EP0136713A2 - Elektrisches Kontaktstück und Verfahren zu dessen Herstellung - Google Patents

Elektrisches Kontaktstück und Verfahren zu dessen Herstellung Download PDF

Info

Publication number
EP0136713A2
EP0136713A2 EP84111843A EP84111843A EP0136713A2 EP 0136713 A2 EP0136713 A2 EP 0136713A2 EP 84111843 A EP84111843 A EP 84111843A EP 84111843 A EP84111843 A EP 84111843A EP 0136713 A2 EP0136713 A2 EP 0136713A2
Authority
EP
European Patent Office
Prior art keywords
stainless steel
steel sheet
electric contact
contact member
gold
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Withdrawn
Application number
EP84111843A
Other languages
English (en)
French (fr)
Other versions
EP0136713A3 (de
Inventor
Masami Kobayashi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Publication of EP0136713A2 publication Critical patent/EP0136713A2/de
Publication of EP0136713A3 publication Critical patent/EP0136713A3/de
Withdrawn legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H11/00—Apparatus or processes specially adapted for the manufacture of electric switches
    • H01H11/04—Apparatus or processes specially adapted for the manufacture of electric switches of switch contacts

Definitions

  • the present invention relates to an electric contact member and a process for making it. More particularly, the present invention relates to an electric contact member comprising a contacting projection formed on a thin sheet of stainless steel, and a process for making it.
  • Movable contacts of keyboard switches or cameras have heretofore been formed by punching into predetermined sizes thin sheets of copper alloys such as phosphor bronze, nickel silver and beryllium copper. Recently, stainless steel thin sheets have also been proposed for use in these contact members.
  • the contacting sides are generally clad or deposited with gold, and in order to ensure the contacting function, conical projections having a diameter of 1 mm and a height of 0.15 mm are mechanically formed in the contacting portions of these metal sheets.
  • Gold is excellent in the corrosion resistance and has a good electrical conductivity and therefore, gold provides a contacting portion having a high reliability. However, gold is expensive.
  • gold was clad in a thickness of 2 to 3 um, but at the present, gold is clad or deposited in the form of a thin film having a thickness of up to about 1 ⁇ m or gold is clad or deposited only on a stripe-like restricted contacting portion.
  • An electric contact member is a very important element in an electronic machine, and is very broadly used in keyboard switches, computers, registers, telephone sets and calculators. Namely, electric contact members are manufactured as large-quantity parts and built in electronic machines.
  • the contacting portion is a most important part of an electric contact member, and this contacting portion should be composed of a metal having a low contact resistance, a high corrosion resistance and an excellent abrasion resistance. According to the standard of the abrasion resistance test for keyboards, the metal of the contacting portion should resist contacting under a pressing force of 20 g, which is repeated 10,000,000 times.
  • the minimum thickness of the gold film of the contacting portion necessary for satisfying this requirement, is about 1 ⁇ m, and if the thickness of the gold-film-is smaller than about 1 ⁇ m, the substrate metal is exposed by abrasion of the gold film to cause corrosion and drastically increase the contact resistance, with the result that transmission of electric signals becomes inaccurate and the function of an electronic machine is lost.
  • an electric contact member comprising a thin sheet of a stainless steel and a projection of a tin-lead alloy solder formed on the surface of the thin sheet as a contacting portion.
  • Figs. 1 through 3 are sectional views showing the steps of the process for forming an electric contact member according to the present invention.
  • the stainless steel is a metal having a good corrosion resistance and an excellent spring property, and the stainless steel is an effective material for an electric contact member. However, the stainless steel is defective in that the platability and solderability are poor.
  • the electric contact member of the present invention comprises a projection (contacting portion) of a tin-lead alloy solder formed on a stainless steel thin sheet, soldering of which has been considered difficult.
  • the solder constituting the contacting portion has the following composition:
  • Silver as one optional component of the solder exerts the function of increasing the hardness.
  • Antimony as another optional component of the solder makes a contribution to enhancement of the dimension stability and bismuth as still another optional component makes a contribution to increase of the hardness.
  • a stainless steel hoop 1 is preliminarily printed with a resist paint 2, as shown in Fig. 1, so that a small circular non-printed portion 3 having a diameter of, for example, 1 mm is formed at a position where a contacting portion is to be formed, and such non-printed portions 3 are arranged at predetermined intervals.
  • an ultraviolet ray-curable paint which is excellent in the chemical resistance and the high-temperature resistance and can be dried in a moment be used as the resist paint.
  • the non-printed portions 3 may be spot-like small circules arranged regularly as described above or they may be stripes.
  • a special preliminary treatment is carried out so that soldering becomes possible on the non-printed portions 3 distributed on the surface of the stainless steel hoop.
  • the stainless steel sheet is dipped in a dilute solution of an alkali degreasing solution at an elevated temperature and electrolytic degreasing is then carried out in a dilute aqueous alkali solution.
  • the stainless steel sheet is subjected to the activating treatment. It is preferred that this activating treatment be carried out in two stages. Namely, the activating treatment comprises the first step of dipping in an activating solution and the subsequent step of cathodic electrolysis in a cathodic electrolytic solution.
  • the activating solution used in the first activating treatment is preferably an aqueous mixed acid solution containing, based on the weight of the solution, (i) 3 to 20% by weight of hydrochloric acid, (ii) 2 to 30% by weight of sulfuric acid, (iii) 0.1 to 5% by weight of a nonionic, cationic or ampholytic surface active agent and (iv) 0.1 to 20% by weight of 2-pyrrolidone or its N-alkyl derivative such as N-erhyl-2-pyrrolidone or N-methyl-2-pyrrolidone.
  • the first activation treatment may be carried out by dipping the stainless steel sheet in the activating solution at a normal temperature for 30 seconds to 7 minutes, preferably under irradiation with ultrasonic waves.
  • the activated stainlees steel sheet is then subjected to the cathodic electrolytic activation.
  • the cathodic electrolytic activation solution used is preferably an aqueous mixed acid solution containing, based on the weight of the solution, (i) 5 to 20% by weight of phosphoric acid, (ii) 2 to 10% by weight of nitric acid, (iii) 0.1 to 5% by weight of a nonionic cationic or ampholytic surface active agent and (iv) 0.1 to 20% by weight of 2-pyrrolidone or its N-alkyl derivative.
  • the electrolysis may be carried out at a normal temperature to about 65°C at a cathode current density of 1 to 7 A/dm for 30 seconds to 5 minutes by using a platinum-coated titanium anode and the stainless steel sheet as the cathode.
  • the stainless steel sheet which has been subjected to the activating treatment is then preferably subjected to nickel plating.
  • This nickel plating is performed according to the conventional electrolytic plating method using nickel salts such as nickel sulfate, nickel sulfamate and nickel chloride.
  • the nickel electroplating may be carried out at a temperature of 45 to 65°C in an electroplating solution at a cathode current density of 4 to 12 A/dm 2 for 10 seconds to 2 minutes by using the stainless steel sheet as the cathode and a nickel plate as the anode.
  • the amount deposited of nickel be so small that a color tone intermediate between the color tone before plating and the color tone of nickel is produced on the surface. Supposing that a uniform film of nickel is formed by plating (actually, no uniform film of nickel is formed because the amount deposited of nickel is very small), the amount of nickel is ordinarily controlled so that a film having a 0 0 thickness of 100 to 1000 A, preferably 300 to 700 A, most preferably about 500 A, is formed.
  • the stainless steel sheet which has been subjected to the activating treatment may be electroplated with gold, silver or palladium or an alloy thereof. If the stainless steel sheet is subjected to the nickel electroplating as mentioned above, the nickel-electroplated stainless steel sheet is immediately electroplated with gold, silver or palladium or an alloy thereof.
  • the electroplating procedure may be conventional. Usually, the electroplating is carried out at a temperature of 20 to 65°C at a cathode current density of 0.5 to 18 A/dm 2 for one second to two minutes by using the stainless steel sheet as the cathode and a nickel plate as the anode.
  • the electroplating of gold may be carried out preferably by using an electroplating solution containing about 80 to 140 g/l of citric acid, about 80 to 140 g/ ⁇ of sodium citrate, about 15 to 40 g/l of nickel sulfamate and about 4 to 10 g/1 of potassium gold cyanide and maintained at a temperature of 40 to 65°C.
  • the electroplating of silver or palladium is preferably carried out at a temperature of 20 to 30°C.
  • the amount deposited of gold, silver, palladium or an alloy thereof is important in the present invention. Namely, the amount deposited is so small that a color tone intermediate between the color tone before plating and the color tone of gold, silver, palladium or an alloy thereof is produced on the plated surface. Supposing that a uniform film of the metal or alloy is formed by plating, the amount deposited of the metal or alloy is controlled so that the thickness of the gold or palladium film is 30 to 500 ⁇ , preferably 50 to 300 ⁇ , and the thickness of the silver film is 50 to 2000 ⁇ , preferably 100 to 1000 ⁇ (actually, no uniform film is formed but the metal or alloy is deposited in the form of spots).
  • the resist paint 2 is removed from the thus-obtained stainless steel plate to expose the texture of the stainless steel sheet 1 and the sheet is then subjected to the punching operation.
  • the insulating function of this resist paint is utilized, the paint is not peeled but the stainless steel sheet 1 is directly subjected to the punching operation and built as a contacting portion into an electronic machine.
  • contacting portions of a solder can be easily formed in an optional shape and arrangement on the stainless steel sheet by changing the printing pattern.
  • the contacting portion of the electric contact member obtained by punching the stainless steel sheet having projections of a solder is formed of a cheap alloy solder, according to the present invention, the cost of electric contacts such as keyboard contacts or movable contacts of cameras, which are used in large quantities in the field of electronic industry, can be greatly reduced.
  • a stainless steel hoop of SUS-304 having a thickness of 0.1 mm, a width of 10 mm and a length of 1200 m was subjected to partial soldering for forming contacting portions through the following steps.
  • the stainless steel hoop was mask-printed with an ultraviolet ray-curable resist paint so that circular non-printed portions having a diameter of 1.5 mm were formed at intervals of 14 mm in the central portion of the stainless steel hoop, and the back surface was entirely printed.
  • a commercially available alkali degreasing solution was heated at 70 to 80°C in a stainless steel tank, and the stainless steel hoop was passed through the degreasing solution in the tank in succession to effect the primary degreasing. Then, in the alkali degreasing solution maintained at 40 to 60°C, direct current electrolytic degreasing was carried out by applying a voltage of 6 volts and using a stainless steel sheet as the anode and the above-mentioned stainless steel hoop as the cathode.
  • the stainless steel hoop was passed through an activating solution formed by adding 0.2% by weight of a nonionic surface active agent such as polyethylene glycol alkyl ether or polyethylene glycol fatty acid ester or an amphoteric surface active agent and 0.1% by weight of an amine type anti-corrosive agent (Armohiboo 28 supplied by Lion-Armar Co.) to a mixed acid comprising 20% by volume of hydrochloric acid (35% solution), 10% by volume of sulfuric acid (85% solution), 10% by weight of citric acid (powder), 1% by volume of acetic acid (90% solution), 5% by volume of nitric acid (68% solution) and 5% by weight of N-methyl-2-pyrrolidone under irradiation with ultrasonic waves of 600 W, whereby the oxides and impurities were removed from the non-printed portions of the stainless steel hoop.
  • a nonionic surface active agent such as polyethylene glycol alkyl ether or polyethylene glycol fatty acid ester or an amphoteric
  • Gold plating was carried out for 3 seconds in a plating solution comprising 120 g/1 citric acid, 120 g/l of sodium citrate, 30 g/l of nickel sulfamate and 8 g/l of potassium gold cyanide at a current density of 10 to 3 A/dm 2 at a plating solution temperature of 35°C by using the stainless steel hoop as the cathode and a platinum-plated titanium plate as the anode.
  • a gold-nickel alloy layer having a thickness of 0.01 ⁇ m was formed as an underground plating layer for soldering on the non-printing portions of the stainless steel hoop.
  • a solder comprising 60% of tin, 36% of lead, 2% of silver and 2% of antimony was melted at 230°C in a soldering tank, and the stainless steel hoop was passed through the soldering tank for an immersion time of 3 seconds, whereby a stainless steel hoop having conical projections of the solder having a bottom diameter of 1.5 mm and a central height of 0.12 mm, as contacting portions arranged continuously, was obtained.
  • a stainless steel hoop of SUS-304 having a thickness of 0.15 mm, a width of 15 mm and a length of 7CO mm was subjected to partial soldering for forming contacting portions through the following steps.
  • the stainless steel hoop was subjected to the pressing operation using a mold so that recesses having a width of 2 mm, a length of 5 mm and a depth of 0.1 mm were formed at intervals of 10 mm in the central portion of the stainless steel hoop.
  • the stainless steel hoop from the step (1) was continuously mask-printed with an ultraviolet ray-curable resist paint so that only the inner faces of the recesses having a width of 2 m and a length of 5 mm were formed into non-printed portions, and the back surface of the stainless steel hoop was entirely printed.
  • the alkali electric degreasing treatment was carried out in the same manner as described in Example 1.
  • the first activation treatment was carried out in the same manner as described in Example 1.
  • the cathodic electrolytic activation treatment was carried out in the same manner as described in Example 1.
  • Flash plating was carried out at a current density of 6 A/dm 2 for 15 seconds at a plating solution temperature of 50°C in a plating solution comprising 300 g/l of nickel sulfate, 40 g/l of nickel chloride and 30 g/l of boric acid by using the stainless steel hoop as the cathode and a nickel plate as the anode.
  • Plating was carried out at a current density of 10 to 3 A/dm 2 for 2 seconds at a plating solution temperature of 45°C in a plating solutiom comprising 120 g/t of citric acid, 120 g/t of sodium citrate, 30 g/l cf nickel sulfamate and 8 g/l of potassium gold cyanide by using the stainless steel hoop as the cathode and a platinum-deposited titanium sheet as the anode.
  • a gold-nickel alloy plating layer having a thickness of 0.007 um was thus formed as an undercoating layer for soldering in the non-printed portions of the stainless steel hoop.
  • the stainless steel hoop was passed through a solution comprising 40% of methylene dichloride and 3% of formic acid and maintained at 35°C for an immersion time of 30 seconds, whereby the ultraviolet ray-curable resist paint was peeld.
  • a solder comprising 88% of tin, 2% of silver, 10% of lead and 2% of antimony was melted at 240°C in a soldering tank, and the stainless steel hoop was passed through the soldering tank for an immersion time of 3 seconds, whereby a stainless steel hoop having contacting portions having a thickness of 0.16 to 0.2 mm, which were continuously formed only on the recesses having a width of 2 mm, a length of 5 mm and a depth of 0.1 mm, was obtained.
  • the projecting contacting portions of the silver-incorporated alloy solder of the stainless steel hoop prepared through the above-mentioned steps had excellent properties described below.
  • the electrical conductivity of the contacting poriton of the silver-incorporated alloy solder corresponded to about 14% of the electric conductivity of copper, which was substantially equal to the electric conductivity of iron corresponding to 14.8% of the electrical conductivity of copper. Thus, it was confirmed that the contact portion could be effectively used as an electric contact.
  • the contacting portion had a Vickers hardness of about 42, which is higher than the Vickers hardness of pure gold (25) but lower than the Vickers hardness of a gold-nickel alloy plating (about 120).
  • the allowable thickness of the gold-nickel plating layer is about 1 um
  • the solder layer of the present invention can be applied in a thickness of 30 to 100 ⁇ m to the contacting portion, whereby the contacting portion which is excellent in the abrasion resistance over the conventional gold-clad or gold-plated contacting portion can be formed.

Landscapes

  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Contacts (AREA)
  • Electroplating Methods And Accessories (AREA)
  • Manufacture Of Switches (AREA)
EP84111843A 1983-10-04 1984-10-03 Elektrisches Kontaktstück und Verfahren zu dessen Herstellung Withdrawn EP0136713A3 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP18446783A JPS6077321A (ja) 1983-10-04 1983-10-04 電気接点
JP184467/83 1983-10-04

Publications (2)

Publication Number Publication Date
EP0136713A2 true EP0136713A2 (de) 1985-04-10
EP0136713A3 EP0136713A3 (de) 1986-10-01

Family

ID=16153661

Family Applications (1)

Application Number Title Priority Date Filing Date
EP84111843A Withdrawn EP0136713A3 (de) 1983-10-04 1984-10-03 Elektrisches Kontaktstück und Verfahren zu dessen Herstellung

Country Status (2)

Country Link
EP (1) EP0136713A3 (de)
JP (1) JPS6077321A (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8016624B2 (en) * 2005-09-22 2011-09-13 Enplas Corporation Electric contact and socket for electrical part

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1514889A1 (de) * 1964-12-23 1969-09-04 Talon Inc Verfahren zum Herstellen zusammengesetzter elektrischer Kontaktaggregate
DE3010970A1 (de) * 1980-03-21 1981-10-01 Siemens AG, 1000 Berlin und 8000 München Verfahren zum aufbringen von kontaktwerkstoff auf elektrische kontakte

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1514889A1 (de) * 1964-12-23 1969-09-04 Talon Inc Verfahren zum Herstellen zusammengesetzter elektrischer Kontaktaggregate
DE3010970A1 (de) * 1980-03-21 1981-10-01 Siemens AG, 1000 Berlin und 8000 München Verfahren zum aufbringen von kontaktwerkstoff auf elektrische kontakte

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
IEEE TRANSACTIONS ON PARTS, HYBRIDS, AND PACKAGING, vol. PHP-11, no. 1, March 1975, pages 35-44, New York, US; M. ANTLER et al.: "Base metal contacts: an exploratory study of separable connection to tin-lead" *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8016624B2 (en) * 2005-09-22 2011-09-13 Enplas Corporation Electric contact and socket for electrical part
USRE45924E1 (en) 2005-09-22 2016-03-15 Enplas Corporation Electric contact and socket for electrical part

Also Published As

Publication number Publication date
EP0136713A3 (de) 1986-10-01
JPS6077321A (ja) 1985-05-01

Similar Documents

Publication Publication Date Title
US5800930A (en) Nodular copper/nickel alloy treatment for copper foil
US7488408B2 (en) Tin-plated film and method for producing the same
US6087714A (en) Semiconductor devices having tin-based solder film containing no lead and process for producing the devices
US4789437A (en) Pulse electroplating process
JP2002100718A (ja) 半導体装置用リードフレーム及びその製造方法及びそれを用いた半導体装置
KR101370137B1 (ko) 전기전자 부품용 복합재료 및 그것을 이용한 전기전자 부품
JP4368931B2 (ja) オス端子及びその製造方法
KR101058763B1 (ko) 휘스커가 억제된 Ｃｕ－Ｚｎ 합금 내열 Ｓｎ도금 스트립
JP7187162B2 (ja) Ｓｎめっき材およびその製造方法
KR101336559B1 (ko) 전기전자 부품용 복합재료 및 그것을 이용한 전기전자 부품
EP0495468A2 (de) Verfahren zur Herstellung behandelter Kupfer-Folien, daraus hergestellte Produkte sowie Elektrolyt zur Verwendung in einem solchen Verfahren
EP1538709A1 (de) Anschlusskontakt mit einer Oberfläche bestehend aus einer Zinn-/Silber-/Kupfer -Legierung
JPH0119000B2 (de)
EP0136713A2 (de) Elektrisches Kontaktstück und Verfahren zu dessen Herstellung
US4345987A (en) Coated electrode and a method of its production
JP2006206977A (ja) ハンダ性に優れた表面処理Ａｌ板
JP5226032B2 (ja) ウィスカーが抑制されたＣｕ−Ｚｎ合金耐熱Ｓｎめっき条
US4028064A (en) Beryllium copper plating process
US4077852A (en) Selective gold plating
JPS5857520B2 (ja) 電子部品用ステンレス鋼帯の金メッキ方法
JPH0328389A (ja) 銅張積層板用銅箔層、その製造方法およびそれに用いるめっき浴
US4566953A (en) Pulse plating of nickel-antimony films
JPH06115045A (ja) メタルマスク
JPH06235088A (ja) 電子部品用鋼材及びその製造方法
JPS6212315B2 (de)

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 19841003

AK Designated contracting states

Designated state(s): BE DE FR GB NL

PUAL Search report despatched

Free format text: ORIGINAL CODE: 0009013

AK Designated contracting states

Kind code of ref document: A3

Designated state(s): BE DE FR GB NL

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 19870402