DE3630952A1 - Method for producing a switching film for mat-type keyboards - Google Patents

Method for producing a switching film for mat-type keyboards

Info

Publication number
DE3630952A1
DE3630952A1 DE19863630952 DE3630952A DE3630952A1 DE 3630952 A1 DE3630952 A1 DE 3630952A1 DE 19863630952 DE19863630952 DE 19863630952 DE 3630952 A DE3630952 A DE 3630952A DE 3630952 A1 DE3630952 A1 DE 3630952A1
Authority
DE
Germany
Prior art keywords
contact points
corrosion
printed
resistant layer
conductor tracks
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Withdrawn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
DE19863630952
Other languages
German (de)
Inventor
Adolf Dipl Ing Schoen
Heinrich Kallhardt
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.)
Siemens AG
Original Assignee
Siemens AG
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 Siemens AG filed Critical Siemens AG
Priority to DE19863630952 priority Critical patent/DE3630952A1/en
Publication of DE3630952A1 publication Critical patent/DE3630952A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H13/00—Switches having rectilinearly-movable operating part or parts adapted for pushing or pulling in one direction only, e.g. push-button switch
    • H01H13/70—Switches having rectilinearly-movable operating part or parts adapted for pushing or pulling in one direction only, e.g. push-button switch having a plurality of operating members associated with different sets of contacts, e.g. keyboard
    • H01H13/78—Switches having rectilinearly-movable operating part or parts adapted for pushing or pulling in one direction only, e.g. push-button switch having a plurality of operating members associated with different sets of contacts, e.g. keyboard characterised by the contacts or the contact sites
    • H01H13/785—Switches having rectilinearly-movable operating part or parts adapted for pushing or pulling in one direction only, e.g. push-button switch having a plurality of operating members associated with different sets of contacts, e.g. keyboard characterised by the contacts or the contact sites characterised by the material of the contacts, e.g. conductive polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H13/00—Switches having rectilinearly-movable operating part or parts adapted for pushing or pulling in one direction only, e.g. push-button switch
    • H01H13/70—Switches having rectilinearly-movable operating part or parts adapted for pushing or pulling in one direction only, e.g. push-button switch having a plurality of operating members associated with different sets of contacts, e.g. keyboard
    • H01H13/702—Switches having rectilinearly-movable operating part or parts adapted for pushing or pulling in one direction only, e.g. push-button switch having a plurality of operating members associated with different sets of contacts, e.g. keyboard with contacts carried by or formed from layers in a multilayer structure, e.g. membrane switches
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/22—Secondary treatment of printed circuits
    • H05K3/24—Reinforcing the conductive pattern
    • H05K3/245—Reinforcing conductive patterns made by printing techniques or by other techniques for applying conductive pastes, inks or powders; Reinforcing other conductive patterns by such techniques
    • H05K3/247—Finish coating of conductors by using conductive pastes, inks or powders
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/22—Secondary treatment of printed circuits
    • H05K3/24—Reinforcing the conductive pattern
    • H05K3/245—Reinforcing conductive patterns made by printing techniques or by other techniques for applying conductive pastes, inks or powders; Reinforcing other conductive patterns by such techniques
    • H05K3/247—Finish coating of conductors by using conductive pastes, inks or powders
    • H05K3/249—Finish coating of conductors by using conductive pastes, inks or powders comprising carbon particles as main constituent
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H2201/00—Contacts
    • H01H2201/022—Material
    • H01H2201/024—Material precious
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H2201/00—Contacts
    • H01H2201/022—Material
    • H01H2201/026—Material non precious
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H2207/00—Connections
    • H01H2207/016—Jumpers; Cross-overs
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H2207/00—Connections
    • H01H2207/04—Details of printed conductors
    • H01H2207/044—Resist layer
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H2239/00—Miscellaneous
    • H01H2239/004—High frequency adaptation or shielding
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/03—Use of materials for the substrate
    • H05K1/0393—Flexible materials
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/09—Use of materials for the conductive, e.g. metallic pattern
    • H05K1/092—Dispersed materials, e.g. conductive pastes or inks
    • H05K1/095—Dispersed materials, e.g. conductive pastes or inks for polymer thick films, i.e. having a permanent organic polymeric binder
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
    • H05K2201/03—Conductive materials
    • H05K2201/0332—Structure of the conductor
    • H05K2201/0335—Layered conductors or foils
    • H05K2201/035—Paste overlayer, i.e. conductive paste or solder paste over conductive layer
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/22—Secondary treatment of printed circuits
    • H05K3/28—Applying non-metallic protective coatings

Landscapes

  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Manufacture Of Switches (AREA)
  • Contacts (AREA)

Abstract

The conductor tracks (2) and the contact points (3) are initially printed onto a carrier film (1) using a copper paste. The printed side is then covered with insulating varnish (4), with the exception of the contact points. The contact points are subsequently covered by a corrosion-resistant layer (5), which is suitable for switching purposes. The invention can be used in the case of switching films for keyboards in telecommunications technology. <IMAGE>

Description

Die Erfindung betrifft ein Verfahren zur Herstellung einer Schaltfolie für Mattentastaturen mit auf einer Trägerfolie aus Isolierstoff aufgebrachten Leiterbahnen sowie Kontakt­ stellen für Tasten und den Steckerbereich.The invention relates to a method for producing a Switching foil for mat keyboards with on a carrier foil made of insulating material applied conductor tracks and contact places for buttons and the connector area.

Schaltfolie für Mattentastaturen werden zur Zeit durch fol­ gendes Verfahren hergestellt. Auf einer Trägerfolie erfolgt ein erster Druck des Leiterbildes mit einer Silberpaste, die in einem zweiten Druckvorgang mit einer Graphitpaste über­ deckt wird. Die Überdeckung mit Graphit führt auch über die fingerartig ineinandergreifenden Kontaktstellen sowie über den Steckerbereich. Diese Maßnahme ist erforderlich, um Sil­ berwanderung zwischen den, ein unterschiedliches elektrisches Potential führenden Leiterbahnen zu unterbinden und die Korrosion des Silbers zu verhindern.Switching foil for mat keyboards are currently by fol manufactured process. Made on a carrier film a first print of the conductor pattern with a silver paste, the in a second printing process using a graphite paste is covered. The covering with graphite also leads to the interlocking contact points as well as over the connector area. This measure is required to Sil migration between the, a different electrical To prevent potential conductive tracks and the To prevent corrosion of the silver.

Werden aufgrund der Schaltungsauflösung Brückendrucke erfor­ derlich, so werden diese, nach Aufbringen eines Dielektri­ kums, in der oben beschriebenen Reihenfolge mit Silber und Graphit fortgeführt. Abschließend wird die gesamte Folie mit Ausnahme der Kontaktstellen in einem letzten Druck mit einem Isolierlack abgedeckt.Are bridge prints required due to the circuit resolution these become, after applying a dielectric kums, in the order described above with silver and Graphite continued. Finally, the entire slide is included Except for the contact points in a last print with a Insulating varnish covered.

Aufgabe der Erfindung ist es, die Funktion dieser Schaltfo­ lien zu verbessern sowie eine Verbilligung im Fertigungsab­ lauf zu erzielen.The object of the invention is the function of this Schaltfo lien to improve as well as a cheaper manufacturing to achieve a run.

Diese Aufgabe wird gemäß einem Verfahren nach der Erfindung dadurch gelöst, daß die Leiterbahnen sowie die Kontaktstel­ len mit einem wanderungsbeständigen Material wie Kupferpaste oder einer entsprechenden Legierung gedruckt werden, daß die gesamte Trägerfolie auf der bedruckten Seite mit Ausnahme der Kontaktstellen mit einem Isolierlack überdeckt werden und daß auf die Kontaktstellen eine korrosionsbeständige, für Schaltzwecke geeignete Schicht aufgebracht wird.This object is achieved according to a method according to the invention solved in that the conductor tracks and the contact point len with a migration-resistant material such as copper paste or a corresponding alloy that the  entire carrier film on the printed side with the exception the contact points are covered with an insulating varnish and that on the contact points a corrosion-resistant, for Suitable layer switching purposes is applied.

Aufgrund der Erfindung werden die Leiterbahnen anstelle mit einer Silberpaste mit einer Kupferpaste gedruckt. Die bisher erforderliche komplette Überbedruckung der Leiterbahnen mit einer Graphitpaste entfällt somit, da Kupfer praktisch wande­ rungsbeständig ist. Darüberhinaus hat Kupfer in etwa die gleiche Leitfähigkeit wie Silber. Da außerdem die Kupferpaste mit einer Isolierlacküberdeckung ausreichend korrosionsbe­ ständig ist, benötigt man nur noch im offenen Kontakt- und Steckerbereich eine Überbedruckung mit einer korrosionsbe­ ständigen, für Schaltzwecke geeignete Schicht.Due to the invention, the conductor tracks are instead of with a silver paste printed with a copper paste. The so far required complete overprinting of the conductor tracks with a graphite paste is therefore not necessary since copper is practically wall is resistant to aging. In addition, copper has about that same conductivity as silver. Since also the copper paste sufficient corrosion protection with an insulating varnish cover is only necessary in open contact and Plug area an overprint with a corrosion permanent layer suitable for switching purposes.

Es ist zweckmäßig, daß die korrosionsbeständige Schicht aus einer Silber-Palladium-Legierung besteht, da eine solche Schicht sich besonders gut für Schaltzwecke eignet.It is expedient that the corrosion-resistant layer is made of a silver-palladium alloy, as such Layer is particularly suitable for switching purposes.

Für andere Schaltströme hat sich als korrosionsbeständige Schicht Gold oder Palladium bewährt.For other switching currents it has proven to be corrosion resistant Gold or palladium layer proven.

Zum Schutz gegen elektromagnetische Beeinflussungen ist es zweckmäßig, daß die Rückseite der Trägerfolie mit einem Netz von Leiterbahnen aus Kupfer oder Nickel bzw. einer entspre­ chenden Legierung bedruckt wird, die mit Ausnahme des An­ schlußbereiches vollständig von Isolierlack bedeckt werden.It is to protect against electromagnetic interference expedient that the back of the carrier film with a network of conductor tracks made of copper or nickel or one Alloy is printed, with the exception of the An closing area are completely covered by insulating varnish.

Weiterhin ist es vorteilhaft, daß zur Herstellung von Brücken der Isolierlack mit einer Kupferpaste bedruckt wird, worauf wiederum eine Isolierlackschicht aufgebracht wird.It is also advantageous that for the production of Bridges the insulating varnish is printed with a copper paste, whereupon an insulating varnish layer is applied.

Durch all diese Maßnahmen werden folgende Vorteile erreicht. Die Verwendung von Silber entfällt im Bereich des Leiterbil­ des. Hierdurch wird eine Einsparung des Edelmetalles erzielt. Weiterhin wird durch Umstellen der Druckpaste im Bereich des Leiterbildes von Silber auf Kupfer eine hohe Wanderungsbe­ ständigkeit erreicht. Aus diesem Grund wird ein Folgedruck nur mehr im offenen Kontakt- bzw. Steckerbereich erforder­ lich, was eine Pasteneinsparung bedeutet. Im Brückenbereich entfällt nach dem Kupferdruck der Graphitfolgedruck völlig. Dies bedeutet eine Einsparung eines Druckvorganges und eine Ersparnis der Paste. Die Möglichkeit, im Kontakt- bzw. im Steckerbereich partiell und damit geringe Mengen beispiels­ weise Silber-Palladium zu drucken, ermöglicht niederohmige Kontaktstellen zu fertigen bzw. den Steckerübergang zu ver­ bessern. Weiterhin wird die Typenauswahl der benötigten Leit­ pasten von bisher drei Sorten auf zwei reduziert. Durch den Entfall des Graphitüberdrucks können schließlich die Leiter­ bahnabstände verringert werden und damit hohe Auflösungen bis hin zum 1,27 mm Raster ausgeführt werden.The following advantages are achieved by all these measures. Silver is not used in the area of the conductor bilge This saves the precious metal. Furthermore, by changing the printing paste in the area of  Head pattern of silver on copper a high migration achieved consistency. For this reason, a subsequent print only required in the open contact or plug area what a paste saving means. In the bridge area After the copper printing, the subsequent graphite printing is completely eliminated. This means saving one printing process and one Saving the paste. The possibility in the contact or in Partial connector area and thus small quantities for example Printing wise silver-palladium enables low-resistance To manufacture contact points or to ver the connector transition improve. Furthermore, the type selection of the required guidance pastes from three types reduced to two. By the The conductors can finally eliminate the excess graphite pressure web distances are reduced and thus high resolutions up towards the 1.27 mm grid.

Im folgenden sei die Erfindung anhand einer Abbildung näher erläutert.In the following, the invention is based on an illustration explained.

Die Abbildung zeigt eine Schaltfolie für Mattentastaturen.The illustration shows a switching foil for mat keyboards.

Auf einer Folie (1) aus Isolierstoff werden zunächst die Lei­ terbahnen (2) sowie die Kontaktstellen (3) mit einer Kupfer­ paste oder einer entsprechenden Legierung gedruckt. Danach wird die gesamte Oberfläche der Folie auf der bedruckten Seite mit Ausnahme der Kontaktstellen (3) mit Isolierlack (4) überdeckt. Die Kontaktstellen werden sodann mit einer korro­ sionsbeständigen für Schaltzwecke geeigneten Schicht (5) wie Silber-Palladium, Gold oder Palladium überdeckt.On a foil ( 1 ) made of insulating material, the conductor tracks ( 2 ) and the contact points ( 3 ) are first printed with a copper paste or a corresponding alloy. Then the entire surface of the film on the printed side, with the exception of the contact points ( 3 ), is covered with insulating varnish ( 4 ). The contact points are then covered with a corrosion-resistant layer ( 5 ) suitable for switching purposes, such as silver-palladium, gold or palladium.

Auf der Rückseite der Folie (1) ist weiterhin ein Netz von Leiterbahnen (6) aus Kupfer oder Nickel aufgedruckt. Auch diese Leiterbahnen werden anschließend mit Ausnahme eines An­ schlußbereiches (8) vollständig mit Isolierlack bedeckt.A network of conductor tracks ( 6 ) made of copper or nickel is also printed on the back of the film ( 1 ). These traces are then completely covered with insulating varnish, with the exception of a connection area ( 8 ).

Claims (7)

1. Verfahren zur Herstellung einer Schaltfolie für Mattenta­ staturen mit auf einer Trägerfolie am Isolierstoff aufgebrach­ ten Leiterbahnen sowie Kontaktstellen für Tasten und den Steckerbereich, dadurch gekennzeichnet, daß die Leiterbahnen (2) sowie die Kontaktstellen (3) mit einem wanderungsbeständigen Material wie Kupferpaste oder einer entsprechenden Legierung gedruckt werden, daß die ge­ samte Trägerfolie (1) auf der bedruckten Seite mit Ausnahme der Kontaktstellen mit einem Isolierlack (4) überdeckt werden und daß auf die Kontaktstellen eine korrosionsbeständige, für Schaltzwecke geeignete Schicht (5) aufgebracht wird.1. A method for producing a switching film for Mattenta stature with on a carrier film on the insulating th conductor tracks and contact points for buttons and the plug area, characterized in that the conductor tracks ( 2 ) and the contact points ( 3 ) with a migration-resistant material such as copper paste or Corresponding alloy are printed that the entire carrier film ( 1 ) on the printed side with the exception of the contact points are covered with an insulating varnish ( 4 ) and that a corrosion-resistant layer ( 5 ) suitable for switching purposes is applied to the contact points. 2. Verfahren nach Anspruch 1, dadurch gekenn­ zeichnet, daß die korrosionsbeständige Schicht (5) aus einer Silber Palladium-Legierung besteht.2. The method according to claim 1, characterized in that the corrosion-resistant layer ( 5 ) consists of a silver palladium alloy. 3. Verfahren nach Anspruch 1, dadurch gekenn­ zeichnet, daß die korrosionsbeständige Schicht (5) aus Graphit besteht.3. The method according to claim 1, characterized in that the corrosion-resistant layer ( 5 ) consists of graphite. 4. Verfahren nach Anspruch 1, dadurch gekenn­ zeichnet, daß die korrosionsbeständige Schicht (5) aus Gold besteht.4. The method according to claim 1, characterized in that the corrosion-resistant layer ( 5 ) consists of gold. 5. Verfahren nach Anspruch 1, dadurch gekenn­ zeichnet, daß die korrosionsbeständige Schicht (5) aus Palladium besteht.5. The method according to claim 1, characterized in that the corrosion-resistant layer ( 5 ) consists of palladium. 6. Verfahren nach Anspruch 1, dadurch gekenn­ zeichnet, daß die Rückseite der Trägerfolie mit einem Netz von Leiterbahnen (6) aus Kupfer oder Nickel bzw. einer entsprechenden Legierung bedruckt wird, die mit Ausnahme des Anschlußbereiches (8) vollständig von Isolier­ lack (7) bedeckt werden. 6. The method according to claim 1, characterized in that the back of the carrier film is printed with a network of conductor tracks ( 6 ) made of copper or nickel or a corresponding alloy, with the exception of the connection area ( 8 ) completely of insulating varnish ( 7th ) are covered. 7. Verfahren nach Anspruch 1, dadurch gekenn­ zeichnet, daß zur Herstellung von Brücken der Iso­ lierlack mit einer Kupferpaste bedruckt wird, worauf wiederum eine Isolierlackschicht aufgebracht wird.7. The method according to claim 1, characterized records that for the production of bridges the Iso varnish is printed with a copper paste, which in turn an insulating varnish layer is applied.
DE19863630952 1986-09-11 1986-09-11 Method for producing a switching film for mat-type keyboards Withdrawn DE3630952A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
DE19863630952 DE3630952A1 (en) 1986-09-11 1986-09-11 Method for producing a switching film for mat-type keyboards

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19863630952 DE3630952A1 (en) 1986-09-11 1986-09-11 Method for producing a switching film for mat-type keyboards

Publications (1)

Publication Number Publication Date
DE3630952A1 true DE3630952A1 (en) 1988-03-17

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ID=6309376

Family Applications (1)

Application Number Title Priority Date Filing Date
DE19863630952 Withdrawn DE3630952A1 (en) 1986-09-11 1986-09-11 Method for producing a switching film for mat-type keyboards

Country Status (1)

Country Link
DE (1) DE3630952A1 (en)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3714316A1 (en) * 1987-04-29 1988-11-10 Siemens Ag Contact mat for keys and keyboards
DE4302892A1 (en) * 1992-02-07 1993-08-12 Matsushita Electric Ind Co Ltd Keyboard switch - has assembly of contact points at upper and lower plates with layers of two adhesives which bond at temps. slightly higher than room temp.
DE4400098A1 (en) * 1993-12-30 1995-07-06 Silitek Corp Membrane switch and method for making membrane switch
DE19533427C1 (en) * 1995-09-11 1996-12-05 Kostal Leopold Gmbh & Co Kg Electrical switching unit used e.g. in remote controls
DE19852815C1 (en) * 1998-11-17 2000-06-08 Kostal Leopold Gmbh & Co Kg Electrical switching device has switching mat area with at least one movable contact part bent out of plane of mat so movable contact part's contact surface opposes main surface of mat
CN113260167A (en) * 2018-08-17 2021-08-13 神讯电脑(昆山)有限公司 Device and method for preventing screw hole and copper foil on PCB from being oxidized

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3714316A1 (en) * 1987-04-29 1988-11-10 Siemens Ag Contact mat for keys and keyboards
DE4302892A1 (en) * 1992-02-07 1993-08-12 Matsushita Electric Ind Co Ltd Keyboard switch - has assembly of contact points at upper and lower plates with layers of two adhesives which bond at temps. slightly higher than room temp.
DE4302892C2 (en) * 1992-02-07 1998-05-07 Matsushita Electric Ind Co Ltd Method of making a key switch
DE4400098A1 (en) * 1993-12-30 1995-07-06 Silitek Corp Membrane switch and method for making membrane switch
DE19533427C1 (en) * 1995-09-11 1996-12-05 Kostal Leopold Gmbh & Co Kg Electrical switching unit used e.g. in remote controls
DE19852815C1 (en) * 1998-11-17 2000-06-08 Kostal Leopold Gmbh & Co Kg Electrical switching device has switching mat area with at least one movable contact part bent out of plane of mat so movable contact part's contact surface opposes main surface of mat
CN113260167A (en) * 2018-08-17 2021-08-13 神讯电脑(昆山)有限公司 Device and method for preventing screw hole and copper foil on PCB from being oxidized

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