GB2093634A - Capacitive keyswitch circuit boards - Google Patents
Capacitive keyswitch circuit boards Download PDFInfo
- Publication number
- GB2093634A GB2093634A GB8205132A GB8205132A GB2093634A GB 2093634 A GB2093634 A GB 2093634A GB 8205132 A GB8205132 A GB 8205132A GB 8205132 A GB8205132 A GB 8205132A GB 2093634 A GB2093634 A GB 2093634A
- Authority
- GB
- United Kingdom
- Prior art keywords
- board
- conductive ink
- circuit board
- insulating material
- 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.)
- Granted
Links
- 239000003990 capacitor Substances 0.000 claims abstract description 14
- 239000000463 material Substances 0.000 claims abstract description 10
- 229910000679 solder Inorganic materials 0.000 claims abstract description 9
- 239000004593 Epoxy Substances 0.000 claims description 4
- 239000011810 insulating material Substances 0.000 claims 5
- 239000000758 substrate Substances 0.000 claims 3
- 229920006254 polymer film Polymers 0.000 claims 1
- 230000001154 acute effect Effects 0.000 abstract 1
- 229910052802 copper Inorganic materials 0.000 description 4
- 239000010949 copper Substances 0.000 description 4
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 3
- 238000005476 soldering Methods 0.000 description 3
- 230000000994 depressogenic effect Effects 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000002991 molded plastic Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
- H01G5/00—Capacitors in which the capacitance is varied by mechanical means, e.g. by turning a shaft; Processes of their manufacture
- H01G5/01—Details
- H01G5/013—Dielectrics
- H01G5/0134—Solid dielectrics
- H01G5/0136—Solid dielectrics with movable electrodes
-
- 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
- H05K1/16—Printed circuits incorporating printed electric components, e.g. printed resistor, capacitor, inductor
- H05K1/162—Printed circuits incorporating printed electric components, e.g. printed resistor, capacitor, inductor incorporating printed capacitors
-
- 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
- H05K1/18—Printed circuits structurally associated with non-printed electric components
-
- 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
- H05K1/0213—Electrical arrangements not otherwise provided for
- H05K1/0237—High frequency adaptations
- H05K1/0239—Signal transmission by AC coupling
-
- 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
- H05K1/0286—Programmable, customizable or modifiable circuits
-
- 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
- H05K2201/10—Details of components or other objects attached to or integrated in a printed circuit board
- H05K2201/10007—Types of components
- H05K2201/10053—Switch
-
- 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
- H05K2201/10—Details of components or other objects attached to or integrated in a printed circuit board
- H05K2201/10007—Types of components
- H05K2201/10196—Variable component, e.g. variable resistor
-
- 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
- H05K3/30—Assembling printed circuits with electric components, e.g. with resistor
- H05K3/32—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits
- H05K3/34—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits by soldering
- H05K3/3452—Solder masks
Landscapes
- Engineering & Computer Science (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Push-Button Switches (AREA)
- Electronic Switches (AREA)
- Non-Metallic Protective Coatings For Printed Circuits (AREA)
- Input From Keyboards Or The Like (AREA)
- Manufacture Of Switches (AREA)
- Structures For Mounting Electric Components On Printed Circuit Boards (AREA)
Abstract
A capacitive keyswitch circuit board 14 includes an array of flat, horizontal capacitor plates 12 formed of conductive ink which are covered with a dielectric insulative layer 16 of a solder mask material. An etched circuit pattern 32, 34 is formed on the opposite side of the board 14 and is covered with the solder mask material 70 to mask off areas where solder is not to adhere. Through connections may be made from the circuit pattern side to the conductive ink capacitor plates 12 where desired. A movable capacitor plate 40 is secured above each horizontal plate 12 of the circuit board by a pair of tabs 22, 24, and is hinged at 36, 38 so that it projects upwardly at an acute angle with respect to the horizontal circuit board 14. <IMAGE>
Description
SPECIFICATION
Capacitive keyswitch circuit boards
Background of the Invention
Electrical keyboards for manual input to data processing system have increasingly adopted capacitive circuitry in recent years since capacitive keyswitches, when properly designed, may provide reliable operation at low cost. In such keyboards, it is extremely desirable to provide the circuit board at a minimum cost. Double sided circuit boards with etched copper patterns on both sides have been employed in such keyboards because the complexity of the device required double-sided boards. However, the cost of manufacturing such boards is undesirably high.
Conductive ink has been used in various electrical products to lower cost, but patterns formed with such ink cannot be reliably soldered generally with conventional board soldering techniques. The circuit board of the present invention utilizes low cost conductive ink on one side of the circuit board to reduce the cost while maintaining etched circuit patterns on the other side of the board to insure reliable soldering with conventional soldering processes.
Description of the Drawings
The present invention is described by reference to the drawings in which:
Figure 1 is an exploded view of the fixed and moveable plates and the plunger of a capacitive keyswitch attached to the circuit board of the present invention;
Figure 2 is a side cross-sectional view of the switch and circuit board with the plunger in an undepressed postion; and
Figure 3 is a side cross-sectional view of the switch and circuit board with the plunger in a depressed condition when the switch is actuated.
Technical Description of the Invention
Fig. 1 shows a perspective a view of keyswitch 10 attached to the circuit board of the present invention. At each keystation of the keyboard, a fixed horizontal capacitor plate 12 is formed of conductive ink screened or printed on the top face of the printed circuit board 14; and it is covered by a thin dielectric insulative layer 16, which may be an epoxy solder mask material is preferably screened or printed on. One suitable material is sold under the designation "Wornow solder resist SR 1 000R" by the Hyslo Division of the Dexter
Corporation. If the material is screened on, a 200 mesh number stainless steel screen may be used. The moveable plate 18 is formed with a flat, elongated support member 20 which carries a pair of downwardly projecting tabs 22, 24 formed on the bracket 26.The tabs 22, 24 correspondingly fit into the apertures 28, 30 in the printed circuit board so they may be soldered therein to make electrical connection to the conductive-copper paths 32, 34 that are etched on the bottom side of the board 14. The hinges for the moveable plate 36, 38 may be loop hinges of the adjustable capacitor type employed in early radio circuits.
The actuating plunger mechanism 42 for the keyswitch is preferably formed as a molded plastic member which has a key receiving post 44 on its upper end, a spring support ring 46 and a lower plunger section 48. The lower plunger section 48 is formed of four ribs 50 which are aligned to form a cross pattern which projects into a corresponding cross-shaped aperture 52 that is formed in the guide boss 54 which projects from the base 58. As shown in Fig. 2 a return spring 60 is positioned between the bottom of the ring 46 and the top of base 58. A support board 62 fits into the slotted groove 64 in the base 58 to support the actuating mechanism above the moveable capacitor plate.
The overtravel mechanism of the keyswitch is formed by a cantilever mounted resilient integrally formed curvilinear arm 66 that extends from the bottom of one of the ribs of the plunger. The shape of the arm 66 is preferably a segment of the circumference of a circle. At the end of the arm there is transversely mounted cylindrical rod 68 which extends outwardly beyond the width of the generally flat curvilinear arm 66. When the plunger is depressed and the keyswitch is actuated, the surface of the rod 68 bears against the movable capacitive plate 40, as shown in Figs. 2 and 3, thus forcing the moveable capacitor plate to a position approximately parallel to the fixed capacitor plate, so that flexing of the curvilinear arm 66 accomplishes the desired overtravel function.The rod 68 preferably extends across a substantial portion of the width of the moveable plate 40; thereby insuring that the actuating force on the plate is uniformly distributed so that undesirable twisting of the plate does not occur due to unbalanced torque.
The capacitive keyswitch circuit board of the present invention is best shown in Fig. 2.
As previously mentioned, a capacitor plate 12 is formed of conductive ink, preferably a thick polymer-conductive ink. At each keystation of the keyboard, a capacitor plate 12 is formed on the top face of the board while an etched coppr circuit pattern is formed on the bottom side of the board to form the necessary interconnections for the board. Through connections may be made in holes through the board to electrically connect the capacitor plates 12 to the etched copper pattern on the other side of the board.
In order to solder-mask areas of the etched pattern side where solder is not to be depos ited, the insulative epoxy material layer 70 may be screened on in a conventional manner of the etched pattern side of the board. This same material can also be applied over the capacitor plates 12 to form the necessary dielectric layer 16 on the other side of the board. In fact, the entire top, or fixed capacitor plate side of the circuit board may be covered with this material; and all solder connections may then be made to the copper pattern side of the board.
Claims (7)
1. A capacitive keyswitch circuit board comprising a planar insulating substrate, a fixed, flat capacitor plate formed on one side of said substrate by conductive ink, at each keystation, an etched conductive pattern formed on the opposite side of said board, and a layer of an insulating material applied over said conductive ink plates on said one side of said board to act as a dielectric layer, and a layer of an insulating material applied on the other side of said board to act as a solder mask.
2. The board of claim 1, wherein said conductive ink is a thick polymer film ink.
3. The board of claim 2, wherein said conductive ink is screened on said substrate.
4. The board of claim 3, wherein said layer of insulating material is screened over said conductive ink to form said dielectric layer.
5. The board of claim 4, wherein said insulating material is an insulative epoxy material.
6. The board of claim 5, wherein said insulating material is an insulative epoxy solder mask material.
7. The board of claim 1, substantially as described with reference to the accompanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US23825481A | 1981-02-25 | 1981-02-25 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2093634A true GB2093634A (en) | 1982-09-02 |
| GB2093634B GB2093634B (en) | 1985-01-09 |
Family
ID=22897118
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8205132A Expired GB2093634B (en) | 1981-02-25 | 1982-02-22 | Capacitive keyswitch circuit boards |
Country Status (10)
| Country | Link |
|---|---|
| JP (1) | JPS57154721A (en) |
| BR (1) | BR8200678A (en) |
| DE (1) | DE3205936A1 (en) |
| DK (1) | DK83082A (en) |
| FI (1) | FI820630L (en) |
| FR (1) | FR2500714B1 (en) |
| GB (1) | GB2093634B (en) |
| IT (1) | IT1153461B (en) |
| NO (1) | NO820582L (en) |
| SE (1) | SE8201140L (en) |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3778817A (en) * | 1972-08-02 | 1973-12-11 | Xerox Corp | Output keyboard apparatus and signal translating methods therefor |
| US3921167A (en) * | 1974-06-14 | 1975-11-18 | Ibm | Capacitive circuitboard |
| US4049844A (en) * | 1974-09-27 | 1977-09-20 | General Electric Company | Method for making a circuit board and article made thereby |
| US4090229A (en) * | 1976-09-30 | 1978-05-16 | Becton, Dickinson Electronics Company | Capacitive key for keyboard |
| GB1584345A (en) * | 1977-05-11 | 1981-02-11 | Alphameric Keyboards Ltd | Keyboards |
| DE3000940C2 (en) * | 1979-01-12 | 1984-02-02 | Kollmorgen Technologies Corp., 75201 Dallas, Tex. | Mixing for masking masks and layer formers to be applied by screen printing |
-
1982
- 1982-01-26 FR FR8201162A patent/FR2500714B1/en not_active Expired
- 1982-02-09 BR BR8200678A patent/BR8200678A/en unknown
- 1982-02-19 DE DE19823205936 patent/DE3205936A1/en not_active Withdrawn
- 1982-02-19 IT IT19775/82A patent/IT1153461B/en active
- 1982-02-22 GB GB8205132A patent/GB2093634B/en not_active Expired
- 1982-02-24 NO NO820582A patent/NO820582L/en unknown
- 1982-02-24 JP JP57027542A patent/JPS57154721A/en active Pending
- 1982-02-24 FI FI820630A patent/FI820630L/en not_active Application Discontinuation
- 1982-02-24 SE SE8201140A patent/SE8201140L/en not_active Application Discontinuation
- 1982-02-25 DK DK83082A patent/DK83082A/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| FR2500714A1 (en) | 1982-08-27 |
| GB2093634B (en) | 1985-01-09 |
| DE3205936A1 (en) | 1982-10-07 |
| FI820630L (en) | 1982-08-26 |
| FR2500714B1 (en) | 1985-08-23 |
| SE8201140L (en) | 1982-08-26 |
| IT1153461B (en) | 1987-01-14 |
| JPS57154721A (en) | 1982-09-24 |
| BR8200678A (en) | 1982-12-14 |
| DK83082A (en) | 1982-08-26 |
| IT8219775A0 (en) | 1982-02-19 |
| NO820582L (en) | 1982-08-26 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |