EP3018681A1 - Tapis sensible souple et son utilisation - Google Patents

Tapis sensible souple et son utilisation Download PDF

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Publication number
EP3018681A1
EP3018681A1 EP15193344.7A EP15193344A EP3018681A1 EP 3018681 A1 EP3018681 A1 EP 3018681A1 EP 15193344 A EP15193344 A EP 15193344A EP 3018681 A1 EP3018681 A1 EP 3018681A1
Authority
EP
European Patent Office
Prior art keywords
silicone
switching mat
dome
insert
elastomer
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Withdrawn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
EP15193344.7A
Other languages
German (de)
English (en)
Inventor
Christoph Keist
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.)
Abatek International AG
Original Assignee
Abatek International 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 Abatek International AG filed Critical Abatek International AG
Publication of EP3018681A1 publication Critical patent/EP3018681A1/fr
Withdrawn legal-status Critical Current

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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
    • H01H13/702—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
    • H01H13/704—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 characterised by the layers, e.g. by their material or structure
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H2209/00—Layers
    • H01H2209/002—Materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H2209/00—Layers
    • H01H2209/004—Depressions or protrusions on switch sites
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H2209/00—Layers
    • H01H2209/068—Properties of the membrane
    • H01H2209/074—Properties of the membrane elastomeric
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H2221/00—Actuators
    • H01H2221/002—Actuators integral with membrane
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H2229/00—Manufacturing

Definitions

  • the present invention relates to a silicone switching mat, in particular for use as a switch component in the automotive sector. Furthermore, the present invention relates to a method for producing such a silicone switching mat and uses of such a silicone switching mat.
  • Silicone keypads are often used in automobile keys and switches to provide tactile feedback and to close the electrical contact.
  • the switching mat often takes on a sealing function on the circuit board and has integrated light wells to prevent light leakage of the backlighting of the keys.
  • Silicone mats are application specific parts and are redesigned and designed for each switch. Today's technology no longer meets the requirements or is too expensive.
  • Solid silicone silicone mats in the compression process are the low cost of the press tools and the flexible manufacturing process.
  • Solid silicone is available in different grades, but solid silicones have a large hysteresis, which has a negative effect on the life cycles.
  • the pressing process is a manual process, many mistakes are made, which leads to rejects and complaints.
  • a vulcanization cycle in the press is about 5-10 minutes.
  • Safety mats are known from an elastomeric material, wherein contiguous covers are arranged on the top, and also contiguous so-called keypads are arranged underneath.
  • the tactile feedback is generated by metal domes located below both layers.
  • Material properties for the cover and keypad are not quantified US 2010/0067254 are multi-layered structures on printed circuit boards are known to be provided below the tracks metal dome for generating the tactile feedback, and above each over the entire surface of the circuit board coherently formed layers of different plastic material, in which case no material properties are given.
  • the present invention relates to a silicone switching mat for at least partially covering a printed circuit board, wherein the silicone switching mat has at least one button with tactile feedback for generating a contact on the circuit board.
  • a silicone keypad has several such keys, in which case with multiple keys in the same silicone keypad these keys are not related to tactile feedback, but are separate individual keys made of a high-quality elastomer.
  • the proposed silicone switching mat is characterized in that it comprises a cover area forming the cover of a low-grade elastomer having at least one receiving area, and at least one inserted in the receiving area insertion of a high-quality elastomer.
  • a high-quality elastomer of the insert is to be understood as meaning an elastomer having a Shore A hardness of at least 70 and preferably not more than 90, and a tensile strength of at least 300%, preferably of at least 350%.
  • the Shore hardness is determined according to DIN 53 505 and the tensile strength according to DIN 53 504 S2.
  • the high-quality elastomer is furthermore preferably characterized in that it has a low internal damping.
  • the lifetime of a typical dome is in the range of 100,000-500,000 switching cycles, preferably more than 300,000 switching cycles.
  • the high quality elastomer preferably has a tear strength of 150%, a typical dome life in the range of 100,000 to 500,000 cycles, preferably more than 300,000 cycles.
  • a low-grade elastomer of the cover region is meant a material having a Shore A hardness in the range of 30-80, preferably in the range of 30-60 or of less than 70. Preferably, it has a tensile strength of 70 at a Shore hardness of 70 less than 300%, preferably less than 200%, with the internal damping being high.
  • the low-grade elastomer of the cover region is preferably a solid silicone.
  • the high quality elastomer of the insert is preferably a liquid silicone or TPU (thermoplastic polyurethane).
  • One of the core concepts of the present invention is to selectively produce only those parts of high quality material which actually require the high quality.
  • the low-grade material also allows simplified production methods, which are more cost-effective, especially for small series, and accordingly allow adaptation to customer-specific requirements.
  • expensive procedures for the processing of the high-quality material can be used selectively then only for the inserting dome.
  • the insertion dome does not need to be adapted to the customer's requirements to the same extent.
  • a further preferred embodiment of the proposed silicone switching mat is characterized in that the covering area is formed contiguous, and that the respectively the inserting dome are placed on the side facing the circuit board in receiving areas provided for this purpose and are preferably secured therein positively and / or non-positively and / or materially ,
  • At least one receiving area can have a bell membrane without tactile feedback and / or elements, in particular in the area of the receiving area arranged parallel to the surface of the printed circuit board, elements, in particular in the form of recesses and / or elevations (for example, one after downwardly directed pin) are arranged, which are provided by engagement in respectively corresponding elevations or depressions (or even passage opening) of the insert, preferably in the deck area, which for positioning and / or attachment of the insert in the Serve recording area.
  • the silicone keypad of the present invention need not be continuous as a whole.
  • the silicone switching mat in such a way that the covering region has at least one receiving opening in the form of a passage opening for the insertion of an insert, preferably for inserting the insert with its foot region, wherein the receiving opening is preferably stepped and / or a groove or a comb, so that the foot region of the insert can be fixed in a form-fitting manner and forming a closed surface of the silicone switching mat in this area, optionally with the additional aid of a bonding agent.
  • a further preferred embodiment of the proposed silicone switching mat is characterized in that the at least one insert has a preferably circumferential and upwardly projecting from a preferably peripheral foot region cone membrane for the generation of a tactile feedback and a cone cone up in a plane parallel to the circuit board partially or completely concluding deck area, wherein on the circuit board facing the underside of the deck area a contact pill attached and / or embedded and / or injected, preferably based on a metal foam, or a conductive ink is applied.
  • the insert can also consist of conductive liquid silicone, so that can be completely dispensed with a separate contact pill or a Leitlack.
  • Such a silicone switching mat can have at least two, preferably at least 3 or more, keys with tactile feedback in the same silicone switching mat, which are formed by inserting inserts made of high-quality elastomer.
  • such a silicone switching mat can additionally comprise at least one further element from the following list: light shaft, pocket for electronic elements, positioning pins, sealing, etc.
  • the present invention relates to a method for producing a silicone switching mat, as described above, wherein the method is characterized in particular in that the covering area of the low-grade elastomer separately from the insert or the majority of inserting high-grade elastomer, in particular in a Spray process, is produced, and the Inserted domes inserted into the coverage area and preferably in receiving areas provided therein and / or receiving openings are attached.
  • Such a method may be characterized in that the coverage area is designed in an application-specific manner and the insertion diameters are manufactured as a standard component.
  • the present invention relates to the use of a silicone switching mat as described above as switches in the automotive sector or in the field of mobile technology, telecommunications technology, in the field of portable computers, etc.
  • This safety mat contains optional elements for seals, positioning, light shafts, etc.
  • domes only one receptacle for inserting domes is provided in the safety mat.
  • the insert domes are made of a high quality elastomer and have a cone diaphragm that generates the force-displacement curve of the button.
  • the contact pill is no longer inserted in the safety mat, but is attached to the inserting dome.
  • the elastomer for the insert may be a liquid silicone in the hardness of 30-80 ° or 70-90 Shore A or be a TPU or a high-grade solid silicone. Preferred is a liquid silicone in the hardness of 70-80 ° or 70-90 Shore A.
  • the inserting domes are fastened in the receptacles provided for this purpose in the safety mat. There are different variants for positioning and fixing the insert dome.
  • a variant consists of a hole in the mats base in which the insert dome is fitted and fixed with adhesive (cf. FIG. 3a ).
  • a small flange above may provide mechanical attachment.
  • dome is mechanically fixed in all directions by means of a joint and a groove (cf. FIG. 3b ).
  • a pin (see 3d figure ), which engages in the key top of the insert dome and achieves good adhesion.
  • the contact pill in the insert it is also possible to inject an electrically conductive material in the pill area, for example a liquid silicone with a carbon filler.
  • an electrically conductive material for example a liquid silicone with a carbon filler.
  • a contact pill and the whole Eilegedom can be injected from electrically conductive liquid silicone, thereby eliminating the insertion of a contact pill.
  • Application of conductive ink in the contact area is another way of contacting.
  • the application-specific safety mat tool is simplified because no more contact pills need to be inserted and the force-displacement curve must be paid no attention. As a result, the shot time at the press can be significantly shortened and there is much less waste.
  • the silicone used does not need to fulfill any mechanical properties and can therefore be reduced with a lot of filler.
  • the insert domes can be made automatically in a multiple injection mold.
  • the contact pills are placed in the cavities by means of robots and the finished parts are automatically removed. This ensures a consistently high quality.
  • the high-quality liquid silicone is only used where it has to fulfill a function: in the single dome of the safety mat.
  • the key height of the dome can be adjusted to the mounting mat of the installation situation despite standardized Einlegedom by the key top is increased on the recording.
  • the force-displacement curve on the geometry of the bell membrane and the Shore hardness of the keypad can be easily varied application specific.
  • the stroke of a key can also be increased by sinking the insert dome deeper into the mounting pocket, then in a first actuation phase only the bell diaphragm comes into play, which can be used to bias the key.
  • FIG. 1a represents how a dome behaves.
  • the path is shown on the x-axis and the corresponding force on the y-axis. If a dome is loaded over a path, the counterforce of the dome increases successively up to a maximum value, the tripping force F1. If this triggering force F1 is exceeded at the distance s1, the force decreases, which is experienced by the user as snapping and ensures exactly the relevant tactile feedback of the dome. The force then reaches a minimum value at the position s2 at the contact force F2. Now continue to press on the dome to ensure a secure contact on the circuit board.
  • the upper curve in FIG. 1a represents this triggering.
  • the force-displacement diagram follows the lower one Curve.
  • the reason for this is that the restoring force is reduced more rapidly at the discharge than at the initial load, the effect being due to the energy converted into heat by internal friction in the molecular structure. Ultimately, this is a hysteresis.
  • the force at the position s2 correspondingly passes through a lower minimum value than at the initial load, this restoring force F3, compared with the corresponding force F2 during the load, is a measure of the internal damping.
  • High-quality materials have a low internal damping and thus a low hysteresis, considered as the difference between the forces F2 and F3, low-valued materials over a large internal damping and thus a comparatively large hysteresis, ie the difference between the forces F2 and F3 comparatively large.
  • the values of damping, each measured against such a standard dome for the high-quality elastomer of preferred masses, are such that the force difference expressed by the difference in forces F2 and F3 (F2 minus F3) is typically less than 0.5 N, preferably less than 0.2 N.
  • the force difference, expressed by the difference of the forces F2 and F3 (F2 minus F3) is typically greater than 0.5 N, preferably greater than 0.7 N.
  • FIG. 3 shows such a standard dome in different representations.
  • a standard dome is produced and the force / travel diagram is determined.
  • the force / travel diagram is determined.
  • the elastomer is high grade
  • such a standard dome is made which determines the force / path diagram, and if the difference in forces F2 and F3 (F2 minus F3) is less than 0.5N, then It is a high-quality elastomer, if greater to a low-grade elastomer.
  • This standard dome is, as far as not already shown in the figures, as follows: SMT Silicone Key, key top diameter: 3mm; Contact pill: carbon pill; Key height: 4mm; Stroke (stroke): 1.6mm; Diaphragm angle: 60 °; Membrane thickness: 0.6mm.
  • FIG. 1b a silicone switching mat 1 is shown in conventional construction according to the prior art.
  • a printed circuit board 3 not shown here, a printed circuit board 3 is arranged substantially completely covering silicone area.
  • These are contiguous except for specifically provided openings such as a light well 1d Silicone structure has on both sides depending on a Dom 1a, which is designed as a button with a tactile feedback.
  • the dome 1a has a head which is provided for actuation, and this head is connected via a circumferential cone diaphragm 1b to the actual horizontal region of the switching mat.
  • a contact pill 1c is attached.
  • the tactile feedback and the contacting is done in this conventional silicone switching mat so that is pressed on the head of the respective button, and against the restoring force of the cone diaphragm 1b then the dome, and in particular arranged on the bottom contact pill 1c on the conductor track. 3 pressed down.
  • Two spaced-apart conductors are arranged on the conductor track in the region of the contact pill, which conductors are brought into conductive contact upon contact of the contact pill with the conductor track.
  • the object of the present invention is to propose an improved silicone switching mat in this connection.
  • FIG. 2 a silicone switching mat 1 according to the improved construction according to the present invention is shown.
  • a cover region 8 is provided here, which is designed to be continuous with, for example, a light shaft 1d with LED 2 arranged underneath.
  • this cover is only intended to cover and seal and to provide positioning assistance and to define a coherent surface. The tactile feedback of the button and the contact are not guaranteed by this cover.
  • the cover is made of a relatively low-grade elastomeric material, typically a solid silicone. Accordingly, the cover can be made custom comparatively cheap. However, the cover 8 does not have correspondingly high-quality properties; in particular, if tactile feedbacks are generated from such a material, the corresponding regions could not have high life cycles.
  • inserting 4 are provided separately from the cover, which now just made of high quality material and make the tactile feedback available.
  • the inserting dome 4 are inserted into corresponding receiving areas, here in the form of bell membranes 1f, the cover.
  • corresponding receiving areas here in the form of bell membranes 1f, the cover.
  • FIG. 2 As shown construction has the bell membrane 1f in the deck area 1e via a downwardly directed pin. This pin engages in a corresponding recess or opening in the deck area 13 of the insert.
  • this recess is formed in the deck area 13 as a passage opening which is closed downwards only by the contact pill 4b.
  • the insert domes can be fastened in the cover in different ways. Different variants are in FIG. 2 shown, these variants are all slightly different than the ones in FIG. 2 illustrated with a passage opening in the deck area 13 of the insert.
  • FIG. 3a a variant is shown, in which the cover 8 has a passage opening as a receiving opening 11 for the corresponding insert.
  • This passage opening of the cover is stepped but formed so that a circumferential notch is formed on the underside, which faces the circuit board.
  • the corresponding insert dome can be fitted or pressed with his foot. Again, it is possible to ensure a positive connection for fixing the insert dome.
  • the silicone switching mat as a whole, that is cover with inserting dome, forms a closed cover.
  • FIG. 3b A variant of this is in FIG. 3b shown. Again, there is a through hole in the cover 8, but this is not only stepped, but the through hole in the coverage area has a circumferential, for Center of the passage-directed ridge.
  • the foot of the corresponding dome has a corresponding radially outwardly open groove, and the insert dome can now be positively locked in positive fit in a groove / comb connection in this passage opening under positive engagement.
  • FIG. 3c Another simple realization is in Figure 3c shown.
  • the bell membrane 1f is provided as a closed bell membrane in the cover.
  • the insert 4 is inserted from below into this somewhat formed depression.
  • FIG. 2 Another variant is in 3d figure shown.
  • This variant is similar to the one in FIG. 2 shown, and it is referred to the description there.
  • the deck area 13 of the insert dome In the deck area 13 of the insert dome there is no passage opening, but only one recess. In this depression engages a slightly shorter trained pin of the area 1e of the bell membrane.
  • this can be used, for example, to introduce a bonding agent in the appropriate pocket in the deck area 13 of the insert dome 4 before introducing the insert dome in the coverage area, then firmly fasten the insert dome. It is also possible to introduce special components in this area.
  • the bell membrane 1f of the coverage area has a slight extension upwards to be inserted, for example, in a depression over the whole device related cover.
  • a variant is shown where, instead of a downwardly directed pin in the bell membrane 1f to some extent in a kinematic reversal in the bell membrane a recess is formed and in the deck area 13 of the insert dome an upwardly directed pin. Even so, a frictional attachment of a loading dome in the coverage area with good positioning is possible.

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  • Push-Button Switches (AREA)
EP15193344.7A 2014-11-10 2015-11-06 Tapis sensible souple et son utilisation Withdrawn EP3018681A1 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CH17352014 2014-11-10

Publications (1)

Publication Number Publication Date
EP3018681A1 true EP3018681A1 (fr) 2016-05-11

Family

ID=51986962

Family Applications (1)

Application Number Title Priority Date Filing Date
EP15193344.7A Withdrawn EP3018681A1 (fr) 2014-11-10 2015-11-06 Tapis sensible souple et son utilisation

Country Status (1)

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EP (1) EP3018681A1 (fr)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4609791A (en) 1984-12-20 1986-09-02 Itt Corporation Flexible diaphragm keypad and method of manufacture
US5114790A (en) 1988-11-10 1992-05-19 Acushnet Company Keyboard with conductive resilient pad
EP0896349A2 (fr) 1997-08-08 1999-02-10 Shin-Etsu Polymer Co., Ltd. Capuchon pour interrupteur à bouton-poussoir illuminé et procédé de fabrication
EP1662527A1 (fr) 2003-09-03 2006-05-31 Sunarrow Ltd. Clavier et son procede de fabrication
US20100067254A1 (en) 2006-11-24 2010-03-18 Fuji Polymer Industries Co., Ltd. Light guide sheet and electronic equipment utilizing the same

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4609791A (en) 1984-12-20 1986-09-02 Itt Corporation Flexible diaphragm keypad and method of manufacture
US5114790A (en) 1988-11-10 1992-05-19 Acushnet Company Keyboard with conductive resilient pad
EP0896349A2 (fr) 1997-08-08 1999-02-10 Shin-Etsu Polymer Co., Ltd. Capuchon pour interrupteur à bouton-poussoir illuminé et procédé de fabrication
EP1662527A1 (fr) 2003-09-03 2006-05-31 Sunarrow Ltd. Clavier et son procede de fabrication
US20100067254A1 (en) 2006-11-24 2010-03-18 Fuji Polymer Industries Co., Ltd. Light guide sheet and electronic equipment utilizing the same

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