PATENT DOCUMENT

Publication Number: US-8440926-B2
Application Number: US-79758010-A
Country: US
Kind Code: B2

Title: Low profile tape structures

Abstract:
Electronic devices may include electronic device structures such substrates, structures with cavities, and housing structures. Tape may be used to seal components to the surface of a substrate or within a cavity. The tape may have a nonstick polymer layer such as a layer of parylene and one or two layers of adhesive. The nonstick layer may be formed in a pattern so that some of the layer of adhesive is uncovered by the nonstick layer. The nonstick layer may be oriented so that the adhesive is interposed between the nonstick layer and a sealed component or may be oriented so that the nonstick layer is interposed between the adhesive layer and the sealed component. The component that is sealed by the tape may be an electrical component such as a dome switch or other mechanical or electrical component.

Claims:
What is claimed is: 
     
       1. Apparatus comprising:
 a structure having a cavity; 
 a component mounted in the cavity; and 
 tape that is attached to the structure over the cavity, wherein the tape has an adhesive layer having a thickness and has a nonstick polymer layer on the adhesive layer, wherein the nonstick polymer layer has a thickness that is five times less than the thickness of the adhesive layer, wherein the adhesive layer has first and second opposing surfaces, and wherein the nonstick polymer layer is patterned on the first surface so that some regions of the first surface are uncovered by any of the nonstick polymer layer. 
 
     
     
       2. The apparatus defined in  claim 1  wherein the nonstick polymer layer comprises parylene. 
     
     
       3. The apparatus defined in  claim 2  wherein the nonstick polymer layer comprises a layer of parylene and wherein the thickness of the polymer layer is less than three microns. 
     
     
       4. The apparatus defined in  claim 3  wherein the adhesive comprises permanent pressure sensitive adhesive. 
     
     
       5. The apparatus defined in  claim 4  wherein the patterned parylene layer on the first surface faces the component. 
     
     
       6. The apparatus defined in  claim 2  wherein the component comprises a switch. 
     
     
       7. The apparatus defined in  claim 6  wherein the component comprises a dome switch. 
     
     
       8. Apparatus, comprising:
 a structure; 
 a dome switch mounted to the structure; and 
 a tape that covers the dome switch, wherein the tape comprises a layer of adhesive and a layer of parylene on the adhesive and wherein the layer of parylene is interposed between the dome switch and the layer of adhesive. 
 
     
     
       9. The apparatus defined in  claim 8  wherein the structure has a surface to which the dome switch is mounted and wherein the layer of adhesive is attached to the surface and attaches the tape over the dome switch. 
     
     
       10. The apparatus defined in  claim 9  wherein the adhesive comprises permanent pressure sensitive adhesive. 
     
     
       11. The apparatus defined in  claim 10  wherein the layer of parylene has a thickness of less than 3 microns. 
     
     
       12. The apparatus defined in  claim 10  wherein the layer of parylene has a thickness of less than one micron. 
     
     
       13. The apparatus defined in  claim 8  wherein the structure has a cavity in which the dome switch is mounted. 
     
     
       14. The apparatus defined in  claim 13  wherein the parylene layer is patterned and covers only part of the adhesive layer. 
     
     
       15. Apparatus, comprising:
 a first structure; 
 a second structure; 
 double-sided adhesive tape that connects the first structure to the second structure, wherein the double-sided adhesive tape comprises a layer of polymer having a thickness of less than 3 microns and wherein the layer of polymer is interposed between first and second opposing layers of adhesive each having a thickness of greater than ten times the thickness of the layer of polymer. 
 
     
     
       16. The apparatus defined in  claim 15  wherein the layer of polymer comprises a layer of parylene. 
     
     
       17. The apparatus defined in  claim 16  wherein the layer of parylene has a thickness of less than one micron. 
     
     
       18. The apparatus defined in  claim 17  wherein the layers of adhesive comprise permanent pressure sensitive adhesive.

Description:
BACKGROUND 
     This relates generally to adhesive tape, and more particularly, to low profile tapes that connect and seal structures such as structures in electronic devices. 
     Electronic devices include components such as switches and other structures that can be sensitive to environmental intrusion. If dust or moisture invades the interior of a dome switch, for example, the switch may malfunction. Tape layers and coatings may be used to seal components such as these. 
     Electronic devices also include structures that are attached together using adhesive. In some arrangements, layers of adhesive-coated tape are used to connect structures together. 
     Conventional sealing approaches are not always able to provide adequate environmental protection. 
     Adhesive-tape attachment arrangements sometimes produce stack ups that are thicker than desired, due in part to the thickness of the adhesive-backed tape that is used in connecting device structures together. It may therefore not always be possible to use conventional adhesive-backed tape in sealing and attachment applications. 
     It would therefore be desirable to be able to provide improved adhesive-tape-based structures for sealing and securing structures for electronic device. 
     SUMMARY 
     Electronic devices may include electronic device structures such substrates, structures with cavities, and housing structures. Components such as dome switches, other electrical components, and mechanical components may be mounted in the cavities or on substrate surfaces. 
     Tape may be used to attach structures together and to seal electrical and mechanical components to prevent intrusion of dust and moisture. 
     The tape may have a flexible polymer substrate and one or more layers of adhesive. The tape may be implemented in a single-sided configuration, a configuration with a patterned substrate layer, or a double-sided configuration. 
     The flexible polymer substrate in the tape may be formed from a nonstick liner material such as parylene. This allows the thickness of the nonstick polymer layer to be significantly thinner than the thickness of the adhesive in the tape. For example, the nonstick layer may have a thickness that is ten times less than the adhesive (as an example). 
     The nonstick layer may be formed in a pattern so that some of the layer of adhesive is uncovered by the nonstick layer. The nonstick layer may be oriented so that the adhesive is interposed between the nonstick layer and a sealed component or may be oriented so that the nonstick layer is interposed between the adhesive layer and the sealed component. The component that is sealed by the tape may be an electrical component such as a dome switch or may be another mechanical or electrical component. 
     Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description of the preferred embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional side view of a conventional dome switch sealed with a layer of adhesive tape and a coating of parylene. 
         FIG. 2  is a perspective view of a piece of one-sided adhesive tape having an adhesive layer backed by a thin nonstick polymer layer such as a layer of parylene in accordance with an embodiment of the present invention. 
         FIG. 3  is a cross-sectional side view of an electrical component such as a dome switch that has been sealed using a one-sided adhesive tape layer of the type shown in  FIG. 2  in accordance with an embodiment of the present invention. 
         FIG. 4  is a cross-sectional side view of an illustrative electronic component such as a switch that has been covered with a layer of tape of the type shown in  FIG. 2  in accordance with an embodiment of the present invention. 
         FIG. 5  is a perspective view of an illustrative tape-based structure that has a removable backing layer, a layer of adhesive, and a patterned coating of a thin polymer such as parylene in accordance with an embodiment of the present invention. 
         FIG. 6  is a cross-sectional side view showing electronic device structures such as switches and other electrical and mechanical components that have been sealed using a tape structure of the type shown in  FIG. 5  in accordance with an embodiment of the present invention. 
         FIG. 7  is a perspective view of a double-sided adhesive tape formed from a thin polymer layer such as a parylene layer coated on both surfaces with layers of adhesive in accordance with an embodiment of the present invention. 
         FIG. 8  is a cross-sectional side view of an illustrative electronic device including structures attached with various types of adhesive layers including a one-sided tape of the type shown in  FIG. 2 , patterned tape of the type shown in  FIG. 5 , and a two-sided adhesive tape of the type shown in  FIG. 7  in accordance with an embodiment of the present invention. 
         FIG. 9  is a flow chart of illustrative steps involved in forming adhesive tapes and in using adhesive tapes to seal and attach electronic device structures in accordance with an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Layers of adhesive may be used in assembling structures in devices. For example, layers of adhesive-coated tape may be used to seal structures and may be used to attach structures together. The structures that are sealed and fastened together using adhesive-backed tape layers and other layers of adhesive may be, for example, electrical and mechanical structures in an electronic device such as a media player, a cellular telephone, a computer, or other electronic device. Adhesive layers may be helpful for reducing device size, for reducing assembly costs, for reducing part counts by avoiding the need to use fasteners such as screws, and for forming environmental seals to prevent the intrusion of dust and moisture. 
     A conventional switch that has been sealed using tape is shown in  FIG. 1 . As shown in  FIG. 1 , switch  10  has a body  12  that is formed from a material such as plastic. Dome switch  14  is mounted within cavity  16  in body  12 . The underside of dome switch  14  has a conductive coating. Layers  18  cover and seal dome switch  14  within cavity  16 . 
     When a user presses downward in direction  20  on layers  18 , underside  24  of layers  18  presses against upper surface  22  of dome switch  14 . This collapses the dome switch and causes the conductive coating on the interior of the dome switch to short together a pair of associated switch terminals. 
     Layers  18  may include a one-sided adhesive tape formed from adhesive layer  26  and liner layer  28 . In a typical one-sided tape such as the tape used in  FIG. 1 , the thickness T of the one-sided tape formed from layers  26  and  28  is about 100 microns (e.g., with about 50 microns of adhesive layer  26  and about 50 microns of liner  28 ). 
     To form a satisfactory environmental seal, the structures of  FIG. 1  including the adhesive tape formed from layers  26  and  28  may be coated with parylene layer  30 . Parylene is a material formed from poly(p-xylylene) polymers. Parylene is widely used for forming environmental sealing layers (i.e., moisture barriers). In a typical process, parylene layer  30  of  FIG. 1  may be deposited on the structures of  FIG. 1  and the tape layer formed from adhesive  26  and liner  28  using chemical vapor deposition. While this approach may form a satisfactory moisture barrier on switch  10  that prevents moisture from intruding into cavity  16 , there is a potential for the parylene coating itself to intrude into cavity  16  and dome switch  14  during the chemical vapor deposition process. In this situation, dome switch  14  may not function properly. The thickness T of the tape layer formed from adhesive  26  and liner  28  may also be greater than desired, particularly in compact device applications. 
     To reduce tape thickness while reducing the potential for parylene contamination of device components, a one-sided tape of the type shown in  FIG. 2  may be formed. Tape  32  of  FIG. 2  may have a layer of nonstick polymer liner  36  (i.e., a flexible substrate sheet) and a layer of adhesive  34 . 
     Liner layer  36  may be formed from a polymer such as parylene or other suitable material nonstick material that can serve as a substrate for adhesive  34 . For example, layer  36  may be formed from poly(p-xylylene) polymers using chemical vapor deposition. Parylene is able to form pin-hole free layers of several nanometers in thickness, helping to minimize the overall thickness of tape  32 . When tape  32  is implemented using parylene (e.g., when tape  32  is single-sided or double-sided parylene tape), tape thickness can be reduced relative to tape configurations that use relatively thick liner layers. Thickness D 2  of layer  36  may be 2 nm to 5 microns, 5-100 nm, 20-60 nm, about 40 nm, less than 3 microns, less than 1 micron, less than 0.5 microns, less than 100 nm, less than 50 nm, or greater than 50 nm (as examples). 
     Layer  34  may be formed from an adhesive such as a permanent or removable pressure sensitive adhesive (PSA). The thickness D 1  of layer  34  is typically significantly larger than the thickness D 2 . For example, D 1  may be three times thicker than D 2  and D 2  may be three times thinner than D 1 , D 1  may be five times thicker than D 2  and D 2  may be five times thinner than D 1 , D 1  may be ten times thicker than D 2  and D 2  may be ten times thinner than D 1 , or D 1  may be 100 times thicker than D 2  and D 2  may be 100 times thinner than D 1  (as examples). Typical thicknesses D 2  of adhesive layer  34  are 5-100 microns, 5-20 microns, about 10 microns, less than 70 microns, less than 50 microns, less than 20 microns, less than 15 microns, more than 20 microns, about 1-50 microns, etc. Any combination of these illustrative values for thicknesses D 1  and D 2  may be used if desired. 
     Tape  32  may be provided with a removable backing layer and may be dispensed from a roll (as an example). Cut pieces of tape  32  may be placed over a component that is to be sealed. The component that is to be sealed may be, for example, an electrical component such as a switch, a speaker, a microphone, a light source, a sensor, or other electrical device. The component that is to be sealed may also be a mechanical component such as a mechanical component that is sensitive to dust or moisture. 
       FIG. 3  is a cross-sectional side view of an illustrative dome switch that has been sealed using tape of the type shown in  FIG. 2 . As shown in  FIG. 3 , dome switch  38  may be sealed by placing one-sided adhesive tape  32  so that adhesive layer  34  is attached to surface  40  of switch body structure  46 . Structure  46  may be formed form plastic or other suitable materials. The shape of structure  46  may form a cavity such as cavity  42  in which dome switch  44  is mounted. When tape  32  is attached to surface  40  of structure  46  in the orientation shown in  FIG. 3 , adhesive layer  34  is located on the inner (interior) surface of tape (adjacent to internal cavity  42 ) and liner layer  36  is located on the outer (exterior) surface of tape  32 . 
     If desired, tape  32  may be used to seal components that are not mounted within housing cavities. A cross-sectional side view of an illustrative electronic component such as a switch that has been covered with a layer of tape of the type shown in  FIG. 2  is shown in  FIG. 4 . In the  FIG. 4  example, switch  38  has a dome switch element that is mounted on the planar surface of substrate  46 . As shown in  FIG. 4 , dome switch element  44  has been covered with tape  32  so that adhesive  34  is attached to substrate  46 . Substrate  46  may be formed from plastic, metal, glass, ceramic, composite materials, or combinations of these materials. Tape  32  may have a circular or rectangular footprint (i.e., a circular or rectangular outline when viewed in direction  48 ). 
     If desired, tape layers such as adhesive layer  34  and nonstick layer  36  may be patterned.  FIG. 5  shows an illustrative arrangement in which tape layer  32  is formed by depositing adhesive  34  on a removable backing layer such as layer  52  (e.g., a layer of polymer that does not adhere well to adhesive  34 ). Nonstick polymer layer  36  may be formed on top of layer  34 . Layer  36  may be patterned using a mask during chemical vapor deposition, using a laser cutting tool, using a stamp, blade, or other mechanical cutting tool, etc. As shown in  FIG. 5 , portion  36 ′ of layer  36  may then be removed in direction  54 , leaving openings  50  in layer  36 ′ and corresponding patterned portions of layer  36  on adhesive layer  34 . When it is desired to use tape  32  of  FIG. 5  to seal structures in an electronic device, polymer layers  36  may be placed over the structures to be sealed and backing layer  52  may be removed. 
       FIG. 6  is a cross-sectional side view of electronic device structures  56  in which patterned tape such as tape  32  of  FIG. 5  has been used to seal cavities  58  in structure  60 . Structure  60  may be, for example, a housing structure in which electrical and mechanical components  62  have been mounted. Components  62  may include dome switches, other switches, circuits, speakers, microphones, sensors, and other electrical and mechanical devices. Cavities  58  may be filled with air (as an example). Sealing layers  36  may have a shape (e.g., a rectangular footprint) that overlaps the outline of cavities  58  (which may also be rectangular). 
     Adhesive  34  may be used to attach layers  36  to the upper surface of structure  60 . When backing  52  ( FIG. 5 ) is removed, the outer (upper) surface of adhesive layer  34  will be exposed. If desired, additional structures such as structure  64  may be attached to structure  60  by placing structure  64  on adhesive  34 . 
     If desired, polymer layer  36  (e.g., a parylene layer) may be used as a substrate in forming a double-sided tape (i.e., by adding an adhesive layer to the exposed surface of a parylene layer or other polymer layer after a single-sided tape structure has been formed. An illustrative double-sided tape structure that may be used for tape  32  is shown in  FIG. 7 . As shown in  FIG. 7 , tape  32  may have upper adhesive layer  34 A and lower adhesive layer  34 B. Polymer layer  36  may be interposed between layers  34 A and  34 B. Layers  34 A and  34 B may be formed form pressure sensitive adhesive. Layer  36  may be formed from a polymer such as parylene. For example, layer  36  may be formed from poly(p-xylylene) polymers (parylene) using chemical vapor deposition. 
     Layer  36  may have a thickness of 2 nm to 5 microns, 5-100 nm, 20-60 nm, about 40 nm, less than 3 microns, less than 1 micron, less than 0.5 microns, less than 100 nm, less than 50 nm, or greater than 50 nm (as examples). Layers  34 A and  34 B may each have a thickness that is significantly larger than the thickness of layer  36 . For example, layers  34 A and  34 B may each have a thickness of 5-100 microns, 5-20 microns, about 10 microns, less than 70 microns, less than 50 microns, less than 20 microns, less than 15 microns, more than 20 microns, 1-50 microns, etc. 
     Double-sided tapes such as tape  32  of  FIG. 7  may be used to attach structures to each other within an electronic device or other structure.  FIG. 8  is a cross-sectional side view of electronic device structures  68  that include three different types of tape  32  (i.e., tapes  32 A,  32 B, and  32 C). In the example of  FIG. 8 , tape  32 A, tape  32 B, and tape  32 C are attached to structure  66 . Structure  66  may be a housing structure or other electronic device structure (as examples) and may be formed form plastic, metal, ceramic, glass, composite materials, other materials, or combinations of these materials. 
     Tape  32 A of  FIG. 8  is single-sided tape of the type shown in  FIG. 2 . Because the upper surface of tape  32 A is formed from nonstick layer  36 , structures such as structure  70  that are in contact with the exposed surface of nonstick layer  36  are able to move freely. For example, structure  70  may be moved in direction  74  to the position shown by dashed lines  72  without becoming permanently attached to adhesive layer  34  in tape  32 A. 
     Tape  32 B of  FIG. 8  is a tape with a patterned nonstick layer of the type described in connection with  FIG. 5 . As shown in  FIG. 8 , patterned nonstick layer  36  may be aligned with cavity  78  in structure  66 . Adhesive  34  may hold nonstick layer  36  in place over cavity  78 , thereby sealing cavity  78  and preventing components  80  in cavity  78  from being exposed to dust and moisture. Structures such as component  76  may be attached to adhesive layer  34 . When component  76  is attached to adhesive  34 , component  76  becomes attached to structure  66 . 
     Tape  32 C of  FIG. 8  is double-sided tape of the type shown in  FIG. 7 , having an upper adhesive layer  34 A, lower adhesive layer  34 B, and an interposed liner layer  36 . Tapes such as tape  32 C may be used to connect components together. In the  FIG. 8  example, structure  82  has been attached to structure  66  by tape  32 C. 
       FIG. 9  is a flow chart of illustrative steps involved in forming adhesive tapes and in using adhesive tapes to seal and attach electronic device structures. At step  84 , tape  32  may be formed (e.g., parylene or other polymer substances may be formed on adhesive layer  36  using chemical vapor deposition or other suitable techniques). Optional patterning operations may be performed at step  86  (e.g., by using a cutting tool). Tape layers may also be patterned by using masks during chemical vapor deposition operations. 
     At step  88 , tape  32  may be attached to structures such as housing structures, structures with cavities and components that are to be sealed (e.g., dome switches and other components of the types shown in  FIGS. 3 ,  4 ,  6 , and  8 ), etc. 
     At step  90 , optional patterning operations may be performed (e.g., by cutting away excess tape after tape  32  has been attached to a surface). 
     The foregoing is merely illustrative of the principles of this invention and various modifications can be made by those skilled in the art without departing from the scope and spirit of the invention. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20100609
Publication Date: 20130514
Grant Date: 20130514
Priority Date: 20100609
Inventors: STIEHL KURT
GOLKO ALBERT J.
MYERS SCOTT A.
Assignee: APPLE INC
CPC Classifications: [{"code": "Y10T24/33", "inventive": false, "first": false, "tree": "[]"}, {"code": "C09J2465/006", "inventive": false, "first": false, "tree": "[]"}, {"code": "C09J7/403", "inventive": true, "first": true, "tree": "[]"}, {"code": "Y10T428/24959", "inventive": false, "first": false, "tree": "[]"}, {"code": "C08G2261/3424", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T428/28", "inventive": false, "first": false, "tree": "[]"}, {"code": "C09J2465/006", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T24/33", "inventive": false, "first": false, "tree": "[]"}, {"code": "C08G2261/3424", "inventive": false, "first": false, "tree": "[]"}, {"code": "Y10T428/24959", "inventive": false, "first": false, "tree": "[]"}, {"code": "C09J7/403", "inventive": true, "first": true, "tree": "[]"}, {"code": "Y10T428/28", "inventive": false, "first": false, "tree": "[]"}]
Family ID: 45095311