Press cylinder unit of a sintering or diffusion soldering device, sintering or diffusion soldering device and system, process cover and method for operating a press cylinder unit

Abstract

The invention relates to a press cylinder unit (10) for use as a lower and / or upper press tool in a process chamber with an adjustable process atmosphere of a sintering or diffusion soldering device, comprising at least one press cylinder (12) having a movable press piston (14) and at least one press ram (16) associated therewith for generating an adjustable pressing force of a sintering or diffusion soldering application on at least one workpiece (18) arranged in at least one ram cylinder (24) and associated with the end pressing surface (26) of the press ram (16), wherein the end pressing surface (26) of the press ram (16), which exerts a pressing force on the workpiece (18), comprises at least one compressible pressure cushion (30) arranged in at least one pot-shaped ram cylinder (24). According to the invention, the end pressing surface (26) comprises at least one compressible soft ram region (34) of the pressure cushion (30) and at least one incompressible hard ram region (36) of a hard ram material (38), such that the workpiece (18) can be subjected to a balancable isostatic pressing force in some regions by means of a pressure cushion (30) and to a selective uniaxial pressing force in some regions by means of the hard ram material (38), and / or such that the end pressing surfaces (26) of multiple press rams (16) are directly adjacent to one another and can be moved independently relative to one another. The invention also relates to a sintering or diffusion soldering device comprising the press cylinder unit (10) and a sintering or diffusion soldering system which in turn comprises the same, and to a process cover provided therefor and to a corresponding sintering or diffusion soldering method.

Description

[0001] Press cylinder assembly of a sintering or diffusion brazing device, sintering or diffusion brazing device and system, process cover and method for operating a press cylinder assembly

[0002] The present invention relates to a press cylinder device, a sintering or diffusion soldering device, as well as a sintering or diffusion soldering system comprising this device, a process cover provided for this purpose, and an operating method for joining workpieces / products by means of pressure sintering or diffusion soldering.

[0003] STATE OF THE ART

[0004] Various methods are used for mounting and / or connecting semiconductors and semiconductor components in the processing, manufacturing, and assembly of semiconductors and semiconductor components, e.g., in the field of semiconductor components for electronic devices and electronic assemblies. Pressure sintering is an advantageous method with regard to the electrical, thermal, and mechanical connection of components to assemblies. This process offers particular advantages in the application area of ​​manufacturing power electronic modules.

[0005] In pressure sintering or diffusion brazing, two or more elements of a workpiece, particularly electronic components, substrates, heat sinks, or similar items, can be electrically and / or thermally connected using a joining material. The joining material is sintered or diffusion brazed. In such a pressure sintering process, two components are joined together in a single process. A sintering paste or sintering material in chip or pellet form is applied between the two components, or a sintering preform is placed between them. This is followed by a pressure and temperature step in which the two components are pressed together. Through simultaneous heating and the approach of the still weakly contacting sinter particles, they fuse together primarily by solid-state diffusion, resulting in the compaction of the sintered layer.The workpieces to be joined are pressed uniaxially or multiaxially between an upper tool and a lower tool to provide a joining pressure.

[0006] It has been found that compounding under process atmosphere, especially an oxygen-deficient or oxygen-free process atmosphere such as under pressure,

[0007] PNK-8429DE

[0008] November 17, 2025. A nitrogen atmosphere or vacuum is particularly advantageous, especially for suppressing undesirable chemical reactions such as oxidation, preventing gas inclusions, and suppressing impurities. The heat required for sintering or diffusion brazing is generally transferred to the workpieces via the upper and lower dies, but can also be applied as radiant heat from the top and / or bottom surfaces. Often, several components are to be arranged on a common substrate, which may differ in both their lateral dimensions and their height. To ensure uniform pressure transmission, several press dies can be provided on the upper and / or lower die, their dimensions matched to the workpieces to be joined.

[0009] If various assemblies of different types are to be processed on a single machine, the press die arrangement on the upper and / or lower tool must be regularly adjusted. This adjustment is time-consuming and made more difficult by the fact that the tools and / or press dies can be hot. Furthermore, the tools, especially the press dies, are usually made of metal because they must withstand high compressive forces. Therefore, such tools are heavy, cool down slowly, and are expensive. In addition, precise alignment of the tools or press dies with the workpieces to be joined is essential.

[0010] In a sintering process, uniaxial application of pressure using a hard die is generally referred to as hard sintering, where the pressure acts perpendicularly onto a surface of the workpiece in the direction of a counter-pressing tool. Multiaxial application of pressure using a compressible pressure pad is referred to as soft sintering, where the pressure acts both perpendicularly and horizontally on surfaces of the workpiece with respect to a counter-pressing tool.

[0011] To apply a uniaxial equilibrated pressing pressure and to compensate for height differences of a complex workpiece, DE 10 2007 047 698 B4 proposes the arrangement of a sintering pad for a distribution of pressing force onto a large number of individual punches acting on the surface of a workpiece.

[0012] In addition, DE102014114093B4 proposes to arrange a pressure pad, usually a silicone pad, in a punch cylinder of a press punch for multiaxial pressing force application, wherein a punch piston ring is displaced into the interior of the punch cylinder when the pressing tool is placed on a counter-pressing tool in order to allow a pressing force to act multiaxially on the surfaces of a workpiece in the pressure pad.

[0013] PNK-8689WO

[0014] 05.12.2025 DE 10 2021 127 716 B3 and WO 2023 / 061872 A disclose a test system for process development and optimization that can perform a sintering or diffusion brazing process to weld workpieces such as

[0015] • Semiconductors on ceramic substrates and on leadframes

[0016] • Substrates on base plates

[0017] • Copper substrates without oxidation

[0018] • Chip top contact

[0019] • To connect high-power LEDs. This is particularly suitable for connecting cooling elements such as cooling plates to power semiconductors such as inverter components, for example IGBTs, SiCs, MOSFETs or similar. These are widely used in electrical power conversion and electrical motor conversion, e.g. in wind turbines or electric vehicles.

[0020] The resulting advantages include:

[0021] • Sintering of different layouts without changing the upper tool

[0022] • Multi-layer sintering

[0023] • High flexibility and control of the sintering atmosphere

[0024] • Process operation under an inert or reducing atmosphere

[0025] In addition, sintering and diffusion brazing processes are known from WO 2024 / 042155A, in which a flexible press punch configuration is achieved by arranging press punches on the workpieces before they are placed in the process chamber.

[0026] Flexible multiple press die configurations are also known from WO 2023 / 062116 A2.

[0027] One problem with known press cylinder devices, as well as the aforementioned multi-press applications, is achieving a uniform distribution of pressing force within the workpiece, which is essential for a reliable, homogeneous sintered or diffusion brazing joint between the workpiece components, such as power electronic circuit carriers and heat sinks. This is because known press cylinder devices involve either soft sintering or hard sintering, with either a hard or soft stamping element acting upon the workpiece.

[0028] PNK-8689WO

[0029] December 5, 2025, supports the workpiece. However, the joining partners can have complex surface properties with varying heights and different material layers, e.g., areas with hard materials like metal and soft materials like plastic. For example, electronic circuit carriers have so-called spacers as harder material layers, but also substrate and plastic areas as softer material layers. Accordingly, both a full-surface application of a uniaxial pressing force, i.e., pure hard sintering, and a full-surface application of a multiaxial pressing force, i.e., pure soft sintering, to the joining partners of the workpiece regularly result in unsatisfactory joining results due to the inhomogeneous nature of the workpiece surface or workpiece material distribution.

[0030] It is an object of the invention to propose a press cylinder device, a sintering or diffusion soldering device, as well as a sintering or diffusion soldering system comprising these, a process cover provided for this purpose, and an operating method for joining workpieces by means of pressure sintering or diffusion soldering, which allows an optimized press pressure distribution for a homogeneous joining result.

[0031] REVELATION OF THE INVENTION

[0032] The problem is solved by a press cylinder device of a, preferably gas-tight, sintering or diffusion soldering device, for use as a lower and / or upper press tool in a process atmosphere-adjustable, preferably vacuum-sealed process chamber of the sintering or diffusion soldering device, comprising at least one, preferably several, press cylinders with a movable press piston and at least one press punch associated thereto for generating an adjustable pressing force of a sintering or diffusion soldering application on at least one workpiece associated with an end-pressing surface of the press punch arranged in at least one punch cylinder (24).

[0033] According to the invention, it is proposed that the end-pressing surface comprises at least one compressible soft punch area of ​​a pressure pad and at least one incompressible hard punch area of ​​a hard punch material, so that isostatic pressing force can be exerted on the workpiece / product in certain areas by means of the pressure pad and selective uniaxial pressing force can be exerted on the workpiece / product in certain areas by means of the hard punch material. Alternatively or additionally, the end-pressing surfaces of several press punches or several punch cylinders are directly adjacent and can be displaced independently relative to each other.

[0034] A stamp cylinder comprises a front contact surface of a pressure pad, optionally with hard stamping areas, the pressure pad being enclosed in a cylinder. A press stamp is made of

[0035] PNK-8689WO

[0036] December 5, 2025, formed by one or more punch cylinders, with each punch being assigned a single pressure pad, and forming at least one, possibly several, end-pressing surfaces of the pressure pad, which may be guided in several punch cylinders. Thus, a punch can comprise one or more punch cylinders and one pressure pad each.

[0037] In other words, a press cylinder device is proposed that has at least one end-pressing surface of a press ram capable of exerting both uniaxial and isostatic pressing forces on a workpiece. The isostatic pressing force can be exerted via at least one pressure pad as a soft ram element, arranged in the end-pressing surface of the press ram. The uniaxial pressing force is exerted by a hard ram element, in particular a hard metal. The different pressing forces allow for the consideration of material distributions and complex surface geometries of the workpiece, ensuring a homogeneous pressing force distribution for a reliable sintered or diffusion brazed joint.

[0038] In contrast to the prior art, according to the invention, both the hard stamping element and the soft stamping element are supported, at least partially, on the surface of the workpiece during a sintering or diffusion brazing process. Based on the design described above, the press cylinder assembly according to the invention allows for the simultaneous performance of soft and hard sintering, and / or enables the arrangement of several independently movable end-pressing surfaces directly adjacent to one another. The press cylinder assembly according to the invention is designed for hybrid sintering, i.e., a combination of soft and hard sintering.

[0039] Alternatively or additionally, several press dies or several die cylinders of a press die can be positioned directly adjacent to each other and slidably relative to one another, preferably within a die cylinder frame. "Directly adjacent" means that no functional parts are arranged between the individual pressing surfaces of the several press dies or die cylinders of a press die; that is, they are adjacent without any significant gap and can exert a pressing force on one or more associated workpieces independently of each other. Advantageously, the press dies or die cylinders are sealed against each other by means of sliding and sealing elements, for example, plastic sealing elements, so that no pressure pad material can enter the gaps between the press dies or die cylinders.

[0040] A pressing force can be applied to a press die independently of adjacent press dies by means of a press cylinder. The press cylinders are actuated via a pressure pad.

[0041] PNK-8689WO

[0042] December 5, 2025. Even when pressure is applied to multiple cylinders within a common press die, the specific properties of their identical or different end-contact surfaces, such as the different compressible properties of their pressure pads and / or hard die areas, can exert different compressive forces. One or more die cylinders can thus be contained within a press die, and several press dies or die cylinders of a single press die can be directly adjacent. For example, one or more die cylinders associated with a press cylinder can contain end-contact surfaces that may include a pressure pad, a hard die, or a hybrid die with hard die and soft die areas, as suggested above.By closely clustering the press dies or cylinders of a press die, identical or different workpieces can be sintered or pressure-brazed independently of one another in a very small installation space. Selective properties of the end-press surfaces, with hard, pressure-resistant and soft, pressure-elastic areas, allow for optimized pressure application to different areas of a single workpiece. Both of the aforementioned individual or synergistically interacting features of the press cylinder assembly enable improved pressure application in a sintering or diffusion brazing process when simultaneously applying pressure to several identical or different workpieces and when applying heterogeneous pressure within a single workpiece surface.

[0043] In an advantageous embodiment, the end-pressing surface of the press ram, which exerts pressing force on the workpiece, can be formed, at least in part, by a compressible pressure pad arranged within the cup-shaped ram cylinder. In this embodiment, the pressure pad forms at least part of the sintered pressing surface. This surface can be supplemented by further hardened ram sections of the sintered pressing surface. When the ram is placed on a surface area of ​​the workpiece, the pressure pad in the ram cylinder can be compressed by a ram piston ring that encompasses and delimits the pressure pad, displacing pressure pad material towards the workpiece surface. This can be achieved by retracting the ram piston ring into the ram cylinder when the ram is placed on a workpiece surface or a workpiece support frame.The pressure pad can be advantageously inserted into the stamp cylinder in a replaceable manner, so that it can be easily renewed when worn and can adapt to the shape and size of different workpieces.

[0044] In an advantageous embodiment, the hard die material of the face pressure surface can be a hard metal such as stainless steel or similar, and the areas of the pressure pad of the face-

[0045] PNK-8689WO

[0046] December 5, 2025: The pressing surface will consist of an elastomer material such as silicone. These materials are ideally suited for the intended purpose due to their mechanical properties. In this context, the aforementioned materials are robust and wear-resistant, and therefore durable and cost-effective.

[0047] In an advantageous embodiment, the pressure pad can be at least partially, and in particular completely, encompassed by a piston ring designed to rest on at least a partial area of ​​the workpiece. Upon resting on, preferably on, the workpiece, the piston ring can be displaced towards the bottom, i.e., the side opposite the end-pressing surface, into the interior of the cup-shaped piston cylinder. This displacement of the piston ring into the interior of the piston cylinder compresses the pressure pad. The compression of the pressure pad caused by the piston ring's displacement results in a partial displacement of the compressed pressure pad out of the cup-shaped piston cylinder and towards the workpiece. In simpler terms, the pressure pad is displaced towards the workpiece. This generates and exerts the isostatic pressing force.Advantageously, the generation and application of the isostatic pressing force is structurally simple, robust and efficient.

[0048] In an advantageous embodiment, the side of the piston ring facing away from the workpiece, i.e., the side facing the bottom of the punch cylinder, can be sealed against the pressure pad by means of a sealing element, preferably a plastic sealing element. The sealing element prevents the pressure pad or its edge regions from becoming trapped in the gap between the piston ring and the punch cylinder. Advantageously, this minimizes the risk of damage to the pressure pad, particularly damage caused by trapping.

[0049] Advantageously, the hard stamping area can have at least one recess, a so-called pocket, through which no pressure is exerted on one or more areas of the workpiece; that is, one or more hard stamping areas are recessed. These recesses can serve to protect pressure- or break-sensitive workpiece areas, e.g., ceramic areas / edges, temperature sensors, and the like.

[0050] In an advantageous embodiment, the piston ring can form a hardening section. The piston ring serves both to displace the pressure pad and thus indirectly to generate the isostatic pressing force, as well as to generate and exert the uniaxial pressing force. The piston ring can form the single hardening section. Preferably, depending on the application, additional hardening sections provided by elements other than the piston ring are present. The piston ring can form one of many hardening sections. Advantageously, this results in a compact and efficient design of the end-pressing surface.

[0051] In an advantageous embodiment, at least one hardening die area can be designed as a hardening die compression ring, which is located close to or concentric with the die piston ring in the die cylinder. When the die piston ring is displaced by the compressible pressure pad, the hardening die compression ring is compressed towards the product, exerting a selective pressing force. Preferably, the hardening die compression ring is sealed against the pressure pad by means of a sealing element, in particular a plastic sealing element. The hardening die compression ring can form the single hardening die area or an additional hardening die area, in particular one in addition to that of the die piston ring. The hardening die compression ring is pressed outwards towards the end-face by an increase in pressure in the pressure pad, which is caused by the displacement of the die piston ring into the interior of the die cylinder.In particular, the hardening die press ring can be recessed or integrated into the pressure pad so that it is pressed outwards along with the pressure pad when the pad is compressed. The hardening die press ring can advantageously be located concentrically outside the ram piston ring and surround it. It is also conceivable that the hardening die press ring is arranged concentrically inside the ram piston ring and surrounded by it. Preferably, the hardening die press ring is replaceable, so that, depending on the application, a suitable material adjustment can be made for the hardening die area provided by the hardening die press ring, or the ring can be replaced when worn. Advantageously, the hardening die press ring further increases the adaptability of the press cylinder assembly and thus the variety of workpieces that can be machined.

[0052] In an advantageous embodiment, at least one hardening section can be designed as a hardening piston guided in the punch cylinder. The hardening piston can form the single hardening section or an additional hardening section, particularly in addition to that of the punch piston ring or the hardening press ring. Preferably, the hardening piston is pressed towards the product by the compressed pressure pad and exerts a selective pressing force. In particular, the hardening piston can be recessed or integrated into the pressure pad so that it is pressed outwards with the pressure pad when the pad is compressed. Alternatively, the hardening piston can also be fixed, in particular connected to the base of the punch cylinder or formed integrally with it. The hardening piston can be separated from the

[0053] PNK-8689WO

[0054] December 5, 2025. The hardening piston is enclosed or surrounded by elements forming the pressure pad and / or other hardening areas, such as the piston ring and / or the hardening press ring. The hardening piston can be positioned centrally in the end-face or off-center. Optionally, multiple hardening pistons, each providing an additional hardening area, can be present. The hardening piston is particularly replaceable. The material, size or diameter, surface geometry or shape (square, round, etc.), and / or number of hardening pistons can vary depending on the application. The hardening piston can be used, in particular, to connect peripheral elements of the product, such as copper connection lugs or external parts of the product. Advantageously, the adaptability of the press cylinder assembly is further improved by the hardening piston.

[0055] In an advantageous embodiment, the press punch(es) can be detachably designed from the press piston, in particular allowing the press punch to be placed on the workpiece(s) / product(s) outside the press cylinder assembly before the start of a sintering or diffusion brazing application. In this embodiment, a weightbar concept is proposed for the application of the press punch or punch cylinder or punch cylinder unit, as already shown in WO 2024 / 042155A. The additional advantages described therein result.

[0056] In an advantageous embodiment, at least one press ram and / or at least one ram cylinder can be interchangeably received in a ram carrier of the press cylinder assembly, and in particular, can be interchangeably inserted into recesses of the ram carrier. Preferably, force-fit and / or form-fit fixing means, e.g., locking devices, screws, etc., are provided to secure or prevent loss of the received ram cylinder in the ram carrier. In particular, the press ram or the ram cylinder can be easily inserted into the ram carrier and securely locked there. Advantageously, this allows for easy replacement, especially for adaptation to the application and / or in case of wear, thus ensuring easy interchangeability and adjustment of the end-press surface of the press cylinder assembly in case of wear or changes in workpiece geometry.

[0057] In an advantageous embodiment, two, three or more press punches or several punch cylinders can be included in a punch cylinder unit, wherein at least one punch cylinder unit can be received in the at least one punch carrier, preferably interchangeably, and in particular can be inserted interchangeably into recesses of the punch carrier.

[0058] PNK-8689WO

[0059] December 5, 2025. In particular, the press punches or punch cylinders are interchangeably mounted in the punch cylinder unit. Preferably, force-fit and / or form-fit fixing means, e.g., locking devices, screws, etc., are provided to secure or prevent loss of the press punches or punch cylinders and / or the punch cylinder unit. Advantageously, this allows the type of punch cylinder units or press punches installed in the punch carrier to be easily adapted, so that the properties of the press cylinder assembly can be optimally tailored to the specific application and interchanged.

[0060] If a press ram comprises several ram cylinders, it forms multiple end-faces. Each ram cylinder can contain a ram core made of an incompressible material such as metal to support the pressure pad from the rear. The ram core is preferably attached, in particular screwed, to a cylinder base of the press ram, to the ram carrier of the press cylinder assembly, or to the ram cylinder unit, which is interchangeably arranged on the ram carrier. Advantageously, the pressure pad of the press ram, which forms the multiple end-faces of the ram cylinders, can be compressibly displaceable by a one-piece ram pad ring within a ram cylinder frame. The ram pad ring can be sealed against the pressure pad by a ram pad ring seal, for example, a plastic ring made of polyetheretherketone (PEEK).The stamp pad ring defines several stamp guide cylinders through which the end-pressure surfaces of the pressure pad are guided, whereby when the stamp pad ring is placed on a workpiece, the pressure pad is displaced and the end-pressure surfaces are thereby pressed out of the stamp guide cylinders towards the workpiece surface.

[0061] In an advantageous embodiment, the stamp cylinder unit can include a releasable handle element, preferably one that can be inserted at least partially into the stamp cylinder unit. Preferably, the handle element provides a mechanical locking function, in particular a latching function, for the stamp cylinder unit arranged in the stamp carrier or interacts at least with a locking element of the stamp carrier. In other words, the handle element can function as a kind of key according to the key-lock principle. Using the handle element, the stamp cylinder unit can be conveniently gripped and inserted into and removed from the stamp carrier. In particular, by interacting with the handle element, e.g., by pulling it in, pulling it out, and / or rotating it, the stamp cylinder unit can be secured in the intended position relative to the stamp carrier, especially at the insertion point.Advantageously, this allows for convenient insertion and securing of the stamp cylinder unit in the stamp holder.

[0062] PNK-8689WO

[0063] December 5, 2025. In an advantageous embodiment, the die carrier can have multiple slots, each for a die, a die cylinder, or a die cylinder unit. In particular, each slot is assigned to a specific die, die cylinder, or die cylinder unit. "Specific" can refer to a concretely named die cylinder unit, die, or die cylinder, or it can be generic and refer to a particular type of die, die cylinder, or unit. The die, die cylinder, or die cylinder unit can be inserted or slid into its respective assigned slot. The slots can have geometries complementary to the dies, die cylinders, or units. This advantageously simplifies assembly and effectively prevents installation errors.

[0064] In an advantageous embodiment, the punch carrier can include guide units for the guided arrangement or insertion of at least one press punch or punch cylinder into the punch carrier, and / or guide units for the guided arrangement or insertion of at least one punch cylinder unit into the punch carrier. The punch carrier has guide rails or guide grooves that are complementary to guide grooves or guide rails of the press punches, punch cylinders, or punch cylinder units. In particular, the said guide grooves or guide rails of the punch carrier are arranged in corresponding slots for the press punches, punch cylinders, or punch cylinder units, into which the press punch, punch cylinder, or punch cylinder unit can or should be inserted. Advantageously, this allows for the easy exchange of different geometries and numbers of end faces.

[0065] In an advantageous embodiment, a position sensor can be included which is configured to detect and verify the position of the press ram, ram cylinder, and / or ram cylinder unit in the arranged or inserted state. A correct arrangement can be detected and verified by means of the position sensor. Advantageously, a faulty arrangement can be quickly detected and corrected.

[0066] Preferably, at least one mechanical stop element, particularly one arranged in the slot, is included to limit the maximum insertion depth of the press punch, punch cylinder, or punch cylinder unit. In particular, the stop element can provide an alignment function, especially a centering function, and an aligning or centering design for this purpose.

[0067] In an advantageous embodiment, the press punch, punch cylinder and / or the

[0068] PNK-8689WO

[0069] December 5, 2025. The stamp cylinder unit comprises an identification unit. Preferably, the identification unit can be read by contact when arranging the stamp, stamp cylinder, and / or stamp cylinder unit in the stamp cylinder unit or the stamp carrier. The stamp cylinder unit or the stamp carrier can have a reading means corresponding to the identification unit; however, the reading means can also be hand-operated. The identification unit can serve both for the general identification (type, condition) of the stamp / stamp cylinder / stamp cylinder unit and for identifying the correct arrangement position on the stamp carrier. In this regard, for example, if a stamp cylinder unit has been arranged in the wrong slot and thus not in its intended slot (e.g., slot 4 instead of 1), this can be detected using the identification unit.Advantageously, the corresponding element can be reliably identified, so that in the event of an accidentally incorrect selection or arrangement, the error can be corrected without problems.

[0070] In a related aspect, the invention relates to a sintering or diffusion brazing device with a press cylinder assembly for generating an adjustable pressing force for a sintering or diffusion brazing application on at least one associated workpiece, preferably under an adjustable process gas atmosphere or vacuum. The aforementioned embodiment of the press cylinder assembly is proposed. The advantages already mentioned above are derived from this embodiment.

[0071] In a further subordinate aspect, the invention relates to a sintering or diffusion soldering system comprising at least one process chamber configured as a sintering or diffusion soldering chamber, preferably two, preferably three or more process chambers, in particular at least one preheating chamber, a sintering or diffusion soldering chamber with a sintering or diffusion soldering device and a cooling chamber, wherein preferably at least the sintering or diffusion soldering chamber is configured to be gas-tight and can provide an adjustable process gas atmosphere or vacuum, and wherein further preferably a transport unit is provided for the automatic transport of workpieces / products, in particular those arranged on a process carrier, through the process chambers.

[0072] It is proposed that the sintering or diffusion soldering chamber be designed as the aforementioned sintering or diffusion soldering device. This offers the advantages already mentioned in advance.

[0073] In a further subordinate aspect, a process cover for a press cylinder device, particularly according to one of the preceding embodiments, is proposed, wherein the process cover can be arranged between the sintered pressing surface of the press punch PNK-8689WO 05.12.2025 and the workpiece to be pressed, and is made of a heat-resistant polymer, particularly Teflon (PTFE), and comprises glass fiber components, in particular in the form of a glass fiber-reinforced Teflon film. The process cover advantageously provides a non-stick barrier and a sealing element between the press punch and the workpiece, thus effectively preventing the adhesion of sinter paste or similar substances and contamination of the press punch. Advantageously, the process cover in this design is particularly robust and reusable.

[0074] In a further subordinate aspect, a sintering or diffusion brazing process is proposed using a press cylinder assembly of a, preferably gas-tight, sintering or diffusion brazing device, in particular a press cylinder assembly of the aforementioned type, wherein the press cylinder assembly is used as a lower and / or upper press tool in a process atmosphere-adjustable, preferably vacuum-sealed process chamber of the sintering or diffusion brazing device, and the press cylinder assembly comprises at least one, preferably several, press cylinders with a movable press piston and with at least one press punch associated thereto for generating an adjustable press force of a sintering or diffusion application on at least one workpiece, an end-face of the press punch arranged in at least one punch cylinder.

[0075] It is proposed that the end-pressing surface comprise at least one compressible soft-punch area of ​​a pressure pad and at least one incompressible hard-punch area of ​​a hard-punch material, so that the workpiece is subjected to isostatic pressing force that can be equilibrated in certain areas by means of the pressure pad and selective uniaxial pressing force in certain areas by means of the hard-punch material. Alternatively or additionally, the end-pressing surfaces of several press punches or several punch cylinders are directly adjacent and can be displaced independently relative to each other. This results in the advantages already mentioned above.

[0076] In a further advantageous development of the process, a process cover can be arranged between the sintering press surface and the workpiece. This results in the advantages already mentioned above.

[0077] Typically, the press die(s) or die cylinder(s) press onto the surface of a power electronics component to connect it to a heat sink, also known as a baseplate, located underneath on a counter-pressing tool, via a sintering or diffusion soldering process. In an advantageous embodiment of the process, the workpiece can have at least one heat sink and at least one component to be joined to it.

[0078] PNK-8689WO

[0079] December 5, 2025, comprising a bonded power semiconductor component, in particular a power semiconductor circuit carrier, wherein the heat sink is associated with the sintering press surface, and the power semiconductor component is associated with a counter-pressing tool in a repelling position relative to the sintering press surface. Typically, a sintering paste or a sintering preform is arranged between the heat sink and the power semiconductor component. Advantageously, a robust and durable, and therefore high-quality, connection between the heat sink and the power semiconductor component can be provided.

[0080] For example, power semiconductor circuit carriers can be those manufactured by Schweizer Electronic AG under the brand name "Smart p". 2These power semiconductor circuit carriers, offered in a "pack" format, can be advantageously sintered or diffusion-soldered using the press cylinder device according to the invention. These power semiconductor circuit carriers offer reduced thermal resistance, reduced switching losses due to lower inductance in the system, reduced conduction losses in static conditions, and enable higher power densities with increased robustness and service life. These power semiconductor circuit carriers have a sandwich-like structure, with the actual power semiconductors located in one plane of the sandwich configuration and connected to an overlying PCB interconnection via copper-filled blind holes. Bond connections are not required. The symmetrical design simplifies connection to a heat sink with close thermal contact to the power semiconductors, with the PCB interconnection typically located on the side facing away from the heat sink.

[0081] Due to the inhomogeneous structure of the sandwich, in particular the only partial covering of the circuit carrier by the heat sink, there is a particular challenge in distributing the pressing forces in such a way as to enable a homogeneous connection of the circuit carrier with the heat sink by sintering or diffusion brazing, whereby the press cylinder device according to the invention is particularly suitable for this purpose.

[0082] DRAWINGS

[0083] Further advantages become apparent from the drawing and the accompanying drawing description. The drawings illustrate exemplary embodiments of the invention. The drawings, the description, and the claims contain numerous features in combination. It is advantageous for a person skilled in the art to also consider the features individually and combine them into meaningful further combinations. In particular, a person skilled in the art will also apply features described in relation to embodiments of the sintering device to embodiments of the method according to the invention, and vice versa.

[0084] PNK-8689WO

[0085] December 5, 2025 Shown:

[0086] Fig. 1 A simplified perspective view of a section of an advantageous press cylinder device;

[0087] Figs. 2A and 2B each show a schematic view of a press ram of the press cylinder device with ram cylinder units to be received therein;

[0088] Fig. 3 a perspective view of a stamp cylinder unit of a

[0089] embodiment with integrated stamp cylinders;

[0090] Figs. 4A and 4B show different representations of a stamp cylinder;

[0091] Fig. 5 shows a cross-section through the punch cylinder in the area of ​​an end-pressing surface;

[0092] Fig. 6 shows a simplified schematic representation of a pressing process of the

[0093] Press cylinder device;

[0094] Figs. 7a to 7c show a perspective view and top view of a punch cylinder unit of a further embodiment; and

[0095] Figs. 8a to 8d perspective view, exploded view and sectional view of a stamp cylinder unit of a further embodiment.

[0096] In the figures, similar elements are numbered with the same reference symbols. The figures merely show examples and are not to be understood as limiting.

[0097] Figure 1 shows a simplified perspective view of a section of an advantageous press cylinder assembly 10. The press cylinder assembly 10 is used here as a lower press tool in a process atmosphere-adjustable process chamber of a sintering or diffusion brazing device which is not shown in detail here for the sake of clarity.

[0098] The press cylinder assembly 10 comprises at least one press cylinder 12 with a movable press piston 14. Furthermore, the press cylinder assembly 10 comprises at least one press ram 16, which, according to the present embodiment, is detachably designed from the press piston 14. The press ram 16 serves to generate an adjustable pressing force for a sintering or diffusion brazing application on a component associated with the press ram 16.

[0099] PNK-8689WO

[0100] December 5, 2025. Workpiece 18. In this case, several press punches 16, arranged on a punch carrier 66, are assigned to the press piston 14, each resting on a corresponding workpiece 18. During the sintering or diffusion brazing process, the punch carrier 66 with the press punches 16 is pressed onto the workpiece 18 on one side by means of the press piston 14, whereby the opposite side of the workpiece 18 is pressed against a lower or counter-pressing tool 20 of the sintering or diffusion brazing device. In other words, the workpiece 18 is pressed between the upper pressing tool formed by the press cylinder 12, press piston 14, and press punch 16, and the counter-pressing tool 20.

[0101] Due to the detachable design of the press punch 16 from the press piston 14, the present embodiment provides that the press punches 16 are placed on the respective workpiece 18 with the punch carrier 66 outside the press cylinder device 10 before the start of the sintering or diffusion brazing application and are then moved together with the tool 18 into the area between the press piston 14 and the counter-pressing tool 20.

[0102] Figures 2A and 2B each show a simplified schematic sectional and perspective view of a press cylinder assembly with several press punches 16. A punch carrier 66 of the press cylinder assembly 10 comprises several, in this case four, punch cylinder units 22, each of which is interchangeably arranged in a slot 23 of the punch carrier 66, specifically assigned to the punch cylinder unit 22. The interchangeable arrangement by insertion is visualized by way of example, in Figure 2B. In each punch cylinder unit 22, at least one punch cylinder 24 of a press punch 16 is interchangeably received, which at least partially forms or provides an end-pressing surface 26 of the press punch 16 that can be assigned to the workpiece 18 or is assigned during the pressing process.The punch cylinders 24 of the press dies 16 are also interchangeably received or inserted into the respective punch cylinder unit 22. According to an embodiment not shown, the press dies 16 can also be arranged directly in slots 23 of the die carrier 66, so that combining them into a punch cylinder unit 22 is not absolutely necessary.

[0103] Depending on the intended sintering or diffusion brazing application, the properties of the press cylinder units based on the multiple punch cylinder units 22 or multiple press punches 16 with punch cylinders 24 accommodated in the punch carrier 66 can be

[0104] PNK-8689WO

[0105] 05.12.2025 direction 10 can be adapted as required. The adaptation is achieved by simply replacing individual press punches 16, punch cylinders 24 and / or punch cylinder units 22. This creates a quick-change system in which the arrangement and number of press punches 16, punch cylinders 24 or punch cylinder units 22 can be easily adapted to different workpieces 18 to be processed, which are automatically guided through a sintering or diffusion soldering system.

[0106] As schematically illustrated in Figure 2A, each punch cylinder unit 22 is assigned an identification unit 28. The identification means 28 serves to, or is designed to, verify the correct selection and arrangement of the punch cylinder units 22 or the punch cylinders 24 during the sintering or diffusion soldering application, and to enable the identification of the punch cylinder units 22 and / or punch cylinders 24 currently inserted into the press punch 16. The respective identification means 28 can be read by contact when the punch cylinder 24 and / or punch cylinder unit 22 are arranged in the punch cylinder unit 22 or the press punch 16. For this purpose, the punch cylinder unit 22 or the press punch 16 has a corresponding reading means, not shown in detail here, that corresponds to the identification means 28.

[0107] As can be clearly seen in Figure 2B, each slot 23 has guide rails 28 forming guide projections that are complementary to the guide grooves 29 formed on the outside of the punch cylinder units 22. The guide rails 28 and guide grooves 29 form guide units for the punch carrier 66 of the press cylinder assembly 10, enabling the punch cylinder units 22 to be inserted into their respective slots 23 in a guided manner. Optionally, the punch cylinder units 22 can have corresponding guide units for the interchangeably mounted punch cylinders 24. As further shown in Figure 2B, each punch cylinder unit 22 has a handle element 31, which, at least in part, can be inserted into the punch cylinder unit 22 in the manner of a key and can be mechanically detached from it.The handle element 31 can be inserted into the stamp cylinder unit 22 as needed for replacement and thereby secured by force and / or form locking, so that the stamp cylinder unit 22 can be removed from and / or inserted into the slot 23 using the inserted handle element 31. Preferably, the handle element 31 fulfills a mechanical locking function, in particular a latching function, for the stamp cylinder unit 22 arranged in the stamp carrier 66. For this purpose, the handle element 31 can, for example, interact with a locking unit of the stamp carrier 66 or slot 23 in the manner of a key, so that the inserted stamp cylinder unit 22 is locked onto or released from the slot 23.

[0108] PNK-8689WO

[0109] 05.12.2025 Optionally, preferably integrated into the guide rails 28, mechanical stop elements (not shown in detail here) are provided, by means of which the maximum insertion depth of the punch cylinders 24 into the punch cylinder unit 22 and / or the punch cylinder units 22 into the respective slots 23 can be limited. In particular, the stop elements can have an alignment function, especially a centering function. Preferably, a position sensor is also included, which is designed to detect the position of the punch cylinder 24 and / or the punch cylinder unit 22 in the arranged or inserted state.

[0110] Figure 3 shows an example of a perspective view of one of the punch cylinder units 22 from below. The punch cylinder unit 22 comprises three press punches 16 with punch cylinders 24 for the parallel pressing of several workpieces 18 or several sections of a workpiece 18, such as power semiconductor devices 54 with a heat sink 52. The punch cylinder units 22 are mounted in a punch cylinder frame 56 of the punch cylinder unit 22. The punch cylinder frame 56 is part of a punch carrier 66, which is arranged on a lower or upper tool (not shown) of a sintering press. As can be clearly seen in Figure 3, each punch cylinder 24 has a compressible pressure pad 30 in the area of ​​the end-face 26, or for forming the end-face 26, which is fully enclosed by a punch piston ring 32. The end-face 26 is formed at least substantially by the pressure pad 30 and the punch piston ring 32.The piston ring 32 serves as a frame for the pressure pad 30 in order to guide its compression or displacement during the pressing process in a targeted direction, namely in the direction of the workpiece 18.

[0111] In the present press cylinder assembly 10, it is advantageously provided that the end-pressing surface 26 comprises at least one compressible soft punch area 34 provided by the pressure pad 30 and at least one incompressible hard punch area 36 made of a hard punch material 38. According to the embodiment shown in Figure 3, the hard punch area 36 is formed by the punch piston ring 32. During the pressing process, both the soft punch area 34 and the hard punch area 36 rest on or press against the workpiece 18. This advantageously results in an equilibrated isostatic pressing force being exerted on the workpiece 18 in certain areas and a selective uniaxial pressing force being exerted on certain areas. The isostatic pressing force is exerted by means of the pressure pad 30, and the uniaxial pressing force by means of the hard punch material 38.The combination of the two pressing forces results in a particularly advantageous distribution of the total pressing force applied to the workpiece 18, so that uniform pressing takes place and a high-quality result is obtained.

[0112] PNK-8689WO

[0113] December 5, 2025 It is proposed that the hard stamp material 38 be a hard metal such as stainless steel or similar, and that the pressure pad 30 be made of an elastomer material such as silicone. Depending on the application, other suitable materials are of course also conceivable.

[0114] Figures 4A and 4B show a single press ram 16. Figure 4A shows a perspective view of the press ram 16 looking towards the end-pressing surface 26, while Figure 4B shows a top view from below of the end-pressing surface 26. As can be clearly seen in Figures 4A and 4B, the press ram 16 is cup-shaped, and the pressure pad 30 and the ram piston ring 32, as will be discussed in more detail below, can be pressed into the interior of the corresponding cup-shaped base body of the ram cylinder 24. The pressure pad 30 and the ram piston ring 32 are replaceable, allowing for replacement, particularly in case of wear. For the replaceable arrangement of the ram piston ring 32 and pressure pad 30, they are detachably fixed to the base body of the ram cylinder 24 by means of fixing means 40, in particular screws, which are shown schematically in Figures 4A and 4B.

[0115] Figure 5 shows a simplified sectional view through the press ram 16 in the area of ​​the end-pressing surface 26. As can be clearly seen in Figure 5, the press ram 16 has a circumferential recess 42 in its base body on the bottom side in the area below the pressure pad 30 and the ram piston ring 32. During the pressing process, the pressure pad 30 and the ram piston ring 32 contact the workpiece 18. Upon contact, the ram piston ring 32 and the pressure pad 30 are displaced towards the bottom of the ram cylinder 24 due to the corresponding resistance, with the recess 42 forming a corresponding receiving space for the displaced elements. The displacement of the ram piston ring 32 into the recess 42 compresses the pressure pad 30, and the compressed or displaced areas are then forced towards the workpiece 18 in a known manner to generate the equilibrated isostatic pressing force.

[0116] To prevent the pressure pad 30 from being pinched and damaged during compression, a circumferential sealing element 44 is provided, by means of which the area of ​​the piston ring 32 facing the base of the piston cylinder 24 is sealed against the pressure pad 30. This effectively prevents the displaced portions of the pressure pad 30 from becoming jammed between the piston ring 32 and the base of the piston cylinder 24.

[0117] As further indicated by the dashed elements in Figure 5, according to further embodiments it can be provided that not only the piston ring 32 itself has a

[0118] PNK-8689WO

[0119] 05.12.2025 hard stamping area 36 is formed, but that there are further hard stamping areas 36 which are also formed from a, preferably different, hard stamping material 38.

[0120] According to a preferred embodiment, at least one (additional) hardening die section 36 is designed as a hardening die compression ring 46. The hardening die compression ring 46, like the die piston ring 32, encompasses the pressure pad 30 and is arranged in close proximity, preferably directly adjacent, or concentrically to the die piston ring 32 in the die cylinder 24. When the die piston ring 32 is displaced by the compressible pressure pad 30, the hardening die compression ring 46 can be compressed towards the workpiece 18, so that a selective pressing force is exerted by the hardening die compression ring 46. In this case, both the hardening die section 36 formed by the die piston ring 32 and the additional hardening die section 36 formed by the hardening die compression ring 46 can press against the workpiece 18.However, it can also be provided that only one of the two hard die areas 36, preferably the hard die area 36 formed by the hard die press ring 46, rests on the workpiece 18, while the die piston ring 32 does not rest on the workpiece 18 or only on peripheral elements of the workpiece 18, for example cables, and fulfills a position-fixing function for the workpiece 18.

[0121] Additionally or alternatively, it can be provided that at least one other or further hardening die area 36 is designed as a hardening die piston 48 guided in the die cylinder 24. The hardening die piston 48 can be compressed by the compressed pressure pad 30 in the direction of the workpiece 18 and thereby exerts a selective pressing force on the workpiece 18. As shown by way of example in Figure 5, the hardening die piston 48 can be arranged centrally in the end-face 26 and centered relative to the pressure pad 30 and the die piston ring 32. However, it is also conceivable that the hardening die piston 48 or further hardening die pistons 48 can be arranged at various other positions, i.e., off-center.

[0122] Thus, as exemplified in Figure 5, the end-pressing surface 26 can have several, in particular different, hard die areas 36 and soft die areas 34. The number and position of the hard die areas 36 and soft die areas 34 can be varied or adapted depending on the application by appropriately providing and arranging the hard die pressing ring 46 and hard die piston 48. This enables a distribution of isostatic and uniaxial pressing force optimized for the workpiece 18.

[0123] PNK-8689WO

[0124] December 5, 2025. Figure 6 shows a simplified schematic representation of the press cylinder assembly 10 during the pressing of the workpiece 18. In the state shown in Figure 6, the press rams 16, by means of the press pistons 14, press against various areas of the workpiece 18 and press it against the counter-pressing tool 20. The workpiece 18 comprises several power semiconductor components 54 and a heat sink 52, which is also referred to as a baseplate. In this embodiment, the press rams 16 press against the heat sink 52, with the power semiconductor components 54 being supported on the counter-pressing tool 20. As shown by way of example in Figure 6, a process cover 50 can be provided, which can be arranged between the end-pressing surface 26 and the workpiece 18 to be pressed. The process cover 50 is placed on the workpiece 18 before the start of the pressing process. The process cover 50 serves in particular to prevent sticking or...To effectively prevent areas of the workpiece 18 and / or sintered paste from adhering to the press die 16, the process cover 50 is designed to be made of a heat-resistant polymer and also incorporates glass fiber components. Specifically, the process cover 50 is designed as a glass fiber-reinforced silicone film. The use of glass fiber filaments significantly increases the service life and robustness of the process cover 50. Furthermore, the process cover 50 is advantageously reusable.

[0125] As schematically illustrated in Figure 6, the workpiece 18 can comprise a heat sink 52 and one or more power semiconductor components 54 to be connected to it. The heat sink 52 serves to dissipate heat generated by the power semiconductor components 54 and is to be permanently connected to the power semiconductor component 54 during the pressing process. For this purpose, the heat sink 52 is placed onto the power semiconductor component 54, with the heat sink 52 facing the end-pressing surface 26 and the power semiconductor component 54 facing the counter-pressing tool 20, respectively, in relation to the subsequent pressing process. The heat sink 52 and the power semiconductor component 54 are then pressed together by means of the press cylinder assembly 10 in the manner described above.

[0126] Figure 7 shows a further embodiment of a punch cylinder unit 22 according to the second alternative of the invention in a perspective view 7a and in top views 7b. The second alternative relates to an arrangement of end-pressure surfaces 26 of several press punches 16 or several punch cylinders 24 that are directly adjacent to each other and can be moved independently relative to one another. Figure 7b shows a punch cylinder frame 56 of the punch cylinder unit 22 without inserted press punches 16 or punch cylinders 24, whereas Figure 7c shows the punch cylinder frame 56 with inserted press punches 16 or punch cylinders 24.

[0127] PNK-8689WO

[0128] December 5, 2025. The views in Fig. 7 are chosen to show only the die cylinder frame 56 of the die cylinder unit 22 and a workpiece 18 underneath. The workpiece 18 comprises a heat sink 52 (baseplate) and three groups of power semiconductor components 54 arranged on it. Each group of power semiconductor components 54 can, for example, be configured as one or more inverter half-bridges of a multi-phase converter, or each can comprise an entire inverter semiconductor assembly. The three groups of power semiconductor components 54 are connected to the heat sink 52 underneath by a sintering or diffusion soldering process under pressure from the press dies 16 or die cylinders 24.

[0129] In the punch cylinder frame 56, three movable press punches 16 are arranged directly adjacent to each other and can be moved independently relative to one another. Each of these three press punches can be moved by a press cylinder 12 (not shown). Alternatively, instead of separately operable press punches 16, punch cylinders 24 can be arranged, with each punch cylinder frame 56 having a press punch 16 (not shown) assigned to it. In contrast to the independently operable press punches 16, the punch cylinders 24 exert pressure, which may be different, on the workpiece 12 by means of a common press drive via a press cylinder 12.

[0130] In the perspective view of Fig. 7a and the top view of Fig. 7b, which do not show the press dies 16 or die cylinders 24, three closely adjacent die piston rings 32 can be seen. As illustrated in Fig. 7c, pressure pads 30 or hybrid die configurations with hard and soft die areas can be inserted into these rings. The die piston rings 32 can be sealed against each other and against the die cylinder frame 56 by means of plastic sealing elements to prevent pressure pad material from entering the limiting gaps. The die piston rings 32 are directly adjacent and can be moved independently of each other, so that each of the power semiconductor devices 54 can be individually pressurized. Thus, the power semiconductor devices 54 can be arranged and pressed onto the heat sink 52 in close proximity and independently of each other.

[0131] Figures 8a to 8d show a further embodiment of a press cylinder assembly 10 in a perspective view (Fig. 8a), a top view (Fig. 8b), an exploded view (Fig. 8c), and a sectional view AA of Fig. 8b through Fig. 8d. However, the press cylinder assembly 10, which is attached to a punch carrier 66 (not shown), can also be designed as a punch cylinder unit 22 for temporary insertion and attachment to a punch carrier 66. The embodiment shown in Fig. 8 comprises

[0132] PNK-8689WO

[0133] 05.12.2025 a single press punch 16 with a pressure pad 30. This embodiment can correspond to that of Fig. 7, however, the press punches of Fig. 7 can also comprise separate pressure pads 30, insofar as the parallel guided punch cylinders 24 comprise individual pressure pads 30 of separate press punches 16.

[0134] As already mentioned, the press cylinder assembly 10 of Fig. 8 comprises a single pressure pad 30 of a press ram 16, which includes three projecting end-faces 26. To mechanically support the end-faces 26, hard material ram cores 62 are inserted into pockets of the pressure pad 30 to define the end-faces 26. These cores can be screwed into the ram cylinder frame 56 of the ram carrier 66. A grid-shaped ram pad ring 58, which is sealed against the pressure pad 30 by a ram pad ring seal 60, can be inserted around the edges of the pressure pad 30 into the ram cylinder frame 58 and secured to the ram cylinder frame 58 by means of a fixing element 64, for example, rectangular washers. The ram pad ring 58 provides three openings as cylinder guide areas in which the end-faces 26 of the ram cylinders 24 of the pressure pad 30 are guided.When the stamping pad ring 58 is placed on the surface of a workpiece 18, here on a heat sink 52 with three groups of power semiconductor components 54, the stamping pad ring 58 is pressed into the interior of the stamping cylinder frame 56 and displaces the pressure pad 30, so that the end-contact surface 26 is pressed correctly onto the three groups of power semiconductor components 54 for sintering with the heat sink 52 by means of an interposed sintering paste (not shown). A process cover 50, as mentioned above, is typically placed temporarily between the press cylinder assembly 10 and the workpiece 18. Each of the three end-contact surfaces 26 can be sealed against the grid-shaped cylinder guide areas of the stamping pad ring 58 by a sealing element (not shown), in particular a plastic sealing ring.

[0135] PNK-8689WO

[0136] 05.12.2025 Reference List 0 Press cylinder assembly 2 Press cylinder 4 Press piston 6 Press punch 8 Workpiece 0 Counter press tool 2 Star cylinder unit 3 Slot 4 Punch cylinder 6 Face press surface 7 Identification unit 8 Guide rail 9 Guide groove 0 Handle element 1 Pressure pad 2 Punch piston ring 4 Soft punch area 6 Hard punch area 8 Hard punch material 0 Fixing agent 2 Recess 4 Sealing element 6 Hard punch press ring 8 Hard punch piston

[0137] 50 process coverage

[0138] 52 heat sinks

[0139] 54 Power semiconductor component

[0140] 56 stamp cylinder frames

[0141] 58 Stamp pad ring

[0142] 60 Stamp pad ring seal

[0143] 62 stamp core

[0144] PNK-8689WO

[0145] 05.12.2025 64 Fixing element

[0146] 66 stamp bearers

[0147] PNK-8689WO

[0148] 05.12.2025

Claims

Patent claims 1. Press cylinder assembly (10) of a preferably gas-tight sintering or diffusion soldering device, for use as a lower and / or upper press tool in a process atmosphere adjustable, preferably vacuumable process chamber of the sintering or diffusion soldering device, comprising at least one, preferably several, press cylinders (12) with a movable press piston (14) and at least one press punch (16) associated therewith for generating an adjustable pressing force of a sintering or diffusion soldering application on at least one workpiece (18) associated with an end-face pressing surface (26) of the press punch (16) arranged in at least one punch cylinder (24), characterized in that the end-face pressing surface (26) comprises at least one compressible soft punch area (34) of a pressure pad (30) and at least one incompressible hard punch area (36) of a hard punch material (38),so that isostatic pressing force that can be equilibrated in certain areas can be exerted on the workpiece (18) by means of the pressure pad (30) and selective uniaxial pressing force that can be exerted in certain areas by means of the hard die material (38), and / or that the end pressing surfaces (26) of several press dies (16) or several die cylinders (24) are directly adjacent and can be displaced independently relative to each other.

2. Press cylinder device (10) according to one of the preceding claims, characterized in that the end pressing surface (26) of the press punch (16) exerting pressing force on the workpiece (18) is formed at least partially by a compressible pressure cushion (30) arranged in the punch cylinder (24).

3. Press cylinder device according to claim 2, characterized in that the hard die material (38) of the end pressing surface (26) is a hard metal such as stainless steel or similar, and the areas of the pressure pad (30) of the end pressing surface (26) consist of an elastomer material such as silicone. PNK-8689WO December 5, 2025 4. Press cylinder device (10) according to claim 2 or 3, characterized in that the pressure cushion (30) is at least partially, in particular circumferentially, encompassed by a piston ring (32) which is designed to rest on at least a partial area of ​​the workpiece (18), wherein the piston ring (32) is displaceable when resting on, preferably external areas of, the workpiece (18) in the direction of the bottom of the cylinder (24) and the pressure cushion (30) is compressible by the displacement of the piston ring (32).

5. Press cylinder device (10) according to claim 4, characterized in that the side of the piston ring (32) facing away from the workpiece (18) is sealed against the pressure cushion (30) by means of a sealing element (44), preferably a plastic sealing element.

6. Press cylinder device (10) according to claim 4 or 5, characterized in that the piston ring (32) forms a hardening section (36).

7. Press cylinder device (10) according to one of claims 4 to 6, characterized in that at least one hard die area (36) is designed as a hard die press ring (46) which is formed in close proximity to or concentric with the die piston ring (32) in the die cylinder (24), and which can be compressed when the die piston ring (32) is displaced by the compressible pressure cushion (30) in the direction of the workpiece (18) and exerts a selective pressing force, wherein preferably the hard die press ring (46) is sealed against the pressure cushion (30) by means of a sealing element (44), in particular a plastic sealing element.

8. Press cylinder device (10) according to one of claims 2 to 7, characterized in that at least one hard punch area (36) is designed as a hard punch piston (48) guided in the punch cylinder (24), which is preferably pressable by the compressed pressure cushion (30) in the direction of the workpiece (18) and exerts a selective uniaxial pressing force.

9. Press cylinder device (10) according to one of the preceding claims, characterized in that the press punch (16) is designed to be detachable from the press piston (14), in particular the press punch (16) can be placed on the workpiece (18) outside the press cylinder device (10) before the start of a sintering or diffusion brazing process. PNK-8689WO December 5, 2025 10. Press cylinder device (10) according to one of the preceding claims, characterized in that the at least one press punch (16) and / or the at least one punch cylinder (24) can be interchangeably received in a punch carrier (66) of the press cylinder device (10), in particular can be interchangeably inserted into recesses of the punch carrier (66) of the press cylinder device (10).

11. Press cylinder device (10) according to claim 10, characterized in that several press punches (16) and / or several punch cylinders (24) are included in a punch cylinder unit (22), wherein at least one punch cylinder unit (22) is to be received into the at least one punch carrier (66) of the press cylinder device (10), preferably interchangeably, in particular inserted into recesses of the punch carrier (66).

12. Press cylinder device (10) according to claim 11, characterized in that the punch cylinder unit (22) comprises a releasable handle element (31) which is preferably at least partially insertable into the punch cylinder unit (22), wherein the handle element (31) preferably provides a mechanical locking function, in particular a detent function, for the punch cylinder unit (22) arranged in the punch carrier (66) of the press cylinder device (10) or at least cooperates with a locking element of the punch carrier (66) of the press cylinder device (10).

13. Press cylinder device (10) according to one of claims 10 to 12, characterized in that the punch carrier (66) has a plurality of slots (23) for each press punch (16) and / or punch cylinder (24) or a punch cylinder unit (22), wherein preferably each slot (23) is assigned to a specific press punch (16), a specific punch cylinder (24) or a specific punch cylinder unit (22) and / or preferably comprises at least one, in particular arranged in a slot (23), mechanical stop element for limiting a maximum insertion depth of the press punch (16), the punch cylinder (24) or the punch cylinder unit (22). PNK-8689WO December 5, 2025 14. Press cylinder device (10) according to claim 13, characterized in that the punch carrier (66) comprises guide units (28, 29) for guided insertion of at least one press punch (16) and / or punch cylinder (24) into the punch carrier (66), and / or guide units (28, 29) for guided arrangement or insertion of at least one punch cylinder unit (22) into the punch carrier (66), wherein preferably at least one position sensor is included which is configured to detect and check a position of the punch cylinder (24) and / or the punch cylinder unit (22) in the inserted state.

15. Press cylinder device (10) according to one of claims 10 to 14, characterized in that the at least one press punch (16), punch cylinder (24) and / or the punch cylinder unit (22) comprises an identification unit (27), wherein preferably the identification unit (27) can be read by contact when arranging the punch cylinder (24) and / or punch cylinder unit (22) in the press punch (16).

16. Sintering or diffusion soldering device with a press cylinder assembly (10) for generating an adjustable pressing force of a sintering or diffusion application on at least one associated workpiece (18) under a, preferably adjustable, process gas atmosphere or vacuum, characterized by a design of the press cylinder assembly (10) according to one of the preceding claims.

17. Sintering or diffusion soldering system comprising at least one process chamber configured as a sintering or diffusion soldering chamber, preferably two, in particular three or more process chambers, in particular at least one preheating chamber, a sintering or diffusion soldering chamber with a sintering or diffusion soldering device and a cooling chamber, wherein preferably at least the sintering or diffusion soldering chamber is gas-tight and can provide an adjustable process gas atmosphere or vacuum, and wherein further preferably a transport unit for the automatic transport of workpieces (18), in particular arranged on a process carrier, through the process chambers is provided, characterized by a configuration of the sintering or diffusion soldering chamber as a sintering or diffusion soldering device according to claim 16. PNK-8689WO December 5, 2025 18. Process cover (50) for a press cylinder device (10), in particular a press cylinder device (10) according to one of the preceding claims 1 to 15, characterized in that the process cover (50) can be arranged between the end pressing surface (26) of the press punch (16) and the workpiece (18) to be pressed, and is made of a heat-resistant polymer, in particular Teflon (PTFE), and comprises glass fiber components, in particular as a glass fiber reinforced Teflon film.

19. Sintering or diffusion soldering process using a press cylinder assembly (10) of a, preferably gas-tight, sintering or diffusion soldering device, in particular a press cylinder assembly (10) according to one of claims 1 to 15, as a lower and / or upper press tool in a process atmosphere-adjustable, preferably vacuum-sealed process chamber of the sintering or diffusion soldering device, comprising at least one, preferably several, press cylinders (12) with a movable press piston (14) and with at least one press punch (16) associated thereto for generating an adjustable press force of a sintering or diffusion application on at least one workpiece (18) associated with an end-face (26) of the press punch (16) arranged in at least one punch cylinder (24), characterized in thatthat the end-pressing surface (26) comprises at least one compressible soft punch area (34) of a pressure pad (30) and at least one incompressible hard punch area (36) of a hard punch material (38), such that isostatic pressing force that can be equilibrated in certain areas is exerted on the workpiece (18) by means of the pressure pad (30) and selective uniaxial pressing force that can be exerted in certain areas by means of the hard punch material (38), and / or that the end-pressing surfaces (26) of several press punches (16) or several punch cylinders (24) are directly adjacent and can be displaced independently relative to each other.

20. Sintering or diffusion soldering process according to claim 19, characterized in that a process cover (50) according to claim 18 is arranged between the sintering press surface (26) and the workpiece (18). PNK-8689WO December 5, 2025 21. Sintering or diffusion soldering process according to claim 19 or 20, characterized in that the workpiece (18) comprises at least one heat sink (52) and at least one power semiconductor component (54) to be connected thereto, in particular a power semiconductor circuit carrier, wherein the heat sink (52) is associated with the end-pressing surface (26), and the power semiconductor component (54) is associated with a counter-pressing tool (20) in a manner repelling the sintering press surface (26). PNK-8689WO December 5, 2025

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