EP4010283A1

EP4010283A1 - Hermetically sealed glass enclosure

Info

Publication number: EP4010283A1
Application number: EP20753928.9A
Authority: EP
Inventors: Thomas Zetterer; Robert Hettler; Antti Määttänen; Jens Ulrich Thomas; Yutaka ONEZAWA; Frank Gindele
Original assignee: Schott AG
Current assignee: Schott AG
Priority date: 2019-08-07
Filing date: 2020-08-07
Publication date: 2022-06-15
Also published as: DE102019121298A1; JP2022543633A; WO2021023856A1; CN114206771A; US20220157684A1

Abstract

The invention relates to a hermetically sealed enclosure which preferably comprises a vitreous material. The enclosure comprises: a heat-dissipating base substrate for dissipating heat from the hermetically sealed enclosure; and a cap. The enclosure also comprises at least one functional area, in particular a cavity, which is hermetically sealed by the enclosure. The cap is positioned on the base substrate, wherein the cap together with the base substrate form at least one portion of the enclosure. The enclosure also comprises at least one laser bonding line for hermetically sealing the enclosure, wherein the laser bonding line has a height HL perpendicular to its connection plane.

Description

Hermetically sealed glass casing

Description Field of the Invention

The invention relates to a hermetically sealed glass casing and a method for providing a hermetically sealed glass casing.

Background and general description of the invention

Hermetically sealed enclosures can be used to protect sensitive electronics, circuits or, for example, sensors. Medical implants can be used, for example, in the heart area, in the retina or for bio-processors. Bio-processors are known which are made from titanium and used.

Sensors can be protected with an enclosure according to the invention for particularly adverse environmental conditions. This area also includes, for example, MEMS (micro-electro-mechanical systems), barometers, blood gas sensors, glucose sensors, etc.

Another field for the use of a housing according to the invention can be found in a cover for a smartphone, in the area of virtual reality glasses and similar devices. An enclosure according to the invention can also be used for the production of flow cells, for example in the context of electromobility. However, housings according to the invention can also be used in aerospace, in high-temperature applications and in the field of micro-optics.

It can be problematic if the sensitive electronics are to be connected to the outside with electrical connections. Or if the electronics to be protected have larger dimensions, for example comprise an entire printed circuit board. The protection of a larger area, such as a printed circuit board, is possible, but expensive and time-consuming.

The aforementioned uses have in common that high demands are made on the electronics with regard to their robustness. In order to enable the use of electronics that can not be expected to withstand these external influences, the housing must be protected from such adverse environmental influences. In addition, there may be a requirement that an exchange with the inner area of the housing, that is to say the cavity formed by the housing, for example with electromagnetic radiation in particular in the visible range and / or in the range of microwave radiation, is guaranteed, that is, the housing is at least partially - that is, at least in some areas and / or at least for a wavelength range - transparent. This transparency allows communication processes, data or energy transmission, measurements from and with the electronics or sensors arranged in the cavity. In particular, optical communication methods or optical data or energy transmission can be made possible.

It is basically known to join several parts together and to arrange these parts in such a way that a receiving area is created in an intermediate space in which components can be accommodated. For example, EP 3 012 059 B1 shows a method for producing a transparent part for protecting an optical component. A new type of laser process is used.

The present invention is to be seen in the context that housings are to be improved and, in particular, built to be more resistant. This increases the robustness against environmental influences and also against mechanical loads.

In other words, the invention is based on the object of providing an improved housing for a cavity in order to withstand even more adverse environmental conditions and influences or to make the finished housings cheaper to produce. If necessary, the housing according to the invention allows the use of cheaper components due to the protective effect that it creates.

A further aspect of the present invention is therefore to provide the improvement of the housing in a particularly cost-effective, but also reliable and long-lasting manner, since the improved housing also has to assert itself in the competitive situation on the market.

Yet another aspect of the present invention is based on the fact that it has been recognized that in the case of a hermetically sealed housing solution, special precautions may have to be taken in order to dissipate any heat generated in the housing, such as in particular from power semiconductors. Known highly thermally conductive components can prove to be difficult with regard to their connection in order to hermetically seal them or housings with them.

One aspect of the task is, in the case of heat generation from the interior of the hermetically sealed housing, which is generated in particular by power semiconductors in the housing, the dissipation or dissipation of the heat and thus constant operation of the possibly arranged in the housing Circuit too enable. In addition, thermal aging processes should be reduced and avoided as far as possible.

A hermetically sealed housing according to the invention therefore comprises a heat-dissipating base substrate for dissipating heat from the hermetically sealed housing. The base substrate is in particular constructed or composed in such a way that heat dissipation from the housing is promoted, in particular due to the material of the base substrate and / or its construction or design. In the case of the material of the base substrate, it is taken into account that the task-related hermetic sealing of the functional area is promoted or can be implemented. If necessary, the hermetic seal can be achieved by coating the base substrate. It is preferred if the base substrate itself is constructed in such a way that a hermetic seal is achieved through the material of the heat-dissipating base substrate.

The hermetically sealed housing further comprises a cap, preferably made of a glass-like material, and at least one functional area, in particular a cavity, that is hermetically sealed by the housing. The cap is arranged or placed on the base substrate so that it is located above at least part or the larger part of the base substrate. Together with the base substrate, the cap forms at least part of the housing. In other words, the base substrate or cap are designed or prepared in such a way that they together form a housing and can enclose a functional area.

The housing further comprises at least one laser bond line for the hermetically sealed joining of the housing. The laser bond line has a height HL perpendicular to its connection plane. In other words, the laser bond line is arranged or constructed in such a way that it is able to bridge gaps in the hermetic seal of the housing by, for example, joining two components to one another by means of the laser bond line. In the event that the housing only has the base substrate and cap in order to completely enclose the functional area, the contact area between base substrate and cap, i.e. the point or area at which cap and base substrate adjoin one another, is bridged or connected by means of the laser bond line . As a result, the housing forms as if it were formed in one piece, with the separation point between the components also being hermetically sealed by means of the laser bond line. The cap preferably comprises a vitreous material. The cap is thereby preferably transparent or permeable to at least one wavelength range, for example optically transparent. Depending on the application, it can also be advantageous if the cap is designed to be opaque, ie optically opaque. A reduced transparency or partial permeability can also be sufficient for the function. For example, the cap can comprise glass, glass ceramic, silicon, sapphire or a combination of the aforementioned materials. In a preferred embodiment, the cap is a glass cap, for example made of hardened glass, special glass, high-temperature-resistant glass from the applicant's product portfolio.

The base substrate includes, in particular, a material with high thermal conductivity or is made up of this. The thermal conductivity of the heat-dissipating base substrate is preferably in a range of 100 W / (m * K) or greater, preferably 150 W / (m * K) or greater, and more preferably 170 W / (m * K) or greater. A material that is particularly suitable for the construction of the heat-dissipating base substrate is a metallic nitride, such as aluminum nitride ceramic or silicon nitride ceramic.

The at least one laser bond line preferably encircles the functional area at a distance DF. In one example, the distance DF is constant around the functional area, so that the laser bond line is approximately the same distance around the functional area on all sides. The distance DF can, however, also fluctuate depending on the application. This can be more favorable in terms of production technology if a plurality of housings are joined at the same time in one work step and, for example, straight joining lines or laser bond lines are made on the respective contact surfaces of the individual housings. This can also be the case if the functional area or the housing is, for example, round or has any shape and the laser bond line, which hermetically seals the functional area, is drawn in straight lines. In a particular example, the functional area can be designed as a cavity and the cavity can in turn have optical properties, for example in the form of a lens, such as a collecting lens, and the laser bond line can be drawn around the cavity in a different pattern.

The cap is preferably joined to the base substrate by means of the laser bonding line. In other words, the cap is placed on or in the base substrate without an intermediate layer and with the base substrate directly and directly with one or a plurality of common laser bond lines joined together. In this case the cap together with the base substrate together form the complete housing. In other words, no additional or further part is required to form or close the housing, but rather the base substrate, the at least one laser bond line and the cap together completely and hermetically seal the functional area or the cavity.

The functional area is preferably prepared to accommodate at least one accommodation object, such as an electronic circuit, a sensor or MEMS. For example, the accommodation object is arranged on the base substrate in the area of an underside of the cavity and the cap is arranged above the accommodation object and placed on the underside of the cavity. In this case, at least one accommodation object is arranged on the base substrate and within the housing.

The at least one accommodation object includes, for example, a power semiconductor chip, e.g. a GaN LED, a SiC, GaAs or GaN power transistor. Such power semiconductor chips give off a non-negligible amount of heat during operation. Particularly when one of the aforementioned accommodation objects is arranged in the cavity, sufficient heat dissipation from the housing must be ensured in order to ensure the permanent operation of the accommodation object or objects.

If the cap is a cap that is permeable in the optical wavelength range, for example an optically transparent cap, energy can be supplied to the housing optically, for example by means of a photovoltaic cell arranged in the housing or another type of optical receptor for provision of electrical energy. The housing can then be described as a self-sufficient housing.

The cap is more preferably joined to the base substrate at room temperature. For example, the joining process used can be carried out at room temperature. Only a negligible amount of heat penetrates into the functional area as a result of the joining process, or the amount of heat generated by the joining process can be kept away from the functional area by the heat-dissipating base substrate.

The laser bond line preferably extends into the material of the cap with the height HL. On the opposite side, the laser bond line extends into the material of the base substrate, the heat-dissipating base substrate and the cap being joined to one another in a melting manner. In other words, mixes in the joining step or in the Melting laser bond line Material of the base substrate with the material of the cap to produce the fixed and non-detachable hermetic bond between the base substrate and cap.

In another example, an intermediate substrate is arranged between the heat-dissipating base substrate and the cap, wherein in this example the base substrate is joined to the intermediate substrate in a first connection plane by means of at least one first laser bond line and the cap with the intermediate substrate in a second connection plane with at least one second laser bond line is joined.

A marker can preferably be introduced into the cap, the base substrate and / or the intermediate substrate.

In the housing, according to one embodiment, the cap forms an upper side and a laterally circumferential edge of the functional area, and the heat-dissipating base substrate forms an underside of the functional area, which together completely enclose the accommodation cavity. In this example, the cap is designed in such a way that it extends laterally as far as the functional area, that is to say, for example, to the side of the at least one accommodation object. For example, in this case the cap has lateral flanks on which an upper part of the cap rests, the flanks then being joined to the base substrate. This embodiment has the advantage that a larger proportion of the surface of the housing has the preferably transparent material of the cap and thus a larger proportion of the housing is available for any type of communication or exchange with the environment.

On the other hand, in a further example, the cap can form the upper side of the functional area and the heat-dissipating base substrate the laterally circumferential edge and the underside of the functional area, so that the functional area or the accommodation cavity is also completely enclosed. In this example, the base substrate extends next to the functional area or next to the at least one accommodation object. This can be implemented, for example, when the functional area is introduced into the base substrate, i.e. by, for example, abrasively hollowing out a recess from the base substrate and thus the functional area and / or the at least one accommodation object is surrounded by the material of the base substrate at the bottom and side. This embodiment has the advantage that a comparatively larger proportion of the surface has the heat-dissipating material of the base substrate and thus the heat dissipation is improved. In a further example, the cap can form the top of the functional area or cavity, the intermediate substrate form the laterally circumferential edge and the heat-dissipating base substrate form the bottom of the functional area or cavity, which together completely enclose the accommodation cavity.

The housing formed at least from a laterally circumferential edge, bottom or top is preferably at least partially transparent for a wavelength range.

The heat-dissipating base substrate and / or the cap preferably have a thickness of less than 500 mhi, preferably less than 300 mhi, more preferably less than 120 mhi and even more preferably a thickness of less than 80 mhi.

The heat-dissipating base substrate can furthermore have at least a first and a second contact, the first contact being arranged, for example, on the underside of the functional area or the cavity. The second contact can be arranged outside the underside of the functional area or the cavity and be electrically connected to the first contact.

The housing preferably has a size of 10mm x 10mm or less, preferably 5mm x 5mm or smaller, more preferably 3mm x 3mm or less, even more preferably 2mm x 2mm, more preferably 1mm x 1mm or also 0.2mm x 0.2 mm or smaller. The housing is in no way limited to a square floor plan, but rather a housing can also have 10mm x 3mm or any other shape such as round or oval. The cap preferably has a flea of 2 mm or less. The flank of the cap preferably has a flank of 2 mm or less. On the other hand, the transparent housing can also be made larger, depending on the area of application, several centimeters in length and more is possible. A size limitation from practice, which results from the preferred positioning method, but which should not be understood as a size limitation per se, consists simply in the size of the wafers to be cut. However, the use of wafers for positioning is only to be understood as an example. It is entirely possible, for example, to use glass plates to position the transparent housing, which can also have larger dimensions than typical wafer sizes.

In the context of the invention, a method for providing a hermetically sealed housing is also presented, with a functional area of the housing, in particular a cavity that is enclosed. The functional area or the cavity is enclosed by a laterally circumferential edge, an underside and an upper side of the housing. An accommodation cavity is designed in the functional area to accommodate an accommodation object. The method has the following steps: providing a heat-dissipating base substrate and at least one cap, the cap being transparent at least in some areas and at least for one wavelength range and therefore being a transparent cap; Arranging at least one accommodation object on the underside of the accommodation cavity; Arranging the cap on the heat-dissipating base substrate above the accommodation object, at least one contact surface being formed between the heat-dissipating base substrate and the cap, so that each housing has at least one contact surface; Hermetically sealed sealing of the cavities by forming a laser bond line on the at least one contact surface of each housing.

In the event that a plurality of housings are efficiently produced together in one work step, the respective housing is separated by means of a cutting or severing step.

The cap preferably has a flank and an upper part, so that the upper side of the upper part of the cap and at least part of the edge of the accommodation cavity is formed by the flank, and the flank or a contact surface is formed on the end face.

The further step is preferably carried out that the laser beam is guided around the functional area to form the laser bond line, so that the functional area is hermetically sealed all the way around the contact surface. If necessary, the laser beam can be guided around multiple times and / or a plurality of laser bond lines can be formed.

A plurality of undersides for a plurality of accommodation cavities to be formed can be formed on the heat-dissipating base substrate and a plurality of caps can be applied to the base substrate to form a plurality of housings on the base substrate. In other words, in this case the base substrate is larger, at least in its lateral extension, than the dimensions of an enclosure, so that a plurality of later enclosures share a common base substrate. In this case the individual enclosures are obtained by taking the additional step it is carried out that the (large) base substrate is cut or divided in such a way that each housing receives part of the base substrate. For this purpose, each housing forms an underside on the base substrate, and the base substrate is cut in such a way that the respective underside remains with the respective housing.

A plurality of undersides for a plurality of accommodation cavities to be formed can also be formed on the base substrate, and a plurality of caps can be applied to the substrate in order to form a plurality of housings on the base substrate. In other words, a single substrate, such as a printed circuit board in particular, can have sensitive electronics at different points in such a way that a plurality of caps - which can also be constructed in different ways, for example in terms of shape, height and size - are applied to the same substrate around the sensitive Protect electronics while not covering too much area of the substrate. In this way, material can be saved in an advantageous manner and a cost-effective method for producing a housing can be provided, with which sensitive electronics can be protected from external environmental influences. In this case it can also be designed so that the individual housings are not separated afterwards, but rather remain on the common base substrate.

With at least one of the features listed above, a housing with a hermetically sealed accommodation cavity enclosed therein can be produced. A housing produced in this way with a hermetically sealed accommodation cavity enclosed therein can be used in particular as a medical implant or as a sensor, for example as a barometer.

In the context of the invention, among other things, a method for providing a plurality of hermetically sealed housings is presented. Although the method could be changed in such a way that only a single housing is produced with the method, it makes sense for economic reasons to produce a plurality of housings in the same process sequence. This saves time, effort and / or raw material.

In other words, a first (base substrate) and at least one second substrate (cap) are provided to provide a housing in a first step, the at least one second substrate (the cap) comprising transparent material, i.e. at least in some areas or partially for at least one wavelength range is transparent. The cap io is preferably arranged directly on the base substrate, that is to say, for example, the cavity to be sealed is covered by the cap, and the respective bottom side of the respective housing is formed by the base substrate. At least one contact area is formed between the at least two substrates, so that each housing has at least one contact area. The cavities are then hermetically sealed by joining the at least two substrates along the contact surface (s) of each housing, in particular on the contact surface along a line at the edge of each housing. The housings can advantageously be manufactured jointly, for example from a common starting substrate, for example in the form of wafers of a wafer stack, or only the base substrate can be provided as a wafer. Then, in the process, the individual housing can also be separated by means of a cutting or severing step.

For the purposes of this application, the underside or the upper side is a geometrical construct that can also be any other side with regard to the final position of the housing. If you consider the size of the housing and its possible areas of application, it is clear that the housing can assume any position in the room during operation. The terms were used to enable easy access to the invention, and components are typically nowadays assembled by machine “from above”, for example by means of a gripper; This also leads to the description of the position of the sides of the housing, which is preferably arranged for its production in such a way that it correspondingly forms the underside to be equipped with accommodation objects and the upper side covering the accommodation objects.

Alternatively, the upper side can be described as a first side, the lower side as a second side opposite the first side and the edge as the intermediate area between the first and second side, the edge typically being essentially perpendicular to the first and / or second side stands. In order to facilitate the understanding of the invention and to approximate the invention to a typical description, the terms top side, bottom side and circumferential edge are used below - as explained. The edge can also have a height of 0, so that the top side then rests directly on the bottom side, for example when the functional area only has a thin functional layer.

The top of the cavity can then be formed by a top layer, such as a substrate, wafer or plate. The peripheral edge of the cavity can also be formed, for example, in that the upper layer protrudes downwards or the lower layer protrudes upwards, for example by the lower layer being abrasively hollowed out. The underside of the cavity can finally be formed by a lower layer, a substrate, small discs or platelets and be arranged below the upper layer.

The cavities are designed in particular as accommodation cavities. This means that electronic circuits, sensors, MEMS or MOEMS, for example, can be used in the respective cavities. These aforementioned devices, such as in particular electronic circuits, sensors or MEMS, are therefore enclosed on all sides by the housing, since they are arranged within the accommodation cavity.

The at least two substrates or the base substrate and the cap are arranged or attached to one another in such a way that they come to lie flat against one another without other layers, plies or inclusions being present between the at least two substrates or between the base substrate and the cap. For technical reasons, it is possible that the slightest gas inclusions between the layers in the area of the contact surfaces cannot be avoided, which also result from possible unevenness. For example, by increasing the pressure, in particular by pressing, or by treating the surface of the substrate layers, in particular the contact surfaces, such as a grinding process, the amount of gas enclosed in the area of the flat contact surface can be further reduced. Prior evacuation is beneficial. Filling with a type of gas or a liquid can also be advantageous, depending on the process parameters and the materials to be used.

In other words, the substrate layers or the base substrate with the cap are stacked directly and in direct contact with one another, that is to say they are arranged on one another. Foreign materials between the substrate layers are preferably excluded as far as possible, so that the most cohesive and flat contact possible is produced from one substrate layer to the adjacent substrate layer. In the case of two substrates, for example, the base substrate is arranged in direct contact with the cover substrate with respect to one another, in particular without other materials or a spacing between the base substrate and cover substrate being present. In the example of more than two substrates, the base substrate is arranged directly adjacent to the first or the first of the intermediate substrate layers, and the cover substrate is in turn arranged directly adjacent to the last or the last of the intermediate substrate layers. In the example of the base substrate and cap, these are arranged next to one another in such a way that the End faces of the cap, the contact surface is arranged on which a direct, direct and as flat as possible contact between the end faces of the cap and the base substrate is created.

Then the substrates are joined together with the new laser joining process. In this case, a flat substrate layer with the flat substrate layer or flat end face arranged immediately adjacent is joined directly to one another without foreign materials or non-flat materials or intermediate layers being provided or required for this. The substrates are therefore each joined directly to one another. The laser bond line created in the two-dimensional contact area between two substrate layers non-releasably connects the substrate layers that are directly adjacent to one another, i.e. directly adjacent to one another. The fused area of the laser bond line is thus located in both substrates and merges seamlessly from the first substrate into the immediately adjacent second substrate, that is, for example, from the base substrate into the cap.

A direct, flat or even full-area transition is thus formed from one substrate layer to the next substrate layer, such as a substrate-substrate transition or a glass-glass transition. A locally delimited volume is formed as a joining zone or laser bond line, in which there is a material transfer or mixing between the adjacent substrate layers, which are in particular flat. In other words, material of the first substrate, for example the cover substrate, penetrates the adjacent substrate, for example the intermediate substrate or the base substrate, and vice versa, so material from the adjacent substrate penetrates the first substrate, so that in the joining zone there is complete material intermixing of the substrates arranged next to one another. The joining zone can therefore also be referred to as a convection zone.

The new laser joining technology for producing the non-releasable glass-glass transition or substrate-substrate transition is particularly advantageously free of intermediate layers, glass frits, foils or adhesives that had to be introduced between the substrates in earlier known processes. Rather, the non-releasable connection can be produced without corresponding interfering intermediate layers or additional materials. This saves the use of additional materials, increases the achievable hardness of the end product and enables reliable hermetic sealing of the functional area or the cavity / s. The laser joining zone can be passed through in the finished end product, for example detect the specific local refractive index change of the material in the small fusion area.

It is particularly preferred if a possibly occurring gap between the substrates or between the base substrate and the cap is less than or equal to 5 mhi thick, more preferably less than or equal to 1 mhi. Such a gap is created, for example, by tolerances in the production of the substrate, by thermal influences or by inclusions of particles such as dust. Even with such a tolerable spacing, which in the context of this invention is also to be regarded as immediately adjacent, it is possible to join with the laser in such a way that the joining zone has a thickness between 10 to 50 mhi and thus a hermetic seal is ensured. In this case, too, the joining zone extends from the first substrate into the second substrate arranged adjacent to the first substrate. The joining zone is therefore introduced in the contact area between the first and second substrate and fuses the substrates directly with one another to form an inseparable bond. In other words, when the adjacent substrates are joined in the joining zone, material of both substrates that lies in the joining zone is melted directly, and the material of the first substrate mixes with the material of the second substrate to form an inseparable one-piece composite. The housing produced in this way thus has a one-piece, that is to say monolithic bond between the substrates in the joining zone.

A contact surface does not have to be optically transparent. It is also advantageous if the transparent substrate or the transparent cap is opaque in the visible wavelength range. Only the substrate through which the laser passes in order to reach the contact surface has at least one spectral “window” so that at least the wavelength of the laser used can pass through the substrate at least partially or at least in areas. The contact surface is designed so that the laser can perform an energy deposition on it. For example, the surfaces of the two substrates lying against one another can be sprinkled and more preferably have a roughness in the nm range. The laser is at least partially absorbed on this surface, so that energy can be introduced there. In general, a contact surface in the sense of this application is to be understood as a surface on which the incident laser beam can deposit energy and thus a joining process can be carried out along the contact surface. A simple case of such an interface is the contact area between the cap and the base substrate. The Substrates are glued or joined to one another to form a common housing and to hermetically seal the cavities.

The step of hermetically sealing the housing is carried out by joining along the at least one contact surface of each housing by means of a laser joining process. In other words, energy can be deposited by means of a laser in the area of the contact surface, specifically so locally that it is referred to as a cold joining process. The thermal energy provided for joining is therefore concentrated on the course of the laser bond line and diffuses only comparatively slowly into the rest of the material of the housing, so that in particular no significant temperature rise occurs in the cavity. This protects the electronics arranged in the cavity from overheating.

By means of the laser, material of the two substrates or caps to be joined is melted locally in the area of the respective housing along the laser bonding line, so that the at least two substrates are connected locally. For this purpose, the person skilled in the art can refer, for example, to EP 3 012 059 B1 of the applicant, which is hereby incorporated by reference.

In the case of a transparent housing made of glass or predominantly made of glass, in particular made of borosilicate glass, it is particularly advantageous that this is chemically inert.

The substrate or substrates can also have a coating. AR coatings, protective coatings, bioactive films, optical filters, conductive layers, e.g. made of ITO or gold, can be used, for example, as long as it is ensured that there is transparency or at least partial transparency for the laser wavelength used in the radiation area.

The at least one transparent substrate is preferably made of glass, glass ceramic, silicon or sapphire or a combination of the aforementioned materials, that is to say, for example, of glass-silicon, glass / silicon / sapphire combination or silicon / sapphire combination. The further substrate or substrates can also comprise or consist of Al 2 O 3, sapphire, Si 3 N 4 or AlN. By combining a transparent substrate with a substrate of different types, for example, semiconductor properties can be realized. Coatings can also be used, for example piezoresistive Si layers, in particular for pressure sensors, or thicker layers for micromechanical applications, such as pulse measurement via a MEMS. At least one of the laterally circumferential edge, underside or upper side are here at least partially transparent for a wavelength range. In other words, it is sufficient if at least one sub-element of the housing is transparent at least in a sub-area of the sub-element for a preferred wavelength range, the wavelength range being known in advance and the material being able to be adjusted accordingly to the wavelength of the laser to be used, if desired is.

The housing is joined to the hermetically sealed housing using a laser joining process. In other words, the edge, bottom and top side of the housing initially consist of more than one part, for example two or three parts or even more, and the parts are laser-joined to one another to complete the housing.

In a further embodiment, the housing can be chemically hardened at least partially and / or in areas. For example, one surface of the housing, i.e. for example the top, is chemically hardened. The top and edge can also be chemically hardened. Both the upper side and the edge as well as the underside are particularly preferably chemically hardened, so that both the respective surface of the upper side or underside is chemically hardened and the respective edge, that is to say the edge.

Before the step of producing the laser bond line for joining along the contact surfaces of each housing, the substrates can be connected to one another at least temporarily by means of wringing.

The invention is explained in more detail below using exemplary embodiments and with reference to the figures, with identical and similar elements in some cases being provided with the same reference symbols and the features of the various exemplary embodiments being able to be combined with one another.

Brief description of the figures

Show it:

Fig. 1 a is a plan view of the opened accommodation cavity,

1 b shows a 3D view of a closed housing,

Fig. 1c shows an alternative open housing,

1d shows a section through the joining zone,

2 shows a plan view of a housing on a base substrate, 3-13 sections along the lines A-> B and C-> D of embodiments of a housing shown in FIG. 2, FIG. 14 steps of a method for producing a housing.

Detailed description of the invention

1a shows the accommodation object 2 to be protected inserted in a base substrate 3, for example in a wafer or a printed circuit board, in particular made of aluminum nitride. The functional area 13 is designed as a recess in the base substrate 3, for example by means of an abrasive method such as a sandblasting method. In other words, the base substrate 3 has a recess 13 into which the accommodation object 2 is inserted. The base substrate 3 thus has the partial area 3 a, which forms the underside 22 of the housing 1. In other words, the housing 1 is formed with a part of the substrate 3 as the underside 22 (cf. FIG. 6), the housing 1 being firmly connected, in particular joined, to the substrate 3. A cap 5 is shown, with which the accommodation object 2 is to be covered. The cap 5 can, for example, be a glass plate which is placed on the recess 13 in the base substrate 3. The elements 3 and 5 thus together form the housing 1 around the accommodation object 2, which is arranged in the functional area 13, here a cavity 12 (cf. FIG. 1c), when the housing 1 is closed. In other words, when the cap 5 is placed on the base substrate 3 in the example in FIG. 1a, a closed accommodation cavity 12 is formed, which will have to be hermetically sealed in a subsequent step.

1 b shows the hermetically sealed housing 1 formed, which was joined by means of a laser joining process. The housing has the cap 5 stacked one on top of the other on the base substrate 3, a contact surface 25 being formed between the cap 5 and the substrate 3, along which a laser bond line 8 is introduced.

Fig. 1c shows a further embodiment of the housing 1, the cap 5 having the upper part 5b and a circumferential flank 5a. The cap 5 is placed with the contact surface on the end face of the circumferential flank 5a on the substrate 3, specifically in the area of the underside 3a of the housing 1, which later forms the underside 22 (cf. FIG. 6) of the cavity 12 when the Housing 1 is composed. 1d shows a detail of the joining area, the interface zone, ie the contact surface 25, and the laser joining zone 8 clearly emerging. The laser joining zone 8 is arranged in the area of the contact surface 25.

2 shows a plan view of a housing 1 according to the invention, the circumferential laser joining zone 8 surrounding the functional area 13. The functional area 13 can be constructed in different ways. Examples of the design of the functional area 13, as well as other options for an enclosure, can be found in FIGS. 3 to 12. The various designs of the functional area 13 can be graphically combined in FIG are. Sections are sketched on the lines A-B and C-> D, which are reproduced accordingly in FIGS. 3 to 12.

The functional area can realize various tasks, for example this can be an optical receptor or a technical, electromechanical and / or electronic component which is arranged in the functional area 13. Several of these tasks can also be implemented in functional area 13. The housing 1 is covered on the top by the upper substrate 5 or the cap 5. The laser joining zone 8 extends into this upper substrate 5.

Referring to FIG. 3, a first sectional view of a first embodiment of a housing 1 is shown, which has a base substrate 3 and a flat cap 5 in the form of a cover substrate 5. In other words, the housing 1 is constructed or composed of two layers, namely the base layer 3 and the cover layer 5. Fig. 3 also shows the structure of the laser joining line 8 from a series of a plurality of laser pulse hit areas 16, which are placed so close to one another that the material of the base substrate 3 and the cover substrate 5 melts together seamlessly and thus the functional area 13 or the cavity 12 hermetically seals.

FIG. 4 shows a sectional view of an embodiment of a housing 1 along the line C-> D, as shown in FIG. 2. FIG. 4 also shows a section through the functional area 13, 13 a, which extends, for example, as a continuous cavity or cavity in the housing 1. In other words, the cavity extends from the base substrate 3 into the cover substrate 5 and is, for example, in the form of a recess made from the base substrate 3 and / or the cap 5. For example, the functional area 13a can also include an active layer, for example an electrically conductive layer, and the functional area 13 includes the cavity. The laser joining zone 8 runs around the functional area 13, 13a arranged, by means of which the functional area 13, 13a is closed all around on the sides. It is conceivable to leave open areas in the laser joining zone 8 so that the functional area 13, 13a is not closed all around, for example to leave open a communication channel or space for an electrical connection, with which, for example, fluid communication with the environment can also be established is. In other words, it can be provided that pre-planned locations or positions are not closed with the focused laser beam 9, but that the hermetic seal is set up there by other means such as an adhesive. It is preferred to close the functional area 13, 13a on all sides and without gaps.

Referring to FIG. 5, a further embodiment is shown, in which the laser joining zone 8 is created along the contact surface 25 by means of the laser pulse hits 16, at which the cover substrate 5 is welded or joined to the base substrate 3.

This embodiment has the further special feature that the surfaces of the first substrate 3 and of the second substrate 5 are hardened all around, that is to say have the hardened layers 27, 28 and 29. For example, the top of the cap 5 can be immersed in a hardening bath before a connection to the base substrate 3 or also after the connection to the base substrate 3, so that the finished housing 1 is chemically hardened, i.e. has at least one hardened surface 27 and / or has at least one hardened layer. In other words, the finished housing 1 is at least partially or at least partially hardened, in particular chemically hardened. During the chemical hardening, compressive stress is formed on the cover substrate 5.

In the embodiment shown in FIG. 5, the housing 1 is hardened on all outer sides, ie both the two opposite long sides have hardened layers 27 and 29, and the circumferential edge 14 of the housing has the hardened layer 28, with the circumferential edge 14 extends around the housing 1. In other words, in the case of a cuboid housing, all four narrow sides, which a cuboid has, are combined to form the edge 14. The edge 14 can also be understood or referred to as the edge 21 of the housing, which extends around the cavity 12. A housing 1 as shown in FIG. 5 can be obtained, for example, by dipping the assembled housing, which comprises the cap 5 and the base substrate 3, in a hardening solution and, in particular, is chemically hardened there. The hardened layers 27, 28, 29 are thus arranged directly on the outer sides of the housing 1. Inside the hardened layers 27, 28, 29 thus remains an area for the joining line 8, which is possibly introduced at a distance from the hardened layers 27, 28, 29.

FIG. 6 shows an embodiment of the housing 1 with a cap 5 with flanks 5 a placed on the base substrate 3. The illustration in FIG. 6 can correspond to a section along the line C-> D shown in FIG. 2. In this embodiment, the functional area 12, 13, 13a is arranged such that it is arranged on the base substrate 3 and extends into the cap 5. The joining line 8 is arranged around the cavity 12, so that the cavity 12 is hermetically sealed on all sides. The cap 5 can be round or square and can basically have a free shape.

The accommodation object 2, for example a sensor or actuator, is arranged on the underside 22 of the cavity 12, for example glued there. Metal pads 32, 32a for making electrical contact with the accommodation object 2 are arranged on both sides of the accommodation object. The accommodation object 2 is electrically contacted with the contact points 32, 32a by means of contact lines 36, 36a, such as bond wires, for example. The contact points 32, 32a can be metal contact surfaces.

The electrical contact to second contacts 34, 34a arranged outside the cavity 12 is established via connectors 35, 35a, so that contact can be made with the accommodation object on the base substrate 3, such as a printed circuit board 3, from outside. In this example, the second contacts 34, 34a are arranged on the underside of the base substrate 3, as a result of which the size of the individual housing 1 can be kept small. It must be ensured that the contact lines 36, 36a are hermetically sealed, for example by the second contacts 34, 34a being applied directly to the connectors 34, 34a. The cap 5 is joined directly to the base substrate 3 by means of laser bonding lines 8. In this case, two closed circumferential laser joining zones 8 were formed by guiding the laser 9 twice around the cavity along the contact surface 25 or along the outer edges of the cap 5, but not on an exactly identical path. Rather, the laser 9 was guided on a laterally offset path with each revolution around the cavity 12, so that two laser joining zones 8 lying next to one another are created. The microbonding zones 8 in this example have a dimension of, for example, 5mhi x 10mhi or 10mhi x 50mhi.

For example, AF45 can be used as the material for the cap 5. The base substrate 3 can have an AlN ceramic in a single-layer design. This is advantageous when inexpensive production is desired, for example for power semiconductors (HL) or for LED. The characteristic value of the coefficient of thermal expansion (CTE) of the two, in particular, different materials of the cap 5 and the base substrate 3 can be selected so that it is matched to one another between the layers. For example, the CTEs can be similar or even the same, so that there is little or no thermal stress in the housing 1. The CTE of AF45 and AIN fits surprisingly well for the desired application; hardly any thermal stress on the housing 1 could be determined. Si3N4 can also be used as the material for the base substrate. A special feature of the housing 1 according to the invention is that the substrate 3 is a highly thermally conductive material, in the embodiments of FIGS. 6-9 and 13 as a single-layer ceramic, in the embodiments of FIGS. 10-12 as a multilayer ceramic.

7 shows a further embodiment of a housing 1 along the section line C-> D, with the functional area 13 or the cavity 12 also being arranged in the cap 5 in this example. In this example, the accommodation object 2, for example a high-power LED, has an upper and a lower contact area. The accommodation object 2 is therefore arranged on the contact 32a and there is direct electrical contact; a second electrical contact to the contact 32 is established via the contact line 36 to the top of the accommodation object 2. The cap 5 is fused to the base substrate 3 by means of the bond lines 8 and is hermetically sealed. The same reference numerals show the same features in the figures in all embodiments.

The joint along the joint line 8 was preferably made in relaxed material of the cap 5 as well as of the base substrate 3. The base substrate 3 is joined directly and immediately to the cap 5, so that no further layer or no further substrate is arranged between the base substrate 3 and the cap 5. The functional area 13 is designed as a cavity 12. For the cap 5, for example, AF45 or 8337b can be used as the material, the base substrate 3 can be a single or multi-layer AlN ceramic.

The contact bushings 35, 35a are filled, that is, in particular, are hermetically sealed.

Referring to FIG. 8, a further embodiment of the housing 1 is shown, a plurality of contacts 32, 32a, 32b, 32c being provided in the cavity and, by means of the feedthroughs 35, 35a, 35b, 35c, to the second contacts 34, 34a, 34b, 34c are guided outside the housing 1. The second contacts 34, 34a, 34b, 34c are arranged on the underside of the base substrate 3 in this example. The accommodation object, for example a microprocessor or a power transistor, can be on the underside and on the top Have contacts. In this example, the microprocessor has three contacts on the bottom, the microprocessor 2 being arranged directly on the three contacts 32a, 32b, 32c, and the contact on the top being connected to the contact 32 by means of the contact line 36. Cap 5 and base substrate 3 are hermetically joined to one another with two laser bonding lines 8.

FIG. 9 shows an embodiment of the housing 1, the accommodation object 2 only having contacts on the underside. The accommodation object 2 can then be arranged in a simple manner directly above the contacts 32, 32a, the connecting lines 36, 36a being omitted.

10 shows an embodiment of the housing 1, the second contacts 34, 34a being arranged on the top of the base substrate 3 and to the side of the housing 1. Although the area of the base substrate 3 to be used per housing 1 is larger in this embodiment, the advantages result that on the one hand the contacting of the second contacts 34, 34a can be carried out from above, which may be simpler. In addition, the base substrate 3 is not drilled through, so that the hermetic seal may be easier to implement if the base substrate as such is to ensure a hermetic seal. This embodiment can be advantageous, for example, when a plurality of housings 1 are arranged on a common base substrate 3 (see FIG. 12) or when the contacts are later to be further contacted from above. It is clear that more than 4 contacts and these can also be arranged only below the accommodation object 2 or distributed below and above, as well as that these can be arranged below and / or above the base substrate 3. AIN can be used as the material of the base substrate, single-layer or multi-layer, and Si3N4 can be used. 11 shows a further embodiment with second contacts 34, 34a arranged on the top, the accommodation object 2 being arranged on the contact 32a and being contacted with the contact 32 by means of the connecting line 36.

Referring to FIG. 12, a common base substrate 3 is shown, on which two undersides 22 of two housings 1 are formed. On the base substrate 3, one accommodation object 2 is arranged in each housing 1, which objects are through-contacted to the outside by means of the respective second contacts 34 and 34a. In the manner of the embodiment of FIG. 12, it is understandable that a common base substrate 3 can also have a multiplicity of housings 1 which, if necessary, also perform common tasks, that is to say can also be in contact with one another. FIG. 13 shows an embodiment of the housing 1, a cavity 12 being introduced into the base substrate 3. For example, the cavity 12 can be introduced into the base substrate 3 by means of a sandblasting method, that is to say hollowed out of the base substrate 3, generally using an abrasive method. Chemical etching is also possible in order to introduce the cavity 12 into the base substrate 3. This embodiment is advantageous that the cap 5 can be made, for example, as a simple glass plate, which is connected to the basic substrate 3 by means of microbonding and laser bonding lines 8. AIN or HTCC can again be used as the material of the base substrate 3. In the case of a multilayer ceramic, the machining of the cavity 12 has proven to be particularly easy to implement if these cavities 12 have already been produced in the green state, for example by a stamping process.

Referring to FIG. 14, an embodiment of the method for producing a multiplicity of housings 1 on the substrate 3 is shown. It is clear to the person skilled in the art that only a single housing or a single cap 5 can be attached to a substrate, depending on the process requirements. This method for attaching an individual cap 5 to a substrate 3 is ultimately a simplification of the method shown here with FIG. 14 with regard to the process sequences.

In a step A, a plurality of accommodation objects 2 are arranged on the base substrate 3, for example soldered to provided contacts 32, 32a (cf. FIG. 3). Provision is made for a cap 5 to be attached to each accommodation object 2, i.e. a separate cavity 12 to be created for each accommodation object 2. However, several accommodation objects 2 can also be accommodated in a common cavity 12 by a common cap 5.

With step B, the glass caps 5 are placed on the base substrate 3 and the cavities 12 are thus completely formed.

Step C shows the laser joining of the respective accommodation cavities 12, i.e. the closing of the cavities 12 on all sides along the contact surfaces 25 and the introduction of the at least one laser bond line 8 per housing 1. For this purpose, a laser unit 15 is guided from above the caps 5 over the surface of the substrate 3 and a focused laser beam 9 pointed at the zones to be joined, that is to say on the contact surfaces 25. After completion of step C of the manufacturing process, all cavities 12 are hermetic closed. It is possible to separate the individual housings 1 after step C by means of a cutting process, and thus to obtain individual separate housings.

In step D, the components are separated from one another along separating or cutting lines 10. For this purpose, the same laser can optionally be used as for the laser joining in step C. However, a conventional cutting method can also be used if this is advantageous.

It is evident to the person skilled in the art that the embodiments described above are to be understood as examples and that the invention is not restricted to these, but can be varied in many ways without departing from the scope of protection of the claims. It can also be seen that the features, regardless of whether they are in the

The description, the claims, the figures or otherwise disclosed also individually define essential components of the invention, even if they are described together with other features. In all figures, the same reference symbols denote the same features, so that descriptions of features that are possibly only mentioned in one or at least not with regard to all figures can also be transferred to these figures, with regard to which the feature is not explicitly described in the description.

Reference list:

1 Hermetically sealed, chemically hardened housing 2 Accommodation object

3 Lower substrate, layer or wafer, base substrate or lower cover, good thermal conductivity

5 Upper substrate, layer or wafer, cover substrate or upper cover, optically transparent for laser bonding 8 Laser joining zone

9 focused laser beam

10 dividing or cutting lines 12 accommodation cavity

13 functional area 13a second functional area

14 edge

15 Laser unit for joining and / or cutting

16 Laser pulse hit area 21 Edge of the cavity 22 Bottom of the cavity

23 top of cavity 25 contact surface

27 hardening zone or first hardened layer

28 hardening zone or second hardened layer 29 hardening zone or third hardened layer

Claims

Patent claims:

1. Hermetically sealed housing (1) comprising: a heat-dissipating base substrate (3) for dissipating heat from the hermetically sealed housing (1), a cap (5), which preferably comprises a glass-like material, at least one of the housing (1) Hermetically sealed functional area (12, 13, 13a), in particular a cavity, the cap (5) being arranged on the base substrate (3), the cap (5) with the base substrate (3) together at least part of the housing (1 ), further comprising at least one laser bond line (8) for hermetically sealed joining of the housing (1), the laser bond line having a height (HL) perpendicular to its connection plane.

2. Hermetically sealed housing (1) according to the preceding claim, wherein the heat-dissipating base substrate (3) made of a material higher

There is thermal conductivity, and / or where the thermal conductivity of the heat-dissipating base substrate (3) 100 W / (m * K) or greater, preferably 150 W / (m * K) or greater, and more preferably 170 W / (m * K) or is better.

3. Hermetically sealed housing (1) according to at least one of the preceding claims, wherein the cap (5) comprises a glass-like material, for example glass, glass ceramic, silicon, sapphire or a combination of the aforementioned materials, and / or wherein the base substrate (3) in particular comprises a metallic nitride such as aluminum nitride ceramic.

4. Hermetically sealed housing (1) according to at least one of the preceding claims, wherein the at least one laser bond line (8) surrounds the functional area (12, 13, 13a) at a distance (DF) circumferentially.

5. Hermetically sealed housing (1) according to at least one of the preceding claims, wherein the cap (5) is joined to the base substrate (3) by means of the laser bond line (8) and / or wherein the cap (5) is connected to the base substrate (3 ) together form the complete housing (1).

6. Hermetically sealed housing (1) according to at least one of the preceding claims, wherein the functional area (12, 13, 13a) is prepared to accommodate at least one accommodation object (2), such as an electronic circuit, a sensor or MEMS, and / or wherein at least one accommodation object (2) is arranged on the base substrate (3) and within the housing (1).

7. Hermetically sealed housing (1) according to the preceding claim, wherein the at least one accommodation object (2) comprises a power semiconductor chip, for example a GaN LED, a SiC, GaAs or GaN power transistor, in particular one of the aforementioned is arranged in the cavity.

8. Hermetically sealed housing (1) according to at least one of the preceding claims, wherein the cap (5) is joined to the base substrate (3) at room temperature, and only a negligible amount in the functional area (12, 13, 13a) due to the joining process Amount of heat enters, and / or the amount of heat generated by the joining process being kept away from the functional area (12, 13, 13a) by the heat-dissipating base substrate (3).

9. Hermetically sealed housing (1) according to at least one of the preceding claims, wherein the height (HL) of the laser bond line (8) extends into the material of the cap (5) and, on the opposite side, extends into the material of the base substrate (3), and the heat-dissipating base substrate (3) with the cap (5) being joined to one another by melting is.

10. Hermetically sealed housing (1) according to at least one of the preceding claims, wherein an intermediate substrate (4) is arranged between the heat-dissipating base substrate (3) and the cap (5), the base substrate (3) and the intermediate substrate in a first connecting plane is joined, and wherein the cap (5) is joined to the intermediate substrate in a second connection plane.

11. Hermetically sealed housing (1) according to at least one of the preceding claims, wherein a marker is introduced into at least one of the substrates (3, 4, 5).

12. Hermetically sealed housing (1) according to at least one of the preceding claims, wherein the cap (5) forms an upper side (23) and a laterally circumferential edge (21) of the functional area (12, 13, 13a) and the heat-dissipating base substrate (3 ) forms an underside (22) of the functional area, which together completely enclose the accommodation cavity, and / or wherein the cap (5) forms an upper side (23) of the functional area (12, 13, 13a) and the heat-dissipating base substrate (3) forms a side the peripheral edge (21) and an underside (22) of the functional area, which together completely enclose the accommodation cavity, and / or wherein the cap (5) forms an upper side (23) of the functional area (12, 13, 13a), the intermediate substrate ( 4) forms a laterally circumferential edge (21) of the functional area and the heat-dissipating base substrate (3) forms an underside (22) of the functional area, which together provide the accommodation Completely enclose the cavity.

13. Hermetically sealed housing (1) according to at least one of the preceding claims, wherein the at least from a laterally circumferential edge, or bottom Housing (1) formed on the top side is at least partially transparent for a wavelength range.

14. Hermetically sealed housing (1) according to at least one of the preceding claims, wherein the heat-dissipating base substrate (3) and / or the cap (5) has a thickness of less than 500 mhi, preferably less than 300 mhi, more preferably less than 120 mhi and even more preferably has a thickness of less than 80 mhi.

15. Hermetically sealed housing (1) according to at least one of the preceding claims, wherein the heat-dissipating base substrate (3) has at least a first (32, 32a) and a second contact (34, 34a), and wherein the first contact is on the underside ( 22) of the functional area (13, 13a) or the cavity (12) is arranged.

16. Hermetically sealed housing (1) according to the preceding claim, wherein the second contact (34, 34a) is arranged outside the underside (22) of the functional area (13, 13a) or the cavity (12) and is electrically connected to the first contact (32, 32a) is connected.

17. Hermetically sealed housing (1) according to at least one of the preceding claims, wherein the housing (1) has a size of 10mm x 10mm or less, preferably 5mm x 5mm or less, more preferably 2mm x 2mm or smaller or 0.2mm x 0.2mm or smaller, and / or wherein the cap (5) has a height of 2mm or less, and / or wherein the flank (5a) of the cap (5) has a height of 2mm or less.

18. A method for providing a hermetically sealed housing (1), the housing (1) enclosing a functional area (12, 13, 13a), in particular a cavity, which is surrounded by a laterally circumferential edge (21), an underside ( 22) and an upper side (23) of the housing (1) is enclosed, and wherein an accommodation cavity is designed to accommodate an accommodation object (2), with the steps:

- Provision of a heat-dissipating base substrate (3) and at least one cap (5), wherein the cap (5) is transparent at least in some areas and at least for one wavelength range and is therefore a transparent cap (5),

- Arranging at least one accommodation object (2) on the underside of the accommodation cavity,

- Arranging the cap (5) on the heat-dissipating base substrate (3) above the accommodation object (2), with at least one contact surface (25) being formed between the heat-dissipating base substrate (3) and the cap (5) so that each housing (1) has at least one contact surface,

- Hermetically sealed sealing of the cavities by forming a laser bond line (8) on the at least one contact surface of each housing (1).

19. The method according to the preceding claim, wherein the cap (5) comprises a flank (5a) and an upper part (5b), so that of the upper part of the cap (5) the top and of the flank at least part of the edge of the accommodation -Cavity is formed, and this or a contact surface (25) is formed on the end face of the flank.

20. The method according to at least one of the preceding claims, wherein the laser beam (9) is guided around the functional area (12, 13, 13a) to form the laser bond line (8), so that the functional area is hermetically sealed along the contact surface (25) If necessary, the laser beam can be circulated several times and / or a plurality of laser bond lines (8) can be formed.

21. The method according to at least one of the preceding claims, wherein a plurality of undersides (22) for a plurality of accommodation cavities (12) to be formed are formed on the heat-dissipating base substrate (3) and a plurality of caps (5) are formed on the base substrate (3) are applied to form a plurality of housings (1) on the base substrate (3).

22. Housing (1) with hermetically sealed accommodation cavity (12) enclosed therein, produced according to one of the above processes.

23. Use of a housing (1) produced according to the above method with a hermetically sealed accommodation cavity (12) enclosed therein as a medical implant or as a sensor, in particular as a barometer.