mated and unmated states and also after 20 days exposure to 60 the SOz/COz industrial atmosphere test in the mated state as specified for BS 9000 qualified 60
components. Again no resistance increase was observed after 500 hours storage at 85°C in air in the mated and unmated states.
The resistance of this material to silver migration is good. Silver migration was monitored using the so called "Water Drop" test. In this test a drop of deionised water is placed so as to bridge the gap 65 between two conductor lines and the migration of silver is observed upon applying a bias between the 65
3
GB 2 069 005 A 3
two conductors. The diffused tin silver layer shows no evidence of silver migration after 30 minutes at 5, 10 or 15 volts for a 1 mm gap. Under the same test conditions silver shows clear evidence of migration after only 2 minutes at 5 volts.
Silver Tin Alloys can also be directly electrodeposited from solutions containing silver and tin 5 ions. Several formulations are possible. One example of such a solution has the following composition: 5
Silver Cyanide AgCN 0.019 M
Potassium Stannate K2Sn033H20 0.375 M
Potassium Hydroxide KOH 1.25 M
Potassium Cyanide KCN 1.40 M
10 The deposit produced from this solution consists mainly of the intermetallic compound Ag3Sn. 10 A second example of a solution of electrodepositing silver tin alloys has the following composition:
Potassium Pyrophosphate K4P207 3.30 M
Potassium Silver Cyanide KAg(CN)2 0.20 M
Potassium Stannate K2Sn03 3.80 M
15 This solution produces a deposit containing 88% silver and 12% tin. 15
A third example has the composition:
Potassium Pyrophosphate K4P2O7 0.39—0.67 M
Potassium Ferrocyanide K4Fe(CN)6 0.012 M
Silver Ferrocyanide Ag4Fe(CN)6 0.020—0.046 M
20 Tin Pyrophosphate Sn2P207 0.090—0.13 M 20
The relative concentrations of silver and tin ions in solution determine the composition and structure of the electrodeposit. Under certain conditions a deposit containing intermetallic or intermediate compounds and free tin can be produced.
Deposits have been prepared from the Ag CN K2 Sn 03 solution described above. The deposit 25 plated at a temperature of 55°C and at a current density of 6 m Amps/cm2 was shown by X ray 25
diffraction to contain the Ag3Sn intermetallic with traces of free tin and silver. The contact resistance values varied between 3 and 6.5 ohms during 500 wipe cycles under a 100 gr contact load and the corresponding friction rose from 50 to 100 grammes force during the test. The coating had worn through approximately 10 fim during the 500 wipe operations.
30 To summarise the Ag-Sn intermetallic connector system offers a considerable improvement in 30 contact properties over pure silver and pure tin. It also offers a considerable cost reduction if used as an alternative to gold.
Claims (12)
1. A metallic finish for connectors including a mixture of silver and tin in which the silver and tin
35 are combined in part or whole to form an intermetallic or intermediate compound. 35
2. A metallic finish for connectors as claimed in claim 1 containing from 25 to 100% by volume of the intermetallic or intermediate compound.
3. A metallic finish for connectors as claimed in claim 1 in which a layer of iron is deposited on the connector substrate to provide a barrier layer between the substrate and the intermetallic or
-40 intermediate compound. 40
4. A method of producing a metallic finish for connectors in which a layer of silver is deposited on a connector contact, a layer of tin is deposited on the silver and the resultant layers are diffused to produce a combined silver-tin intermetallic or intermediate connector finish.
5. A method of producing a metallic finish for connectors as claimed in claim 4 in which a layer of
45 iron is initially deposited on to the connector contact to form a barrier layer between the contact and the 45 intermetallic or intermediate connector finish.
6. A method of producing a metallic finish for connectors in which a layer of tin is deposited on a connector contact, a layer of silver is deposited on the tin and the result layers are diffused to produce a combined silver-tin intermetallic or intermediate connector finish.
50
7. A method of producing a metallic finish for connectors as claimed in claim 4 or claim 6 in which 50
4
GB 2 069 005 A 4
a plurality of silver and tin layers are deposited prior to the diffusion process.
8. A method of producing a metallic finish for connectors by direct electrodeposition from a solution containing silver and tin ions to form a layer containing an intermetallic or intermediate compound.
5
9. A method of producing a metallic finish for connectors as claimed in claim 8 in which the 5
electrodeposition layer is subjected to a subsequent heat treatment.
10. A method of producing a metallic finish for connectors as claimed in claim 9 wherein an iron barrier layer is present on the connector substrate to separate the deposition from the connector substrate.
10
11. A metallic finish for connectors substantially as described. 10
.
12. A method of producing a metallic finish for connectors substantially as described.
Printed for Her Majesty's Stationery Office by the Courier Press, Leamington Spa, 1981. Published by the Patent Office, 25 Southampton Buildings, London, WC2A 1AY, from which copies may be obtained.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8003847 | 1980-02-05 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB2069005A true GB2069005A (en) | 1981-08-19 |
Family
ID=10511136
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8102987A Withdrawn GB2069005A (en) | 1980-02-05 | 1981-01-30 | Intermetallic connector contact finishes |
Country Status (3)
| Country | Link |
|---|---|
| EP (1) | EP0033644A1 (en) |
| JP (1) | JPS56123365A (en) |
| GB (1) | GB2069005A (en) |
Families Citing this family (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3932536C1 (en) * | 1989-09-29 | 1990-08-09 | W.C. Heraeus Gmbh, 6450 Hanau, De | Wear resistant contact material - in which is applied to support comprising copper alloy and non-noble metal contg. silver, palladium or palladium-silver alloy |
| DE9216717U1 (en) * | 1992-12-08 | 1993-02-11 | W.C. Heraeus Gmbh, 6450 Hanau | Electrical connector |
| GB0218138D0 (en) * | 2002-08-05 | 2002-09-11 | Strix Ltd | Electrical terminals |
| US20080308300A1 (en) * | 2007-06-18 | 2008-12-18 | Conti Mark A | Method of manufacturing electrically conductive strips |
| JP5086485B1 (en) | 2011-09-20 | 2012-11-28 | Ｊｘ日鉱日石金属株式会社 | Metal material for electronic parts and method for producing the same |
| JP5284526B1 (en) | 2011-10-04 | 2013-09-11 | Ｊｘ日鉱日石金属株式会社 | Metal material for electronic parts and method for producing the same |
| TWI493798B (en) | 2012-02-03 | 2015-07-21 | Jx Nippon Mining & Metals Corp | Push-in terminals and electronic parts for their use |
| JP6029435B2 (en) | 2012-06-27 | 2016-11-24 | Ｊｘ金属株式会社 | METAL MATERIAL FOR ELECTRONIC COMPONENT AND ITS MANUFACTURING METHOD, CONNECTOR TERMINAL USING THE SAME, CONNECTOR AND ELECTRONIC COMPONENT |
| JP6050664B2 (en) * | 2012-06-27 | 2016-12-21 | Ｊｘ金属株式会社 | METAL MATERIAL FOR ELECTRONIC COMPONENT AND ITS MANUFACTURING METHOD, CONNECTOR TERMINAL USING THE SAME, CONNECTOR AND ELECTRONIC COMPONENT |
| US9512529B2 (en) | 2013-06-04 | 2016-12-06 | Rohm And Haas Electronic Materials Llc | Electroplating baths of silver and tin alloys |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL267282A (en) * | 1960-04-12 | |||
| DE1564069C2 (en) * | 1966-03-26 | 1974-07-18 | W.C. Heraeus Gmbh, 6450 Hanau | Composite material for electrical contacts |
| US3598550A (en) * | 1966-12-28 | 1971-08-10 | Hitachi Cable | Electric connecting planes of composite metal having a silver alloy layer |
| US3562467A (en) * | 1969-06-04 | 1971-02-09 | Engelhard Min & Chem | Electrical contact |
| DE2540956C3 (en) * | 1975-09-13 | 1978-06-08 | W.C. Heraeus Gmbh, 6450 Hanau | Gold alloy as a material for electrical contacts |
| DE2540944C3 (en) * | 1975-09-13 | 1978-10-12 | W.C. Heraeus Gmbh, 6450 Hanau | Contact body for an electrical plug contact |
| US4141727A (en) * | 1976-12-03 | 1979-02-27 | Matsushita Electric Industrial Co., Ltd. | Electrical contact material and method of making the same |
-
1981
- 1981-01-30 EP EP81300397A patent/EP0033644A1/en not_active Withdrawn
- 1981-01-30 GB GB8102987A patent/GB2069005A/en not_active Withdrawn
- 1981-02-05 JP JP1628481A patent/JPS56123365A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| EP0033644A1 (en) | 1981-08-12 |
| JPS56123365A (en) | 1981-09-28 |
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| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |