The present disclosure generally relates to methods of protecting electronic devices, such as a cell phone or computer, by applying an electrically insulating polymer to certain device components, and a polymer capable of conducting a charge to different device components. The present disclosure also relates to methods of rendering an electronic device hydrophobic by applying these different materials to different components on the printed circuit board of the device. The present disclosure further relates to devices protected by such polymeric coatings, including any device containing a printed circuit board.
Electronic devices are comprised of electrically conductive and insulating components, which can be adversely affected by a variety of contaminants. Exposure to liquids like water, will often lead to corrosion of these components that will eventually destroy the function of the electronic device. In addition, as such devices become more sophisticated with increased functionality, they are being used in more hazardous environments that require greater protection from contaminants, especially liquids.
As a result, water resistant coatings are becoming a more popular form of protection of such devices. However, most water resistance technologies provide only one form of nano-coating (one molecule) and one method of application. Accordingly, there is need for coated electronic devices and methods that allow for protection of electronic devices from contaminates, such as liquids comprising water, including bodily fluids, such as sweat.
In view of the foregoing, there is disclosed a method for protecting an electronic device by applying different insulating and conducting materials on specified components of the device. In one embodiment, the disclosed method generally comprises treating, in any order, the backside and front side of the printed circuit board. In one embodiment, treating the backside of the circuit board comprises: applying an electrically insulating material to the surface of at least one component located on the backside of the circuit board. Non-limiting examples of the components that can be treated with the insulating polymer include at least one component and/or connector chosen from a printed circuit board, such as a flexible printed circuit connector, an LCD, a battery connector, a speaker connector, a camera connector, a light connector, and combinations thereof.
The method next comprises curing the insulating material, followed by applying a polymer capable of conducting a charge to at least one different component than the component containing the insulating polymer. Non-limiting examples of the components on which the polymer capable of conducting a charge is applied include at least one component and/or connector chosen from a power switch, a volume switch, RAM Chips, ROM Chips, USB charging port, MEMS, Microphone, SIM card housings, headphone jack, and combinations thereof.
The method of treating the front side of the printed circuit board comprises: applying an insulating polymer to the surface of at least component located on the front side of the circuit board. The previously mentioned components that are covered with the insulating polymer on the back side of the PCB are the same as on the front side, e.g., at least one component and/or connector chosen from an FPC connector, an LCD, a battery connector, a speaker connector, a camera connector, a light connector, and combinations thereof.
The method also comprises curing the insulating polymer, and applying a polymer capable of conducting a charge to at least one different component than the component containing the insulating polymer. The previously mentioned components that are covered with the polymer capable of conducting a charge on the back side of the PCB are the same as on the front side, e.g., at least one component and/or connector chosen from a power switch, a volume switch, RAM Chips, ROM Chips, USB charging port, MEMS, Microphone, SIM card housings, headphone jack, and combinations thereof.
The above methods next comprise assembling the electronic device by installing the printed circuit board and battery in a housing; connecting the male connectors of the device to base female connectors mounted on the back side of the printed circuit board; and applying the insulating polymer to the side of the connector in an amount sufficient to achieve wicking coverage around perimeter.
In one embodiment, the insulating polymer described herein may comprise an acrylic-based polymer, or a rubber, such as isobutylene isoprene rubber. In one embodiment, the polymers used herein can be fully cured when exposed to ambient conditions. For example, in one embodiment, the polymer capable of conducting a charge comprises a silicone-based polymer. Such a polymer can be cured when exposed to ambient conditions for up to 30 minutes. The insulating polymer can be cured when exposed to ambient conditions for up to 24 hours, such as 12 to 18 hours.
There is also disclosed an electronic device protected from contaminants by the treatment method described herein. For example, there is described a printed circuit board having a front side and a back side, the backside comprising: at least one female connector having an insulating polymer located around the perimeter; at least one internal component having the insulating polymer located thereon; and at least one different internal component having a polymer capable of conducting a charge located thereon.
In an embodiment, the electronic device, such as a smart phone, described herein comprises: a printed circuit board having a front side and a back side, the backside comprising: at least one internal connector having an electrically insulating polymer located around the perimeter; at least one internal component having the insulating polymer located thereon; and at least one different internal component having a polymer capable of conducting a charge located thereon.
In this embodiment, the front side of the printed circuit board comprises: at least one internal connector having the insulating polymer located around the perimeter; at least one camera having the insulating polymer located around the perimeter; at least one internal component having the insulating polymer located thereon; and at least one different internal component having a polymer capable of conducting a charge located thereon.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.
The accompanying figures, which are incorporated in and constitute a part of this specification, illustrate several embodiments of the invention and together with the description, serve to explain the principles of the invention.
As used herein, “ambient conditions” refers to 72° F. and 45% humidity.
As used herein, “inert to conductivity” means that the material does not conduct or resist electrical charge.
As used herein, “insulating polymer” means the polymer does not conduct electricity.
As used herein, “insulating polymer” may be used interchangeably with the “first polymer” or “Polymer 1”, as used in the attached Figures.
As used herein, “conducting polymer” may be used interchangeably with the “second polymer” or “Polymer 2”, as used in the attached Figures.
In one embodiment, the “water contact angle” is measured using droplets of water that are placed onto a 304 stainless steel surface that has been treated with any of the described polymer(s). For example, a first polymer having a water contact angle greater than 90 degrees after curing means that a 304 stainless steel surface has been coated with the first polymer, which is then cured prior to a droplet of water being dropped thereon. The same is true for the water contact angle for a second polymer.
Other contact angles may also be used to characterize the hydrophobic properties of the described coatings placed on different substrates. For example, the oil contact angles described herein, were measured on treated glass slides and treated aluminum substrates. The methods used to measure these contact angles are similar to those described for the treated 304 stainless steel surface.
To protect an electronic device from contaminants, such as water and bodily fluid, there is disclosed a method of different polymers to different connections and components located on the printed circuit board.
Referring now to the
As described in
Treating the front side of the circuit board 150 comprises applying the first polymer around the perimeter of at least one female connector 160, around the perimeter of one or more connected cameras 170, to the surface of at least one internal component 180, or combinations thereof. Next, the first polymer is cured 190, prior to applying the second polymer to a different set of one or more internal components 192.
As further described in the flow chart of
In one embodiment, the first polymer in electrically insulating and has a higher hardness than the second polymer. For example, the first polymer may comprise an acrylic-based polymer, such as a fluoroacrylate. One non-limiting example of a fluorinated acrylic that can be used herein is shown in (I) below:
Upon curing, a coating comprising the acrylic-based polymer provides a hard barrier that exhibits excellent electrically insulating and anti-corrosion properties. Curing of the fluorinated, acrylic-based polymer typically comprises exposing the polymer to ambient conditions for at least 24 hours. This may be done under thermal conditions, for times less than 24 hours. When curing is done at a temperature above ambient temperature, it is done for a time sufficient to cure the polymer material. In one embodiment, first polymer is applied to the connector(s) and/or components in a single layer or in multiple discrete layers. In one embodiment, the thickness of each acrylic-based polymer layer ranges from 20 to 1000 nm, such as 100 to 800 nm, such as from 200 to 700 nm, or even 300 to 500 nm.
In another embodiment, the first polymer, which is electrically insulating, is a soft barrier coating, and not the hard barrier layer described above. In this embodiment, the first polymer has a hardness value less than the previously described acrylic-based polymer. For example, the first polymer may comprise a rubber, preferably a butyl rubber. Butyl rubbers, which are also called isobutylene-isoprene rubber, are synthetic rubbers produced by copolymerizing isobutylene with small amounts of isoprene.
Isobutylene isoprene rubber is known for its excellent resistance to water, steam, alkalis, and oxygenated solvents. It also very low gas permeation properties making it attractive for a barrier layer. In addition, to these excellent impermeability properties, the long polyisobutylene segments of the polymer chains of isobutylene isoprene rubber give it good flex properties.
For example, the polymer repeating units have the following structures:
Because the base polymer, polyisobutylene, is stereoregular (i.e., its pendant groups are arranged in a regular order along the polymer chains) and because the chains crystallize rapidly on stretching, butyl rubber containing only a small amount of isoprene is as strong as natural rubber. In one embodiment, first polymer is applied to the connector(s) and/or components in a single layer or in multiple discrete layers. In one embodiment, the thickness of each isobutylene isoprene rubber layer ranges from 20 to 1000 nm, such as 100 to 800 nm, such as from 200 to 700 nm, or even 300 to 500 nm.
In one embodiment, the second polymer is capable of carrying a charge, such as a silicone-based polymer. One non-limiting example of a silicone-based polymer that can be used herein is aliphatic siloxane, as shown in (II) below:
Upon curing, a coating comprising the silicon-based polymer provides improved surface properties, including improved hydrophobicity, improved oleophobicity and reduced friction. The coated surface also exhibits anti-corrosion properties. Curing of the silicone-based polymer typically comprises exposing the polymer to ambient conditions for at least 30 minutes. Alternatively, curing may be done under thermal conditions, such as heating above 80° C., such as from 90-110° C. for a time sufficient to cure the polymer. Such times ranges are typically up to 5 minutes, but may range from 2 to 10 minutes depending on the polymer composition and layer thickness. In one embodiment, the thickness of the silicone-based polymer layer ranges from 50 to 500 nm, such as 100 to 400 nm, 150 to 350 nm, or even 200 to 300 nm.
The silicone-based polymer may further comprise at least one hydrophobic agent, such as an organometallic compound. In one embodiment, the organometallic halogen material comprises at least one alkyl group and at least one halogen atom linked to a metal atom. Non-limiting examples of the metal atom include titanium, zirconium, tantalum, germanium, boron, strontium, iron, praseodymium, erbium, cerium, lithium, magnesium, aluminum, phosphorus and silicon.
In one embodiment, the first and second polymers are applied by at least one automated or manual deposition technique independently chosen from dipping, spraying, vacuum deposition, syringe dispensing, and wipe coating. The technique employed is selected to achieve the previously described thicknesses of each polymer deposited, e.g., an isobutylene isoprene rubber layer ranging from 20 to 1000 nm, and a silicone-based polymer layer ranging from 50 to 500 nm, including the nested ranges described above for each polymer.
One particularly useful automated coating system that can be used to deposit the first and/or second polymer is The Nordson ASYMTEK™ Select Coat® SL-940 Series conformal coating system. The Delta 6 S
Additional steps may be carried out before or after applying the first and/or second polymers. For example, in one embodiment, the method may further comprise cleaning the electronic component prior to applying either polymer material to remove dust, grime or other surface dirt.
Non-limiting examples of the electronic component that may be coated using the disclosed method include a power switch, a volume switch, a light, a liquid crystal display, a touch-screen, a touch panel, a camera, an antenna, an internal connector, such as a printed circuit board, and combinations thereof.
It is understood that when an internal connector has a male end and a female end, the method comprises applying the polymers to both the male end and the female end of the internal connector prior to connecting the male end to the female end.
There is also disclosed an electronic device that is protected from contaminants, such as water, because it comprises a hydrophobic polymer on at least one internal connector and/or one internal component.
Non-limiting examples of at least one or more devices that can be protected using the disclosed method include a cellular phone, a personal digital assistant (PDA), a tablet, a notebook, a laptop, a desktop computer, a music player, a camera, a video recorder, a battery, an electronic reader, a radio device, a gaming device, a server, headphones, terminal blocks, and control panels. In addition, other devices that can be protected using the disclosed method include a wearable device, a medical device, a radio controlled device, an industrial device, and an appliance device.
As discussed, both the first polymer and the second polymer exhibit hydrophobic properties, as determined by a water contact angle greater than 90° such that the first layer and second layer form a multilayer, hydrophobic coating on top of the internal component. In one embodiment, the first and second polymers have a water contact angle of at least 110°, such as 115° or greater, or any contact angle ranging from 90° to 120°, such as 100° to 120°.
It has been discovered that electronic devices that have been protected as described herein, have increased water resistance by at least one order of magnitude, as measured by the time to malfunction when immersed in water. In particular, the Inventors have discovered that by providing the multilayer, hydrophobic coating as a barrier layer on the vital, and highly susceptible parts of an electronic device, water resistance of the device can increase at least 10 times, such as more than 25 times, or even more than 50 times when compared to an unprotected device. Furthermore, because the multilayer, hydrophobic coating described herein is inert to conductivity, it does not interfere with the function of the resulting electronic device, while adding the improved water resistance.
Low surface tension of the coating solution as disclosed herein provides increased surface wetting, especially under low profile components. The polymers described herein also provide excellent repellency, anti-wetting and anti-sticking properties against fluids, including but not limited to water, hydrocarbons, silicones and photoresists. As a result, the dried film has low surface energy allowing water-based liquids to bead and drain freely.
In addition the polymers described herein, when applied as coatings, are insoluble in solvents such heptane, toluene and water. An additional benefit associated with the polymers described herein in their flexibility. As these layers do not require thermal treatment, or harsh chemicals, they can be applied to many different substrates, including glass, metals, such as aluminum, stainless, and polymers.
The features and advantages of the present invention are more fully shown by the following examples which are provided for purposes of illustration, and are not to be construed as limiting the invention in any way.
The following examples provide a step-by-step process of protecting a smart phone from contaminants by applying two different polymers to different components of the smart phone prior to final assembly of the device.
The process is described in
Then the isobutylene isoprene rubber was cured by exposing it to ambient conditions for 24 hours 225. After it was completely cured, an aliphatic siloxane was applied on various internal components 230 located on the backside of the PCB 200.
Next, the front side of the circuit board 240 was treated. This method comprised applying the isobutylene isoprene rubber around the perimeter of a flexible printed circuit (FPC) based female connector of the front side of the PCB 250. In subsequent steps, the isobutylene isoprene rubber was then applied around the perimeter of a connected camera 260 and various internal components 270 located on the front side of the circuit board 240.
The isobutylene isoprene rubber was cured by exposing it to ambient conditions for 24 hours 280. After it was completely cured, the aliphatic siloxane was applied on various internal components 285 located on the front side of the PCB 240.
The method next comprised assembling the electronic device 290. Assembling the electronic device included installing the printed circuit board and a battery in appropriate housing and connecting male connectors of the device to the base female connectors mounted on the back side of the printed circuit board. Finally, the isobutylene isoprene rubber was applied the side of each connector until full wicking around the perimeter occurred 295.
The smart phone protected by the process of this Example was then tested to determine the efficacy of the inventive process. It was discovered that a smart-phone device protected with the different polymers as described above exhibited at least one order of magnitude longer protection time when compared to the same device not protected with the disclosed polymers.
With reference to
In this embodiment, the isobutylene isoprene rubber was applied to perimeter of female connector and to other internal components, followed by curing the rubber. Next, aliphatic siloxane was applied to different internal components, which was followed by curing of this polymer.
With regard to the treatment of the front side of the PCB, again, isobutylene isoprene rubber was applied to internal components of the PCB via the Precision Spray Machine. For example, the isobutylene isoprene rubber was applied to the perimeter of female connectors, which was followed by curing the butyl rubber. Next, the aliphatic siloxane polymer was applied to different internal components, which is followed by curing of this polymer.
With reference to
With regard to the front side of the PCB, again both Polymers are hand dispensed, with Isobutylene isoprene rubber being applied to internal components, including to the perimeter of female connectors. Isobutylene isoprene rubber is then cured. Aliphatic siloxane is then applied to different internal component.
The process next focuses on the assembly of the device, which includes assembling the PCB completely into the device in order to make various connections, including FPC connections followed by applying isobutylene isoprene rubber to the connections. Next, a battery connection is made, followed by applying isobutylene isoprene rubber to the connection and curing it. After the phone assembly is complete, it is set aside for 24 Hours before testing.
In an embodiment according to the present disclosure, and with reference to
With reference to
In an embodiment according to the present disclosure, and with reference to
With reference to
Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with the true scope of the invention being indicated by the following claims.
This application claims is a continuation in part of U.S. patent application Ser. No. 15/268,373, filed on Sep. 16, 2016, which claims priority to U.S. Provisional Application No. 62/220,230, filed on Sep. 17, 2015, both of which are incorporated herein by reference in their entireties.
Number | Date | Country | |
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Parent | 15268373 | Sep 2016 | US |
Child | 15382241 | US |