Bonded substrate configurations and methods for manufacturing such configurations - Patents.com

Abstract

A configuration (1) is provided that includes a first substrate (10) that is transparent in a defined wavelength range and a second substrate (20) disposed adjacent to the first substrate (10), wherein the first substrate (10) and / or the second substrate (20) have coatings (12, 22) formed on the sides facing a first laser treatment zone (30) that includes an interface and a weld line (100) between the first substrate (10) and the second substrate (20), where the materials of the first substrate (10) and the second substrate (20) melt and mix to bond the two substrates (10, 20) together. The coatings (12, 22) of the first substrate (10) and / or the second substrate (20) have an absorption of less than 10% for light within the defined wavelength range prior to laser treatment. The coatings (12, 22) are selectively heat treated by heat generated in one or more second laser treatment zones (40) and / or the coatings (12, 22) are selectively removed by selectively melting portions of the first substrate (10) or the second substrate (20) in one or more third laser treatment zones (50). Further aspects of the invention relate to methods of manufacturing such structures and uses of such structures.

Description

[Technical Field]

[0001] The present invention relates to a composition comprising a first substrate transparent in a defined wavelength range and a second substrate disposed adjacent to the first substrate, the first substrate and / or the second substrate having a coating formed on a side facing the interface between the first substrate and the second substrate, and a first laser treatment zone comprising a weld line, in which the materials of the first substrate and the second substrate are melted and mixed to bond the two substrates together. Further aspects of the present invention relate to methods for manufacturing such a composition and to uses of such a composition. [Background technology]

[0002] Hermetic enclosures can be used, for example, to protect one or more components within the enclosure from adverse environmental conditions. Applications for such hermetic enclosures can be found, for example, in electronic applications to protect sensitive electronic components and in optical applications to enclose optical components. Other applications can be found in the fields of medical implants, microfluidic chips, and sensor technologies (e.g., pressure sensors) for augmented reality and mobility, among others.

[0003] In particular for optical applications, transparent materials for encapsulation such as glass are desirable in this context, but also for electronic applications where wireless communication or wireless charging is desired, glass materials have advantages over common metal housings, for example made of titanium, since they do not shield the radiation used in the respective cases.

[0004] There are many methods for bonding flat glass, glass ceramic or crystalline flat piece wafers through their interfaces, such as laser frit bonding, anodic bonding, contact bonding.

[0005] Furthermore, it is mainly known to stack several parts or layers on top of each other and join them by laser welding. For example, EP 3012059 shows a method for manufacturing a transparent part for protecting an optical component. In this specification, a new laser welding method is used.

[0006] U.S. Patent Application Publication No. 2015 / 027168 discloses a method for laser welding transparent glass sheets. To enhance the laser bond, an absorbing film is deposited at the interface between two glass sheets, for example, in the form of an absorbing coating on at least one of the glass sheets. The absorption of the welding laser in the absorbing film is at least 10%. Such an absorbing coating absorbs the laser radiation, stores its power, and converts it into heat, forming a fusion zone between the two glass sheets, thereby bonding the sheets together.

[0007] The drawback of this method is that the coating needs to be absorptive to the wavelength of the incident laser, which reduces the design freedom, e.g., chemical composition for homogeneous coatings or layer thickness for dielectric coatings.

[0008] EP 3812352 discloses a substrate stack including a base substrate and a cover substrate, in which a first laser weld line is used to bond the substrates together. A second laser weld line positioned adjacent to the first laser weld line reduces stress at the first laser weld line, thereby improving the mechanical stability of the substrate stack. In EP 3812352, a multilayer compound containing multiple layers may be used as one of the substrates to be welded. Such a multilayer compound may contain an internal coating layer that, if placed at the interface where another substrate is joined, would adversely affect the laser welding process. Furthermore, if the coating is transparent to the wavelength of the laser, the surfaces of the substrates forming the interface during the laser joining process may be coated with an optical anti-reflective coating. For example, a substrate coated with a reflective coating in the visible wavelength range may be used in a laser joining process using a laser emitting in the near-infrared wavelength range.

[0009] What is needed is an arrangement having hermetically bonded coated substrates where the choice of coating is not limited to coatings that are transparent to the laser used in the bonding process. Summary of the Invention [Means for solving the problem]

[0010] A configuration is proposed comprising a first substrate that is transparent and therefore transmissive to light in a defined wavelength range, allowing the use of a laser welding process, and a second substrate arranged adjacent to the first substrate, wherein the first substrate and / or the second substrate have a coating formed on the side facing the interface between the first substrate and the second substrate, and a first laser treatment zone including a weld line, in which the materials of the first substrate and the second substrate are melted and mixed to join the two substrates together.

[0011] Furthermore, the coating of the first substrate and / or the second substrate has an absorption of less than 10% for light within a defined wavelength range before laser treatment, and therefore outside the laser treatment zone.

[0012] The defined wavelength range particularly includes the wavelength of the laser used in the laser bonding process used to bond the first and second substrates together. The defined wavelength range is 900 nm to 1500 nm, preferably 1000 nm to 1100 nm.

[0013] Transparency in the context of the present disclosure means, in particular, that the transparent substrate is suitable for use in a laser welding process, thus allowing the transmission of a laser beam towards the interface between two substrates. In particular, the transparent substrate is transparent to light within a defined wavelength range, and has a transmittance T of 50% or more, preferably more than 60%, more preferably more than 70% for light having a wavelength within the defined wavelength range. The transmittance is preferably such that T=P out / P in is defined as P in represents the total light power incident on the first substrate, and P out represents the light output transmitted through the first substrate. The transmittance T may also be defined as T=1−RA, where R represents the fraction of light reflected and A represents the fraction of light absorbed by the first substrate.

[0014] The inventors have surprisingly found that the coating of the first and / or second substrate does not need to be substantially transparent to the laser used in the laser bonding process in which the materials of the first and second substrates are melted and mixed to form the bond. It is sufficient that the coating does not absorb, or at least does not substantially absorb, laser light so as not to interfere with the laser bonding process. This allows, for example, the use of a coating that is highly reflective to the wavelength range used by the bonding laser and therefore substantially opaque to, and therefore not transparent to, light at the laser wavelength.

[0015] It is important to note here that a coating that only absorbs a small amount of light within a defined wavelength range, for example a coating with a maximum absorption of 10%, does not mean that the coating is essentially transparent and has a transmittance of at least 90%, since this simplification does not take into account reflection. Therefore, the transmittance or transparency T of a coating cannot be determined solely by measuring the absorption A, since the reflectance R of the coating must also be taken into account. Transmittance T is given by T=P out / P in = 1-RA, and P in represents the total light power incident on the coating, and P out represents the light output transmitted through the coating. The transmittance T of a coating can be measured, for example, by comparing the transmittance of coated and uncoated substrates of the same substrate material.

[0016] Thus, the coating may be highly reflective within a defined wavelength range, for example, the reflectivity for light within the defined wavelength range may be at least 80%, preferably at least 90%, more preferably at least 95%, and most preferably at least 98%.

[0017] The use of coatings with absorption less than 10% is particularly useful in conjunction with laser joining processes, where absorption of the laser energy in one of the substrates being joined is due to nonlinear effects within the substrate, as described, for example, in EP 3812352. In such laser welding processes, a laser weld line is typically obtained by firing a short pulsed laser beam of a defined wavelength and energy from a laser source into the pre-formed substrate stack, resulting in a series of laser pulses being deposited into the material of the substrate stack. By selecting the repetition rate and scanning speed of the laser, individual laser pulses are spaced very closely together, and the resulting nonlinear absorption zone of one laser pulse within the material can contact or overlap with an adjacent nonlinear absorption zone of another laser pulse, resulting in heat accumulation. This heat accumulation locally melts the material of the substrate stack, resulting in a continuous weld "line." To create such a continuous weld line, the focal plane of the laser beam is positioned near, but not at, the interface between the first and second substrates. The laser beam is positioned a distance H1 below the interface between the two substrates so that heat accumulation locally melts and mixes the materials of the first and second substrates, forming a hermetic bond. The region where the heat accumulation of the incident laser melts and mixes the materials of the first and second substrates is designated as the first laser processing zone. Material of the coating on the first and / or second substrates typically also melts in this process and becomes part of the resulting material mixture. This effectively removes the coating within the first laser processing zone.

[0018] Therefore, in contrast to the bonding process of U.S. Patent Application Publication No. 2015 / 027168, there is no need to increase the absorption of the incident laser by applying an absorbing coating, since the absorption occurs in one of the substrates and not in the coating. Energy loss due to reflection caused by the coating can be compensated for by increasing the power of the incident laser beam.

[0019] Because absorption of laser energy by the coating is not necessary to form a stable hermetic bond between the first and second substrates, the absorption of the coating may be selected to be much less than about 10%. Preferably, the absorption of light within the defined wavelength range of the coating is less than 5%, more preferably less than 1%, and most preferably less than 0.5%.

[0020] Outside the region where the incident laser heat accumulation is sufficient to locally melt the material of the first and / or second substrate, there is a region where the heat accumulation is insufficient to melt the material, but sufficient to modify the material properties of the coating. This region where the incident laser heat accumulation causes a change in the material properties of the coating is designated the second laser treatment zone.

[0021] Preferably, the configuration includes one or more second laser treatment zones, and the coating is selectively heat treated by heat generated in the one or more second laser treatment zones. Preferably, intermixing of the materials of the first and second substrates does not occur in the one or more second laser treatment zones.

[0022] Such a second laser processing zone may occur adjacent to, but be independent of, the first laser processing zone. A second laser processing zone that is independent from the first laser processing zone allows for selective thermal processing of the coating without creating a bond between the first and second substrates. For example, such an independent second laser processing zone can be obtained by positioning the focal plane of the incident laser so that the distance H2 of the focal plane from the interface between the first and second substrates is greater than the height of the zone where heat accumulation causes melting of the material.

[0023] The coating can be selectively removed by positioning the focal plane of the incident laser at a distance H3 from the surface of the substrate so that only one of the first and second substrates melts, thereby preventing intermixing of the materials of the two substrates, but melting the coating located on each substrate. Such a zone where the coating is selectively removed without intermixing of the materials of the first and second substrates is called a third laser processing zone. Such a zone can be particularly easily located in an area where the first and second substrates are not in direct contact with each other, or in an area where one of the first and second substrates has an opening or recess.

[0024] Preferably, the configuration has one or more third laser treatment zones in which the coating is selectively removed by selectively melting portions of the first substrate or the second substrate, and no intermixing of the materials of the first and second substrates occurs within said one or more third laser treatment zones.

[0025] An advantage of the present invention is that any modification to the coating applied to the first and / or second substrate is highly localized and limited, with the coating being removed in the first laser treatment zone and, if present, in the third laser treatment zone, and thermally modified in one or more second laser treatment zones, with no damage or modification of the coating and its properties occurring outside of said defined zones.

[0026] The laser treatment zones are highly localized, with typical widths ranging from 20 μm to 80 μm for the first laser treatment zone, 30 μm to 300 μm for the second laser treatment zone, and 0.5 μm to 80 μm for the third laser treatment zone. The shape of the zones can be customized as needed, particularly continuous lines and discrete spots, by scanning the laser beam over the substrate stack including the first and second substrates.

[0027] Since the laser treatment allows for selective modification and / or removal of the coating, it is preferred to apply the coating to the entire planar surface or surface of the substrate, in particular the coating may be applied to the entire surface of the substrate facing another substrate.

[0028] The coating of the first substrate and / or the second substrate can have at least one property selected from transparency, reflectivity, absorbance, color, conductivity, optical phase retardation, roughness, hardness and surface tension, which property is affected by the thermal treatment in the one or more second laser treatment zones.

[0029] By selectively placing one or more second laser treatment zones, the coating can be constructed independently of the placement of the laser weld line joining the first and second substrates together, allowing for the construction of complex structures and / or patterns.

[0030] For example, if the coating has electrical conductivity that is modified by thermal treatment in one or more second laser treatment zones, it is possible to form antenna structures, heating structures, electrode structures for detecting or generating electric fields, and electrical paths on the first and / or second substrates, suitable for receiving and / or transmitting RF signals or for wireless charging. The coating pattern or structure can be formed independently of the bonding of the two substrates by placing one or more second and / or third laser treatment zones. Furthermore, it is of course possible to combine some of the examples mentioned. The pattern or structure can also be part of a sensor. For example, the structure for generating and detecting an electric field can be configured and arranged to detect moisture or pH when immersed in a liquid.

[0031] If the coating is a light-reflective or anti-reflective coating, particularly for visible, near-infrared and / or UV light, and the reflectivity of the coating is modified in at least one of the one or more second laser treatment zones, it is possible to form a pattern of coated and uncoated areas, which can serve as alignment structures or reference labels (e.g., barcodes or QR codes), or may even have sufficient resolution as a diffraction grating structure.

[0032] As used herein, the UV range is from 200 nm to 380 nm, the visible light or VIS range is from 380 nm to 690 nm, and the near infrared or NIR range is from 690 to 2500 nm.

[0033] The heat-affected zone, or second laser-treated zone, surrounding the weld line and therefore the first laser-treated zone when performing the laser welding process to join the two substrates together extends approximately 300 μm away from the weld line. Thus, the first laser-treated zone of the coating is limited to the area near the weld line and has a width w m The area with a minimum distance of typically 500 μm from the weld line is not affected by the heat treatment. The width w, which includes the width of the first laser-treated zone and the width of two adjacent second laser-treated zones, is haz corresponds to the width of the heat affected zone on the surface of the substrate and therefore on the coating. Preferably, the laser process is haz / w m is greater than 1, preferably less than 10, less than 5, less than 3, less than 2, and most preferably less than 1.5.

[0034] By creating a third laser treatment zone, where the laser focus is positioned further away from the material interface and thus further away from the coating, the zone where the material melts can be controlled even more precisely to selectively remove the coating and create fine, sharp patterns, with a typical minimum feature size of 0.5 μm.

[0035] Conventional bonding processes, such as anodic bonding or adhesive bonding, damage or modify coating properties over large areas, much larger than the typical structure sizes mentioned herein, due to the highly localized coating structuring and / or modification achieved by the proposed laser process. Common bonding methods, such as fusion bonding, require heating the entire sample to temperatures ranging from 400°C to 600°C, which can degrade many optical coatings. Epoxy and glass frit bonding typically damage the coating in the areas where the epoxy adhesive or glass frit lines contact the coating. The thickness of these lines can range from 500 μm to several mm in width.

[0036] The present configuration may further include an inner coating disposed on an inner wall, particularly a side wall of the cavity, that does not face the interface between the first and second substrates. Therefore, such an inner coating is disposed on a wall or surface that is not parallel to the interface between the first and second substrates. In particular, when a cavity is formed, the side wall may be disposed perpendicular to the interface between the first and second substrates.

[0037] The inner coating is preferably selected to have light-absorbing or light-reflecting properties. Such an inner coating may be combined with a structuring of the respective surface, in particular a structuring that increases the surface roughness. For example, by combining such an absorbing coating with a rough surface, the light-absorbing properties of the light-absorbing coating can be further increased.

[0038] Preferably, the surface of the inner coating has an arithmetic mean roughness of 0.05 μm to 2 μm, more preferably 0.1 μm to 1 μm, most preferably 0.2 μm to 0.5 μm.

[0039] The coating on the first substrate and / or the second substrate may be configured as a single layer or a multilayer structure. One or at least one layer of the coating is preferably configured as an inorganic layer. Such inorganic layers include, for example, metal layers, nitride layers, or oxide layers. Suitable examples of oxide layers include ITO, AZO, SiO2, Al2O3, TiO2, HfO2, Ta2O5, ZrO2, and Nb2O5. Examples of suitable nitride layers include Si3N4 and AlN.

[0040] Suitable examples of metallic and / or semiconducting layers include Ti, Si, Mo, W, Zr, Al, Cu, Nb, Ta and Cr.

[0041] Furthermore, different materials, especially different types of materials, can be combined either in a single layer or in multiple layers, for example different oxides or nitrides, or even mixtures of nitrides and oxides can be used.

[0042] For optical coatings, such as reflective or anti-reflective coatings, at least two different dielectric materials with different refractive indices are combined in a multilayer structure. Such a structure may in particular have alternating layers of materials with high and low refractive indices, typically the high refractive index being 1.7 or higher and the low refractive index being 1.5 or lower (for light at 550 nm).

[0043] To ensure that the coating has low optical absorption within the defined wavelength range, materials with a low extinction coefficient k are preferred for the coating of the first and / or second substrate. Extinction coefficient <= 1 10 -3 Particularly preferred are materials having the formula:

[0044] For example, anti-reflective or reflective coatings can be based on TiO2 and SiO2. An anti-reflective coating can consist of, for example, four layers, starting with a high-refractive-index material. In the case of TiO2 and SiO2, a suitable sequence would be 23 nm of TiO2, 34 nm of SiO2, 37 nm of TiO2, and 100 nm of SiO2. The average reflectance of a glass substrate between 450 nm and 650 nm drops to less than 0.5%. In the VIS wavelength range, the extinction coefficient of SiO2 is equal to 0, and the extinction coefficient of TiO2 is <1.9E-4 at λ > 550 nm, so the average absorption of the coating is <0.05%.

[0045] An example of a conductive coating is indium tin oxide (ITO), which, when heat treated, changes its conductivity and therefore its electrical resistance.

[0046] An example of a coating that changes color and thus optical properties, particularly in the VIS range, is an anti-reflection coating in the IR range. When viewed undamaged, such a coating has a purple reflection (e.g., when placed in front of a black background) and produces a green color in transmission (e.g., when placed in front of a white background). When the glass interface or interfaces carrying this coating are heated to near or above their softening point, the coating properties can be permanently altered. This can be by damaging or removing one or more layers, by introducing color or absorption centers and / or changing the density of one or more layers, or by other effects that cause permanent or longer-lasting modifications to the coating. These effects can then lead to modifications of the spectral response in the VIS range, such as color changes.

[0047] In principle, the same materials and structures are also suitable for the inner coating, however, for the inner coating, if absorption properties are desired, materials with high extinction coefficients may be preferred.

[0048] The inner coating may have a thickness of 5 nm to 5 μm, preferably 15 nm to 1000 nm, more preferably 50 nm to 500 nm.

[0049] In embodiments of the present invention having an inner coating with light absorbing properties, the coating may be made of the following materials: Al2O3, B2O3, Co2O3, Cr2O3, CuO, Fe2O3, Ga2O3, HfO2, In2O3, MgO, Nb2O5, NiO, Pd, Pt, Al, Ag, Mo, W, Si, SiO2, SnO2, Ta2O5, TiO2, TaNx, (Ta,Al)N, TiCrO x , (Ti,Al)N, (Ti,Al)C, TiC, AlC, AlN, TiN, VO2, WO3, ZnO, (Al,Zn)O, ZnS, ZnSe, ZrO2, rare earth (RE) oxides, Sc2O3, Y2O3, carbon, carbon black, Ca 10 (PO4)6(OH)2), polyimide, PMDA-ODA, PMDA-DAH, 3-aminopropyltrimethoxysilane coupling agent.

[0050] The coating and / or inner coating can be applied using any known deposition technique. Examples of suitable deposition methods include physical vapor deposition (PVD), especially sputtering, chemical vapor deposition (CVD), especially thermal CVD, plasma-enhanced CVD, and atomic layer deposition (ALD).

[0051] The arrangement may be configured such that a hermetic enclosure is formed, with the cavity or functional zone enclosed within such enclosure. As used herein, hermetic means, in particular, 1 / 10 -8 Helium leak rate less than 1 mbar·l / sec, preferably 1·10 -10 mbar·l / sec~1·10 -9 This refers to an enclosure in the range of mbar·l / sec.

[0052] For example, the first substrate in this configuration may be configured as a cover substrate and the second substrate may be configured as a base substrate, with the two substrates forming an enclosure for a cavity or functional zone. In this example, the base substrate may have a recess formed, for example by etching, to define the cavity.

[0053] In a further example, the configuration additionally comprises a further substrate, wherein the first substrate is configured as a cover substrate, the second substrate is configured as an intermediate substrate, and the further substrate is configured as a bottom substrate, and the three substrates form an enclosure for a cavity or a functional zone. In this example, the bonding between the second substrate and the further substrate may be performed in the same way as the bonding between the first substrate and the second substrate, and the further substrate may have a coating disposed on the side facing the interface between the second substrate and the further substrate.

[0054] If the structure includes a cavity or functional zone, the first laser-treated zone preferably completely surrounds the cavity or functional zone, and the bond between the first substrate and the second substrate formed in the first laser-treated zone is preferably hermetic. If the structure includes an additional substrate, the bond between the second substrate and the additional substrate is also hermetic and preferably includes the first laser-treated zone surrounding the cavity or functional zone. The structure may, of course, include more than one cavity or functional zone. In such a case, all cavities and / or functional zones are preferably completely surrounded by the first laser-treated zone, thereby sealing each cavity and / or functional zone within the structure. After forming such a structure with multiple cavities or functional zones, it is possible to obtain multiple parts from a single bonded substrate stack by cutting the structure to separate the cavities or functional zones.

[0055] Preferably, the first substrate and / or the further substrates, if present, are selected from glass, glass ceramic, silicon, sapphire, diamond or other inorganic crystals.

[0056] Preferably, the second substrate is selected from glasses, especially volume-absorbing glasses, glass ceramics, silicon, sapphire, diamond, other inorganic crystals, plastic materials and metals or metal alloys.

[0057] Suitable examples of volume absorbing glasses include optical filter glasses in particular.

[0058] In a further aspect of the invention, there is provided a method for manufacturing the structures described herein, and therefore all features described with respect to the structures apply to the method and vice versa.

[0059] A method for manufacturing an arrangement of at least two connected substrates is proposed.

[0060] In a first step, a first substrate and a second substrate are provided to form a substrate stack, and at least one of the first substrate and the second substrate has a coating disposed on a side facing the interface between the first substrate and the second substrate.

[0061] In a subsequent step, a first laser treatment zone for joining the first substrate and the second substrate is formed by laser welding, wherein at least the first substrate is transparent to the laser and transmissive to the light of the welding laser, and the coating has an absorption of less than 10% for the welding laser light before the laser treatment, and the first laser treatment zone is formed by introducing at least one laser weld line, and in the first laser treatment zone, the materials of the first substrate and the second substrate are melted and mixed to join the first substrate and the second substrate to each other.

[0062] In a subsequent step, a second laser treatment zone is formed to selectively heat treat the coating, modifying the properties of the coating, and / or a third laser treatment zone is formed to selectively remove the coating, without intermixing the materials of the first substrate and the second substrate.

[0063] The first substrate is transparent to the light of the laser, allowing the laser beam to travel through the first substrate toward the interface between the first substrate and the second substrate to form a laser treatment zone.

[0064] In a further optional step, a further substrate can be provided and placed next to the second substrate, and the bonding and optional structuring of the coating can be carried out as described for the first and second substrates.

[0065] This method is particularly suitable for producing one of the configurations described herein, wherein the defined laser wavelength range is selected such that said defined wavelength range includes the wavelength of the welding laser.

[0066] Preferably, at least one laser weld seam is produced using an ultrashort pulse laser, with typical pulse durations in the range of 100 fs to 100 ps. A method for producing such a welded joint using one or more laser weld seams is known, for example, from EP 3012059.

[0067] The method may include a further inspection step performed after formation of one or more first laser treatment zones to assess the quality of the bond formed in the first laser treatment zones.

[0068] Preferably, the coating is selected so that the coating changes color upon heat treatment. In such a configuration, the substrate stack has a first observed color in areas or zones where the coating is not treated, a second color in areas or zones where the coating is heat treated, and a third color when the coating is removed by laser treatment. In the inspection step, weld line interruptions and / or weld line non-uniformities in at least one laser weld line are identified by detecting a color change in the heat treated coating or the presence of untreated coating along the intended laser weld line.

[0069] Additionally or alternatively, the coating may be selected to change its electrical conductivity upon heat treatment. For example, the coating may have a first electrical conductivity when untreated, a second electrical conductivity when heat treated, and no electrical conductivity when removed by laser treatment. The inspection step identifies weld line interruptions and / or weld line non-uniformities in at least one laser weld line by measuring the electrical resistance between the coating within the inner zone or functional zone and a portion of the coating outside the zone. For example, if the weld line completely surrounds the inner zone defining the cavity or functional zone, there should be no electrical continuity if there is no interruption in the weld line. If current flow is detected, at least one gap exists in the weld line.

[0070] A further aspect of the present invention relates to the use of the arrangements described herein as enclosures or caps for medical implants or sensors.

[0071] When the present configuration is configured as a cap, the cap may be configured to be bonded to a base to form a housing for a component or device. In particular, the cap is preferably configured to be bonded to a substrate or header to form the housing. The formed housing is preferably airtight and particularly suitable for receiving a component, such as an electronic or optoelectronic component. The housing includes a surface formed by a first and / or second substrate, a coating applied to the first and / or second substrate, and may additionally include an inner coating. The substrate configuration and the coating and inner coating of the first and / or second substrate may be selected so that the formed housing has an opaque top wall and one or more anti-reflective coated side walls. Alternatively, the top wall may be configured to be transparent, and the side walls may be opaque.

[0072] It will be understood that the features mentioned above and those described below can be used not only in the respective combinations as illustrated, but also in other combinations or by themselves without departing from the scope of the invention.

[0073] Preferred embodiments of the present invention are illustrated in the drawings and explained in more detail in the following description, where like reference numerals refer to the same or similar parts or elements.

[0074] The figure is shown in a schematic diagram. [Brief explanation of the drawings]

[0075] [Figure 1] 1 is a schematic top view of a first exemplary configuration of bonded laminated substrates. FIG. [Figure 2] FIG. 2 is a cross-sectional side view of the configuration of FIG. 1. [Figure 3] FIG. 2 is an enlarged cross-sectional view of a joint between two substrates. [Figure 4] FIG. 1 is an enlarged top view of the bond between two substrates. [Figure 5]FIG. 2 is an enlarged cross-sectional view of a substrate having a modified coating. [Figure 6] FIG. 2 is an enlarged top view of a substrate having a modified coating. [Figure 7] FIG. 10 is a schematic top view of a second exemplary configuration having an antenna structure. [Figure 8] FIG. 8 is an enlarged cross-sectional view of the configuration of FIG. 7. [Figure 9] This is a close-up photo of two weld lines seen from above. [Figure 10] 10 is a further example of a third exemplary configuration including two substrates. [Figure 11] FIG. 10 is a cross-sectional view of a fourth exemplary configuration. [Figure 12] FIG. 10 is a cross-sectional view of a fifth exemplary configuration. [Figure 13] FIG. 13 is a cross-sectional view of the cap taken from the configuration of FIG. 12. DETAILED DESCRIPTION OF THE INVENTION

[0076] 1 shows in a schematic top view a first exemplary configuration 1 of two bonded laminate substrates 10, 20 (see FIG. 2). In the example shown, the surface of the first substrate 10 facing the second substrate 20 is covered with a coating 12. In the embodiment shown in FIG. 1, the entire surface facing the second substrate 20 is covered with the coating 12. At least one of the substrates 10, 20 is selected to be transparent to a laser beam, in order to enable a hermetic bond to be established between the two substrates 10, 20 using a laser bonding process. Here, the first substrate 10 is configured to be transparent to laser radiation.

[0077] To reliably and hermetically bond the first substrate 10 to the second substrate 20, a laser weld line 100 is placed in the contact area 200 of the two substrates 10, 20. Referring to FIG. 3, the remaining gap between the two substrates 10, 20 within the contact area 200 is less than approximately 250 nm. To achieve hermetic bonding between the two substrates 10, 20 within the contact area 200, the laser weld line 100 is introduced by melting the materials of the first substrate 10 and the second substrate 20 using an ultrashort pulse laser and then cooling the resulting mixed material, thereby bonding the two substrates 10, 20 together. The width of the laser weld line 100 is typically in the range of approximately 20 μm to 75 μm.

[0078] As can be seen in Figure 1, the weld line 100 surrounds a space that defines a cavity 500. Figure 1 further shows that within the first laser treatment zone 30, which includes the weld line 100, the coating 12 has been removed. In the adjacent second laser treatment zone 40, the original coating 12 has been modified by heat introduced by the laser, but the coating 12 is still present.

[0079] Figure 2 shows a schematic cross-sectional side view of Configuration 1 of Figure 1 taken along the line marked AB. In this side view, it can be seen that the first substrate 10 is configured as a solid base substrate, and the second substrate 20 is configured as a spacer substrate. The two substrates 10, 20 define a cavity 500, with the first substrate 10 defining the bottom wall and the second substrate defining the sidewall. A coating 12 is disposed on the side of the first substrate 10 facing the second substrate 20 and is disposed over the entire surface of the first substrate 10. Referring to Figure 12, an additional substrate 10' can be bonded to the open side of the second substrate 20 to completely close the cavity 500.

[0080] The interface between the two substrates 10, 20 and the joining by the laser weld line 100 will now be described with reference to FIG.

[0081] Figure 3 shows an enlarged cross-sectional side view of the bond between two substrates 10, 20. In the example shown in Figure 3, the first substrate 10 is uncoated, and only the second substrate 20 has a coating 22 disposed on the side facing the first substrate 10.

[0082] In Figure 3, a cross section of two weld lines 100 is visible. The weld lines 100 are formed by multiple overlapping laser pulses that allow heat to build up within the substrates 10, 20. The laser beam used in the welding process enters the substrate stack from above, allowing the light of the laser beam to pass through the transparent first substrate 10. The areas affected by the laser pulses are pear-shaped, representing the areas of the substrates 10, 20 that have been treated by each laser pulse; this treatment occurs when the material reaches its glass transition temperature T G The laser pulse is heated to or above the melting temperature in such a way that, if the gap d is less than approximately 250 nm, the adjacent substrates 10, 20 can be bonded to each other in a material bond. Most of the energy of the laser pulse is absorbed in an absorption zone 110, located at the focal plane of the laser, where light is absorbed by nonlinear effects. The focal plane is located at a first depth H1 measured from the surface of the first substrate 10, including its coating. The light absorbed in the absorption zone 110 melts the material in a melt zone 114. Within the melt zone 114, elongated volumes with locally low material density, or even gas enclosures, can occur periodically or aperiodically along the weld line. In cross section, this zone is shown as a "bubble-shaped" zone 112.

[0083] The melt zone 114 with its elongated bubble-shaped zone 112 is usually clearly identifiable, for example using an optical microscope, because its density and therefore refractive index is changed relative to the surrounding glass.

[0084] The heat affected zone 120 surrounds the melt zone 114 and represents an area that is heated, but the accumulated heat is not sufficient to melt the material.

[0085] The portion of the coating 22 of the second substrate 20 located within the melt zone 114 is effectively removed from the surface of the first substrate 10 because that material mixes with the molten material of the first substrate 10 and the second substrate 20. The region of the interface between the first and second substrates 10, 20 located within said melt zone 114 is referred to as the first laser treatment zone.

[0086] The portion of the coating 22 of the second substrate 20 located outside the melt zone 114 but within the heat affected zone 116 is not removed, but is subjected to heat from the laser. If the coating 22 is properly selected, heat can be used to selectively modify the properties of the coating 22. This heat-treated portion of the coating 22 is referred to as the second laser treatment zone.

[0087] 4 shows two parallel weld lines 100 used to join two substrates 10, 20 together, at least one of which has a coating 12, 22. As can be seen in the top view of FIG. 4, each laser weld line 100 has a melt zone 114 with a width w m 3, each of the first laser-treated zones 30 includes a respective laser weld line 100, effectively removing the coatings 12, 22. Furthermore, each of the first laser-treated zones 30 is surrounded by a second laser-treated zone 40, where the coatings 12, 22 have been modified by the heat of the laser pulse. The width of the surrounding second laser-treated zone 40, including the width of the first laser-treated zone 30, is the total width w of the heat-affected zone 116. haz corresponds to (see Figure 3).

[0088] In the example of FIG. 4 , the coatings 12, 22 on the first substrate 10 and / or the second substrate 20 are selected to have a first color in their untreated state and a second color in their heat-treated state. Furthermore, the coatings 12, 22 are selected so that the resulting color of the substrate stack is different from the first and second colors of the first laser-treated region 30 where the coatings 12, 22 have been removed. This allows for easy identification of interruptions or gaps 130 in the laser weld line 100, or irregularities 132 that cause the width of the laser weld line 100 to differ from a set value. This is particularly useful when perfect hermeticity is required, as it allows for easy identification of incomplete laser weld lines 100 that could cause leakage into or out of the cavity 500 through simple optical inspection. Thus, in the illustrated example, it is easily determined that the first weld line 101 is free of interruptions and non-uniformities 132, while the second weld line 102 has gaps 130 and a reduced-width non-uniformity 132.

[0089] 5 illustrates the modification of the properties of coatings 12, 22, and in the illustrated example, coating 12 is disposed on a first substrate 10. In the illustrated cross section of first substrate 10, first substrate 10 is not in contact with second substrate 20. For example, in a configuration 1 similar to that shown in FIGS. 1 and 2, the portion of first substrate 10 shown in FIG. 5 can correspond to a portion of the bottom wall of cavity 500.

[0090] To modify the properties of the coating 12, 22, it is desirable to heat the coating 12, 22 without melting the coating 12, 22 or the portion of the substrate 10, 20 carrying the coating 12, 22. Therefore, the focal plane where the absorption zone 110 is located moves deeper into the substrate 10 and has a second depth H2 measured from the surface containing the coating 12. The melt zone 114 is then completely embedded within the substrate 10 and does not contact the surface of the substrate 10 or the coating 12. Only the heat-affected zone 114 reaches the coating 12, thereby heat-treating the portion of the coating 12 located within the heat-affected zone 114. This zone is referred to as the second heat-treatment zone 40. The second heat-treatment zone 40, as shown in FIG. 5, can be used to structure the coating 12 independently of the first laser-treatment zone 30, as shown in FIGS. 3 and 4. The coating 12 can be structured or patterned by scanning laser pulses over the substrate 10 in a manner similar to creating the laser weld seam 100.

[0091] 6 shows a top view of a substrate 10 having a coating 12 modified by heat treatment in a second laser treatment zone 40. In the illustrated case, the second laser treatment zone 40 has a width w corresponding to the width of the heat affected zone 120 created during laser treatment. haz The linear shape has the following structure:

[0092] FIG. 7 shows a schematic top view of a second exemplary configuration 1 having an antenna structure 400.

[0093] The configuration 1 shown in Figure 7 comprises a substrate stack having a first substrate 10 and a second substrate 20 similar to those described with reference to Figures 1 to 4. The coating 12 located on the side of the first substrate 10 facing the second substrate 20 is a conductive coating, such as an indium tin oxide (ITO) coating. The material of the substrates 10, 20 is selected in this case to be non-conductive.

[0094] In the first laser treatment zone 30, which includes the weld line 100, the coating 12 is effectively removed, so there is no conductive path from the area inside the space defined by the weld line 100 to the outside. For example, there is no continuity between point A, which is outside the defined space, and point B, which is inside the defined space. The remaining coating 12 within the defined space is configured into a coil by providing a third laser treatment zone 50, which effectively removes the coating 12 but does not form a bond between the first substrate 10 and the second substrate 20.

[0095] Additionally, the electrical resistance of the coating 12 can be affected by heat treatment in the second laser treatment zone 40. The coating 12 in the second laser treatment zone 40 is not removed, but rather thermally modified so that its electrical conductivity is adjusted.

[0096] Figure 8 shows an enlarged cross-sectional view of Configuration 1 of Figure 7. From the side view of Figure 8, it can be seen that the second substrate 20 is configured as a spacer defining a sidewall, and the coating 12 does not cover the entire surface of the first substrate 10. In the contact area where the first substrate 10 with the coating 12 directly contacts the second substrate 20, two welding lines 100, a first welding line 101 and a second welding line 102, are arranged parallel to each other. The heat introduced by the two welding lines 100 melts and mixes the materials of the first substrate 10, the coating 12, and the second substrate 20, forming a first laser treatment zone 30, which forms a hermetic bond between the two substrates 10 and 20. The material of the coating 12 is part of the material mixture, which effectively removes the coating 12 from the surface of the first substrate 10. As can be seen in Figure 8, the focal plane for forming the first laser treatment zone 30 is located at a first depth H1. This depth is selected so that the melt zone 114 created by the laser reaches from the lower first substrate 10 to the upper second substrate 20 .

[0097] In the second laser treatment zone 40, the coating 12 is not removed, but its properties are changed by a heat-affected zone 120 caused by the additional laser lines 104 located at a second depth H2 from the surface of the first substrate 10. In the case of a conductive ITO coating as the coating 12, the electrical resistance increases in the second laser treatment zone 40, resulting in the formation of a resistor by the selective laser treatment.

[0098] In the third laser treatment zone 50, the coating 12 is effectively removed without bonding the first substrate 10 to the second substrate 20. This is achieved by forming a third laser treatment zone 50 in which the melt zone of the additional laser weld line 104 located at a third depth H3 contacts the surface of the first substrate 10, causing melting of the coating 12. The molten material of the coating 12 in the third laser treatment zone 50 mixes with the molten material of the first substrate 10, resulting in effective removal from the surface of the first substrate 10. In this case, since the first substrate 10 is electrically insulating, a non-conductive structure is formed.

[0099] 9 shows a close-up photograph of two laser weld seams 100 viewed from above, where one of the substrates 10, 20 of the formed substrate stack has a coating 12, 22 on the side facing the other substrate 10, 20. In the example shown, the coating is a broadband IR coating, which exhibits a yellow-brown hue in VIS when illuminated from above.

[0100] Within the melt zone 114, the coatings 12, 22 have been completely removed by a molten pool of material melted by the laser. When illuminated from above, this area is no longer reflective and therefore appears darker than the intact, untreated coated area, as can be seen in the photograph shown in Figure 9. Most notably, there is again no Fresnel reflection, as there is no air gap between the two substrates 10, 20.

[0101] A continuous color change gradient relative to the unaffected coating can be observed within the heat affected zone 120 surrounding the melt zone 114. In this example, this color change is due to a permanent change in the thermal dependence of the layer thickness, and is stronger closer to the melt zone 114.

[0102] The heat affected zone 120 extends symmetrically from the melt zone 114. Its width w haz is the width of the molten zone w m At least equal to, preferably, condition 1 <w haz / w m <10. In the photograph shown in Figure 9, w m is 17 μm, and w haz is 35 μm.

[0103] 10 shows a further example of the third exemplary configuration 1 comprising two substrates 10, 20. In the example shown, the first substrate 10 is configured as a spacer and does not cover the entire surface of the second substrate 20. The second substrate 20 has a non-absorbing coating 22 located on the surface facing the first substrate 10. In this example, the coating 22 is configured as an anti-reflective coating to improve light transmission from the second substrate 20 to the first substrate 10 and vice versa.

[0104] The first substrate 10 has an inner coating 26 located on its sidewall that is not parallel to the interface between the two substrates 10, 20, but is disposed at an angle θ relative to the surface normal of the interface plane. The inner coating 26 is a light-absorbing coating in this example. In this example, two weld lines 100 are used to join the two substrates 10, 20 together, and the coating 26 is effectively removed in a melt zone 114 and modified in a heat-affected zone 120.

[0105] Configuration 1 of FIG. 10 may be used, for example, to form a photoconductive structure, the structure being shielded from stray light by inner coating 26 and the internal transmission being enhanced by coating 22.

[0106] FIG. 11 shows a cross-sectional view of a fourth exemplary configuration 1 configured as a cap having a top or bottom formed by a first substrate 10 and sidewalls formed by a second substrate 20.

[0107] In this example, the coating 12 of the first substrate 10 is configured as an anti-reflective coating, and the inner coating 26 located on the sidewall of the second substrate 20 is configured as an absorbing coating. The two substrates 10, 20 are hermetically bonded together by a bond line 100 to form a cap-like structure.

[0108] The cap is highly transparent in one direction, allowing light to pass easily through the top or bottom of the cap, and highly absorptive in a second direction, blocking nearly all light passing through the sidewalls. Such a configuration is particularly useful in many optical devices, such as sensor packages, where the goal is to reduce stray light.

[0109] It is important to note that we take into account the coating absorption A, which is not equal to the transparency T, since the reflectivity R of the coating must also be taken into account. T=P out / P in =1-RA<1-A

[0110] As can be seen from Figure 11, P out / P in The transmittance T, defined by: is high in the direction perpendicular to the plane of the coating 12 of the first substrate and low in the direction perpendicular to the plane of the inner coating 26 of the second substrate.

[0111] Of most importance is the transmittance T of light perpendicular to the coating 12. What is surprising here is that it is possible to use a coating 12 that absorbs less than 10%, less than 5%, less than 1%, or even less than 0.5% in this direction. This contradicts the common wisdom that for good coating-assisted laser bonding, you need to have a coating layer that absorbs at least 10% of the incident laser light.

[0112] 12 shows a cross-sectional view of a fifth exemplary configuration 1. In this example, several cap-like elements are manufactured simultaneously by stacking large wafers as substrates 10, 10', 20 on top of each other and then dicing along dicing lines 300 to separate the individual caps.

[0113] In the illustrated example, the first substrate 10 is first bonded to a second substrate 20 configured as a spacer. In a next step, this intermediate stack is bonded to a further substrate 10'. The first substrate 10 and the further substrate 10' each comprise a coating 12, 12', configured in this example as an anti-reflective coating. The sidewalls of the second substrate 20 are coated with an inner coating 26, configured in this example as a light-absorbing coating. Prior to dicing, a plurality of cavities 500 are formed.

[0114] FIG. 13 shows a cross-sectional view of the cap taken from configuration 1 of FIG.

[0115] Structure 1 of Figure 13 is obtained by dicing the substrate stack of Figure 12 along the indicated dicing lines 300. The resulting structure 1 is similar to structure 1 shown in Figure 11, but has highly transparent sidewalls and opaque top or bottom walls.

[0116] Although the present invention has been described above by giving preferred examples of embodiments, the present invention is not limited to these and various modifications are possible. [Explanation of symbols]

[0117] 1 Configuration 10 First substrate 10' Further boards 12 Coating of the first substrate 12' Further Coating 20 Second substrate 22 Coating of second substrate 24 Lower surface of second substrate 26 Inner coating θ Wall inclination angle 30 First laser treatment zone 40 Second laser treatment zone 50 Third laser treatment zone 100 welding lines 101 First Weld Line 102 Second Weld Line 104 additional laser lines 110 Absorption Zone 112 Long and thin bubbles 114 Melting Zone 120 Heat Affected Zone 130 Interrupted weld line 132 Unevenness of the weld line 200 contact area 300 dicing lines 400 Antenna Structure 500 cavity H1, H2, H3 laser focal plane depth d Gap between boards w m Melt Zone Width w haz Heat Affected Zone Width

Claims

1. A configuration (1) comprising a transparent first substrate (10) and a second substrate (20) arranged adjacent to the first substrate (10), a first laser treatment zone (30) including a welding line (100), the first substrate (10) being transparent and therefore transmissive to light in a defined wavelength range of 900 nm to 1500 nm, allowing laser welding for joining the first substrate (10) to the second substrate (20), in which the materials of the first substrate (10) and the second substrate (20) are melted and mixed, and the two substrates (10, 20) are joined together; the coatings (12, 22) of the first substrate (10) and / or the second substrate (20) outside the laser treatment zones (30, 40, 50) have an absorption of less than 10% for light having a wavelength in the wavelength range of 900 nm to 1500 nm, the coatings (12, 22) being selectively heat treated by heat generated in one or more second laser treatment zones (40), and no intermixing of materials of the first substrate (10) and the second substrate (20) occurs within the one or more second laser treatment zones (40); and / or the coating (12, 22) is selectively removed by selectively melting portions of the first substrate (10) or the second substrate (20) in the one or more third laser treatment zones (50), and no intermixing of materials of the first substrate (10) and the second substrate (20) occurs in the one or more third laser treatment zones (50); Configuration (1).

2. the absorption of the coating (12, 22) for light having a wavelength within the defined wavelength range is less than 5%, preferably less than 1%, particularly preferably less than 0.5%; The arrangement (1) according to claim 1.

3. the coating (12, 22) of the first substrate (10) and / or the second substrate (20) has at least one property selected from transparency, reflectivity, absorbance, color, electrical conductivity, optical phase retardation, roughness, hardness, and surface tension that is affected by the thermal treatment in the one or more second laser treatment zones (40); The arrangement (1) according to claim 1 or 2.

4. The electrical conductivity of the coating (12, 22) is modified in at least one of the one or more second laser treatment zones (40); an antenna structure (400) suitable for receiving and / or transmitting RF signals or suitable for wireless charging; a heating structure, - an electrode structure for detecting or generating an electric field; - electrical paths on said first and / or said second substrate; forming at least one of Arrangement (1) according to any one of claims 1 to 3.

5. the coating (12, 22) is a light reflective or anti-reflective coating for visible, near-infrared and / or UV light, the reflectivity of the coating being modified in at least one of the one or more second laser treatment zones (40) to thereby - non-reflective or reflective areas, - alignment structures or fiducials; a diffraction grating structure, - a label, - a barcode or a QR code, forming at least one of Arrangement (1) according to any one of claims 1 to 3.

6. the coating (12, 22) of the first substrate (10) and / or the second substrate (20) is a single-layer or multi-layer structure, the single layer or at least one layer of the coating being configured as an inorganic layer, preferably selected from a metal layer, a nitride layer or an oxide layer; Arrangement (1) according to any one of claims 1 to 5.

7. an inner coating (26) is arranged on the inner walls, in particular the side walls, of the cavity (500) that do not face the interface between the first substrate (10) and the second substrate (20), characterized in that the inner coating (26) is preferably light-absorbing or light-reflective; Arrangement (1) according to any one of claims 1 to 6.

8. the first substrate (10) is configured as a cover substrate and the second substrate (20) is configured as a base substrate, the two substrates forming a cavity (500) or an enclosure for a functional zone, or the arrangement (1) additionally comprises a further substrate (10'), the first substrate (10) being configured as a cover substrate, the second substrate (20) being configured as an intermediate substrate and the further substrate (10') being configured as a bottom substrate, the three substrates forming a cavity (500) or an enclosure for a functional zone, Arrangement (1) according to any one of claims 1 to 7.

9. The first laser treatment zone (30) surrounds a cavity (500) or a functional zone, and the bond between the first substrate (10) and the second substrate (20) formed in the first laser treatment zone (30) is gas-tight. Arrangement (1) according to any one of claims 1 to 8.

10. said first substrate (10) and / or said further substrate (10'), if present, are characterized in that they are glass, glass ceramic, silicon and inorganic crystals such as sapphire or diamond; and / or characterised in that the second substrate (20) is selected from glass, in particular volume-absorbing glass, glass ceramic, inorganic crystals such as silicon, sapphire or diamond, metals or metal alloys and plastic materials; Arrangement (1) according to any one of claims 1 to 9.

11. the first substrate (10) has a transmittance of at least 50% for light having a wavelength within the defined wavelength range; Arrangement (1) according to any one of claims 1 to 10.

12. A method for manufacturing an arrangement (1) of at least two connected substrates (10, 20, 10'), said method comprising the steps of: - providing a first substrate (10) and a second substrate (20) to form a substrate stack, at least one of said first substrate (10) and said second substrate (20) having a coating (12, 22) arranged on a side facing the interface between said first substrate (10) and said second substrate (20); - forming a first laser treatment zone (30) for joining the first substrate (10) and the second substrate (20) by laser welding, wherein at least the first substrate (10) is transparent, so that the first substrate (10) is transparent to the light of the laser, and the coating (12, 22) has an absorption of the welding laser light of less than 10% before the laser treatment, and the first laser treatment zone (30) is formed by introducing at least one laser weld line (100), in which the materials of the first substrate (10) and the second substrate (20) melt and mix to join the first substrate (10) and the second substrate (20); forming a second laser treatment zone (40) to selectively heat treat the coating (12, 22), whereby properties of the coating (12, 22) are modified and / or forming a third laser treatment zone (50) to selectively remove the coating (12, 22), whereby intermixing of materials of the first substrate (10) and the second substrate (20) does not occur; A method comprising:

13. The method is used to manufacture a configuration (1) according to any one of claims 1 to 11, wherein the defined wavelength range includes the wavelength of a welding laser light. The method of claim 12.

14. the coating (12, 22) is selected such that upon heat treatment the color of the coating (12, 22) changes; The method further comprises an inspection step, wherein weld line interruptions (130) and / or weld line non-uniformities (132) in the at least one laser weld line (100) are identified by detecting a change in the color of a heat treated coating (12, 22) or the presence of an untreated coating (12, 22) along the intended laser weld line (100), or the coating (12, 22) is selected to change its electrical conductivity when heat treated; The method further comprises an inspection step, in which weld line interruptions (130) and / or weld line non-uniformities (132) in the at least one laser weld line (100) are identified by measuring the electrical resistance between the coating (12, 22) in an inner or functional zone and a portion of the coating (12, 22) outside the zone.

14. The method of claim 12 or 13.

15. The position of the laser focus is a first distance H from the interface between the first substrate (10) and the second substrate (20) to form at least one first laser treatment zone (30). １ and the position of the focus of the laser is set at a second distance H from the interface to form at least one second laser treatment zone (40). ２ and the position of the focus of the laser is set at a third distance H from the interface to form at least one third laser treatment zone (50). ３ is set to H １ <H ３ <H ２ That is, 15. The method according to any one of claims 12 to 14.

16. Use of a configuration (1) according to any one of claims 1 to 11 or a configuration manufactured according to a method according to any one of claims 12 to 15 as an enclosure or as a cap for a medical implant or sensor.

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