Brazed aluminum / copper hybrid heat exchangers

Abstract

The systems relate to a machined brazing sheet (PBS) for a heat exchanger. In one example, a machined brazing sheet (PBS) comprises at least one aluminum layer (Al) with at least one plated side and a melting point depressor (MPD) layer made of copper (Cu). The Al layer is coated on at least one side with a metal that has a lower melting point than Al.

Description

TECHNICAL FIELD

[0001] This description generally relates to methods and systems for hybrid aluminum / copper heat exchangers. BACKGROUND AND OVERVIEW

[0002] Heat exchangers can be made from either aluminum (Al) / aluminum alloys or copper (Cu) / copper alloys. For some applications, Cu and / or copper alloys may be preferred due to their higher thermal conductivity compared to that of Al and / or aluminum alloys. However, Cu is heavier and more expensive than Al. For applications where cost and / or weight reduction is required, such as automotive heat exchangers, heat exchangers can incorporate Al and / or its alloys to reduce cost and weight despite lower thermal conductivity.

[0003] The inventors here have developed a solution to at least partially address the above-mentioned problem. In one example, a system for a processed brazing sheet (PBS) comprises a processed brazing sheet (PBS) with at least one layer of aluminum (Al) or an aluminum alloy, with at least one side having a melting point depressor (MPD) layer of copper (Cu). In this way, the low cost of Al can be utilized while leveraging the advantages of Cu.

[0004] In one example, the MPD layer may be coated with a braze coating (BP). The BP layer may contain one or more of the elements nickel (Ni), cobalt (Co), and iron (Fe). The BP layer may be coated with a viscosity-modifying and / or surface-tension-modifying (VM) layer containing one or more of the elements bismuth (Bi), lead (Pb), tin (Sn), antimony (Sb), and thallium (Ti). The position of the VM layer relative to the MPD layer and the BP layer can be varied to meet the requirements of different heat exchanger applications. In this way, the cost of manufacturing a heat exchanger with the properties of Cu can be reduced.

[0005] It should be understood that the above summary is intended to introduce, in simplified form, a selection of concepts that are further explained in the detailed description. It is not intended to identify the most important or essential features of the claimed subject matter, the scope of which is clearly defined by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that address the disadvantages noted above or elsewhere in this disclosure. SHORT DESCRIPTION OF THE CHARACTERS Fig. 1 shows a first embodiment of a processed brazing sheet; Fig. 2 shows a second embodiment of a processed brazing sheet; Fig. 3 shows a third embodiment of a processed brazing sheet; Fig. 4 shows a fourth embodiment of a processed brazing sheet; Fig. 5 shows a fifth embodiment of a processed brazing sheet; Fig. 6 shows a sixth embodiment of a processed brazing sheet; Fig. 7 shows a seventh embodiment of a processed brazing sheet; Fig. 8 shows an eighth embodiment of a processed brazing sheet; and Fig. 9 shows an example of a method for manufacturing the processed brazing sheet. DETAILED DESCRIPTION

[0006] The following disclosure relates to a brazing sheet. The disclosure provides support for various patterns of layers included in the processed brazing sheet. Various embodiments of processed brazing sheets are described in Fig. 1-8. A manufacturing process for a processed brazing sheet is shown in Fig. 9 shown.

[0007] The Fig. Figures 1 to 8 show various examples of brazing sheets with a different number of layers and materials within each layer. The brazing sheet may comprise a core Al sheet material laminated or "clad" on one or both sides with filler metal in a sheet. The laminated or clad filler metal may be interchangeably referred to as "clad." Components may be cut and formed from the brazing sheet and assembled for brazing in a furnace, with only the cladding melting to form the heat exchanger braze joints. Additionally or alternatively, heat exchanger components may also be formed from "core" or "cladding" material in separate sheets. Additional steps or precautions are also taken to eliminate the stubborn aluminum oxide that would otherwise impede the flow of the cladding to form brazed joints, e.g.,Nocolok flux brazing, vacuum brazing and Ni-Al brazing.

[0008] Nocolok brazing flux may contain a non-hygroscopic and non-corrosive potassium fluoroaluminate flux that removes the oxide layer on aluminum, does not react with aluminum in the molten or solid state, and whose residues are poorly soluble in water. Vacuum brazing can be similar to fluxless brazing, eliminating the need for post-treatment. With fluxless and / or vacuum brazing, furnace temperatures, surface cleanliness, and atmospheric purity can be maintained within tight tolerances.

[0009] The disclosure supports a manufacturing method for producing a brazing sheet made of aluminum, optionally including an aluminum alloy, for use in brazing mixed metals in a furnace brazing environment, such as controlled atmosphere brazing or vacuum brazing. The processed brazing sheet (PBS) can be used without additional treatment or protocols in standard controlled atmosphere brazing furnaces, such as belt furnaces with an inert nitrogen atmosphere, or in vacuum furnaces. The PBS can be used to braze Al to Al, Cu to Al, and / or Ni to Al, in combination and all simultaneously in the furnace, to produce mixed metal heat exchangers for a vehicle. Some embodiments of the processed brazing sheet also enable fluxless brazing of mixed metal heat exchangers. The brazing sheet may include an aluminum alloy, which may be clad on one or both sides.The PBS may define a material containing the brazing sheet that is subjected to a coating process as described herein.

[0010] The PBS can comprise a plurality of layers over an aluminum brazing sheet containing at least one layer from the Al4000 series. During processing of the aluminum brazing sheet, up to three layers are added to at least one side of the Al4000 layer. The three layers can include a melting point depressant (MPD) layer containing Cu, a brazing agent (BP) layer containing Ni, Fe, or Co, and a viscosity and / or surface tension modifying (VM) layer containing bismuth (Bi) and / or lead (Pb) and / or other low-melting elements, such as tin (Sn), antimony (Sb), and thallium (Ti). The MPD layer is located below the BP layer, while the VM layer can be closer to the aluminum layer than the MPD layer, between the MPD and BP layers, or farther from the aluminum layer than the BP layer.

[0011] The MPD layer can reduce the cladding solidus from 577°C to approximately 525°C due to the formation of a ternary Al-Cu-Si eutectic. This layer enables brazing of Al to Al, Cu to Al, and / or Ni to Al at temperatures below the melting point of the cladding of 577°C and, particularly in the case of Cu to Al, below the temperature of the binary Al-Cu eutectic of 548°C. Therefore, at brazing temperatures above approximately 525°C, the MPD layer can diffuse into the plated layer between the MPD layer and the Al layer, forming in-situ a ternary liquid metal Al-Cu-Si eutectic that serves as a brazing filler metal during brazing. It is possible to braze functional heat exchangers using only the MPD layer, however, the inclusion of the VM layer and, in the case of fluxless brazing, also the BP layer can improve the heat exchanger.Direct contact between the MPD layer and the plating can promote the formation of a more stable ternary Al-Cu-Si eutectic. Therefore, the layer deposition process must not include intermediate steps where coatings are deposited between the plated and MPD layers, such as zinc plating before copper plating in the case of an electroplating process. The advantage of this PBS is that such intermediate layers or steps are not required for good soldering, which reduces manufacturing costs.

[0012] The BP layer can tolerate oxides during brazing due to the exothermic reaction between Ni and liquid Al at brazing temperatures. In this way, the BP layer can support fluxless brazing. While the ternary eutectic Al-Cu-Si liquid generated with the MPD layer alone can seep through the oxides during brazing (and form braze joints), the oxides can form continuous layers (as opposed to fractured layers or layers incorporated into the cladding) that can serve as nucleation sites for crack initiation and subsequent propagation. The BP layer can eliminate this phenomenon and promote the formation of strong braze joints. Another benefit of the BP layer can be that it protects the underlying MPD layer from partial oxidation, either during processing of the PBS or from oxidation in the furnace atmosphere due to trace oxygen.In addition, the BP layer can further reduce the plating solidus to about 520 °C due to the formation of a quaternary eutectic Al-Cu-Si-Ni liquid.

[0013] One or more VM layers can alter the viscosity and / or surface tension of the liquid metal once formed, which supports the capillary action of the molten plating and thus promotes its flow at brazing temperatures. The VM layer contains one or more elements from the group consisting of bismuth (Bi), lead (Pb), tin, antimony, and thallium, but preferably Bi and / or Pb. It should be noted that Bi and / or Pb can reduce the shrinkage porosity otherwise observed and thus promote the formation of continuous braze joints, which has a positive effect on the service life, strength, and corrosion resistance of the joint.

[0014] While an embodiment in which the BP layer and the VM layer are configured as separate layers is practical, flexible, and functional, it has been found to be economical to combine the BP and VM layers into a single layer over the MPD layer, which may be referred to herein as the BPVM layer. Thus, two layers may be deposited over the clad layer or the Al4000 layer: the MPD layer in surface contact with the clad layer or the Al4000 layer of the brazing sheet, and the BPVM layer directly over the MPD layer. This embodiment offers all of the above advantages at lower manufacturing costs and complexity. A processed brazing sheet with MPD, BP, VM, and / or BPVM layers can be used without further treatment for brazing heat exchangers in controlled atmosphere furnaces or for vacuum brazing.

[0015] Fig. 1 shows a first embodiment of a brazing sheet 100. The brazing sheet 100 may include a first layer 110, a second layer 120, and a third layer 130. The first layer 110 may be different from the second layer 120. The second layer 120 may be different from the third layer 130. The second layer 120 may be interposed between the first layer 110 and the third layer 130. In one example, a first surface of the second layer 120 is in surface contact with the first layer 110, and a second surface of the second layer 120, opposite the first surface, is in surface contact with the third layer 130.

[0016] In one example, the first layer 110 is a core layer. The first layer 110 may comprise an aluminum sheet laminated or "clad" to the second layer 120 on at least a first surface. The second layer 120 may be a different alloy than the first layer 110, which may have a lower melting point than the first layer 110. The second layer 120 may include one or more alloys of Al, Cu, and silicon (Si).

[0017] In one example, the third layer 130 is an MPD layer comprising one or more of the elements Cu, Bi, Pb, Sn, Sb, and Tl. The third layer 130 may be configured to lower the melting point of the second layer 120.

[0018] In one example, the first layer is an alloy of aluminum sheet (e.g., a layer from the Al3000 or Al6000 series), the second layer is a cladding (e.g., a layer from the Al4000 series), and the third layer is a sheet containing Cu or another metal.

[0019] Fig. Figure 2 shows a second embodiment of a second brazing sheet 200. The second brazing sheet 200 may include the first layer 110, the second layer 120, and the third layer 130. Therefore, the previously introduced components may be numbered similarly in this and subsequent figures.

[0020] In one example, the second layer 120 is a first second layer 120, wherein the second brazing sheet 200 further includes a second second layer 220 that is identical to the first second layer 120. The second second layer 220 is in surface contact with an opposite side of the first layer 110 relative to the first second layer 120. The first layer 110 is thus embedded between the first second layer 120 and the second second layer 220. In this way, the first layer 110 can be laminated on both long sides. In this way, both sides of the first layer 110 are clad.

[0021] In one example, the third layer 130 is additionally or alternatively a first third layer 130, wherein the second brazing sheet 200 further includes a second third layer 230. The second third layer 230 may be identical to the first third layer 130. The second third layer 230 may be in surface contact with the second second layer 220. In this way, the second second layer 220 is embedded between the first layer 110 and the second third layer 230.

[0022] Fig. 3 shows a third embodiment of a third brazing sheet 300. The third brazing sheet 300 may include the first third layer 130, the second third layer 230, and a fourth layer 310. In one example, the fourth layer 310 is an aluminum 4000 series alloy.

[0023] In one example, the aluminum 4000 series layer may be an alloy of Al and Si included in the aluminum 4000 series, such as AL4343, Al4045, Al4047, and / or Al4150. The Si may lower the melting point of Al. For example, at 12.5 wt% Si, the melting point of Al may drop from 660°C to about 577°C. Core Al alloys, such as the first layer 110 in Fig. 1 and Fig. 2, may contain alloys of the Al3000 or Al6000 series, such as Al3003 or Al6061. The Al core alloy may contain less Si than the Al4000 layer, or it may be Si-free.

[0024] Fig. 4 shows a fourth embodiment of a fourth brazing sheet 400. The fourth brazing sheet 400 can be the first brazing sheet 100 of Fig. 1 in that the fourth brazing sheet 400 includes the second layer 120 sandwiched between the first layer 110 and the third layer 130. Furthermore, the first layer 110 is laminated over the second layer 120 on only one side. The fourth brazing sheet 400 may further include a fifth layer 410 and a sixth layer 420.

[0025] In one example, the fifth layer 410 may be a brazing (BP) layer. The sixth layer 420 may be a viscosity-modifying and / or surface tension-modifying (e.g., VM) layer. The fifth layer 410 may contain Ni, and the sixth layer 420 may contain one or more of the elements Cu, Bi, Pb, Sn, Sb, and Ti. Additionally or alternatively, the fifth layer 410 may be a VM layer and the sixth layer 420 may be a BP layer.

[0026] Fig. 5 shows a fifth embodiment of a fifth brazing sheet 500. The fifth brazing sheet 500 may be similar to the fourth brazing sheet 400 in that it includes the first layer 110, the second layer 120, the third layer 130, a BP layer, and a VM layer. The fifth brazing sheet 500 may differ from the fourth brazing sheet 400 in that a seventh layer 510 of the fifth brazing sheet 500 includes a combination of the BP layer and the VM layer. In one example, the seventh layer 510 is a BPVM layer that includes a mixture of the BP layer and the VM layer.

[0027] Fig. 6 shows a sixth embodiment of a sixth brazing sheet 600. The sixth brazing sheet 600 may be similar to the fourth brazing sheet 400, except that the sixth brazing sheet 600 does not include the sixth layer 420. Thus, the fifth layer 410 may only be in surface contact with the third layer 130 along a first surface and be exposed at a second surface opposite the first surface.

[0028] Fig. 7 shows a seventh embodiment of a seventh brazing sheet 700. The seventh brazing sheet 700 may be similar to the fifth brazing sheet 500 in that it includes the first layer 110, the second layer 120, the third layer 130, and the seventh layer 510. The seventh brazing sheet 700 may differ from the fifth brazing sheet 500 in that the first layer 110 is laminated to each of its long sides, such that the seventh brazing sheet 700 includes the first second layer 120 and the second second layer 220. The seventh brazing sheet 700 may also include the first third layer 130 and the second third layer 230. The first second layer 120 lies between the first layer 110 and the first third layer 130. The second second layer 220 is embedded between the first layer 110 and the second third layer 230.

[0029] In one example, the seventh layer 510 is a first seventh layer 510, and the seventh brazing sheet 700 further includes a second seventh layer 710. The first third layer 130 is sandwiched between the first second layer 120 and the first seventh layer 510. The second third layer 230 is sandwiched between the second second layer 220 and the second seventh layer 710. The first seventh layer 510 and the second seventh layer 710 are identical.

[0030] Fig. 8 shows an eighth embodiment of an eighth brazing sheet 800. The eighth brazing sheet 800 may be similar to the third brazing sheet 300 in that it includes the fourth layer 310 located between the first third layer 130 and the second third layer 230. The eighth brazing sheet 800 also includes the seventh layer 510, which is in surface contact with the first third layer 130. In this way, the first third layer 130 is in surface contact with the fourth layer 310 and the seventh layer 510 and is sandwiched between them.

[0031] In one example, the seventh layer 510 is a first seventh layer 510, and the eighth brazing sheet 800 further includes a second seventh layer 710. The second seventh layer 710 may be in surface contact with the second third layer 230. In this way, the second third layer 230 is sandwiched between the fourth layer 310 and the second seventh layer 710.

[0032] Starting from an aluminum brazing sheet, the MPD and BPVM layers are added to the clad or Al4000 layer by plating, which schematically involves up to three steps. A first step can be a mechanical and / or chemical pretreatment of the Al brazing sheet to remove any aluminum oxide present. In a second step, the MPD layer can be formed by direct coating with Cu. A third step can involve the subsequent coating of Ni with co-deposited Bi and / or Pb to form the BPVM layer. As already indicated, Bi and / or Pb can be deposited as one or more separate VM layers, but it may be more efficient to deposit Bi and / or Pb together with Ni to form the BPVM layer.

[0033] The MPD layer thickness can be at least 20µ''. The amount of liquid filler metal formed in-situ during brazing below 577°C can be proportional to the MPD layer thickness, and depending on the application, larger thicknesses can be used to allow some liquid filler metal to form in-situ.

[0034] The thickness of the BPVM layer can be at least 5µ''. The Bi and / or Pb content in the BPVM layer can be up to 20 wt.%. If Bi and / or Pb are present in a separate VM layer, the target thickness can be determined based on the thickness of the BP layer so that the Bi or Pb weight fraction falls within the specified ranges. If separate BP and VM layers are used, the Bi and / or Pb content of the combined BP and VM layers can also be up to 20%.

[0035] Weight percentage ranges after brazing for processed brazing sheet (PBS) based on amalgamated layers from the outer edge of the material to the core part of the material for the Fig. 1-2, 4-7 and through all the material for the Fig. 3 and Fig. 8, may contain Cu: 0.4 - 37%, Ni (or Co or Fe): 0.08 - 16%, Pb or Bi (or Sn or Sb or Ti): 0.002 - 3.4%, Si: 3.5 - 13%, and a balance including Al + impurities.

[0036] The processed brazing sheet (PBS) can be used directly in controlled atmosphere furnace brazing processes or in vacuum brazing processes.

[0037] When using the PBS for brazing Al to Al, brazing can be performed at a brazing temperature between approximately 530°C and 610°C. Therefore, the PBS of the present disclosure enables brazing of Al at low temperatures, below the melting point of other clad alloys such as Al4343, Al4045, and Al4047. The PBS can be used in products as a replacement for aluminum brazing sheets used in the manufacture of heat exchangers in the automotive industry.

[0038] The PBS also enables improved brazing of Cu directly to Al, optionally including alloys of Cu and / or Al, on one or more cladding sides of the PBS, with a brazing temperature between 530°C and 560°C. This allows Cu components to be brazed to Al assemblies in a single brazing operation using the PBS. For example, a Cu component such as a turbulator or other extended heat transfer surface can be brazed to an Al heat exchanger assembly to benefit from the higher thermal conductivity of Cu, without the need to braze a heat exchanger containing only Cu or Cu alloy components. The PBS can therefore offer significant cost and weight advantages in the manufacture of automotive heat exchangers.

[0039] Additionally, Ni and / or its alloys can be brazed to the plated side(s) of the Al PBS, with the brazing temperature ranging from approximately 530°C to 610°C. This can be useful in applications where HX components are Ni-plated prior to assembly and subsequent brazing, e.g., a Ni-plated Cu turbulizer.

[0040] Fig. 9 shows a processing routine 900 for producing the embodiments of processed brazing sheets from Fig. 1-8. A core sheet 905, such as the first layer 110, the fourth layer 310, and / or a brazing sheet, may be pretreated at 912 to clean the brazing sheet of oxides. The brazing sheet may be single-sided or double-sided clad and may resemble only the fourth layer 310, a combination of the first layer 110 and the second layer 120, or a combination of the first layer 110, the second layer 120, and the second second layer 220. An MPD layer, such as the first third layer 130 or the second third layer 230, may be bonded to the core foil 905 at 914. In one example, the pretreatment and MPD are applied to the brazing sheet in a single step 910.

[0041] At 915, the sheet can be punched with the MPD (e.g., the PBS) to form one or more components.

[0042] At 920, the components can be assembled with the stamped PBS and soldered in the oven.

[0043] If BP and VM layers are desired, the PBS can be first coated with a BP layer prior to 915 and then with a VM layer at 925, or vice versa. Adding the BP layer can involve plating the MPD layer(s) with Ni, and adding the VM layer can involve plating the Ni layer(s) with Bi and / or Pb. Additionally or alternatively, a single BPVM can be applied to the MPD layer(s) at 930.

[0044] Following 925 and / or 930, the brazing sheet can be punched and the resulting parts can be assembled and soldered.

[0045] It will be appreciated that in embodiments where layers can be built up on one side of a starting layer of an Al sheet, it is also possible to build up the same or different layers on another side of the Al sheet. Some, but not all, of the examples provided are included in the figures. It is also possible for multi-layer brazing sheets (e.g., a starting material such as 4045 / 3003 / 4045) to be coated on only one side. Other scenarios include the possibility of the VM layer being above or below the BP layer, or between the MPD layer and the clad layer, although these various scenarios are not specifically described.

[0046] The disclosure provides support for a system including a processed brazing sheet (PBS) comprising at least one layer of aluminum (Al) or an aluminum alloy having at least one side containing a melting point depressant (MPD) layer of copper (Cu). In a first example of the system, the Al layer is coated on at least one side with a metal alloy having a lower melting point than Al. A second example of the system, optionally including the first example, further includes having an Al layer from the Al4000 series comprising an alloy of Al and silicon (Si). A third example of the system, optionally including one or more of the previous examples, further includes the MPD layer being coated with a brazing promotion (BP) layer comprising one or more of the elements nickel (Ni), cobalt (Co), and iron (Fe).A fourth example of the system, optionally including one or more of the preceding examples, further includes the BP layer being coated with a viscosity-modifying (VM) layer comprising one or more of the elements bismuth (Bi), lead (Pb), tin (Sn), antimony (Sb), and thallium (Ti). A fifth example of the system, optionally including one or more of the preceding examples, further includes the VM layer being located between the MPD layer and the Al layer. A sixth example of the system, optionally including one or more of the preceding examples, further includes the BP layer comprising a viscosity-modifying (VM) layer integrally disposed therein.A seventh example of the system, optionally comprising one or more of the preceding examples, further includes the MPD layer being located between a VM layer and the Al layer, wherein the VM layer comprises one or more of the elements bismuth (Bi), lead (Pb), tin (Sn), antimony (Sb), and thallium (Ti).

[0047] The disclosure provides an additional support for a processed brazing sheet (PBS) comprising a first layer plated along at least a first surface with a second layer, wherein the first layer comprises at least aluminum (Al) and the second layer comprises a metal alloy having a lower melting point than Al, and a third layer in surface contact with the second layer, wherein the third layer comprises copper (Cu). A first example of the PBS further comprises the second layer being a first second layer and the first layer being plated along a second surface with a second second layer. A second example of the PBS, optionally including the first example, further comprises the third layer being a first third layer, and wherein the second second layer is in surface contact with a second third layer.A third example of the PBS, optionally including one or more of the preceding examples, further includes a brazing promotion layer (BP) in surface contact with the third layer, wherein the BP layer comprises one or more of the elements nickel (Ni), cobalt (Co), and iron (Fe). A fourth example of the PBS, optionally including one or more of the preceding examples, further includes the BP layer in surface contact with a viscosity-modifying (VM) layer, wherein the VM layer comprises one or more of the elements bismuth (Bi), lead (Pb), tin (Sn), antimony (Sb), and thallium (Ti).A fifth example of the PBS, optionally including one or more of the preceding examples, further includes a viscosity-modifying (VM) layer disposed integrally within the BP layer, wherein the VM layer comprises one or more of the elements bismuth (Bi), lead (Pb), tin (Sn), antimony (Sb), and thallium (Ti). A sixth example of the PBS, optionally including one or more of the preceding examples, further includes the second layer further comprising silicon (Si).

[0048] The disclosure further supports a system including a processed brazing sheet (PBS) configured for use by a heat exchanger, wherein the PBS comprises a core layer comprising aluminum (Al), a melting point depressant (MPD) layer comprising copper (Cu) in surface contact with a clad side of the core layer, and one or more of a brazing promotion (BP) layer and a viscosity modifying (VM) layer in surface contact with the MPD layer. A first example of a system wherein the BP layer comprises one or more of the elements nickel (Ni), cobalt (Co), and iron (Fe) is also possible. A second example of the system, optionally including the first example, further includes the VM layer comprising one or more of the elements bismuth (Bi), lead (Pb), tin (Sn), antimony (Sb), and thallium (Ti).A third example of the system, optionally including one or more of the preceding examples, further includes the BP layer and the VM layer combined and arranged integrally in a single BPVM layer. A fourth example of the system, optionally including one or more of the preceding examples, further includes the core layer being cladding on both sides, with the MPD layer being in surface contact with both cladding sides.

[0049] Fig.1-8 show example configurations with the relative arrangement of the various components. When these elements are in direct contact with each other or are directly coupled, they may be referred to as being in direct contact or directly coupled, respectively, at least in one example. Similarly, elements shown side by side or adjacent to each other may be adjacent to each other or adjacent to each other, at least in one example. For example, components that are in surface-to-surface contact with each other may be referred to as being in surface-to-surface contact. As another example, in at least one instance, elements that are separated from each other with only a space between them and that do not have any other components may be referred to as such.In yet another example, elements depicted above / below, on opposite sides, or to the left / right of each other may be referred to as such, relative to each other. Further, in at least one example, as depicted in the figures, a topmost element or point of an element may be referred to as a "top" of the component, and a bottommost element or point of the element may be referred to as a "bottom" of the component. As used herein, the terms top / bottom, upper / lower, above / below may refer to a vertical axis of the figures and may be used to describe the positioning of elements of the figures relative to each other. For example, in one example, elements displayed above other elements are arranged vertically above the other elements.

[0050] In the present disclosure, the layers described are mutually exclusive, non-overlapping layers. Materials of one layer may not be mixed or dispersed with materials of another layer unless explicitly stated. Each layer may be defined by boundaries, and adjacent layers whose boundaries touch each other may be in surface contact.

[0051] Although various embodiments have been described above, they are to be considered as examples and not as limitations. It will be apparent to those skilled in the art that the disclosed subject matter may be embodied in other specific forms without departing from the spirit of the subject matter. The embodiments described above are, therefore, to be considered in all respects as illustrative and not restrictive. Thus, the configurations and routines disclosed herein are exemplary in nature, and the specific examples are not to be considered limiting, as numerous variations are possible. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations, as well as other features, functions, and / or characteristics disclosed herein.

[0052] The following claims particularly point out certain combinations and subcombinations that are considered novel and non-obvious. These claims may refer to "a" element or "a first" element, or the equivalent thereof. Such claims are to be construed as including the inclusion of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and subcombinations of the disclosed features, functions, elements, and / or properties may be claimed by amending the present claims or by filing new claims in this or a related application. Such claims, whether broader, narrower, equal, or different in scope than the original claims, are also to be considered included within the subject matter of the present disclosure.

Claims

[1] System comprising: a processed brazing sheet (PBS) comprising at least one layer of aluminum (Al) or an aluminum alloy, at least one side having a melting point depressant (MPD) layer comprising copper (Cu). [2] The system of claim 1, wherein the Al layer is plated on at least one side with a metal alloy having a lower melting point than Al. [3] System according to one of the preceding claims, wherein the Al layer belongs to the Al4000 series and contains an alloy of Al and silicon (Si). [4] A system according to any one of the preceding claims, wherein the MPD layer is coated with a brazing promotion layer (BP) containing one or more of the elements nickel (Ni), cobalt (Co) and iron (Fe). [5] The system of claim 4, wherein the BP layer is coated with a viscosity modifying (VM) layer comprising one or more of the elements bismuth (Bi), lead (Pb), tin (Sn), antimony (Sb) and thallium (TI). [6] The system of claim 5, wherein the VM layer is located between the MPD layer and the Al layer. [7] The system of any one of claims 4 to 6, wherein the BP layer further comprises a viscosity modifying (VM) layer integrally disposed therein. [8] A system according to any one of claims 4 to 7, wherein the MPD layer is disposed between a VM layer and the Al layer, and the VM layer contains one or more of the elements bismuth (Bi), lead (Pb), tin (Sn), antimony (Sb) and thallium (Ti). [9] Processed brazing sheet (PBS), comprising: a first layer plated along at least a first surface with a second layer, the first layer comprising at least aluminum (Al) and the second layer comprising a metal alloy having a lower melting point than Al; a third layer in surface contact with the second layer, wherein the third layer comprises copper (Cu). [10] The PBS of claim 9, wherein the second layer is a first second layer, and wherein the first layer is coated along a second surface with a second second layer. [11] PBS according to claim 10, wherein the third layer is a first third layer and wherein the second second layer is in surface contact with a second third layer. [12] PBS according to any one of claims 9 to 11, wherein a brazing promoting layer (BP) is in surface contact with the third layer, wherein the BP layer comprises one or more of the elements nickel (Ni), cobalt (Co) and iron (Fe). [13] PBS according to claim 12, wherein the BP layer is in surface contact with a viscosity modifying (VM) layer, wherein the VM layer comprises one or more of the elements bismuth (Bi), lead (Pb), tin (Sn), antimony (Sb) and thallium (TI). [14] PBS according to claim 12 or 13, wherein a viscosity modifying (VM) layer is disposed integrally within the BP layer, the VM layer comprising one or more of the elements bismuth (Bi), lead (Pb), tin (Sn), antimony (Sb) and thallium (TI). [15] PBS according to any one of claims 9 to 14, wherein the second layer further comprises silicon (Si).

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