Patent Application
20080179081
This invention relates generally to electronic circuits and, more particularly, to the layout and construction of printed electronic circuits.
In the electronics industry, printed circuit boards or PCB's are used to mechanically support and electrically connect electronic components. Such PCB's are mass produced using a variety of different techniques with the majority being formed from a cladding/etching process.
In the cladding/etching process, a conductive material (e.g., copper) is laminated or glued over a substrate of non-conductive or insulating material (e.g., woven fiberglass), a mask is placed over the conductive material, and any unwanted conductive material left exposed by the mask is chemically etched away. When the mask is removed, conductive pathways or traces of the conducting material remain. These traces provide locations for the electronic components to be attached using, for example, solder. As a result, the electronic components are adequately supported by, and electrically coupled through, the PCB.
Unfortunately, many of the prevalent cladding/etching processes are expensive, present potential environmental risks due to the hazardous materials involved, and result in a lengthy fabrication lead time. Even so, the cladding/etching processes are often used because they produce PCB's that permit electronic components to be quickly and easily electrically connected using tin/lead solder. However, recent compliance and regulatory issues with heavy metals have encouraged other soldering materials and other circuit board processes to be contemplated.
In addition to the above, PCB's produced using the standard cladding/etching processes have other significant drawbacks. For example, each of the PCB's requires at least one substrate layer to support the electronic components. The substrate layer takes up a significant amount of space within the housing of electronic device. These PCBs also typically require mechanical connectors to hold them in place within the housing, taking up additional room. As consumers and others demand smaller and smaller electronic devices, the use of any component that uses such a large portion of the area within the electronic device is undesirable.
Conventional PCB's also rely on a relatively costly metal conductive layer such as, for example, copper. As consumers and other demand less and less expensive electronic devices, the use of any component that adds to the overall unit cost of the electronic device is undesirable.
Therefore, an electric circuit that is mechanically supported and electrically connected without the use of a typical PCB would be desirable. The invention provides such an electronic circuit. These and other advantages of the invention, as well as additional inventive features, will be apparent from the description of the invention provided herein.
The invention provides an electronic circuit, and method of fabricating the same, that employs adjacent structure as a substrate for the circuit. As such, the electronic circuit is less costly to manufacture, takes up less space, and provides other advantages compared with the conventional PCB technology discussed above.
In one embodiment, an electronic circuit formed on a non-conductive substrate from a conductive adhesive adhered to the substrate in a trace pattern is provided. The conductive adhesive electrically connects the electronic components to form the electronic circuit.
In another embodiment, an electronic circuit for a consumer product formed on the housing of the consumer product from a conductive adhesive is provided. The housing of the consumer product includes an internal surface and the conductive adhesive is adhered to that internal surface. The electronic components of the electronic circuit are positioned and held by and electrically coupled via the conductive adhesive.
In yet another embodiment, a method of increasing useable space within a housing of a device is provided. The method includes the steps of adhering a conductive adhesive to the housing and electrically connecting electronic components with the conductive adhesive.
In another embodiment, a method of creating an electronic circuit on a non-conductive product is provided. The method includes the steps of adhering a conductive adhesive to the non-conductive product and electrically connecting electronic components using the conductive adhesive.
Other aspects, objectives and advantages of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.
The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention and, together with the description, serve to explain the principles of the invention. In the drawings:
While the invention will be described in connection with certain preferred embodiments, there is no intent to limit it to those embodiments. On the contrary, the intent is to cover all alternatives, modifications and equivalents as included within the spirit and scope of the invention as defined by the appended claims.
Referring to
In the illustrated embodiment as shown in
In one embodiment, the substrate 12 is generally formed from a material or materials not commonly found or expected in a standard or conventional printed circuit board (PCB). Such materials include, by way of example and not limitation, paper impregnated with phenolic resin, woven fiberglass mat impregnated with a flame resistant epoxy resin, plastics with low dielectric constant and dissipation factor, and the like specialty materials. Other materials commonly used to house consumer and commercial products may also form the substrate 12, provided that such materials are non-conductive or otherwise electrically insulated from the conductive adhesive 14 that forms the circuit traces of the present invention.
As shown, the substrate 12 defines a surface 16. In the illustrated embodiment, the surface 16 is an internal surface directed inwardly away from an external environment relative to the electronic device. In one embodiment, the surface 16 is on an external or interior portion of an electronic device, on a portion of a consumer or retail product, and the like. Although shown as a plane in
Still referring to
Suitable conductive adhesives 14 for use in the electronic circuit 10 include, for example, conductive impregnated Epoxy, Cyanoacrylate, Polyurethane and Silicone adhesives. These conductive adhesives 14 can also be used as a base to support the appropriate substrate. In addition, the conductive adhesives 14 are able to adhere to paper, plastic, glass, and other surfaces. In one embodiment, the conductive adhesive 14 is used as a glue or laminate. The conductive adhesive 14 may be in the form of a tape, film, paste or other material. For example, the conductive adhesive 14 can be formed from a sticky-back tape. Also, both isotropically conductive adhesive (ICA) and anisotropically conductive adhesives (ACA) may be used for the conductive adhesive 14.
As shown in
In one embodiment, the conductive adhesive 14 remains flexible or semi-rigid after having been applied such that flexing, stretching, bending, or other movement of the substrate 12 is accommodated without damaging the electronic circuit 10. Because the conductive adhesive 14 has this feature, the electronic circuit 10 is useable in applications where a PCB with a stiff and inflexible substrate and/or brittle solder joints are not practicable or feasible.
The conductive adhesive 14 is applied to the surface 16 of the substrate 12 through a process of, for example, spraying, silk screening, X-Y plotting, printing, stenciling, or another suitable adhesive application or printing method. In one embodiment, the conductive adhesive 14 is situated on the surface 16 of the substrate 12 in a trace or circuit layout pattern similar to those formed during a conventional cladding/etching process. By applying the conductive adhesive 14 in such a pattern, the electronic components 18 are more easily and/or efficiently positioned on the electronic circuit 10.
In one embodiment, after the conductive adhesive 14 is applied to the surface 16 of the substrate 12, depending on the type of adhesive chosen the adhesive may be cured, baked, exposed to a solvent, exposed to an accelerant, or otherwise treated. For example, where a Cyanoacrylate adhesive is selected, either a chemical accelerant or Infrared (IR) radiation may be applied to control the cure rate of the application.
The electronic components 18 shown in
As a result of the conductive adhesive 14 being directly applied to the surface 16 of the substrate 12, the need for a conventional substrate required by conventional PCB's is eliminated. The substrate 12 of
In the embodiment illustrated in
With the first trace 20 secured to the substrate 12 and the electrical components positioned on the first trace, a dielectric material 22 is applied. The dielectric material 22 may be sprayed, printed or otherwise applied to the substrate 12. When applied according to a predetermined path where it encounters the first trace 20, the dielectric material continues over and lays upon the first trace. In one embodiment, the dielectric material 22 is a dielectric spray coating, a strip of dielectric material, a dielectric paste, or another type of dielectric material.
In one embodiment, the dielectric material 22 need not cover a substantial portion of the substrate and may be restricted to areas surrounding or proximate the first trace 20. In other words, the dielectric material may be truncated or otherwise restricted in size and area. For example, in one embodiment the dielectric material 22 may cover only the underlying trace (e.g., the first trace 20) and a portion of the substrate to adjacent to that underlying trace. Also, the dielectric material 22 may have a pattern or path that causes the dielectric material to cover some or all of the electrical components 18 on the first trace 20.
With the dielectric material 22 in place, the conductive adhesive 14 is applied upon the dielectric material 22, the substrate 12, and/or the first trace 20 in the form of a second trace 24. As shown in
In the illustrated embodiment of
In addition to the above, because the electronic components 18 are mechanically coupled to the substrate 12 using the conductive adhesive 14, the electronic circuit 10 of
From the foregoing, those skilled in the art will appreciate that the invention has a myriad of diverse applications. As an example, the electronic circuit 10 is employed in consumer electronics devices where, due to their size, internal space is at a premium. Such devices include, but are not limited to, cell phones, digital cameras, computers, and the like. In such examples, the electronic circuit 10 preferably employs a portion of the device's housing to form the substrate 12. In other applications, the electronic circuit 10 is placed in or on greeting cards, promotional materials, and other paper or non-ridged housing products.
Other advantages of the electronic circuit 10 are readily apparent as well. For example, by eliminating the conventional substrate layer found in PCB's and taking advantage of the existing adjacent housing or product, the electronic circuit 10 has lower production costs. No additional conventional substrate must be purchase or made. The electronic circuit 10 also has a higher level of integration which increases its reliability. In addition, by incorporating existing adjacent structure, the electronic circuit 10 eliminates wasted mechanical space.
All references, including publications, patent applications, and patents cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.
The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) is to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.
Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.
