Complex adhesive boundaries for touch sensors
In one embodiment, an apparatus includes a cover panel. An adhesive layer is coupled to the cover panel. A perimeter of the adhesive layer forms at least a portion of a gasket seal extending substantially perpendicular to an inner surface of the cover panel. An inner surface of the gasket seal defines an edge of a channel. The apparatus also includes a substrate coupled to the adhesive layer. The substrate includes an outer surface having disposed thereon a connection pad region and drive or sense electrodes. The drive or sense electrodes are disposed between the substrate and the cover panel. At least a portion of the channel is disposed between the gasket seal and the connection pad region. The apparatus further includes a flexible printed circuit (FPC) electrically coupled by the connection pad region to the drive or sense electrodes. A first portion of the FPC extends through the channel.
1. An apparatus comprising:
a cover panel having an inner surface;
a first adhesive layer coupled to the cover panel, a perimeter of the first adhesive layer forming at least a portion of a gasket seal extending substantially perpendicular to the inner surface of the cover panel, an inner surface of the gasket seal defining an edge of a channel;
a substrate coupled to the first adhesive layer, the substrate comprising an outer surface having disposed thereon a connection pad region and drive or sense electrodes, the drive or sense electrodes disposed between the substrate and the cover panel, at least a portion of the channel disposed between the gasket seal and the connection pad region; and
a flexible printed circuit (FPC) electrically coupled by the connection pad region to the drive or sense electrodes, a first portion of the FPC extending through the channel in a direction substantially perpendicular to the inner surface of the cover panel and substantially parallel to the inner surface of the gasket seal.
2. The apparatus of claim 1 , further comprising a second adhesive layer conforming to an inner surface of the substrate at a region opposite the connection pad region on the outer surface of the substrate, the inner and outer surfaces of the substrate being on opposite sides of the substrate with respect to each other.
3. The apparatus of claim 2 , wherein the gasket seal comprises respective portions of the first and second adhesive layers.
4. The apparatus of claim 3 , wherein the respective portions of the first and second adhesive layers are coupled to each other.
5. The apparatus of claim 2 , wherein the first and second adhesive layers form one continuous adhesive layer.
6. The apparatus of claim 2 , wherein the gasket seal comprises respective portions of the first adhesive layer, the substrate, and the second adhesive layer, the substrate being disposed between the first and second adhesive layers.
7. The apparatus of claim 6 , wherein the channel extends through each of the first adhesive layer, the substrate, and the second adhesive layer.
8. The apparatus of claim 1 , the substrate further comprising an inner surface having disposed thereon a connection pad region and drive or sense electrodes, the inner and outer surfaces of the substrate being on opposite sides of the substrate with respect to each other.
9. The apparatus of claim 8 , wherein the first adhesive layer substantially fills a volume disposed between the cover panel and a portion of the outer surface of the substrate, the portion of the outer surface of the substrate and the connection pad region on the inner surface of the substrate being disposed on opposite sides of the substrate with respect to each other.
10. The apparatus of claim 8 , wherein the FPC is electrically coupled by the connection pad region on the inner surface of the substrate to the drive or sense electrodes on the inner surface of the substrate.
11. The apparatus of claim 8 , wherein a second FPC is electrically coupled by the connection pad region on the inner surface of the substrate to the drive or sense electrodes on the inner surface of the substrate.
12. The apparatus of claim 1 , wherein a second portion of the FPC is bonded to the connection pad region on the outer surface of the substrate.
13. The apparatus of claim 12 , wherein the FPC comprises a bend such that the first and second portions of the FPC are at substantially right angles with respect to each other.
14. The apparatus of claim 1 , wherein the inner surface of the cover panel and the inner surface of the gasket seal are each substantially disposed along respective planes that are substantially perpendicular with respect to each other.
15. The apparatus of claim 1 , wherein the first adhesive layer comprises an optically clear adhesive (OCA).
16. A method comprising:
forming a connection pad region and drive or sense electrodes on an outer surface of a substrate;
forming a connection pad region and drive or sense electrodes on an inner surface of the substrate;
adhering a first adhesive layer to the outer surface of the substrate;
adhering a second adhesive layer to the inner surface of the substrate;
forming a channel extending in a direction substantially perpendicular to the inner and outer surfaces of the substrate, at least in part, by cutting away selective portions of the substrate and the first and second adhesive layers;
inserting a portion of a flexible printed circuit (FPC) into the channel formed, at least in part, by selectively removing portions of the substrate and the first and second adhesive layers;
bending the FPC, such that a first portion of the FPC is disposed outwardly from the connection pad region formed on the outer surface of the substrate and a second portion of the FPC is disposed within the channel; and
electrically coupling the FPC to the drive or sense electrodes formed on the outer surface of the substrate, at least in part, by bonding the FPC to the connection pad region formed on the outer surface of the substrate.
17. The method of claim 16 , wherein selectively removing portions of the substrate and the first and second adhesive layers comprises cutting through the substrate and the first and second adhesive layers.
18. The method of claim 16 , further comprising coupling a cover panel to the first adhesive layer using adhesion of the first adhesive layer.
19. The method of claim 16 , further comprising electrically coupling the FPC to the drive or sense electrodes formed on the inner surface of the substrate, at least in part, by bonding the FPC to the connection pad region formed on the inner surface of the substrate.
20. An apparatus comprising:
a cover panel having an inner surface;
a first optically clear adhesive layer coupled to the cover panel,
a substrate coupled to the first adhesive layer, the substrate comprising:
an outer surface having disposed thereon a first connection pad region and first drive or sense electrodes, the drive or sense electrodes disposed between the substrate and the cover panel;
an inner surface having disposed thereon a second connection pad region and second drive or sense electrodes, the outer and inner surfaces of the substrate being on opposite sides of the substrate with respect to each other;
a second adhesive layer coupled to the inner surface of the substrate;
a dielectric layer coupled to the second adhesive layer; and
a flexible printed circuit (FPC) electrically coupled by the first connection pad region to the first drive or sense electrodes;
wherein respective portions of the first adhesive layer, the substrate, the second adhesive layer, and the dielectric layer collectively form a gasket seal around a perimeter of the cover panel, the gasket seal extending in a direction away from the cover panel along an axis substantially perpendicular to the outer and inner surfaces of the substrate, an inner surface of the gasket seal defining an edge of a channel; and
wherein a portion of the FPC is disposed within the channel and extends through respective openings in each of the first adhesive layer, the substrate, the second adhesive layer, and the dielectric layer.