Method for manufacturing a transparent element with invisible electrodes

• US 20050130400A1
• Filed: 11/30/2004
• Published: 06/16/2005
• Est. Priority Date: 12/16/2003
• Status: Active Grant

• Current Assignee: The Swatch Group Research And Development Ltd
• Original Assignee: Asulab SA (The Swatch Group AG)
• Inventors: Grupp, Joachim, Poli, Gian-Carlo
• Granted Patent: US 7,247,568 B2
• Time in Patent Office: Days
• US Class Current: 438/609
• CPC Class Codes: C03C 17/3411 with at least two coatings of inorganic materials C03C17/36, C03C17/42 take precedence
• CPC Class Codes: C03C 17/3417 all coatings being oxide coatings
• CPC Class Codes: C03C 17/3452 comprising a fluoride
• CPC Class Codes: C03C 2217/734 comprising an alternation of high and low refractive indexes
• CPC Class Codes: C03C 2217/94 Transparent conductive oxide layers [TCO] being part of a multilayer coating
• CPC Class Codes: C03C 2218/33 by etching
• CPC Class Codes: C03C 2218/34 Masking
• CPC Class Codes: G04B 39/002 made of glass
• CPC Class Codes: G04B 39/006 out of wear resistant material, e.g. sapphire
• CPC Class Codes: G06F 3/044 by capacitive means
• CPC Class Codes: H03K 17/962 Capacitive touch switches
• CPC Class Codes: Y10S 977/811 Of specified metal oxide composition, e.g. conducting or semiconducting compositions such as ITO, ZnOx

Abstract

A conductive pattern, made of a transparent conductive oxide, such as ITO including electrodes (2) and conductive paths (4) is formed on one face of a transparent substrate (3) made of sapphire or toughened glass, then coated with a first layer (5) of a transparent dielectric with a low refractive index, such as MgF₂ or LiF₂, and then a second layer (7) of another transparent dielectric having a higher refractive index than the first, such as Al₂O₃, Ta₂O₅ or DLC.

Claims

1. A method of manufacturing a transparent element with invisible electrodes formed by a transparent substrate one face of which is provided with a conductive pattern formed by electrodes, conductive paths and contact zones, wherein it includes the steps of:

depositing over the entire surface of the substrate a transparent conductive oxide film (TCO), removing via etching through a mask the zones of TCO that do not form the conductive pattern, then the residual parts of the mask,

depositing a first layer of a transparent dielectric material having a low refractive index (L),

depositing a second layer of another transparent dielectric material having a high refractive index (H) relative to that of the first layer.

2. The method according to claim 1, wherein the transparent conductive oxide is a tin and indium oxide (ITO).

3. The method according to claim 2, wherein the substrate is previously brought to a temperature of around 250°

C. under oxygen partial pressure before deposition of the first dielectric layer is carried out.

4. The method according to claim 1, wherein the dielectric depositions (L, H) are carried out in the same closed chamber.

5. The method according to claim 1, wherein the dielectrics of the first and second layers are chosen from among the following compounds classed by order of increasing refractive index;

MgF₂, LiF, SiO₂, SiO_X, AlO₃, Si₃N₄, ZnS, TiO₂, AlN, Ta₂O₅ and DLC (diamond-like carbon).

6. The method according to claim 5, wherein the dielectric of the first layer is a magnesium or lithium fluoride and that of the second layer, is alumina, tantalum pentoxide or diamond-like carbon.

7. The method according to claim 1, wherein the first layer has a thickness comprised between 50 nm and 100 nm, preferably around 60 nm and wherein the second layer has a thickness comprised between 8 nm and 25 nm, preferably around 16 nm.

8. The method according to claim 1, wherein the transparent substrate is made of sapphire or toughened glass.

9. The method according to any of the preceding claims, wherein the depositions of the dielectric layers are renewed at least once keeping the order L, H.

10. The method according to claim 1, wherein the electrodes form the sensors of a capacitive touch screen.

11. The method according to claim 1, wherein the transparent element is a wristwatch glass.