Patent Application
20180302089
Decorative laminates have been used as surfacing materials for many years, in both commercial and residential applications, where pleasing aesthetic effects in conjunction with desired functional behavior (such as superior wear, heat and stain resistance, cleanability and cost) are preferred. Typical applications have historically included furniture, kitchen countertops, table tops, store fixtures, bathroom vanity tops, cabinets, wall paneling, office partitions, and the like.
Laminates are useful as surfacing materials, including as decorative surfaces, in many situations due to their combination of desirable qualities (e.g., superior wear, heat and stain resistance, cleanability, and cost). Laminate surfaces are composed of discrete layers, such as layers of resin-impregnated kraft paper that are pressed to form the laminate. One conventional decorative laminate is made by stacking three sheets of treated kraft paper (e.g., three sheets of phenol-formaldehyde resin-impregnated kraft paper), dry decorative paper (e.g., a print sheet), and a sheet of treated overlay paper (e.g., melamine-formaldehyde resin-impregnated tissue paper or acrylic resin-impregnated tissue paper), one on top of another and then bonded together with heat and pressure.
A high-pressure laminate process (HPL) is an irreversible thermal process wherein resin-impregnated sheets of kraft paper undergo a simultaneous pressing and heating process at relatively high levels of heat and pressure, such as temperatures greater than or equal to 125° C. and at least 5 mega Pascals (MPa) of pressure, typically for a press cycle of 30-50 minutes. An HPL process contrasts with low pressure laminate processes (LPL) that is conducted at pressures of less than 5.0 MPa, typically between 2-3 MPa.
This summary is provided to introduce a selection of concepts in a simplified form that are further described in the Detailed Descriptions. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.
A laminate with an electrical element (e.g., a capacitive switch) embedded within the laminate comprising a first paper layer having at least first and second vias through the first paper layer, a first electrically-conductive layer comprising a first electrically-conductive material, the first electrically-conductive layer being disposed over a portion of the first paper layer, a second electrically-conductive layer comprising the electrically-conductive material, the second electrically-conductive layer being disposed over another portion of the first paper layer, and an insulating layer disposed over the first and second electrically-conductive layers, wherein the first paper layer and the insulating layer encapsulate the first and second electrically-conductive layers within the laminate, and wherein the first electrically-conductive layer is electrically coupled to the first via and the second electrically-conductive layer is electrically coupled to the second via, the first and second vias including the electrically-conductive material therein, the first via making electrical contact with the first electrically-conductive layer and the second via making electrical contact with the second electrically-conductive layer is disclosed.
A method for manufacturing a laminate with an electrical element (e.g., a capacitive switch) embedded within the laminate comprising forming at least first and second via holes through a first paper layer, disposing a first electrically-conductive layer over a portion of the first paper layer, wherein the first electrically-conductive layer comprises an electrically-conductive material, disposing a second electrically-conductive layer over another portion of the first paper layer, wherein the second electrically-conductive layer comprises the electrically-conductive material, disposing an insulating layer over the first and second electrically-conductive layers, and compressing the first paper layer, the first and second electrically-conductive layers, and the insulating layer according to a lamination process, thereby forming a first via electrically coupled to the first electrically-conductive layer and a second via electrically coupled to the second electrically-coupled layer is disclosed.
A laminate with an electrical element (e.g., a capacitive switch) embedded within the laminate comprising a first paper layer having at least first and second vias through the first paper layer, a first electrically-conductive layer comprising a first electrically-conductive material, the first electrically-conductive layer being disposed over a portion of the first paper layer, a second electrically-conductive layer comprising the electrically-conductive material, the second electrically-conductive layer being disposed over another portion of the first paper layer, and an insulating layer disposed over the first and second electrically-conductive layers is disclosed. In embodiments, the first paper layer and the insulating layer may encapsulate the first and second electrically-conductive layers within the laminate. The first electrically-conductive layer may be electrically coupled to the first via and the second electrically-conductive layer may be electrically coupled to the second via, the first and second vias including the electrically-conductive material therein, the first via making electrical contact with the first electrically-conductive layer and the second via making electrical contact with the second electrically-conductive layer. In embodiments, the insulating layer may comprise a decorative layer. For example, the insulating layer may comprise a resin-impregnated decorative layer. As another example, the insulating layer may comprise a treated overlay paper layer. When the insulating layer comprises a treated overlay paper layer, the laminate may further comprise a dry or untreated decorative paper (also known as a print sheet) between the treated overlay paper layer and the second paper layer. Of course, the laminate may also comprise glue film layers, for example when untreated kraft paper layers are included as further described below.
Generally, as used herein, a “decorative layer” is a visible outer layer in the (final, assembled) laminate. A decorative layer may have decorative colors and/or designs. Of course, as mentioned above, an overlay layer may be disposed above a decorative layer provided that the decorative layer is at least partially visible through the overlay layer.
A laminate surfacing material with the electrical element arranged on different paper layers (e.g., resin-impregnated paper layers) of the laminate surfacing material has particularly useful characteristics, including: the ability to add more electrical elements in a space-efficient manner by providing additional electrically-conductive materials on different layers of the laminate; favorable heat-dissipation properties due to the lack of insulating air inside the laminate and optional use of fillers with high heat transfer coefficients (e.g., ceramics such as aluminum nitride, aluminum oxide, boron nitride, and combinations thereof) in the resin formulations used to prepare the resin-impregnated paper layers such that heat transfer away from the electrical element is enhanced, effectively turning the laminate surfacing material into an efficient heat sink and facilitating the utilization of the electrical element; unexpected and surprising electrical conductivity of the electrically-conductive material used to provide the electrical element even after undergoing an HPL process; and the ability to be integrated into almost any surface (e.g., countertop, wall, piece of furniture, door, window frame, interior of a vehicle, etc.). The resin-impregnated paper layers also provide a durable enclosure for the electrical element.
The electrical element may be formed by providing (e.g., disposing) an electrically-conductive material (e.g., electrically-conductive ink) onto a first paper layer (e.g., kraft paper) having at least first and second via holes cut through the paper layer for electrically coupling the electrical element. Disposing (e.g., printing) the electrically-conductive material onto two different portions of a first paper layer and other paper layers that may be included in the laminate allows the paper fibers to act as reinforcements for the electrical element created from the electrically-conductive material, preventing breakage of the electrical element due to shrinkage or expansion due to various environmental conditions. The layers of the electrical element may be stacked and encapsulated between discrete paper layers using a lamination process. While low pressure lamination may be used to prepare laminates according to the disclosure, a high pressure lamination process including a re-cooling stage (referred to herein as “high pressure lamination process”) is preferred.
As described herein, the electrical element is “encapsulated” or substantially protected by providing the electrically-conductive material for the electrical element on a first paper layer and disposing an insulating layer above the electrically-conductive material such that the electrical element is at least partially protected or shielded from ambient atmosphere by the overlying layer.
It has been found that when laminates are exposed to the heat and pressure in the high pressure lamination process, the risk of breaking or delamination of the sub-elements or layers of the electrical element is greatly reduced. The high pressure lamination process allows the electrical element to have electrically-conductive tracks having improved track densification, which achieves surprisingly higher conductivities than through other conventional manufacturing techniques. Initiating the high pressure lamination process after stacking the electrical element between the paper layers collectively cures layers included in the laminate simultaneously, which eliminates the conventional need for using an adhesive to adhere together layers that have individually been fully cured. The high pressure lamination process allows for accurate control of temperature and pressure (e.g., heating and cooling cycles) in order to control the rate of dimensional change of layers and surprisingly leads to enhanced electrical conductivity of the electrically-conductive material used in the laminate process.
Various embodiments of the present disclosure are methods for preparing such laminates with the electrical element embedded within the laminate. The methods include forming at least first and second via holes through a first paper layer, disposing (e.g., inkjet printing, flexographic printing, gravure printing, screen printing, extrusion printing, and the like) sub-elements or layers of the electrical element with electrically-conductive material onto different portions of the first paper layer, and providing vias through the paper layer at selected via hole locations with electrically-conductive material to electrically couple various layers of the electrical element. Factors in determining the selected locations may include efficient layout design, avoiding shorting layers of the electrical element, etc. The layers of the electrical element may be stacked and encapsulated between the paper layers by subjecting the laminate to the high pressure lamination process, which surprisingly results in advantageously enhanced densification of the electrically-conductive material and excellent conductivity. It should be noted that the same electrically-conductive material may be used for the electrical element and the vias, but different electrically-conductive materials may also be used.
In one preferred embodiment, a method of making a laminated surface material comprises providing at least an first untreated kraft paper layer, a glue film layer, and an insulating layer; forming a capacitive switch comprising first and second electrically-conductive materials arranged on the first untreated kraft paper layer; arranging a stack comprising at least the first untreated kraft paper layer, the glue film layer, and the insulating layer such that the insulating layer is disposed above the glue film layer; compressing the stack according to a lamination process. Typically, the stack includes an additional glue film layer disposed below the first untreated kraft paper layer so as to allow a sufficient amount of resin to saturate the laminate during a lamination process, in order to provide sufficient mechanical strength to the final formed laminate. By providing the first and electrically-conductive layers on untreated kraft paper, significantly improved alignment of holes formed in the stack can be achieved than when the first and second electrically-conductive layers are disposed on resin-impregnated paper layers. A glue film layer as used herein is a layer having a sufficient amount of thermoset resin to saturate an adjacent untreated paper layer (e.g., a decorative layer or a kraft paper layer).
Typically, a glue film layer will comprise a paper layer having between 30-80 percent by weight of a thermoset resin. Preferably, the thermoset resin of the glue film comprises phenol-formaldehyde resin.
Thus, a preferred laminated surface material comprises a stack comprising at least an first untreated kraft paper layer, a glue film layer, and an insulating layer such that the insulating layer is disposed above the glue film layer; a capacitive switch comprising an electrically-conductive material, the electrical element further comprising first and second electrically-conductive materials arranged on the first untreated kraft paper layer. Typically, the stack includes an additional glue film layer disposed below the first untreated kraft paper layer so as to allow a sufficient amount of resin to saturate the laminate during a lamination process, in order to provide sufficient mechanical strength to the final formed laminate.
Electrically-conductive materials suitable for use in accordance with the various embodiments of the present disclosure include any material which can be deposited upon the first paper layer and other paper layers that may be included as part of the laminate, such as resin-impregnated paper, and which may be electrically electrically-conductive. In some embodiments, the composition of the electrically-conductive material includes: (i) a particulate, electrically-conductive material; (ii) a binder; and optionally (iii) a microcrystalline cellulose component.
The particulate, electrically-conductive material may include any one of metals, alloys, electrically-conductive carbons (e.g., electrically-conductive allotropes of carbon, graphites), electrically-conductive polymers (e.g., polypyrrole), electrically-conductive metallized polymers (e.g., metallized polyethylene terephthalates), and combinations thereof. In a preferred aspect, the particulate electrically-conductive material comprises silver and/or silver alloys. Electrically-conductive ink compositions which may be disposed to provide electrically-conductive material on a paper layer and are thus suitable for use in various embodiments of the present disclosure typically include particles comprising metal, metal alloys, electrically-conductive carbon, or other electrically-conductive materials such as polymers, in a carrier medium which may include other polymers, solvents and additives. Various known methodologies such as inkjet printing, screen printing, flexographic printing, gravure printing, or extrusion printing may be used to dispose the electrically-conductive ink compositions on the substrate.
One embodiment of an electrically-conductive ink composition suitable for providing the particulate electrically-conductive material is an electrically-conductive ink composition comprising: (i) a particulate, electrically-conductive material; (ii) a carrier liquid; (iii) a polymer binder; and (iv) a microcrystalline cellulose component. Another embodiment of an electrically-conductive ink composition suitable for providing the particulate electrically-conductive material is an electrically-conductive ink composition comprising: (i) a particulate, electrically-conductive material; (ii) a carrier liquid; (iii) a polymer binder; and (iv) a microcrystalline cellulose component; wherein the particulate, electrically-conductive material comprises a component selected from the group consisting of silver and silver alloys; and wherein the microcrystalline cellulose component is present in an amount of from about 0.05% to about 10% by weight based on the composition and has an average particle size of from about 20 to about 100 μm. In certain embodiments of the present disclosure, the microcrystalline cellulose component may include two or more microcrystalline celluloses having different average particle sizes. As noted above, disposing methods such as inkjet printing, flexographic printing, gravure printing, screen printing, and extrusion printing may dispose the electrically-conductive material onto the paper layers, such as kraft paper and overlay paper, but depending on the type of paper, the electrically-conductive material may or may not penetrate completely through the paper.
If kraft paper (i.e., unbleached paper that is between 50-400 GSM (or g/m2)) is used, and an electrically-conductive ink composition is disposed thereon, the electrically-conductive material may penetrate halfway through the kraft paper, whereas if overlay paper (i.e., bleached paper that is between 10-50 GSM) having less than half the basis weight of kraft paper is used, and an electrically-conductive ink composition is disposed thereon, the electrically-conductive material will typically penetrate completely through the overlay paper. As such, in order to couple electrically-conductive material provided on different layers of kraft paper together, apertures can be cut at least halfway through the kraft paper, so that electrically-conductive material disposed over a top surface of the kraft paper penetrates halfway through the first kraft paper to form a via and establish an electrical connection with a same type or different type electrically-conductive material provided on a top surface of a second kraft paper layer underlying the first kraft paper layer. Because disposed electrically-conductive material may penetrate completely through overlay paper, it is not necessary to cut apertures in the overlay paper to form a via and couple the electrically-conductive material disposed on a top surface of a first overlay paper layer to a same type or different type electrically-conductive material disposed on a top surface of a second paper layer disposed thereunder. Once disposed, the electrically-conductive material may be subject to the high pressure lamination process involving pressing at elevated temperature and pressure.
The electrically-conductive material described above may be disposed in a pattern over the paper layers in various embodiments of the present disclosure. Suitable patterns include, but are not limited to: continuous, meandering lines, spirals, circles, ovals, polyhedral shapes such as rectangles, squares, hexagons, octagons, spirangles, sawtooth waves, and combinations thereof. Preferably, electrically-conductive materials may be disposed in patterns which provide a relatively large amount of electrically-conductive material on the paper layer while maintaining a gap between adjacent portions of the electrically-conductive pathway. The cross-sectional area of any linear portion of an electrically-conductive material may be important in circumstances where electrical resistance is to be minimized as the total electrical resistance of any electrically-conductive track is the product of the specific resistance per square (related to cross-sectional area) and the track length. In other words, as understood by those skilled in the art, greater cross-sectional areas lead to lower overall track resistances which lead to lower resistive heating for similar electric current levels.
It may be preferable to optimize the relationship between track vertical thickness, the cross sectional area and the pitch (i.e., the distance between two adjacent linear portions or tracks of the electrically-conductive material disposed on a paper layer) which should be controlled to be as small as possible while ensuring that the two adjacent linear portions do not touch. It is also important to note that the pressure involved in the compression steps of the high pressure lamination process reduces the vertical thickness of the electrically-conductive track. The overall effect on total electrical resistance may vary as the compression may increase specific resistance of the electrically-conductive material by decreasing the cross-sectional area, while also increasing electrically-conductive contact between electrically-conductive particles within the electrically-conductive materials, thus decreasing resistance. Thus, various factors affect overall resistance. Preferably one or more such factors are considered in efforts to reduce overall resistance, and thus, heat generation.
The laminate in accordance with the various embodiments of the present disclosure may include one or more electrical contact pads which allow an electrical connection to be established to a via from the exterior of the laminate. In various embodiments wherein the laminate includes the electrical element comprising same or different electrically-conductive materials connected together, as described herein, the laminate may include an electrical contact pad coupled to a via providing a site for making an electrical connection to a first terminus of the first electrically-conductive material, and a second electrical contact pad coupled to a second via providing a site for making an electrical connection to the second terminus of the second electrically-conductive material. In the various embodiments of the present disclosure, the laminate may further be coupled to a component or components connected to the electrical contact pads on the exterior of the laminate which component(s) are configured to accept AC, or pulsed DC, voltage input from an electrical source such that the electrically-conductive material(s) are provided with a current. Such components may include, but are not limited to various receptacles for AC and DC plugs, and terminal boxes or the like for hard-wiring AC or DC inputs. Electrical contact with the vias may also be established by coupling any electrically-conductive material to the electrical contact pads using various structures including but not limited to metal tabs, screws, prongs, cylindrical receptacles, spring-loaded pins, etc. Additionally, methods of establishing permanent electrical contact can be established by affixing an external component or conductor to the electrical contact pads by soldering or the use of conductive adhesives.
A laminate's paper layers may be impregnated with resin such that the paper layers, when stacked and compressed in the high pressure lamination process, can be cured or cross-linked. The resin can be a thermoset resin such that the paper layers in a stacked relationship can be compressed and heated to cure the thermoset resin. Specific suitable resins for use in the various embodiments of the present disclosure may differ depending on whether the resin-impregnated paper layer is an outer protective layer (e.g., an insulating layer), or an interior core layer (e.g., a treated kraft paper layer), or a base layer of the laminate surfacing material (e.g., a treated kraft paper layer). Generally, resin-impregnated paper layers are impregnated with any suitable thermoset resin including, but not limited to, acrylics, polyesters, polyurethanes, phenolics, phenol-formaldehydes, urea-formaldehydes, aminoplastics, melamines, melamine formaldehydes, diallyl-phthalates, epoxides, polyimides, cyanates, and polycyanurates, or copolymers, terpolymers or combinations thereof. Phenol-formaldehydes are generally preferred for impregnating kraft paper and acrylics or melamine-formaldehydes are generally preferred for impregnating overlay paper. As used in this disclosure, an insulating layer may be a translucent layer. A translucent layer means any layer that permits at least some light to pass there through. In other words, layers that are partially opaque are included as translucent layers.
In some implementations, resin-impregnated paper layers which are core layers are impregnated with a phenolic and/or epoxy resin, such as, for example, a phenolic-formaldehyde resin. Impregnating paper layers with a resin can be carried out in any suitable manner sufficient to apply a controlled quantity of resin to the paper, including but not limited to, screen printing, rotary screen printing, dip and squeeze, dip and scrape, reverse roll-coating, Meyer bar, curtain coating, slot-dye and gravure roller. The weight percentage of resin applied, relative to the weight of the paper layer as measured on an oven dried basis, is in the range of about 5 to 75%, with a preferred resin content percent (determined relative to final weight) of about 15-45%. As the resins used in the impregnating step are normally aqueous or solvent based solutions, it is common in the laminating process to include a paper drying stage to reduce the paper solvent loading. In the various embodiments of the present disclosure, the weight percent level of residual solvent in the impregnated paper may be 2.5-15% with a typical level of about 5%. As used herein, cured can refer to both curing of a thermoset resin in the sense of its irreversible setting, or the crosslinking of other polymers with a separate cross-linker or by various forms of energy, or any means of fixing the resin when the laminate surfacing material is in its compressed form such that the electrically-conductive materials are encapsulated and will remain so during normal operation.
Suitable papers which may be used in resin-impregnated paper layers in accordance with the various embodiments of the present disclosure include but are not limited to: cellulose fiber, synthetic woven or non-woven fiber, or/and microfiber or/and nanofiber, mixtures of cellulose or/and synthetic fiber based papers or/and mineral fiber based papers or/and glass fiber based papers, coated or non-coated, pre-impregnated or non pre-impregnated that could be generally used for the production of laminates. In various embodiments of the present disclosure, paper suitable for use in resin-impregnated paper layers has at least one of the following properties: a minimum wet strength in the machine direction of 1400 cN/30 mm in accordance with the test method of the International Standard DIN ISO 3781, a Klemm absorbency range (capillary rise) in the machine direction of 30 to 90 mm/10 min in accordance with the test method of the International Standard DIN ISO 8787 with a preferred absorbency of 45 mm/10 min, Ash content 0 to 50% depending of the intrinsic nature of the paper used in accordance with the test method of the International Standard Din ISO 2144, a basis weight range of 10 to 400 GSM at moisture content range of 2 to 8% in accordance with the test method of the International Standard DIN ISO 536, a pH (on hot extract) between about 4 to 9 in accordance with the test method of the International Standard DIN ISO 6588. In various embodiments of the present invention, papers comprising at least a portion of recycled materials may be used.
In various preferred embodiments of methods of manufacturing surfacing materials in accordance with the present disclosure, the high pressure lamination process may be employed. In accordance with such various preferred embodiments, the multiple layers, including both paper layers and layers of the electrical element according to any of the previously described embodiments are positioned in a stacked relationship between two pressing plates. In such a high pressure lamination process, the plates are then pressed to a specific pressure of at least 5 MPa. The temperature is then raised in excess of 125° C., typically to about 140° C. The plates are then held at the elevated pressure and temperature for a period of time suitable for curing the resin. The temperature may then be lowered to 40° C., while maintaining the elevated pressure. The typical cycle time under pressure is between about 25 and about 50 minutes. Upon achieving a temperature of 40° C., the pressure on the plates may then be reduced to zero gauge pressure. While it is important to take care in ensuring that the stacked layers are aligned where a conductive connection between adjacent electrically-conductive materials through an aperture in an intervening layer is to be established, the layers need not otherwise be placed in perfect edge to edge alignment, as a post-pressing trimming may be carried out to shape the final surfacing material.
While resin-impregnated layers are typically used to prepare the laminates comprising an electrical element disposed on discrete layers of the laminate according to the disclosure, alternatively, paper layers having pressure-sensitive adhesives thereon can be compressed with the pressure-sensitive adhesives in a facing relationship to form a comparable laminate structure. In such a process, a mask can be applied at any locations where vias are desired in the final laminate product to facilitate via formation, similar to the procedure described herein with reference to
Other examples of electronic components that may be included in the core of the laminate include components needed to provide current to the electrical element. In an implementation, a power transistor serves as an amplifier for driving the electrical element in the installed laminate. A full wave rectifier is configured to convert incoming AC power from a power source to a DC value for use in driving the electrical element in the installed laminate. A voltage regulator is configured to create a usable voltage for charging depleted batteries in an electronic component. A control circuit is configured to manage the charging process for lithium-ion (Li-Ion) or NiMH battery chemistries, etc.) in electronic components. An integrated circuit comprising an RC oscillator is configured to detect changes in, capacitance in the electrical element. Each of these components can be coupled to the electrical element in the laminate surfacing material and disposed between discrete layers of the laminate surfacing material.
Bubble 104 illustrates a cross-section view of an example laminate including the electrical element disposed on different layers of the laminate. In an implementation, electrically-conductive material (e.g., electrically-conductive ink) is disposed in the shape of electrically-conductive plates on paper layers of the substrate. Throughout this disclosure, references to electrically-conductive material or ink should be understood to include the electrically-conductive material or ink itself in addition to electrically-conductive particles left behind after the electrically-conductive material or ink has dried.
Several layers forming the electrical element are generally illustrated in bubble 104. In the cross-section view of bubble 104, paper layer 112, optional additional paper layers 114, 116, optional decorative paper layer 110, and insulating layer 108 are visible along the cross-section. Paper layers 112-116 each illustrate at least first and second via holes through each layer. In an implementation, electrically-conductive material may be disposed on one or more layers 112-116 constituting the laminate surfacing material 106. In such a cross-section view, a capacitive switch or other electrical component(s) embedded in layers 112-116 of the laminate surfacing material may extend linearly along the line L or may be in a direction perpendicular to the line L, in which case the layers of the capacitive switch or other electrical component(s) would appear shorter in the cross-section view because only the width of the electrically-conductive track, and not the length, would be visible.
In use, the surface 102 may be equipped with an electronic component (e.g., an oscillator capable of producing a chosen resonant frequency, a power transistor to serve as an amplifier for driving the electrically-conductive material(s), a full wave rectifier to convert incoming AC power to a DC value, a voltage regulator to create a usable voltage for charging depleted batteries, a control circuit to manage the charging process for lithium-ion (Li-Ion) or NiMH battery chemistries), or a power supply to provide AC, or pulsed DC), voltage such that the electrically-conductive material(s) are provided with a current. The electronic component may be electrically connected to the electrically-conductive material(s) disposed in layers 112-116 to provide the voltage. In at least one implementation, the electronic device may be physically enclosed in a structure beneath surface 102 and user interface controls are displayed to the user via surface 102 (e.g., LED lights embedded in surface 102, a control panel installed in surface 102).
As shown in row 204, any one or more of the paper layers 112-114 may include a hole or via that may be formed or cut through the entire paper layer. For example, paper layer 112 includes via holes 212, 218. If the laminate 200 requires additional paper layers, additional paper layers 114, 116 include via holes 210, 216 and via holes 208, 214, respectively. The via holes described may be formed, cut through, or punched through, such as by a mechanical device or a laser, such that upon stacking paper layers on top of each other, when filled with electrically conductive material, the via holes are vertically aligned. For example, via holes 208, 210, and 212 are vertically aligned and via holes 214, 216, and 218 are vertically aligned when paper layers 112-116 in row 204 are stacked on top of each other. As such, via holes of one paper layer may overlie via holes of another paper layer such that the holes are vertically aligned, so as to facilitate via formation.
As shown in row 206, an electrically-conductive material may be disposed over a portion of paper layer 112 to form a first electrically-conductive layer 220 of the capacitive switch. Similarly, the electrically-conductive material may be disposed over another portion of paper layer 112 to form a second electrically-conductive layer 222 of the capacitive switch. In various embodiments of the present disclosure, one or more electrically-conductive materials may be disposed on either side or both of one or more paper layers. The electrically-conductive materials may be disposed in any shape, size, and may even form an outline of an aesthetic design. Electrically-conductive materials suitable for use in accordance with the various embodiments of the laminate 200 include any material which can be deposited upon paper, particularly resin-impregnated paper, and which may be electrically electrically-conductive. Suitable electrically-conductive materials include metals, alloys, and electrically-conductive inks. Electrically-conductive inks are commercially available from a number of sources and can be prepared using a number of known methods. Particularly preferred electrically-conductive inks suitable for use in various preferred embodiments of the present disclosure include silver and/or electrically-conductive carbon particles.
By filling the via holes 212, 218 with an electrically-conductive material, the first electrically-conductive layer 220 may be electrically coupled to the via hole 212 because the via hole 212 makes electrical contact with the first electrically-conductive layer 220 disposed over paper layer 112. Similarly, the second electrically-conductive layer 222 may be electrically coupled to the via hole 218 because the via hole 218 makes electrical contact with the second electrically-conductive layer 222 disposed over paper layer 112. The electrically-conductive material used to fill via holes 212 and 218 may be the same or different material as the electrically-conductive material disposed over paper layer 112 to form the first electrically-conductive layer 220 and the second electrically-conductive layer 222. If additional paper layers 114, 116 are disposed on the side of the paper layer 112 opposite the first electrically-conductive layer 220 and second electrically-conductive layer 222 of the capacitive switch, the electrically-conductive material may fill via holes 208, 210 and be electrically coupled to the first electrically-conductive layer 220 with via hole 212. Similarly, the electrically-conductive material may fill via holes 214, 216 and be electrically coupled to the second electrically-conductive layer 222 with via hole 218. If needed, the decorative paper layer 110 may be disposed over first electrically-conductive layer 220 and second electrically-conductive layer 222. It should be understood that throughout this application via holes are alternatively referred to as vias once conductive material is included therein and a lamination process that establishes electrical contact between conductive elements is performed
After a lamination process, the paper layer 112 and the insulating layer 108 encapsulate the first electrically-conductive layer 220 and second electrically-conductive layer 222 within the laminate 200. Specifically, after the layers described above undergo a lamination process, preferably a high pressure lamination process, the resin that may be impregnated in the paper layer 112 consolidates and bonds together (by heat and pressure) the first electrically-conductive layer 220 and second electrically-conductive layer 222 into a substantially continuous resin structure having significant mechanical structure, thereby forming the laminate 222.
An integrated circuit comprising an RC oscillator may provide an electrical signal to the first electrically-conductive layer 220 of the capacitive switch, which subsequently generates an electric field based on the electrical signal. The RC oscillator may then measure the capacitance between the first electrically-conductive layer 220 of the capacitive switch and a second electrically-conductive layer 222 of the capacitive switch, which may be ground potential. The capacitance may be changed by for example, a finger of a user being brought close to a region of the first electrically-conductive layer 220 formed by the electric field. The change in capacitance influences the oscillation amplitude of the RC oscillator, and this change may be compared with a predetermineable threshold using a comparison unit in the integrated circuit. If the threshold is reached or exceeded, the electrical source may trigger an action, such as switching on or off a light that may be controlled by the integrated circuit.
A resin-treating operation 304 impregnates the kraft paper 314 with a resin to form resin-treated paper 322. The mask 316 protects a portion 324 of the resin-treated kraft paper 322 during the resin-treating operation 304 and the portion 324 does not become impregnated with the resin. A removing operation 306 removes the mask 316, exposing the untreated region 324 of the resin-treated kraft paper 322.
A disposing operation 308 disposes electrically-conductive material (e.g., the first electrically-conductive material 318) onto the untreated region 324 of the resin-treated kraft paper 322. The electrically-conductive material saturates untreated region 324, but does not saturate the resin-treated region of kraft paper 314, thereby allowing for electrical conductivity through the paper 314.
The method 500 may begin by forming first and second via holes through a first paper layer (block 502). With reference to
Method 500 proceeds by disposing a first electrically-conductive layer over a portion of the first paper layer, the first electrically-conductive layer including an electrically-conductive material (block 504). With reference to
Method 500 proceeds by disposing an insulating layer over the first and second electrically-conductive layers, thereby encapsulating with the first paper layer, the first and second electrically-conductive layers within the laminate (block 510). Lastly, method 500 proceeds by compressing the first paper layer, the first and second electrically-conductive layers, the insulating layer, and the filled first and second via holes according to a lamination process, thereby electrically connecting the first via to the first electrically-conductive layer and the second via to the second electrically-conductive layer and encapsulating with the first paper layer 112, the first electrically-conductive layer 220 and second electrically-conductive layer 22 within the laminate (block 512).
By using via holes, the disclosed laminate advantageously utilizes different layers to interconnect layers of a capacitive switch disposed within the laminate 200. In addition, because the paper layer 112 and the insulating layer 108 encapsulate the first electrically-conductive layer 220 and the second electrically-conductive layer 222 within the laminate 200, layers of a capacitive switch may be protected during usage of the laminate 200.
In addition to the advantages listed above, further advantages can be realized with additional structural modifications to the laminate 200. For instance, in order to encapsulate the first electrically-conductive layer 220 and the second electrically-conductive layer 222 into a continuous resin structure, rather than impregnating the paper layer 112 with a resin material, a glue film layer impregnated with a resin material may be disposed between untreated paper layer 112 and the insulating layer 108. Similarly, if decorative paper layer 110 is needed, the glue film layer impregnated with a resin material may be disposed between the paper layer 112 and the decorative paper layer 110. After undergoing the high pressure lamination process, the resin material from the glue film layer can saturate untreated paper, such as untreated paper layer 112, untreated decorative paper layer 110, and insulating layer 108, to encapsulate the first electrically-conductive layer 220 and the second electrically-conductive layer 222 into a continuous resin structure.
Although the laminate 200 as illustrated includes paper layer 112 and optional paper layers 114, 116, optional decorative paper layer 110, and an insulating layer 108, it should be understood that the present disclosure is not limited to the precise configuration shown. For instance, additional paper layers may be stacked below optional paper layer 116. Such additional paper layers may provide space for embedding one or more electrical components to drive the capacitive switch disposed within the laminate.
For example,
First electrically-conductive layer 610 may be electrically coupled to first via hole 608 of untreated paper layer 606 (when filled with electrically-conductive material), and second electrically-conductive layer 614 may be electrically coupled to second via hole 612 of untreated paper layer 606 (when filled with electrically-conductive material). Glue film layer 616.1 may have via holes 618 and 620 that traverse via holes 608 and 612 of untreated paper layer 606 such that electrically-conductive material may electrically couple first electrically-conductive layer 610 and second electrically-conductive layer 614 to other electrical elements or electrically-conductive layers within the laminate 600. Untreated paper layer 606.1 may have via holes 608.1 and 612.1 that traverse via holes 618 and 620 of glue film layer 616.1 such that electrically-conductive material (610.1, 612.1) may electrically couple first electrically-conductive layer 610 and second electrically-conductive layer 614 to other electrical elements or electrically-conductive layers within the laminate 600, if untreated paper layer 606.1 is necessary. Glue film layer 616.2 may have via holes 622 and 624 that traverse via holes 608.1 and 612.1 of untreated paper layer 606.1 such that electrically-conductive material (610.1, 612.1) may electrically couple first electrically-conductive layer 610 and second electrically-conductive layer 614 to other electrical elements or electrically-conductive layers within the laminate 600, if glue film layer 616.2 is necessary. Untreated paper layer 606.2 may have via holes 608.2 and 612.2 that traverse via holes 622 and 624 of glue film layer 616.2 such that electrically-conductive material (610.2, 612.2) may electrically couple first electrically-conductive layer 610 and second electrically-conductive layer 614 to other electrical elements or electrically-conductive layers within the laminate 600, if untreated paper layer 606.2 is necessary. Glue film layer 616.3 may have via holes 626 and 628 that traverse via holes 608.2 and 612.2 of untreated paper layer 606.2 such that electrically-conductive material (610.2, 612.2) may electrically couple first electrically-conductive layer 610 and second electrically-conductive layer 614 to other electrical elements or electrically-conductive layers within the laminate 600, if glue film layer 616.3 is necessary.
The untreated paper layer 606 (and additional paper layers 606.1 and/or 606.2 if necessary) and the insulating layer 602 may encapsulate the first electrically-conductive layer 610 and second electrically-conductive layer 614 within the laminate 600 after the high pressure lamination process, to produce laminate 630.
As used herein, the singular terms “a” and “the” are synonymous and used interchangeably with “one or more” and “at least one,” unless the language and/or context clearly indicates otherwise. Accordingly, for example, reference to “a paper layer” or “the paper layer” herein or in the appended claims can refer to a single paper layer or more than one paper layer. Additionally, all numerical values, unless otherwise specifically noted, are understood to be modified by the word “about.”
For simplicity and clarity of illustration, elements in the figures are not necessarily to scale, and the same reference numbers in different figures denote the same elements. For clarity of the drawing, layers and electrically-conductive materials may be shown as having generally straight line edges and precise angular corners. However, those skilled in the art understand that the edges need not be straight lines and the corners need not be precise angles.
Certain terminology is used in the following description for convenience only and is not limiting. Ordinal designations used herein and an it appended claims, such as “first”, “second”, “third”, etc., are solely for the purpose of distinguishing separate, multiple, similar elements (e.g., a first paper layer and a second paper layer), and do not import any specific ordering or spatial limitations unless otherwise required by context.
The applications and benefits of the systems, methods and techniques described herein are not limited to only the above examples. Many other applications and benefits are possible by using the systems, methods and techniques described herein.
Moreover, although the foregoing text sets forth a detailed description of numerous different embodiments, it should be understood that the scope of the patent is defined by the words of the claims set forth at the end of this patent. The detailed description is to be construed as exemplary only and does not describe every possible embodiment because describing every possible embodiment would be impractical, if not impossible. Numerous alternative embodiments could be implemented, using either current technology or technology developed after the filing date of this patent, which would still fall within the scope of the claims.
It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims.
