Reversible and debondable structural solder for connecting a glass substrate to a second substrate

Abstract

Method of manufacturing a debondable structural solder joint (1) comprising a glass substrate (110) that is joined to a second substrate (222), wherein the method comprises the steps of: - providing the glass substrate (110), wherein said glass substrate is arranged with a layer of a metal-alloy based solder material that is deposited on a first section of a surface of the glass substrate, wherein said first section corresponds to only a section of the surface and wherein said layer of solder material is no thicker than 100 / lm; - providing a second substrate (222), said second substrate being a glass, ceramic or metal substrate; - providing a pre-formed interconnecting solder body (31) that is made from a metal-alloy based solder material, wherein one side of said pre-formed interconnecting solder body is arranged to be positioned onto the first section of the glass substrate; - arranging the glass substrate, pre-formed interconnecting solder body and second substrate in a predefined arrangement by positioning the one side of said pre-formed interconnecting solder body onto the layer of a metal-alloy based solder material deposited on the first section of the surface of the glass substrate, and positioning the second substrate onto another side of the pre-formed interconnecting solder body; - arranging an enclosure between the glass substrate and the second substrate and around the pre-formed interconnecting solder body; - providing heat and compressive pressure to the predefined arrangement for soldering said solder joint such that, after cooling, the pre-formed interconnecting solder body is bonded to the second substrate and is bonded to the layer of metal-alloy based solder material that is deposited on the first section of a surface of the glass substrate.

Description

[0001] Reversible and debondable structural solder for connecting a glass substrate to a second substrate

[0002] The current invention relates to a method of manufacturing a debondable structural solder joint comprising a glass substrate that is bonded to a second substrate, the debondable structural solder joint, a method of disassembling the debondable structural solder joint and an architectural glazed wall comprising the debondable structural solder joint.

[0003] In many different applications it is required to attach (i.e. connect,join, bond) a glass substrate to a second substrate, such as a glass, ceramic or metal substrate. Applications range, for instance, from windscreens in automotive technology, optical elements in electronical technology to glazed facades in architectural engineering. In many cases a connection is made by bonding the glass substrate to the second substrate with a polymeric adhesive or glue. Although, due to the range of different adhesives that exist, each with their specific structural properties, a reliable connection with a desired stiffness, strength and failure strain can thereby be obtained, the different substrates are typically hard to separate from each other at the end of life. In other words, these products made by bonding glass to other materials using adhesives can be hard to reuse or recycle as the substrates are, firstly, hard to separate and, secondly, any adhesive residues left on the detached substrates can contaminate the substrates. This thereby hinders a direct reuse of the substrates for a different purpose, but also hinders high-quality recycling (i.e. remelting) of the substrates as the glue residues can lead to a degradation of the quality of the recycled materials and / or emit CO2 emissions along with other by-products as a consequence of thermal decomposition.

[0004] Alternatively, metal-alloy solders may be used to connect a glass substrate to a metal component. However, soldering glass using a metal-alloy based solder is typically a relatively difficult process, as directly soldering the glass substrate typically leads to a bond having a poor quality. An inter-metallic compound (IMC) may then be deposited to the glass surface using, for instance, a High Velocity Oxygen Fuel (HVOF) for depositing a series of thin metal layers onto the glass in order to promote bonding to the metal-alloy based solder. Such an IMC is typically composed of metal-alloys having a high melting temperatures and are typically hard to separate from the glass during recycling, such that it also hinders high-quality recycling of the glass.

[0005] It is a goal of the current invention to provide for a method of bonding a glass substrate to a second substrate that can provide a reliable connection with a desired stiffness, strength and failure strain but can be recycled more easily, wherein at least some of the above mentioned problems are at least partly alleviated. In a first aspect, the disclosure relates to a method of manufacturing a, preferably debondable, structural solder joint comprising a glass substrate that is joined to a second substrate, wherein the method comprises the steps of:

[0006] - providing the glass substrate, wherein said glass substrate is arranged with a layer of a metalalloy based solder material that is deposited on a first section of a surface of the glass substrate, wherein said first section corresponds to only a part of the surface and wherein said layer of solder material is no thicker than 100 pm;

[0007] - providing a second substrate, said second substrate being a glass, ceramic or metal substrate;

[0008] - providing a pre-formed interconnecting solder body that is made from a metal-alloy based solder material, wherein one side of said pre-formed interconnecting solder body is arranged to be positioned onto the first section of the glass substrate, preferably such that the cross-section is sized equally to, or smaller than, the first section;

[0009] - arranging the glass substrate, pre-formed interconnecting solder body and second substrate in a predefined arrangement by positioning the one side of said pre-formed interconnecting solder body onto the layer of a metal-alloy based solder material deposited on the first section of the surface of the glass substrate, and positioning the first section of the surface of the second substrate onto another side of the pre-formed interconnecting solder body (e.g. such that the pre-formed interconnecting solder body is arranged in between the glass substrate and the second substrate);

[0010] - preferably, arranging a, preferably temporary, enclosure between the glass substrate and the second substrate and around the pre-formed interconnecting solder body;

[0011] - providing heat and compressive pressure to the predefined arrangement for soldering said solder joint such that, after cooling, the pre-formed interconnecting solder body is bonded to the second substrate and bonded to the layer of metal-alloy based solder material that is deposited on the first section of a surface of the glass substrate.

[0012] The method employs a metal-alloy based solder for connecting the glass substrate to the second substrate. The pre-formed interconnecting solder body is arranged between the second substrate and the glass substrate this is having the thin solder layer thereon. By applying a compression and heating to at least the pre-formed interconnecting solder body, the solder will (at least locally) flow causing, once cooled, that a bond is formed. When required, the substrates can also be separated by reheating the structural solder joint to the required temperature, such that the issue of a difficult to separate connection during disassembly (e.g. comprising a step of debonding the bonded substrates) of the (debondable) structural solder joint is at least relieved. The solder can thereby be collected and recycled and the (clean or cleaned) substrates may be directly reused. In particular, using the below introduced electro-assisted disassembly method, a less energy-intensive, good quality separation between the various components of the structural solder joint can be obtained, such that a reduced amount of solder residue can be obtained. This enables a better recycling of the various materials used in the structural solder joint, which will be discussed in more detail below. The mechanical properties of the structural solder joint can be tailored to meet the desired specification by tuning, for instance, the geometry (such as a thickness) of the pre-formed interconnecting solder body. In their uses, different joints may have different requirements, for instance in terms of allowing certain relative movements between the substrates (for instance, due to thermal expansion of substrates and / or the in use loading applied to them). For instance, a thicker body will allow for an increased flexibility of the joint, as the joint is able to use the inherent flexibility of the pre-formed interconnecting solder body.

[0013] It is noted that, after the step of providing heat and compressive pressure to the predefined arrangement for soldering, the joint is to be cooled in order for the all the components to be structurally bonded together. Preferably, the joint is slowly cooled, such that the (average) cooling rate does not exceed 50K / min, more preferably does not exceed 30K / min, most preferably does not exceed 20K / min, as this prevents, or at least reduces, thermal shock effects in at least the glass substrate.

[0014] By arranging the, preferably temporary, enclosure between the glass substrate and the second substrate and around the pre-formed interconnecting solder body, the pre-formed interconnecting solder body is substantially confined by the temporary enclosure in an enclosed space that is delimited by the glass substrate, second substrate and the enclosure. A temporarily sealed space comprising the pre-formed interconnecting solder body and the first section is thereby obtained. This prevents that, during the step of providing heat and compressive pressure to the predefined arrangement, the molten solder flows away from the joint area, such that desired (debondable) structural solder joint is obtained after cooling. The temporary enclosure may subsequently be removed.

[0015] The (temporary) enclosure (e.g. a mould-like member) is preferably made from a material that does not bound to solder upon heating alone. Suitable materials therefore are, for example, titanium or graphite. Alternatively, a coating and / or film, such as Kapton, that does not bound to solder upon heating alone may be provided onto the temporary enclosure. The temporary enclosure may by formed as a planar member having an opening shaped accordingly with the pre-formed interconnecting solder body therein and may be formed from a plurality of parts, such as a plurality of mutually cooperating ring-sectors, that, once assembled, form the temporary enclosure. The plurality of parts may comprise locking means for locking the plurality of parts in an assembled state thereof. After disengaging the locking means, the temporary enclosure may be easily removable afterwards.

[0016] The inventors furthermore found that, by depositing a thin layer of metal-alloy based solder onto the glass substrate, a layer is obtained that is able to bond with the pre-formed interconnecting solder body for obtaining a reliable bonding between the pre-formed interconnecting solder body and the glass substrate. At the same time, as this layer is formed from a metal-alloy based solder (i.e. having a relatively low melting point with respect to metallic layers according to the prior art), it can be separated from the glass substrate more easily when compared to the metallic layers according to the prior art, such that a high- quality recycling of the glass substrate is enabled.

[0017] The term “bonding” is defined (by the Oxford Dictionary) as “the action of joining things securely by means of adhesive, heat, or pressure or by chemical bonds" . as such the term “debonding” is the opposite action thereof, or in other words, the action of separating things that have been bonded. A debondable structural solder joint is thereby a joint that may, after the joint is formed by bonding the various parts thereof, be separated again. In the context of the current disclosure, this implies, and is as such understood by the skilled person, that a debondable structural solder joint according to the current disclosure is a structural solder joint wherein at least the glass substrate may be separated again from the second substrate (for instance, by means of a suitable method of disassembling, as is disclosed in the third aspect in the current disclosure) and, preferably, the metal-alloy based solder material of the pre-formed interconnecting solder body may, at least partly, be separated from the glass and / or second substrate.

[0018] In particular, the debondable structural solder joint is a reversible and debondable structural solder joint, as after the joint is debonded, the individual (separated) components thereof can more easily be re-used, without, for instance, the need for fully remelting the substrates in order to be able to manufacture new substrates thereof. For example, any remainder of the solder can be cleaned from, for instance, a glass panel, such that the cleaned panel can directly be re-used in, for instance, a newly constructed glass facade. As the used glass panel is, prior to re-using, effectively brought back into its original state (or at least close enough to allow for a direct re-usage), the solder joint is not only debondable, but also reversible.

[0019] In a preferred embodiment, the step of providing the glass substrate comprises the step of depositing the layer of a metal-alloy based solder material onto the first section by means of ultrasonic soldering. Ultrasonic soldering allows for a relatively simple method to deposit the thin layer (preferably in the order of 10-20 pm) of metal-alloy based solder material onto the first section that is bonded with the glass substrate. Preferably, the layer of solder material is no thicker than 50 pm, more preferably no thicker than 30 pm, most preferably no thicker than 10 pm. Such a thin layer may be applied as it merely serves to enable the bond between the pre-formed interconnecting solder body and the glass substrate.

[0020] The high frequencies of the ultrasound vibrations allow to deposit the thin layer of a metal-alloy based solder material onto the glass substrate such that it bonds with the glass substrate. The layer of a metalalloy based solder material enables, in a second step, to bond with the metal-alloy based solder material that is used in the pre-formed interconnecting solder body, by simply heating the joint to cause a softening, or (localized) melting, of the solder, such that, after cooling, the bond is formed. In a preferred embodiment, the second substrate is arranged with a layer of a metal-alloy based solder material that is deposited on at least a part of the surface of the second substrate, wherein said layer of solder material of the second substrate is no thicker than 100 pm, preferably no thicker than 50 pm, more preferably no thicker than 30 pm, most preferably no thicker than 10 pm; and wherein the step of arranging the glass substrate, pre-formed interconnecting solder body and second substrate in the predefined arrangement comprises positioning the layer of a metal-allow based solder that is deposited on the second substrate onto the other side of the pre-formed interconnecting solder body. As not all metals, ceramics and glasses bound to solder upon heating alone, the surface of the second substrate may also be provided with a (thin) layer of a metal-alloy based solder material. The layer may again be formed by ultrasound soldering.

[0021] Preferably, the pre-formed interconnecting solder body is cast in a predefined geometry, prior to the step of arranging the glass substrate, pre-formed interconnecting solder body and second substrate in the predefined arrangement, using a casting process; or wherein the pre-formed interconnecting solder body is formed in the predefined geometry, prior to the step of arranging the glass substrate, pre-formed interconnecting solder body and second substrate in the predefined arrangement, using an additive manufacturing process, such as a 3D printing process; preferably, wherein the method comprises the step of forming the pre-formed interconnecting solder body in the predefined geometry, prior to the step of arranging the glass substrate, pre-formed interconnecting solder body and second substrate in the predefined arrangement, using the casting process and / or additive manufacturing process. By pre-forming the interconnecting solder body, the geometry of the solder joint can be precisely controlled, such that its predefined structural properties can be obtained in a relatively simple and controlled manner.

[0022] In a preferred embodiment, the pre-formed interconnecting solder body is formed by the 3D printing process comprising the steps of: feeding a solder material filament through a heated stainless steel 3D-printing tip that heats the solder material to a temperature above the solidus point of the solder composition, causing the solder material filament to melt, or at least soften to allow it to flow; moving, in a predefined path, the heated stainless steel 3D-printing tip above and over a depositing surface while feeding the solder material filament, such that the solder material is deposited onto the printing surface and allowing the depsosited solder material to cool and solidify; and preferably, wherein said depositing surface comprises a metallic top surface and the 3D printing process further comprises separating the pre-formed interconnecting solder body from the printing surface.

[0023] By feeding the solder material filament through the heated stainless steel 3D-printing tip, the solder material filament to melt, or at least soften to allow it to flow, while clogging of the tip is prevented, or at least reduced, as the molten / softened solder material does not stick to the stainless steel material upon heat alone. By moving the tip along a predefined path, a pre-formed interconnecting solder body having a predefined geometry is obtained, whose thickness can be varied by varying the number of printed layers of solder material.

[0024] In a preferred embodiment, said pre-formed interconnecting solder body comprises a solid composite metallic foam-solder body and / or a solid solder body. A solid composite metallic foam-solder body is a solder embedded metallic foam, such that the pores of the solid foam are (at least partially) filled with the solder material. As the solid foam is made from a different metal alloy typically have higher melting temperature than the embedded solder, only the solder will flow upon heating the solid composite metallic form solder body for forming the joint. A composite metallic foam-solder body can be arranged to be more flexible, thereby allowing a tailored stiffness. Hence, in dependence of the desired mechanical properties of the pre-formed interconnecting solder body, whereby a thicker body will be more flexible having lower stiffness, it may have a thickness in the range of 1 mm - 30 mm, preferably 2 mm - 20 mm, more preferably 3 mm - 15 mm, even more preferably 5 mm - 12 mm, most preferably 8 mm - 10 mm, wherein said thickness of the pre-formed interconnecting solder body is defined in a direction perpendicular to the one side of the pre-formed interconnecting solder body. Altering the stiffness of the joint will enable to accommodate differential movement between substrates, and / or differential rates of thermal expansion between substrates, as described above.

[0025] Preferably, the method further comprises the step of determining a geometry, such as a thickness and / or foam porosity, of the pre-formed interconnecting solder body on the basis of a predefined stiffness of the debondable structural solder joint, such that a mechanically tuneable solder joint is obtainable.

[0026] In a preferred embodiment, wherein the layer of a metal-alloy based solder material has a melting point in between 105 °C and 300°C, in particular wherein said solder material is a Sn and / or Zn-based solder material; and / or wherein the pre-formed interconnecting solder body is made from a metal-alloy based solder material having a melting point in between 105 °C and 300°C, in particular wherein said solder material is a Sn and / or Zn-based solder material. Solder materials having these properties allow for obtaining sufficient joint strength and stiffness, while at the same time allowing for obtaining a solder joint that is relatively easily disassembled for reuse and recycling purposes.

[0027] The solder materials may consist only of metallic-alloy(s). The metal-alloy based solder material may be a eutectic (i.e. having a single distinct melting point) or a non-eutectic (i.e. having a range of different melting points of the various components of the metal-alloy base solder material) solder material.

[0028] The metal-alloy based solder material may, for instance, be any of the following: 96Sn / Ag; 95.5Sn / 4Cu / 0.5Ag; 91Sn / 9Zn; 85Sn / 15Zn; 92Sn / 4Ag / 3Ti / RE; 95Sn / 3Zn / RE; 85Sn / 13Zn / RE; 70Sn / 3Sn / 25In / RE; 58Sn / 3Zn / 35In / RE; 48Sn / 52In / RE. It is noted that solders without rare earth alloys (indicated as RE) are preferred. The pre-formed interconnecting solder body may be made from the same, or similar, metal-alloy based solder material.

[0029] In a second aspect, the disclosure relates to a, preferably debondable, structural solder joint comprising a glass substrate that is joined to a second substrate obtainable by a method according to any of the preceding embodiments, the, preferably debondable, structural solder joint comprising:

[0030] - the glass substrate, wherein said glass substrate is arranged with a layer of a metal-alloy based solder material that is deposited on a first section of a surface of the glass substrate, wherein said first section corresponds to only a part of the surface and wherein said layer of solder material is no thicker than 100 pm;

[0031] - the second substrate, wherein said second substrate is a glass, ceramic or metal substrate, preferably, wherein said substrate is arranged with a layer of a metal-alloy based solder material that is deposited on a first section of a surface of the second substrate, wherein said first section corresponds to at least a part of the surface and said layer of solder material is no thicker than 100 pm;

[0032] - a interconnecting solder body of a metal-alloy based solder material that is bonded to the second substrate and is bonded to the layer of metal-alloy based solder material that is arranged on the first section of a surface of the glass substrate. This enables to obtain the, preferably debondable, structural solder joint having a desired ultimate strength and stiffness wherein the substrates can be reused or recycled more easily, as was described above.

[0033] Preferably, a planar surface area of the first section is at most 10%, preferably 3%, more preferably 1%, of the planar surface area of the glass substrate. It is noted that the layer of a metal-alloy based solder material is to be deposited only onto the first section(s) of the glass substrate. Thereby, the remainder of the glass substrate can be kept clean, such that it can be more easily be re-used and / or remelted.

[0034] Preferably, the planar surface area of the first section is larger than the surface area of the one side of the pre-formed interconnecting solder body. Thereby, it prevents, or at least reduced the chance that, at the edge of the first section, the molten solder material flows outside of the first section. Solder material that flows outside of the first section will not bond to the glass directly, thereby it does not add to the structural performance of the joint.

[0035] In a third aspect, the disclosure relates to a method of disassembling a, preferably debondable, structural solder joint, wherein the method comprises the steps of:

[0036] - providing a debondable structural solder joint according to the second aspect;

[0037] - debonding the glass substrate, interconnecting solder body and second substrate using thermal and / or electrical energy. By using the solder based connection for bonding the glass substrate to the second substrate, the substrates can be separated by debonding the bonded interfaces between the pre-formed interconnecting solder body, which can be done, for instance, by allowing the solder to reflow by adding thermal energy (which may also involve electrical heating). Alternatively, as is described in more detail below, electrical energy can be used for debonding the substrates and the pre-formed interconnecting solder body.

[0038] In a preferred embodiment, the step of debonding comprises: immersing the debondable structural solder joint in an alkali solution; arranging a secondary electrode in the alkali solution; arranging an electrical potential over the debondable structural solder joint, in particular over the pre-formed interconnecting solder body or over the layer of a metal-alloy based solder material, and the secondary electrode.

[0039] Hereby, the pre-formed interconnecting solder body or over the layer of a metal-alloy based solder material will start to oxidise, thereby debonding from the respective substrates. This enables to debond the various components of the joint while not having to directly employ thermal energy, which typically involves a high energy consumption, such that the recycling process is less attractive from a cost and environmental point of view.

[0040] In a preferred embodiment, the secondary electrode is a metallic element, such as an aluminium, copper or titanium element, and / or wherein the electrical potential is no more than 20 V direct current, preferably no more than 15 V direct current, most preferably no more than 10 V direct current. The process of debonding thereby requires a certain amount of time in order to degrade the solder material sufficiently such that it debonds from the respective substrates. The use of such low voltages leads to an energy efficient debonding process that does not require specific safety measures needed for higher voltage applications. A titanium and aluminium electrode was found to provide good results during the process of debonding.

[0041] Alternatively (or additionally) during the step of debonding, thermal energy is provided by means of a furnace wherein the debondable structural solder joint is placed in or by means of induction heating. This allows to add thermal energy, such that the solder will reflow to allow for the various components of the joint (e.g. glass substrate, pre-formed interconnecting solder body and second substrate) to be separated. Any remaining solder material may, for instance, be removed from the substrate surface with additional mechanical removal methods (e.g. scraping from the surface) whilst the solder is in its molten state.

[0042] In a fourth aspect, the disclosure relates to an architectural building component, such as the glazed wall of a building, comprising a load bearing structure and a glass panel, wherein said glass panel is connected to the load bearing structure at a connecting section by means of a debondable structural solder joint according to the second aspect, such that the glass panel forms the glass substrate and the second substrate is comprised in the load bearing structure, in particular wherein the second substrate is a metal member of the load bearing structure.

[0043] It is thereby enabled to construct building having glass-based components that can easily be reused or recycled at the end of the life of the building. Traditionally, glass panels are, for instance, either provided in elastomeric sealing members within metal frame members, reducing the overall transparency of the building, or the glass panels are attached using polymeric adhesives to metal members of a supporting structure, making them hard to separate and thus recycle properly, or are connected by means of pointfixings requiring holes to be made in the glass panels, in which case the glass needs to be remolten in order to produce a new window pane with the same geometry without holes. The current invention allows to securely fix the glass panels during use, while at the same time allowing for a relatively simple and energy efficient way of debonding, such that the glass panels can (for instance, after some cleaning and polishing) be directly used in a new building structure.

[0044] Examples of such an architectural building component may be a glass canopy, glass stairs, glazed wall (e.g. facade) or floor of a building. In the latter case, the load bearing structure is preferably a steel supporting structure for supporting the glass panels that are connected thereon.

[0045] In a preferred embodiment, the glass panel is connected to the load bearing structure at a plurality of spaced apart connecting sections, wherein at each connecting section the glass panel is connected to the load bearing structure by means of a respective debondable structural solder joints, such that the glass panel forms the glass substrate for each of the debondable structural solder joints and wherein the respective second substrates are formed by one or more metal members of the load bearing structure. This allows to create, for instance, glazed facades having a minimum of metal components for maximum transparency that can be efficiently reused or recycled after the end of life.

[0046] This effect is further obtained by a preferred embodiment the architectural building component comprises a plurality of glass panels that are connected to the load bearing structure and wherein each of the plurality of glass panels are connected to the load bearing structure at one or more connecting sections by means of a respective debondable structural solder joint.

[0047] The present disclosure is further illustrated by the following figures, which show exemplifying embodiments of the, preferably debondable, structural solder joint according to the disclosure, and are not intended to limit the scope of the disclosure in any way, wherein:

[0048] - Figure 1 schematically shows, in a three-dimensional perspective view, a section of an architectural glazed facade. - Figure 2 schematically shows, in a three-dimensional perspective view, a detailed view of an embodiment of the debondable structural solder joint point connection of the architectural facade of figure 1.

[0049] - Figure 3 schematically shows, in a three-dimensional perspective view, a linear connection between a glass panel and a metal structural member.

[0050] - Figure 4 shows, in a schematic cross-sectional view, an overview of the arrangement of various components of an embodiment of an embodiment of the debondable structural solder joint.

[0051] - Figure 5 show a photo taken with a scanning electron microscope of a glass substrate having a layer of a metal-alloy based solder material deposited thereon.

[0052] - Figure 6 shows a mould for forming pre-formed interconnecting solder bodies using a casting process, wherein the casted solder bodies are used in an embodiment of the method of manufacturing a debondable structural solder joint.

[0053] - Figure 7 schematically shows a setup for 3D printing of pre-formed interconnecting solder bodies using solder filament.

[0054] - Figures 8A - 8C show, as a series of photographs, an embodiment of the method for disassembling a debondable structural solder joint.

[0055] Figure 1 schematically shows, in a three-dimensional perspective view, an example of an architectural building component. In the current embodiment, the architectural building component is an architectural glazed facade 1000, of which a section is shown. The facade 1000 is seen to comprise an arrangement of glass panels 10, comprising a number of glass panels 110, a load bearing structure 20, comprising longitudinal structural members 210, in the current example formed as structural columns, and coupling members 220 that are arranged between the structural column members 210 and the glass panels 110.

[0056] The coupling members 220 are seen to comprise a central body 221 formed by a plurality of arms extending radially outwardly from a central section. The central section is arranged to be connected, for instance by means of a bolt, to the structural column members 210

[0057] The coupling members 220 thereby aid in interconnecting a respective glass panel 110 to its direct neighbouring glass panels 110 and in interconnecting the glass panels 110 to the longitudinal structural members 210. At the outer ends of the central body 221, in particular at the outer ends of the arms, coupling points 222 are arranged. These coupling points 222, as is described below, can be connected to the glass by forming a debondable structural solder joint, in particular a reversible and debondable solder joint, according to the current disclosure. In the current embodiment, the longitudinal structural members 210 and coupling members are formed from metal, in particular aluminium or construction steel. It is however also embodied that the longitudinal structural members 210, or other parts of the load bearing structure 20, are also formed from glass members. Additionally, the coupling members 220, or parts thereof, may also be formed from glass or ceramic materials. The glass panels 110 comprise, at the respective first sections, a (thin) layer of a metal-alloy based solder material 111 (i.e. < 100pm thick) that is deposited the surface of the glass panels 110, at the side of the glass panels 110 that faces the load bearing structure 20, in particular the coupling points 222. The metalalloy based solder material 111 enables to reliably join the glass panels 110 to the coupling points 222.

[0058] Figure 2 schematically shows a more detailed view of the reversible and debondable structural solder joint 1 that forms the point connection between the glass panel 110 and the coupling point 222. The coupling point 222 is seen to be formed as a solid (metal) cylinder. Between the glass panel 110, that is arranged with the layer of a metal-alloy based solder material 111, and the coupling point 222 a preformed interconnection solder body 30 is arranged, which, in the current embodiment, is formed as a solid composite metallic foam-solder body 31. By forming the solder body 30 as a solid composite metallic foam-solder body 31, with varied metal foam to solder ratio, a tuneable pre-formed interconnection solder body 30 is obtained that allows for tailored stiffness. In the process of making the reversible and debondable structural solder joint 1, heat and compressive pressure was provided to the predefined arrangement for soldering the joint 1 such that, after cooling, the pre-formed interconnecting solder body 30 was bonded to the coupling point 222 and is bonded to the layer of metal-alloy based solder material 111 that is arranged on the first section of the surface of the glass panel 110. As the layer of metal-alloy based solder material 111 is arranged on the first section of the surface of the glass panel 110, the solder body 30 also bonds well to the glass panel 110, such that a reliable connection is obtained.

[0059] As an alternative to the point connection shown in figures 1 and 2, figure 3 a linear-type of connection between a glass panel and a metal structural member that is obtained by forming a reversible and debondable structural solder joint 1’. The reversible and debondable structural solder joint 1’ is made in substantially the same manner as the reversible and debondable structural solder joint 1, with the difference that, rather than being a point connection (i.e. a connection whereby the area of bonding is substantially smaller in both directions when compared to the dimensions of the surface area of the glass panel 110), the reversible and debondable structural solder joint 1’ is formed as a line connection (i.e. a connection whereby the area of bonding is substantially smaller in one of two directions when compared to the dimensions of the surface area of the glass panel 110). It thereby allows to, for example, directly solder a glass panel 110 to a side surface 222’ of a structural member 220’ that is part of, for instance, the envelope structure of a building.

[0060] Figure 4 shows a schematic cross-sectional view of a further alternative embodiment 1” of the point type of connection shown in figures 1 and 2. The surface of the glass panel 110 is provided with the thin layer of a metal-alloy based solder material 111. A pre-formed interconnection solder body 30, in particular the composite metallic foam-solder or solid solder body 31, is positioned onto, and bonded with, the layer of a metal-alloy based solder material 111. At the opposite side thereof, the coupling point 222 is also provided with a (thin) layer of a metal -alloy based solder material 223 (i.e. < 100pm thick), such that the pre-formed interconnection solder body 30 is positioned onto, and bonded with, the layer of a metal-alloy based solder material 223 of the coupling point 222. As the layers of a metal-alloy based solder material 111, 223 only serve for providing a good bonding between the surfaces of the substrates (i.e. glass panel 110 and coupling point 222) and the pre-formed interconnection solder body 30, it may be very thin, such that a thickness of less than 20 pm is preferred. This is, for instance, seen on the photograph of figure 5, which is taken using a microscope. Here, a thin layer of a metal-alloy based solder material 111 is arranged on top of the surface of a glass substrate 110. On the basis of the legend, it is seen that the layer has a thickness of less than 5 pm, which may even be less than 4 pm. This layer of a metal-alloy based solder material 111 is preferably made using an ultrasonic soldering process. Ultrasonic soldering uses both thermal and ultrasonic energy in the soldering process, as was described earlier.

[0061] Figures 6 and 7 show various embodiments for forming the pre-formed interconnecting solder bodies. In figure 6 a mould 2100 is shown that can be used in a casting process for casting circular disc-shaped interconnecting solder bodies, as were applied in the point connections of figures 1, 2 and 4. A molten metal-alloy based solder is poured, or injected, into the recesses 2111 of a form plate 2110, which is sealed off by a top and bottom plate 2120, 2130 for obtaining circular disc-shaped solder bodies 30 that can be employed for forming the point connections. A further additional weight 2140 may be provided on top of the top plate 2120 for providing compressive pressure to the mould 2100. Form, top and bottom plates 2110, 2120, 2130 are preferably made from a material that does not bound to solder upon heating alone. Suitable materials therefore are, for example, titanium or graphite.

[0062] Alternatively, or additionally, more complex shaped interconnecting solder bodies may be formed using an additive manufacturing or 3D printing technique. Figure 6 shows a schematic and simplified visualization of a 3D printing technique whereby a metal-alloy based solder filament 2210 is fed, by a feeding mechanism 2230, to a heated printing head 2220, comprising a tip 2221. The metal-alloy based solder filament 2210 is heated above its solidus point enabling it to (partly) melt, such that a more complex shaped interconnecting solder body 30 may be formed by printing multiple layers of (partly) melted, metal-alloy based solder fdament 2210 on top of each other. In order for the first layer of the interconnecting solder body 30 to be formed, a printable surface 2240 is required. The printable surface 2240 needs to be arranged such that the initial layer is attracted to the printable surface 2240. The printable surface 2240 may, for instance, be formed by a metal plate of a suitable metal and / or alloy, or may be coated with a suitable metal and / or alloy. It may also be provided with a thin layer of metal-alloy solder material which can be deposited using the ultrasonic soldering technique.

[0063] Figures 8A- 8C show, as a series of photographs, an embodiment 3000 of the method for disassembling a reversible and debondable structural solder joint 1. The reversible and debondable structural solder joint 1 is seen to comprise a glass substrate 110, a solder body 3130 and a steel substrate 230. The solder body 3130 is connected, using a clamp 3120, to the negative terminal of the direct current power source (not shown), which is set to be able to deliver up to 20 V direct current. A titanium strip 3100 is arranged and connected to the positive terminal of the direct current power source, such that is functions as a secondary electrode.

[0064] The arrangement of figure 8 A is submerged in an alkali solution 3140, whereafter the power source is switched on, as is shown in figure 8B. This causes the solder material of the solder body 3130 to degrade and debond from the glass substrate 110. The process of debonding thereby requires a certain amount of time in order to degrade the solder material sufficiently such that it debonds from the respective substrates, causing the various components of the solder joint 1 to be separated, as is shown in figure 8C.

[0065] All possible suitable combinations of the above described embodiments are also part of the current disclosure. Additionally, the present invention is not limited to the embodiments shown, but also extends to other embodiments falling within the scope of the appended claims.

Claims

Claims1. Method of manufacturing a debondable structural solder joint comprising a glass substrate that is joined to a second substrate, wherein the method comprises the steps of:- providing the glass substrate, wherein said glass substrate is arranged with a layer of a metalalloy based solder material that is deposited on a first section of a surface of the glass substrate, wherein said first section corresponds to only a section of the surface and wherein said layer of solder material is no thicker than 100 pm;- providing a second substrate, said second substrate being a glass, ceramic or metal substrate;- providing a pre-formed interconnecting solder body that is made from a metal-alloy based solder material, wherein one side of said pre-formed interconnecting solder body is arranged to be positioned onto the first section of the glass substrate;- arranging the glass substrate, pre-formed interconnecting solder body and second substrate in a predefined arrangement by positioning the one side of said pre-formed interconnecting solder body onto the layer of a metal-alloy based solder material deposited on the first section of the surface of the glass substrate, and positioning the second substrate onto another side of the pre-formed interconnecting solder body;- arranging an enclosure between the glass substrate and the second substrate and around the preformed interconnecting solder body;- providing heat and compressive pressure to the predefined arrangement for soldering said solder joint such that, after cooling, the pre-formed interconnecting solder body is bonded to the second substrate and is bonded to the layer of metal-alloy based solder material that is deposited on the first section of a surface of the glass substrate.

2. Method of manufacturing according to claim 1, wherein the step of providing the glass substrate comprises the step of depositing the layer of a metal-alloy based solder material onto the first section by means of ultrasonic soldering; and preferably, wherein the layer of solder material is no thicker than 50 pm, more preferably no thicker than 30 pm, most preferably no thicker than 10 pm.

3. Method of manufacturing according to claim 1 or 2, wherein said second substrate is arranged with a layer of a metal-alloy based solder material that is deposited on at least a part of the surface of the second substrate, wherein said layer of solder material of the second substrate is no thicker than 100 pm, preferably no thicker than 50 pm, more preferably no thicker than 30 pm, most preferably no thicker than 10 pm; and wherein the step of arranging the glass substrate, pre-formed interconnecting solder body and second substrate in the predefined arrangement comprises positioning the layer of a metal-allow basedsolder that is deposited on the second substrate onto the other side of the pre-formed interconnecting solder body.

4. Method of manufacturing according to any of the preceding claims, wherein the pre-formed interconnecting solder body is cast in a predefined geometry, prior to the step of arranging the glass substrate, pre-formed interconnecting solder body and second substrate in the predefined arrangement, using a casting process; or wherein the pre-formed interconnecting solder body is formed in the predefined geometry, prior to the step of arranging the glass substrate, pre-formed interconnecting solder body and second substrate in the predefined arrangement, using an additive manufacturing process, such as a 3D printing process; preferably, wherein the method comprises the step of forming the pre-formed interconnecting solder body in the predefined geometry, prior to the step of arranging the glass substrate, pre-formed interconnecting solder body and second substrate in the predefined arrangement, using the casting process and / or additive manufacturing process.

5. Method of manufacturing according to claim 4, wherein the pre-formed interconnecting solder body is formed by the 3D printing process comprising the steps of: feeding a solder material filament through a heated stainless steel 3D-printing tip that heats the solder material to a temperature above the solidus point of the solder composition, causing the solder material filament to melt, or at least soften to allow it to flow; moving the heated stainless steel 3D-printing tip along a predefined path above and over a printing surface while feeding the heated solder material filament, such that the solder material is deposited onto the printing surface and allowing the desposited solter material to cool and solidify; and preferably, wherein said printing surface comprises a metallic top surface and the 3D printing process further comprises separating the pre-formed interconnecting solder body from the printing surface.

6. Method of manufacturing according to any of the preceding claims, wherein said pre-formed interconnecting solder body comprises a solid composite metallic foam solder body and / or a solid solder body.

7. Method of manufacturing according to any of the preceding claims, wherein said pre-formed interconnecting solder body has a thickness in the range of 1 mm - 30 mm, preferably 2 mm - 20 mm, more preferably 3 mm - 15 mm, even more preferably 5 mm - 12 mm, most preferably 8 mm - 10 mm, wherein said thickness of the pre-formed interconnecting solder body is defined in a direction perpendicular to the one side of said pre-formed interconnecting solder body.

168. Method of manufacturing according to any of the preceding claims, further comprising the step of determining a geometry, such as a thickness and / or foam porosity, of the pre-formed interconnecting solder body on the basis of a predefined stiffness of the debondable structural solder joint.

9. Method of manufacturing according to any of the preceding claims, wherein the layer of a metalalloy based solder material has a melting point in between 105°C and 300°C, in particular wherein said solder material is a Sn and / or Zn-based solder material; and / or wherein the pre-formed interconnecting solder body is made from a metal-alloy based solder material having a melting point in between 105°C and 300°C, in particular wherein said solder material is a Sn and / or Zn-based solder material.

10. Debondable structural solder joint comprising a glass substrate that is joined to a second substrate obtainable by a method according to any of the preceding claims, the debondable structural solder joint comprising:- the glass substrate, wherein said glass substrate is arranged with a layer of a metal-alloy based solder material that is deposited on a first section of a surface of the glass substrate, wherein said first section corresponds to only a part of the surface and wherein said layer of solder material is no thicker than 100 pm;- the second substrate, wherein said second substrate is a glass, ceramic or metal substrate;- a interconnecting solder body of a metal-alloy based solder material that is bonded to the second substrate and is bonded to the layer of metal-alloy based solder material that is arranged on the first section of a surface of the glass substrate.

11. Debondable structural solder joint according to claim 10, wherein a surface area of the first section is at most 10%, preferably at most 3%, more preferably at most 1%, of the surface area of the glass substrate.

12. Method of disassembling a debondable structural solder joint, wherein the method comprises the steps of:- providing a debondable structural solder joint according to claim 10 or 11;- debonding the glass substrate, interconnecting solder body and second substrate using thermal and / or electrical energy.

13. Method of disassembling according to claim 12, the step of debonding comprises: immersing the debondable structural solder joint in an alkali solution; arranging a secondary electrode in the alkali solution; arranging an electrical potential over the debondable structural solder joint and the secondary electrode.1714. Method of dissembling according to claim 13, wherein the secondary electrode is a metallic element, such as an aluminium, copper or titanium element, and / or wherein the electrical potential is no more than 20 V direct current, preferably no more than 15 V direct current, most preferably no more than 10 V direct current.

15. Method of disassembling according to any of the preceding claims 12 - 14, wherein, during the step of debonding, thermal energy is provided by means of a furnace wherein the debondable structural solder joint is placed in or by means of induction heating.

16. Architectural building component, such as the facade of a building, comprising a load bearing structure and a glass panel, wherein said glass panel is connected to the load bearing structure at a connecting section by means of a debondable structural solder joint according to claim 10 or 11, such that the glass panel forms the glass substrate and the second substrate is comprised in the load bearing structure, in particular wherein the second substrate is a metal member of the load bearing structure.

17. Architectural building component according to claim 16, wherein the glass panel is connected to the load bearing structure at a plurality of spaced apart connecting sections, wherein at each connecting section the glass panel is connected to the load bearing structure by means of a respective debondable structural solder joints, such that the glass panel forms the glass substrate for each of the debondable structural solder joints and wherein the respective second substrates are formed by one or more metal members of the load bearing structure.

18. Architectural building component according to claim 16 or 17, wherein the architectural building component comprises a plurality of glass panels that are connected to the load bearing structure and wherein each of the plurality of glass panels are connected to the load bearing structure at one or more connecting sections by means of a respective debondable structural solder joint.

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