Exchangeable pressure pad and pressure pad unit for a diffusion soldering device and / or sintering device, and associated casting device and manufacturing method

Abstract

The invention relates to a pressure pad (22) for a diffusion soldering device and / or sintering device (10), wherein the pressure pad (22) can be inserted into a tool (12, 14), in particular an upper tool (12), of the diffusion soldering device and / or sintering device (10), said tool having at least one axially movable pressure plunger (16), said pressure pad being designed to transmit an equilibrated compressive force to the at least one pressure plunger (16). According to the invention, the pressure pad (22) is produced as a prefabricated exchange element, in particular by means of a separate casting mould (42), wherein the pressure pad (22) comprises at least one solid core (24), in particular a metal core, said core being fastened at least in sections in or on a pressure-elastic and pourable pad material (26), in particular being cast-in or at least partially overmoulded or inserted, and wherein the solid core (24) is designed and connected to the pad material (26), in particular is embedded in the pad material (26), such that the pressure pad (22) can be inserted into and removed from the tool (12, 14) by means of the solid core (24), in particular without the use of tools. In secondary aspects, the invention relates to a pressure pad unit (20) equipped with the aforementioned pressure pad (22) for a pressure plunger (16) of a lower or upper tool (12, 14), to a casting mould (42), to a casting device (44), and to a production and use method of a pressure pad (22).

Description

[0001] Interchangeable pressure pad and pressure pad unit for a diffusion soldering device and / or sintering device, as well as associated casting device and manufacturing process

[0002] The invention relates to a pressure pad for a diffusion soldering device and / or sintering device, wherein the pressure pad can be inserted into a tool, in particular an upper tool, of the diffusion soldering device and / or sintering device having at least one axially displaceable pressure stamp and is designed to transmit an equilibrated pressure force to the at least one pressure stamp.

[0003] Furthermore, the invention relates to a pressure cushion unit with such a pressure cushion for the tool of the diffusion soldering device and / or sintering device.

[0004] Furthermore, the invention relates to a mold for manufacturing the pressure pad.

[0005] Furthermore, the invention relates to a casting device for manufacturing the pressure cushion using the casting mold.

[0006] Furthermore, the invention relates to a method for manufacturing the pressure pad. Finally, the invention relates to a method for using the pressure pad and the pressure pad unit.

[0007] STATE OF THE ART

[0008] Diffusion solder and / or sintering devices are well known from the prior art and today represent an essential component of a large number of industrial manufacturing processes and value chains.

[0009] A well-known example of this is the manufacture of electronic components and electronic assemblies, including semiconductor components, particularly for the automotive industry, power generation, and industrial electronics. Diffusion solder and / or sintering devices can be used to mechanically, electrically, and thermally connect components of electronic assemblies, especially in high-energy circuits. These components include electronic switching elements such as power transistors, IGBTs, MOSFETs, DTS®, Bond-Buffer®, gallium nitride semiconductors, SiC semiconductors, silicon semiconductors, and / or these assemblies or similar components on circuit carriers such as printed circuit boards (PCBs) and / or heat sinks, for example, using upstream or downstream embedding techniques such as (Smart) p 2 To connect the Swiss Electronic pack.

[0010] In diffusion brazing, atoms of the solid base material mix with atoms of the liquid brazing alloy under pressure. This creates an alloy zone that forms a metallurgical bond between the base material and the brazing alloy. In a variant of pressure sintering, low-temperature pressure sintering, two or more components, particularly electronic components and substrates, can be electrically and / or thermally connected using a joining material, whereby the joining material is sintered. Typically, a sintering or diffusion brazing paste or a preformed sintering or brazing element (preform) is placed between the joining partners, e.g., an electronic workpiece and a heat sink. The joining process, under temperature and pressure, creates the typically intermetallic bond.

[0011] Currently, joining methods are being developed that represent a combination of a diffusion soldering process and a sintering process, whereby the joining agents used can utilize a combination of a diffusion solder and a sintering paste.

[0012] One challenge lies in applying the pressure required for diffusion brazing or sintering to the assemblies as uniformly as possible, so that the components are not subjected to local or temporary pressure peaks and mechanical damage is avoided. Avoiding such local pressure peaks is particularly challenging when diffusion brazing or sintering assemblies where several electronic components of varying heights are arranged on a substrate, base plate, cooler, or workpiece carrier.

[0013] To ensure the most uniform distribution of pressing force or pressure, it is known in the prior art to use pressure pads for generating the pressing force. These pads are in operative contact with pressure stamps of varying heights, which transfer the pressing force from the pressure pad to the assemblies in an equilibrated manner. In this context, "equilibrated" means equalizing the pressing pressure on the pressure stamp(s) to prevent local pressure differences and pressure peaks. The elastic pad material enables pressure equalization on and between the pressure surfaces.

[0014] The pressure pad is typically embedded in a receiving cylinder of a pressure pad unit, commonly referred to as a soft tool. The pressure pad unit or soft tool is subject to wear during use and can be treated as a separately handled product, which can, for example, be manufactured separately by external manufacturers or suppliers and sold or delivered to operators of corresponding diffusion soldering and / or sintering equipment.

[0015] In this context, the pressure pad or separate pressure pad unit is used as a wear part in an upper and / or lower tool of the diffusion soldering device and / or sintering device when used as intended. The pressure pad can be pressed against a pressure plate in which the pressure stamps are axially displaceable. The pressing force generated is thereby equilibrated, i.e., evenly distributed, by the pressure pad and transferred to the individual pressure stamps.

[0016] A sintering device with a pressure pad is disclosed in DE 10 2014 114 095 B4. WO 2016 / 050 466 A1 discloses a similar sintering device with pressure stamps, wherein a receptacle for a pressure pad is provided in a cylinder-piston arrangement.

[0017] Due to the continuous mechanical stress on the pressure pad in the form of alternating compression and decompression, the pressure pad must be replaced regularly due to wear and tear.

[0018] Known diffusion soldering and / or sintering devices that use pressure pads have several disadvantages regarding pressure pad replacement, making maintenance and operation comparatively complex and therefore expensive: The state of the art involves a pressure pad material, usually silicone, being cast directly into the receiving cylinder of the pressure pad unit or soft tool, where it hardens to form the pressure pad. Accordingly, in the prior art, the pressure pad is cast directly into the pressure pad unit or soft tool and is therefore essentially permanently fixed – at least not without considerable mechanical effort – within the receiving cylinder of the pressure pad unit and cannot be easily removed from it.

[0019] If the pressure pad needs to be replaced due to wear, the worn pad material still present in the receiving cylinder must be removed mechanically, for example by scraping, before the pad material can be refilled into the receiving cylinder, requiring considerable effort, and the receiving cylinder must then be thoroughly cleaned.

[0020] Furthermore, the filling process of the cushion material is relatively complex and generally requires specialized expertise and equipment, which is rarely, if ever, readily available on-site by the operators of the respective pressure cushions using the diffusion slot and / or sintering device. In other words, only the suppliers of the pressure cushion unit or soft tool are typically capable of replacing the pressure cushion correctly and professionally.

[0021] Therefore, it is regularly necessary to send the pressure pad unit or soft tool to the supplier, i.e., a qualified specialist workshop, for maintenance, particularly for replacing the pressure pad. The pressure pad unit is generally quite bulky and heavy, making shipping comparatively complex and expensive. Consequently, due to the technical and logistical effort involved, as well as the requirement for skilled personnel, maintaining the soft tool is currently not only extremely time-consuming but also relatively expensive.

[0022] During the maintenance period, the pressure pad unit or soft tool is logically unavailable for further use in the diffusion soldering and / or sintering device. The mandatory sending-in process thus creates the additional problem that, for the duration of the maintenance, the operation of the diffusion soldering and / or sintering device, and consequently the corresponding production, is essentially shut down. To avoid this downtime, operators of the diffusion soldering and / or sintering device typically keep several pressure pad units or soft tools in stock. This ensures that when a pressure pad needs to be replaced and sent in due to wear, a still-functional one is readily available and can be used to maintain production, at least for the duration of the maintenance.However, this need to keep several pressure cushion units on hand is unfortunately accompanied by further, usually considerable, costs for the operators, especially with regard to acquisition costs and storage expenses.

[0023] The object of the invention is to provide a pressure cushion suitable for solving the above problem, as well as a pressure cushion unit or a soft tool, in which the disadvantages discussed above are avoided or at least minimized.

[0024] This problem is solved by a pressure cushion, a pressure cushion unit, a mold, a device, and the methods according to the independent claims. Advantageous embodiments of the invention are the subject of the dependent claims.

[0025] REVELATION OF THE INVENTION

[0026] The invention relates to a pressure pad for a diffusion soldering device and / or sintering device, wherein the pressure pad can be inserted into a tool, in particular an upper tool, of the diffusion soldering device and / or sintering device having at least one axially displaceable pressure stamp and is designed to transmit an equilibrated pressure force to the at least one pressure stamp.

[0027] According to the invention, the pressure cushion is manufactured as a prefabricated replacement element, in particular by means of a separate mold, wherein the pressure cushion comprises at least one solid core, in particular a metal core, which is attached, in particular cast in or at least partially encased or inserted, to a pressure-elastic and castable cushion material, and wherein the solid core is designed and connected to the cushion material, in particular embedded in the cushion material, such that the pressure cushion can be inserted into and removed from a pressure cushion unit of a pressure die of the tool by means of the solid core, in particular without tools.

[0028] Advantageously, in the diffusion plug or sintering device, several pressure pads or pressure pad units, which are assigned to one or more pressure stamps and / or several pressure stamps, which are assigned to one pressure pad, can be arranged in an upper and / or lower tool.

[0029] The solid core is preferably incorporated into or connected to the cushion material in such a way that the cushion material or pressure pad and the solid core can only be handled together or are inextricably linked. Thus, even under mechanical stress (at least under normal use), the solid core cannot be pulled out of the cushion material or pressure pad individually. The solid core can therefore only be handled together with the cushion material; the pressure pad can only be handled as a whole.

[0030] The inventive design of the pressure pad as a prefabricated replacement component offers the advantage that, when the pressure pad is worn, the entire pressure pad unit or soft tool no longer needs to be laboriously removed, sent in for repair, and serviced. Instead, the worn pressure pad can be easily replaced. This ease of replacement allows pressure pads and, if applicable, corresponding receiving cylinders within a pressure pad unit to be provided with arbitrarily customizable, and in particular, larger diameters of the stamping surface, which can be used to increase the throughput of a sintering or diffusion soldering device.

[0031] According to the invention, the pressure pad can be produced easily and cost-effectively, particularly automatically, as a mass-produced component externally or, if necessary, even in-house, and stored in stock. Advantageously, the operator of the corresponding diffusion soldering device and / or sintering device using the pressure pad can keep several interchangeable pressure pads on hand and replace them independently as needed without significant effort. With the solution according to the invention, it is no longer necessary to send the entire pressure pad unit or the soft tool to the supplier, where a time-consuming replacement of the pressure pad would still be required. Instead, the pressure pad can simply be replaced directly on-site by the operator of the diffusion soldering device and / or sintering device.Users can replace the soft tool themselves, thus eliminating the need for time-consuming scraping of worn pad material, cleaning of the receiving cylinder within the pressure pad unit, and the complex process of pouring in new pad material. Advantageously, the receiving cylinder of the pressure pad unit has one or more compressed air connections on its rear side, allowing compressed air to be blown into the space between the receiving cylinder and the pressure pad during replacement, making it easier to remove the pressure pad from the receiving cylinder.

[0032] In simple terms, the invention proposes a principle of interchangeability of a used pressure pad from a pressure pad unit of a pressure stamp of a sintering or diffusion soldering device.

[0033] Accordingly, compared to the state of the art requiring the entire pressure pad unit or soft tool to be sent in for maintenance and servicing, maintenance and / or downtime costs and (logistics) effort are significantly reduced, and simplified adaptation of the pressure pad to workpiece-specific requirements is enabled.

[0034] The possibility of automated mass production offers the further advantage of easy scalability, as well as logistically simple and cost-effective exportability due to the significantly lower weight and volume of the replaceable pressure pad compared to the entire pressure pad unit or soft tool. Furthermore, less storage space is required when multiple pressure pads are stockpiled.

[0035] In particular, the solid core is designed to be bonded to the cushion material in such a way that, under higher mechanical stresses not occurring during normal use of the pressure pad, the solid core can preferably be removed from or separated from the cushion material without leaving any residue. This allows the solid core to be advantageously recycled and thus reused for a new pressure pad by being incorporated into fresh cushion material. This further reduces the manufacturing costs of the pressure pad. Experiments have shown that a shape for the solid core that tapers conically towards the bottom of the stamp is advantageous. Likewise, a higher quantity of cushion material should be provided, especially in the corner areas of the pressure pad, than in other edge areas to ensure a long service life.Rounded corner areas with sufficiently large corner radii have proven advantageous. A substantially circular, oval, rectangular, or square shape for the end face of the pressure pad—that is, its cross-sectional shape—allows for a large pressing surface suitable for a greater number of workpieces or for larger workpieces. The cross-sectional and longitudinal geometry of the pressure pad, particularly the mold and the solid core, especially the corner radii and contours, are crucial for a long service life and optimized pressure effect within the pressure pad unit.

[0036] Preferably, the pressure pad can be attached (removably) to the tool on one mounting side by means of at least one fastening element, preferably a screw, directly or indirectly as part of a pressure pad unit in the installed state. The pressure pad preferably has at least one fastening element, in particular a thread, which interacts with the fastening element, and which is preferably arranged / formed in the solid core. Advantageously, this allows for easy, removable attachment of the pressure pad and thus simple replacement.

[0037] According to a preferred embodiment, the solid core is provided with at least one adhesive section, in particular a tapered section, notch, undercut, barb, or the like, for adhering the solid core to or within the cushion material, acting in a force-, form-, and / or material-locking manner. The adhesive section has the advantage of improving the removal / handling of the pressure cushion.

[0038] The term "adhesive section" refers to any element or section that ensures or promotes the retention of the solid core, preventing it from being easily pulled out of the cushion material, even under mechanical stress. The solid core is integrated into the cushion material in such a way that the adhesive section can function as intended. In particular, the adhesive section allows for the removal of the solid core without damage (with respect to the solid core and / or cushion material), preferably for reuse. According to a preferred embodiment, the cushion material is made of a high-temperature elastomer, especially silicone. Other materials or material combinations are also conceivable, provided they are sufficiently deformable and, in particular, suitable for the intended use of the pressure cushion with regard to temperature resistance up to 260°C, especially 300°C, preferably up to 450°C.Advantageously, the cushion material, and especially the material blend, can be adapted to the specific requirements of the intended use of the pressure cushion. Particularly suitable cushion materials include poly- or elastomeric materials marketed under brand names such as Peek, Vespel, or Teflon, as well as pure aluminum or similar very soft solid materials.

[0039] According to a preferred embodiment, the cushion material has a circumferential lip on a side facing the solid core and / or tapers conically on a side opposite the solid core. Advantageously, this improves force transmission when compressing the pressure cushion during intended use.

[0040] According to a preferred embodiment, the solid core is made of metal, particularly stainless steel, and / or plastic, especially magnetic or magnetizable metal, and / or plastic, and / or tapers towards a side opposite the mounting side of the solid core. This further improves the handling of the pressure pad.

[0041] According to a preferred embodiment, the pressure pad and the solid core are designed for a high-temperature range of 180°C to 380°C, preferably between 220°C and 260°C. In this context, the pressure pad and the solid core feature a material combination designed for or resistant to this temperature range with respect to the materials of the pad material and the solid core. Advantageously, the pressure pad and the solid core thus exhibit sufficient wear resistance with regard to the temperatures occurring in common soldering and sintering processes.

[0042] According to a preferred embodiment, the pressure pad is provided to have a square or rectangular shape, particularly with rounded corners, a circular or elliptical shape, or a polygonal shape. Other shapes, such as a 3D shape, are also conceivable. Advantageously, the shape of the pressure pad can be individually adapted to its intended use or to the shape of the corresponding receiving cylinder of the pressure pad unit, the soft tool, or the tool of the system into which the pressure pad is inserted.

[0043] According to a preferred embodiment, the pressure pad and / or the solid core has a surface profile with at least one protrusion or a core profile on a side of the stamp attributable to the at least one stamp for transmitting the equilibrated pressure force to the stamp, wherein preferably a core insert with a Shore hardness higher than the pad material is embedded in the core profile. The surface profile or the core profile can be produced using a suitably designed negative mold, which can be used in the casting process of the pressure pad, or can be produced more easily by a 3D printing process. The protrusion of the surface profile is thus formed integrally with the other areas of the pressure pad, i.e., it consists of the same pad material. The protrusions of the surface profile constitute a primary contact surface of the pressure pad or the solid core.The raised section represents the contact between the stamping surface and the associated die. In this respect, the raised section contacts the die to transmit the pressure force or acts upon it. The Shore hardness of soft, elastomeric materials, such as silicone, indicates the material's strength and stiffness: a higher Shore value signifies a harder, stiffer material, while a lower value indicates a softer, more flexible material. Hardness is generally measured on a scale, most often as Shore A for soft elastomers. Core profiling allows for the creation of a core insert with a Shore-harder material than the surrounding pad material, with the core insert potentially extending to the bottom of the die. Alternatively, core profiling could create raised sections of the solid core extending to the bottom of the die, forming an incompressible hard die area or areas on the die surface.This allows for the creation of inhomogeneous stamping areas with varying Shore hardnesses on the stamping surface, which can be specifically adapted to the workpieces being pressed. In particular, the core insert can be made of a harder silicone material than the surrounding pad material. The core insert, or multiple core inserts, can be cast into recesses on the underside of the solid core and / or encased by the pad material. This advantageously enables particularly efficient and precise force transmission.

[0044] According to a preferred embodiment, the raised section of a pressure plate is associated with a pressure pad unit that receives the pressure pad. The raised section is essentially complementary to an opening in the pressure plate, allowing the raised section to be inserted into the opening and the equivalent pressure force to be transmitted indirectly through the opening to the printing punch via the pressure plate. The punch side with its raised sections is thus complementary to the associated pressure plate, and the pressure pad with its raised sections can be inserted into the pressure plate. During the printing process, due to the displacement of the pad material associated with compression, the respective raised section is continuously pressed deeper into the respective opening until it ultimately comes into contact with the printing punch for force transmission, particularly after the raised section has already been pushed back out of the opening.Preferably, the raised section can protrude from or be pushed out of the opening during the printing process. In this case, the printing punch can be placed separately or loosely on the workpiece as a so-called "weight bar" and therefore does not necessarily have to be inserted into the printing plate. Rather, the pressure pad can exert pressure on the printing punch through the printing plate via the raised section. Advantageously, this improves force transmission and, due to the precise fit of the raised section to the opening, minimizes pressure-induced wear of the printing pad, especially at the edges.

[0045] The invention further relates to a pressure pad unit or a soft tool for a tool, in particular an upper tool, of a diffusion brazing device and / or sintering device, comprising at least one pressure pad, at least one pressure plunger associated with the pressure pad, and a limiting element encompassing the pressure pad at least partially, into which the pressure pad can be inserted or is inserted, wherein the limiting element is designed to limit deformation of the pressure pad and to seal the pressure pad against a component exerting a pressure force on the pressure pad, in particular a piston ring. It is conceivable and advantageous to arrange the pressure pad unit in the upper tool. However, the pressure pad unit can also be arranged in the lower tool. Furthermore, it is possible to provide an arrangement of one pressure pad unit in the upper tool and one pressure pad unit in the lower tool to enable hydrostatic three-dimensional forming on both sides, i.e.,to be able to press a workpiece isostatically from all sides.

[0046] The pressure pad unit or soft tool is characterized by the fact that the pressure pad is designed according to the invention, as described above. This results in the advantages already mentioned in advance.

[0047] According to a preferred embodiment, the limiting element comprises a receiving cylinder for the pressure pad and a pressure plate that receives and guides the pressure stamp(s), as well as a piston ring, wherein the piston ring preferably causes the pressure pad to be compressed by a stop against an opposing tool, in particular a lower tool, and further preferably compresses the edge lip of the pad material.

[0048] The limiting element preferably comprises at least one receiving cylinder for receiving the pressure pad, a piston ring that can compress the pressure pad or is designed / serves to compress it, and a pressure plate that receives and guides the at least one pressure plunger. In other words, at least the receiving cylinder, the piston ring, and the pressure plate form the limiting element. The component exerting the pressure force on the pressure pad is preferably the piston ring, which can be part of the receiving cylinder or the pressure plate, or can be assigned / is assigned to one of these elements. Advantageously, this makes the soft tool or pressure pad unit formed from the limiting element and pressure pad cost-effective to manufacture, mechanically robust, and ensures efficient pressure generation and transmission.

[0049] According to a preferred embodiment, the limiting element is made of a material that is more rigid than the pressure pad, particularly non-deformable, preferably metal, especially steel, or plastic, and / or the pressure pad is connected to the limiting element, preferably detachably, by means of a material, force, and / or form-fit connection, preferably by means of a quick-release device, and is inserted into the receiving cylinder. This offers the advantage of creating a mechanically highly resilient yet robust pressure pad unit or soft tool, which allows for a secure and easy-to-manufacture attachment and thus also easy replacement of the pressure pad.

[0050] The connection in the installed state is preferably achieved using (releasable) fasteners such as screws or similar components and / or an interference fit for a force-fit and / or form-fit connection. In particular, the pressure cushion can be connected to or attached to the limiting element on one mounting side by means of the fastener. Preferably, the individual elements of the limiting element, in particular the receiving cylinder, piston ring, and pressure plate, are each connected to the pressure cushion, especially by various fasteners such as screws or similar components. For example, the piston ring can be connected to the pressure cushion by means of a quick-release fastener, and the pressure cushion (with the connected piston ring) can be fixed in the receiving cylinder by means of screws in the installed state.

[0051] As mentioned at the outset, the pressure pad preferably has at least one fastening element, in particular a thread, which interacts with the fastening element, and the fastening element is preferably arranged / formed in the solid core. The limiting element with the pressure pad inserted and fastened therein forms the pressure pad unit, which in turn can be inserted into the tool and preferably (removably) connected to it by means of fasteners such as screws or the like.

[0052] According to a preferred embodiment, the limiting element comprises at least one force-locking and / or form-locking fastening device, in particular a quick-release unit or clamping device, for preferably tool-free fastening of the pressure cushion unit or the soft tool to the tool, in particular the upper tool and / or lower tool. By arranging a pressure cushion unit in the lower and upper tool, hydrostatic, three-dimensional clamping of the workpiece can be achieved from all sides. Advantageously, this enables quick, secure, and easy fastening. The fastening of the pressure cushion unit in the upper and / or lower tool can thus be advantageously tool-free, in particular by means of manually operated locking elements.In this context, "tool-free" means that inserting or removing the pressure pad unit does not require any mechanized tools, just as inserting or removing the pressure pad into or out of the pressure pad unit does not require any mechanized tools, although securing the pressure pad securely in the pressure pad unit might require fasteners such as screws and the like.

[0053] According to a preferred further development, the pressure pad is inserted into a pressure plate of the boundary element, at least in part, with a raised surface profile. This results in the advantages already mentioned above.

[0054] According to a preferred embodiment, the pressure plate has at least one opening into which, in particular instead of the pressure stamp, the raised section of the pressure pad is inserted, so that the equivalent pressure force can be indirectly transmitted to the pressure stamp via the pressure plate. In this respect, the pressure stamp can also be inserted into the opening, at least partially, or alternatively, it can be placed loosely on the workpiece outside the pressure plate as a so-called "weight bar." In both cases, the pressure stamp can advantageously make contact with the raised section, and the pressure force can be transmitted accordingly. This results in the advantages already mentioned above.

[0055] The invention also relates to a casting mold, in particular a mold, for producing a pressure pad for a tool of a diffusion soldering device and / or sintering device.

[0056] The mold is characterized in that it is designed for producing the pressure cushion according to the invention for the pressure cushion unit according to the invention, as described above. The advantages already mentioned in this regard result. A mold is defined as a negative form of the pressure cushion that can be filled with a castable pressure cushion material. This can be made, for example, of aluminum or stainless steel, e.g., of stacked aluminum plates. The mold can advantageously be designed with a non-stick coating on the inside so that the poured and solidified cushion material does not stick to the mold. In particular, the mold has a profiling section that is designed to produce the surface profiling with at least one raised area, as described above. The profiling section therefore has, in particular, a recess that is complementary to the raised area.In this context, the mold has a negative cross-section of the pressure pad; the resulting casting cavity is complementary to the desired shape of the pressure pad. Furthermore, the mold may have corresponding inserts, recesses, or the like that allow for the insertion and / or alignment of the solid core.

[0057] The mold can be designed for the parallel filling of multiple pressure pads and can provide separate casting chambers that can be filled and cured simultaneously or sequentially, thus enabling mass production of pressure pads at reduced unit costs. In this respect, the mold allows for the parallel and simultaneous or sequential production of multiple pressure pads arranged in an upper or lower mold. For example, a mold can include multiple mold openings to efficiently produce several pressure pads in parallel and sequentially or simultaneously.

[0058] The invention also relates to a casting device for manufacturing a pressure cushion and includes at least one mold.

[0059] The casting device is characterized in that the pressure pad and the mold are designed according to the invention, as described above. This results in the advantages already mentioned in advance.

[0060] The term casting device is to be understood as any type of device that is suitable for the production of the pressure cushion according to the invention using the casting mold, preferably in an automated manner, and which for this purpose has, for example, appropriately suitable handling means.

[0061] According to a preferred embodiment, the casting device comprises a material feed device, in particular an injection pump, for feeding a material, especially silicone, for the pressure pad into the mold, and / or a handling device for handling the mold, and / or control and / or sensor means, in particular a control unit, sensors, and / or actuators, for automating the production of the pressure pad by the mold. The material feed can be carried out without pressure or at low injection pressures. Advantageously, the casting device can be configured for a vacuum-assisted manufacturing process of the pressure pad, so that oxygen inclusions can be avoided, penetration of the pad material is facilitated, and the quality of the pressure pad can be improved. Advantageously, the casting device is thus designed to produce the pressure pad efficiently and reliably.

[0062] The invention further relates to a method for manufacturing a pressure cushion for a diffusion soldering device and / or sintering device, wherein the pressure cushion is inserted into a tool, in particular an upper tool, of the diffusion soldering device and / or sintering device having at least one axially displaceable pressure stamp, in order to transmit a pressure force to the at least one pressure stamp in an equilibrating manner.

[0063] According to the invention, the pressure cushion is prefabricated separately as an exchange element before being inserted into the tool, using a mold, in particular the mold and / or casting device described above, and the pressure cushion with at least one solid core, in particular a metal core, is produced by a casting step, in particular a vacuum-assisted one, wherein the solid core is attached at least partially to or within a pressure-elastic and castable cushion material, in particular cast in or at least partially encased or inserted, wherein the solid core is arranged in and connected to the cushion material, in particular embedded, in such a way that the pressure cushion can be inserted into and removed from the tool, preferably into a pressure cushion unit of the tool, by means of the solid core, in particular without the need for a tool.

[0064] In particular, the method serves to manufacture the pressure cushion according to the invention described above. The advantages already mentioned in this regard result.

[0065] In the inventive method, the (liquid) cushion material is poured into the corresponding mold, whereupon the solid core is incorporated (while the cushion material is still liquid). In this context, the solid core is inserted into the liquid cushion material in the mold, preferably under reduced pressure or vacuum, then aligned and fixed until the cushion material cools, so that it remains in the intended position. After the cushion material has cooled, the finished pressure cushion is removed from the mold using the solid core. The pressure cushion can then be inserted into the tool for its intended use. In particular, the pressure cushion is manufactured or produced with a surface profile having at least one raised area and / or a core profile of the solid core that accommodates a core insert, as described above.Surface profiling or core profiling can be created by a corresponding profiling section of the mold or a 3D printing process.

[0066] The invention also relates to a method for using the pressure cushion and pressure cushion unit described above according to the invention.

[0067] The method is characterized by the fact that, in a pressure pad unit or soft tool, the pressure pad is inserted into a boundary element that at least partially encompasses the pressure pad, and is, in particular, detachably connected to the boundary element by a material, force, and / or form-fit connection, so that the pressure pad used in the pressure pad unit forms an interchangeable insert for insertion into a pressure die of the lower or upper tool. This results in the advantages already mentioned.

[0068] Therefore, the limiting element and the pressure cushion, analogous to the solid core and the cushion material - i.e., the pressure cushion - can (only) be handled together, at least in its intended use.

[0069] The insertion into the limiting element can take place during the casting of the pressure pad or, preferably, after casting. In the former case, the limiting element can be placed directly into the mold, and then the liquid material and the core (into the limiting element within the mold) can be introduced, so that the bond with the limiting element occurs through the casting and cooling process itself. Preferably, however, the pre-cast pressure pad, especially when using the solid core, is inserted into the limiting element after cooling and thus bonded to it. DRAWINGS

[0070] Further advantages become apparent from the accompanying drawing description. The drawings illustrate exemplary embodiments of the invention. The drawing, the description, and the claims contain numerous features in combination. A person skilled in the art will expediently consider the features individually and combine them into meaningful further combinations.

[0071] They show:

[0072] Fig. 1 A highly simplified schematic cross-sectional representation of a diffusion soldering device and / or sintering device using a pressure pad according to the prior art;

[0073] Figs. 2A and 2B each show a schematic perspective view of an advantageous pressure pad according to the invention;

[0074] Figs. 3A to 3H each show a schematic cross-sectional representation of an embodiment of the pressure pad;

[0075] Figs. 4A and 4B each show a schematic perspective view of an advantageous mold for manufacturing the pressure pad;

[0076] Figs. 5A to 5C each show a perspective view of an advantageous pressure pad unit or a soft tool with the pressure pad;

[0077] Fig. 6 shows an exemplary representation of the further development from Fig. 6 during intended use;

[0078] Figs. 7a to 7e show another embodiment of a pressure pad unit with a pressure pad as a hard stamp with a casting device;

[0079] Figs. 8a to 8d Another embodiment of a pressure pad as a soft stamp with contour-optimized solid core and pad material;

[0080] Figs. 9a to 9c Another embodiment of a pressure cushion unit with embodiments of a pressure cushion according to Fig. 8;

[0081] Fig. 10 shows another embodiment of a casting device for a pressure cushion according to Fig. 8;

[0082] Fig. 11 shows another embodiment of a casting device with an insertable solid core.

[0083] 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.

[0084] Figure 1 shows a highly simplified cross-sectional representation of the essential components of a diffusion soldering device and / or sintering devices 10, as is widely used in the prior art.

[0085] The diffusion soldering device and / or sintering device 10 is designed, among other things, to generate a pressing force and transfer it to the workpieces during a diffusion soldering and / or sintering process for the production of workpieces such as electronic components and electronic assemblies. To generate the pressing force, the diffusion soldering device and / or sintering device 10 has an upper tool 12 and a lower tool 14, wherein at least one of the tools 12, 14 is displaceable in the direction of the other tool 14, 12 to generate the pressing force.

[0086] Typically, a pressure pad unit 20 is arranged in or on the upper tool 12, as shown in Figure 1. If required, the pressure pad unit 20 can also be arranged in the lower tool 14. With one pressure pad unit each in the lower tool 14 and the upper tool 12, hydrostatic compression of a workpiece 80 in all three spatial dimensions can be achieved. A protective film (not shown), e.g., a PTFE (polytetrafluoroethylene) film or a PFA (perfluoroalkoxy) film, or in particular a comparatively thinner PL (polyimide) film, is typically arranged between the pressure pad unit 20 and the workpiece 80 to prevent the compressible punch material, especially the pad material 26, from adhering to the workpiece 80 and to ensure protection against contamination.In the aforementioned hydrostatic pressing process, a workpiece 80 would thus be surrounded by a protective film from both above and below to prevent the stamping material, in particular silicone material, from adhering to the workpiece 80 on both sides. In the embodiment shown in Figure 1, the upper tool 12 is displaceable towards the lower tool 14 to generate the pressing force, and the generated pressing force is transferred to the workpieces by means of a plurality of axially displaceable pressure stamps 16, which are assigned to or arranged in the upper tool 12. Furthermore, a heating element 18, which can be assigned to the lower tool 14, is provided, by means of which any required heat energy can be introduced into the corresponding diffusion bonding and / or sintering process.

[0087] To achieve the most uniform distribution of the pressure force possible, the diffusion brazing device and / or sintering device 10 further comprises a pressure pad unit 20, also called a soft tool, with a pressure pad 22 made of an elastomer material. This pressure pad is attached to the upper tool 12 and is thus positioned between the upper tool 12 and the lower tool 14. The pressure pad 22 of the pressure pad unit 20 enables an equilibrated transmission of the generated pressure force to the pressure dies 16. During the pressure force transmission, the pressure pad 22 is compressed or deformed by the movement of the upper tool 12 towards the lower tool 14, thereby transmitting the pressure force evenly or in an equilibrated manner to the pressure dies 16.

[0088] The diffusion soldering device and / or sintering device 10 discussed with reference to Figure 1 is generally known from the prior art, so that its structure and function were only discussed generically in advance for the sake of clarity, since the corresponding features are generally known to the person skilled in the art.

[0089] Due to the regular compression and decompression of the pressure pad 22 that occurs during normal use, it is subject to considerable wear. It is therefore necessary to replace the pressure pad 22 regularly. To enable quick, uncomplicated, and thus cost-effective replacement, the invention provides that the pressure pad 22 is manufactured as a prefabricated replacement element.

[0090] Figures 2A and 2B each show a perspective view of the pressure pad 22 according to the invention, which is manufactured as a replacement element. To ensure the interchangeability of the pressure pad 22, it advantageously has a solid core 24 which is attached, at least partially, to it or to a pressure-elastic and castable pad material 26. In the present case, during the manufacturing process of the pressure pad 22, the solid core 24 is cast into the pad material 26 or at least partially encased by the pad material 26.

[0091] Preferably, the solid core 24 is made of a metal, particularly a cost-effective and lightweight one, preferably aluminum, while the cushion material 26 is made of a high-temperature-resistant elastomer material, such as silicone. Optionally, a magnetic metal such as magnetic steel may be advantageous to enable magnetic attachment of the pressure cushion 22 to the pressure cushion unit 20.

[0092] The solid core 24 is designed and connected to the cushion material 26 in such a way that the pressure cushion 22 can be inserted into and removed from the upper tool 12, more precisely the pressure cushion unit 20 or the soft tool, preferably without tools, using the solid core 24. The solid core 24 is thus essentially a handling element for the pressure cushion 22, while the cushion material 26 is a deformable transmission element of the pressure cushion 22 that actually transmits the pressure force. Since the solid core 24 and the cushion material 26 are essentially inseparably connected and can therefore only be handled together, the resulting pressure cushion 22 can be handled easily using the solid core 24.This means that the pressure pad 22 is designed as a separately prefabricated and independently manageable replacement element, which can be replaced without major effort in case of wear.

[0093] Figures 3A to 3E each show a simplified cross-sectional representation of various embodiments of the pressure cushion 22 discussed above, which is advantageously manufactured as an interchangeable component.

[0094] The pressure pad 22 has a mounting side 28 associated with the upper tool 12 or the pressure pad unit 20, on which the pressure pad 22 can be attached either directly to the upper tool 12 or to elements of the pressure pad unit 20, which will be discussed in more detail later. For attaching the pressure pad 22 to the upper tool 12 or the pressure pad unit 20, the pressure pad 22 has several mounting elements 30, which, according to the embodiments shown in Figures 3A to 3C, are designed as threads for fasteners in the form of complementary screws.

[0095] Opposite the mounting side 28, the pressure pad 22 has a stamping side 32, which is thus attributable to, or associated with, the pressure stamps 16. Therefore, when used as intended, the pressure pad 22 is arranged in the pressure pad unit 20 or the diffusion soldering device and / or sintering device 10 such that the mounting side 28 faces the upper tool 12 and the stamping side 32 faces the pressure stamps 16 and thus the lower tool 14.

[0096] Preferably, the cushion material 26 has a circumferential lip 34 on one side facing the solid core 24, in this case the mounting side 28. As shown, for example, in Figure 3A, it can optionally also be provided that the cushion material 26 tapers conically on the opposite side, in this case the punch side 32, in particular to achieve a particularly advantageous or improved transmission of the pressure force.

[0097] As further illustrated by way of example in Figures 3B and 3C, it is preferably provided that the solid core 24 has at least one force-, form-, and / or material-locking adhesive section 36 by means of which the adhesion of the solid core 24 to the cushion material 26 is further improved.

[0098] In the embodiment shown in Figure 3B, the adhesive section 36 is designed by way of example with several circumferentially arranged and evenly spaced tapered sections 38.

[0099] In the embodiment shown in Figure 30, the adhesive section 36 has several laterally arranged barbs 40 or is designed as a barb 40. With this design of the adhesive section 36, it is ensured that the solid core 24 cannot be easily separated from or pulled out of the cushion material 26, and in particular, only with an unusually high force. Thus, the adhesive section 36 ensures a load-resistant connection between the solid core 24 and the cushion material 26.

[0100] Figure 3D shows, analogous to Figure 3A, a pressure pad 22 with a solid core 24, which, unlike the embodiment in Figure 3A, has a core profile 74. The core profile 74 has several core punch areas 78 through which the hard, in particular metallic, material of the solid core 24 penetrates to the punch side 32, optionally being slightly enclosed by pad material 26. Thus, the punch side 32, which is in contact with the workpiece(s) to be pressed, is formed by both soft areas of the pad material 26 and hard areas of the material of the solid core 24, resulting in a hybrid punch with soft, pressure-elastic and hard, pressure-resistant punch surfaces. The arrangement can be adapted to workpiece-dependent requirements regarding pressure load and arrangement.

[0101] Figures 3E and 3F show further embodiments of the replaceable pressure pad 2.

[0102] In Fig. 3E, at least one recess is provided in the solid core 24 in the direction of the bottom of the punch 32 as a core profile 74, in which a core insert 76 made of a softer material than the solid core 24, but harder material than the cushion material 24, is inserted, for example a silicone insert with a higher Shore hardness than the cushion material 24.

[0103] In Fig. 3F, the core profile 74 is more complex, featuring a plurality of recessed areas, each containing core inserts 76 made of a Shore-harder material than the surrounding pad material 24. The core inserts 76 extend to the bottom of the punch 32, thus providing a pressure pad with inhomogeneous pressure areas featuring harder and softer pressure surface regions. The core profile 74 of the solid core 24, oriented towards the pressure side (i.e., the bottom of the punch), allows for a workpiece-specific definition of the inhomogeneous pressure areas.

[0104] The core insert(s) 76 can be single-layered or multi-layered and configured with different geometric shapes, particularly contour shapes and depths. It is advantageous to design the core profile 74 of the solid core 24, for example, using a 3D printing process to allow for flexible adaptation to workpiece-specific requirements. The core inserts 76 can be cast into the core profile 74 or subsequently added, for example, as laminated layers, and can be encased with the surrounding cushion material 26.

[0105] Figure 3G shows, analogous to Figure 3F, a pressure pad 22 with a solid core 24 having a core profile 74. In contrast to the embodiment of a pressure pad 22 shown in Figure 3F, the embodiment shown in Figure 3G has core inserts 78 that extend to the punch side 32. This creates an inhomogeneous punch side 32 with soft, soft-compressible punch areas of the pad material 26 and harder, hard-compressible punch areas of the core inserts 78, which, as in the embodiment of Figure 3D, provides a hybrid punch. The arrangement, shape, number, and hardness of the softer and harder punch surface areas can be adapted according to workpiece-specific requirements.

[0106] Figure 3H shows, analogous to Figures 3A to 3G, a simplified cross-sectional view of a preferred embodiment of the pressure pad 22. Identical elements are provided with the same reference numerals, but only the differences will be discussed below.

[0107] The pressure pad 22 shown in Figure 3H differs from the previous embodiments in that the pressure pad 22 has a surface profile 68 on the stamping side 32 associated with the stamp(s) 16, which can, for example, be designed as "weight bars" that can be loosely placed on the workpieces 80. The surface profile 68 comprises at least one, in this case four, projections 70, which extend away from the stamping side 32 or its base. The surface profile 68 thus corresponds to protrusions of the stamping side 32 formed by the projections 70. The projections 70 are integrally formed with the pressure pad 22, i.e., they consist of the same pad material. The projections 70 were produced during the casting of the pressure pad 22 using a profiling section of the mold 42.

[0108] It goes without saying that the features of the embodiments shown in Figures 3A to 3H can be combined as desired for further embodiments. As discussed above, the pressure pad 22 is prefabricated as a replacement component and is preferably manufactured by a casting process.

[0109] Figures 4A and 4B each show a perspective view of a mold 42 for manufacturing the pressure pad 22. The mold 42 is part of a casting device 44, which is only indicated here for the sake of clarity and which, in addition to the mold 42, may include various other elements, such as a material feeding device, a handling device, control units, sensors and / or actuators, and is designed in particular for the automated production of the pressure pad 22.

[0110] As can be clearly seen in Figures 4A and 4B, the mold 42 is designed as a die. The mold 42 has a casting plate 46 with a top and a bottom surface. A negative recess 48 for the pressure pad 22 is formed in the top surface of the casting plate 46. The negative recess 48 is thus complementary to the intended shape of the pressure pad 22 and is designed to hold the components forming the pressure pad 22, at least the solid core 24 and the pad material 26, in shape during the casting process until the pad material 26 cools.

[0111] For filling the (liquid) cushion material 26, the mold 42 has several filling nozzles 50 on its underside, opposite the top or negative recess 48. These nozzles extend through the casting plate 46 and are thus fluidically connected to the negative recess 48. Furthermore, a casting cover 52, which fluid-tightly seals the negative recess 48, can be arranged or is arranged on the casting plate 46 and, in its arranged state, can be fixed there by means of fixing elements 54, in this case screws.

[0112] To produce the pressure cushion 22 using the mold 42 or casting device 44, it can be provided, for example, that at the beginning of the manufacturing process the solid core 24 is positioned in the negative recess 48 of the casting plate 46 in a predetermined position. Subsequently, to fix the solid core 24 in this position and to seal the negative recess 48, the casting cover 52 is placed on top of the casting plate 46 and fixed in a fluid-tight manner by means of the fixing elements 54. Following this, in a single casting step, the liquid, pourable cushion material 26 is poured into the mold 42 or the negative recess 48 via the filling nozzles 50. After the cushion material 26 has cooled, the casting cover 52 is removed by loosening the fixing elements 54, whereupon the cooled and thus finished pressure cushion 22 with the solid core 24 now embedded in the cooled cushion material 26 can be removed.The finished pressure pad 22 can then be used as intended, in particular in conjunction with the pressure pad unit 20.

[0113] Regarding the discussion of the pressure pad unit 20 or the soft tool, figures 5A to 50 each show different views or perspective representations of the pressure pad unit 20.

[0114] The pressure cushion unit 20 essentially comprises the pressure cushion 22 according to the invention as described above, as well as a limiting element 56 which at least partially encompasses the pressure cushion 22. The limiting element 56 in turn has at least one receiving cylinder 58, and may optionally further comprise a pressure plate 60 and a piston ring 62.

[0115] The receiving cylinder 58 is designed to receive the pressure pad 22, so that, under normal use, the pressure pad 22 can be inserted into the receiving cylinder 58 of the limiting element 56 and thus into the pressure pad unit 20 or the soft tool. The pressure plate 60 serves to receive and guide the pressure punches 16 and is sealed against the pressure pad 22 by an annular seal 82, preferably made of plastic material, to prevent the soft pad material 26 from penetrating the gap between the pressure plate 60 and the receiving cylinder 58. The limiting element 56 essentially serves to limit deformation of the pressure pad 22 and to seal the pressure pad 22 against a pressure force exerted on the pressure pad 22 by an element of the diffusion soldering device and / or sintering device 10.For this purpose, the limiting element 56 can include, among other things, the piston ring 62, which causes the pressure pad 22 to be compressed, preferably by a stop against the opposing tool, in this case the lower tool 14, and also compresses the edge lip 34 of the pad material 26. The piston ring 62 can preferably have extraction aids 92, e.g., in the form of threaded bores, to facilitate the removal of the piston ring 62 from the receiving cylinder 58 and the pressure pad 22 for replacement purposes. Referring to the preceding discussion of the pressure pad unit 20 or the soft tool, Figure 5A shows a perspective exploded view of the assembled pressure pad unit 20 or the soft tool. As can be clearly seen in Figure 5A, the pressure pad 22 can be arranged in the receiving cylinder 58 with the mounting side 28 facing forward. Accordingly, the receiving cylinder has a receiving area that is complementary to the shape of the pressure pad 22.The pressure plate 60 with the piston ring 62 is mounted on the plunger side 32 of the pressure pad 22 arranged in the receiving cylinder 58. The individual elements of the assembled pressure pad unit 20 or soft tool are fixed to one another by means of several fastening elements 64, in this case screws, which interact in particular with the fastening elements 30 (threads) of the pressure pad 22. This secures the pressure pad 22 in the limiting element 56 in a way that prevents it from falling out. This allows the individual elements of the pressure pad unit 20 to be handled as a unit, and the resulting pressure pad unit 20 can be used as intended in the diffusion soldering device and / or sintering device 10, as discussed, for example, with reference to Figure 1A.

[0116] Figure 5B shows a top view (from below) of the assembled pressure pad unit 20. As can be seen in Figure 5B, the piston ring 62 can, for example, be attached to the pressure pad 22 by means of a force-fit and / or form-fit fastening device 66, which is marked by circles in Figure 5B. To enable particularly easy assembly and disassembly of the fastening, it is preferably provided that the fastening device 66 is designed as a quick-release device, as disclosed, for example, in EP 4 080 554 of the applicant. By means of such a quick-release device, the pressure pad unit 20 or the soft tool can be disassembled quickly and non-destructively when the pressure pad 22 needs to be replaced, in particular the piston ring 62 can be quickly released, so that the pressure pad 22 can be replaced quickly and efficiently.

[0117] Figure 5C shows a top view of the assembled pressure pad unit 20 or the soft tool, i.e., the top of the receiving cylinder 58.

[0118] As can be clearly seen in Figure 50, the receiving cylinder 58 has several openings on its upper side for the fastening elements 64, marked by circles in Figure 5C. When the pressure pad 22 is properly positioned in the receiving cylinder 58, these openings are aligned with the fastening elements 30 or threads of the pressure pad 22. This allows the pressure pad 22 to be easily fixed in the receiving cylinder 58 by means of the fastening elements 64, which interact with the fastening elements 30. One or more optional compressed air connections for the pneumatically assisted removal of the pressure pad 22 from the receiving cylinder 58 are not shown.

[0119] Figure 6 shows the further development of the pressure pad 22, previously discussed with reference to Figure 3H, during its intended use. Figure 7 shows a simplified perspective view of the diffusion soldering device and / or sintering device 10 in the area between the upper tool 12 and the lower tool 14.

[0120] When used as intended, the pressure pad 22 is inserted into the pressure pad unit 20, as previously described in detail. The pressure pad 22 is designed to be inserted, at least partially, into the limiting element 56. More precisely, the protrusions 70 are inserted into openings 72 of the pressure plate 60. The protrusions 70 are thus essentially complementary to the openings 72. Therefore, at the beginning of the printing process, the pressure pad 22 is already pressed, at least partially (i.e., with the protrusions 70), into the pressure plate 60. During the printing process, the displacement of the pressure pad 22 causes it to be continuously pressed further into the openings 72 with its protrusions 70, until the pressure pad 22 finally comes into contact with the printing dies 16 via the protrusions 70, in order to transmit the equilibrated pressure force to them.

[0121] Compressed air can be blown into the compressed air connection 88 to facilitate the removal of the pressure pad 22 from the pressure pad unit 20, displacing the pressure pad 22 from the receiving cylinder 58. In addition, it can be advantageously possible to apply extra pressing force to the ram side 32 via the compressed air connection 88 during pressing operation by means of overpressure. Compressed air-assisted lifting with pressures of, for example, 8 bar can be advantageous for ram surfaces of 10,000 mm² and above. 2and higher pressures are sometimes required, including additional mechanical support through one or more impacts. Regarding the contacting of the pressure stamps 16 and the transmission of force to them, the representation shown in Figure 6 provides that the pressure stamps 16 are not partially embedded in the pressure plate 60, as previously shown, for example, in Figure 1, but are arranged outside of it. More precisely, the pressure stamps 16 are loosely placed on the workpieces to be pressed in the form of so-called "weight bars." During the pressing process, the protrusions 70, and thus the pressure pad 22, are pressed out of or through the openings 72, whereupon they press onto the loosely placed pressure stamps 16 and thus transmit the pressing force.

[0122] According to an alternative embodiment, not shown here, the pressure stamps 16 can be provided, as shown, for example, in Figure 1, at least partially together with the projections 70 in the pressure plate 60 or its openings 72. In this case, contact between the projections 70 and the pressure stamps 16 occurs within the openings 72. Due to the displacement of the pressure pad 20, the projections 70 press the pressure stamps 16 out of the openings 72 and onto the workpieces.

[0123] Further embodiments of pressure cushions 22, pressure cushion units 20, molds 42 and casting devices 44 are described in Figures 8 to 11.

[0124] Figure 7 shows, in partial images 7a to 7e, an embodiment of a flat pressure pad 22, a pressure pad unit 20, and a casting device 44, which can be used for a hard die as a pressure punch 16 for an upper or lower tool 12, 14. The pressure pad 22 is received in a receiving cylinder 58 of a limiting element 56, after which a hard die 16 is connected as a pressure plate 60. The replaceable pressure pad 22 ensures parallelism of the die side 32 between the lower and upper dies and thus serves to compensate for parallelism of the pressing tools.

[0125] Fig. 7a shows a perspective view of a flat, disc-shaped pressure pad 20, which is shown in section AA in Fig. 7b. The pressure pad 20 consists of a disc-shaped solid core 24 and a similarly disc-shaped pad material 26 in a sandwich arrangement. Fig. 7c shows an installation position of the pressure pad 24 in a receiving cylinder 58 of a limiting element 56, which can be attached to a lower or upper tool 12, 14. A pressure plate 60 is provided as a hard die 16 towards the punch side 32. This is sealed against the pad material 26 of the pressure pad 22 by a circumferential piston ring seal 82, for example made of plastic, which prevents the pad material 26 from penetrating the gap between the receiving cylinder 58 and the pressure plate 60.

[0126] Figures 7d and 7e show a perspective view of a mold 42 of a casting device 44 for the disc-shaped pressure pad 22. This mold consists of a casting plate 46, which includes a negative recess 48 of the pressure pad 22, and a casting cover 52. The casting cover 52 is connected to the casting plate 46 by means of fixing elements 54, usually threaded screws. Liquid pad material 26, usually without pressure, can be injected into the negative recess 48 through a filling nozzle 50. A slight vacuum in the casting chamber assists the penetration of the pad material 26. The solid core 24 can be pre-inserted and is cast in by the pad material 26.

[0127] Figure 8 shows in partial images Fig. 8a to 8d a further embodiment of a pressure pad 22 as a soft stamp with contour-optimized solid core 24 and contour-optimized pad material 26.

[0128] Figures 8a and 8b show perspective views of a pressure pad 22 as a soft stamp from the perspective of the stamp side 32, with Figure 8b showing a section AA through which the solid core 24, pad material 26, and the central injection channel 86 provided in the solid core 24 are visible. Along the outer contour of the pressure pad 22, several guide elements 84 are formed as projecting guide lugs, along which a piston ring 62 (not shown) can be guided axially in a rotationally secure manner.

[0129] Fig. 8c shows a side view of the pressure pad 22, while Fig. 8d shows a sectional view and Fig. 8e an enlarged edge region of the pressure pad 22. The solid core 24 contains fastening elements 30, regularly spaced threaded holes, for mounting in a pressure pad unit 20 (see Fig. 9), as well as a central injection channel 86 through which liquid pad material 26 can be guided towards the punch side 32. The pressure pad 22 has a circumferential edge lip 34, with the pad material 26 tapering conically axially towards the punch side 32. Crucial for a long service life of the pressure pad 22 is the contour 90 of the conical tapering section, in particular the shape of the solid core 24 and the pad material 26 in the edge region, which is shown enlarged in Fig. 8e. The contour 90 is defined in Fig.8d Numerous diameters, heights, and radii are parametrically specified, the relationships of which determine the contour profile 90 and significantly influence the service life of the pressure pad 22. For example, the following dimensions and ratios of dimensions to each other can ensure a long service life for the pressure pad: d1 = 246.5 mm, d2 = 200 mm, h1 = 7 mm, h2 = 15 mm, a1 = 85°, a2 = 87.5°, oc3 = 10°, R1 = 1 mm, R2 = 50 mm, R3 = 4 mm, R4 = 2.5 mm.

[0130] Such a contour profile 90 ensures that, when a piston ring 62 (see Figs. 9a, 9b) is pressed into the pressure cushion 22 inserted in a receiving cylinder 58, the soft cushion material 26, which generates a pressure wave away from the displacement body of the piston ring 62, is deflected towards the ram side 32, thus directing the pressing energy towards the ram side 32. The contour shape of the solid core 24 acts as a deflection mirror for the pressure wave, and the contour shape of the cushion material 26 ensures a long service life. The outer surface of the solid core 24 is encased in the cushion material 26 in the area of ​​the edge lip 24. The solid core 24 also has fastening elements 30, by means of which the pressure cushion 22 can be securely fastened, usually by screws, after tool-free insertion into a pressure cushion unit 20 (see Fig. 9).Furthermore, the solid core 24 has a central injection channel 86 through which liquid cushion material 26 can be directed to the punch side 32 in a casting mold 42.

[0131] Fig. 9 shows a pressure cushion unit 20 in subfigure 9a, and in subfigures 9b, 9c sectional views AA an embodiment of a pressure cushion 22 with piston ring 62 and A'-A' another embodiment of a pressure cushion 22 with piston ring 62.

[0132] The pressure pad unit 20 is shown from the punch side 32 and accommodates a pressure pad 22, which can be, for example, an embodiment as shown in Fig. 8. The pressure pad 22 is encompassed in the direction of the punch side 32 by a piston ring 62, which is axially displaceable in the plane of the image and is guided in a receiving cylinder 58 of a limiting element 56. When the punch side 32 is placed on a workpiece 80 to be pressed, the piston ring 62 is displaced into the interior of the receiving cylinder 58 and compresses the pad material 26 of the pressure pad 22 in the direction of the punch side 32 to exert an isostatic pressure of the pad material 26 on a surface of the workpiece 80. The piston ring 62 is secured by fastening means 94, in this case by curved and recessed fastening plates fastened in the receiving cylinder 58 by three screws.

[0133] Figures 9b and 9c show cross-sections AA and A'-A' of embodiments of a pressure cushion unit 20, wherein the pressure cushions 22 used can be designed similarly to those in Figure 8. The two embodiments differ in the contour 90 of the conical tapered section and in a different cross-sectional geometry of the piston ring 62. The piston ring 62 is sealed against the pressure cushion 22 by a piston ring seal 82 in order to prevent the ingress of cushion material 26 into the cylinder gap between the piston ring 62 and the receiving cylinder 58 when pressure is applied. A compressed air connection 88 is provided at the rear center point of the pressure cushion unit 20 to enable air-assisted replacement of the pressure cushion 20 from the limiting element 56.In the piston ring 68, extraction aids 92 are provided on the punch side 32, which can be designed, for example, as threaded bores, and through which the piston ring 62 can be pulled out of the receiving cylinder 58 and removed from the pressure cushion 22 during the replacement process.

[0134] Fig. 10, analogous to Figs. 4a and 4b, depicts a casting device 44 with a mold 42. The casting device 44 is particularly suitable for producing an embodiment of a pressure pad 22 shown in Fig. 8 and therefore has regularly arranged filling nozzles 50 along a circumference. These filling nozzles 50 can introduce liquid pad material 26, preferably with vacuum assistance, into the area of ​​the edge lip 34 in order to cast a metallic solid core 24 containing pad material 26. Furthermore, pad material 26 can be directed to the punch side 32 via an injection channel 86 in the solid core through a central filling nozzle 50. The mold 42 of the casting device 44 is composed of two parts: a casting plate 46, which receives a negative recess of the pressure pad 22, and a casting cover 52, which supports the filling nozzles 50. The two parts are connected by fixing elements 54, usually long screws and possiblya cast seal connected to each other. Finally, Fig. 11 shows another embodiment of a mold 42 for a relatively compact pressure pad 22, such as can be used, for example, in a multi-press device with a plurality of adjacent and independently movable individual punches. The mold 42 comprises a casting plate 46, which has a negative recess 48 into which liquid pad material 26 can flow. A positive form 96 of a solid core 24 is provided centrally in the negative recess 48, which creates a recess in the solidified pad material 26 into which a solid core 24 can subsequently be inserted. The casting cover 52 is omitted in the illustration. Reference numeral list: Diffusion soldering device and / or sintering device, upper tool.

[0135] Lower tool

[0136] Printing stamp / Weight bar

[0137] heating element

[0138] Pressure pad unit

[0139] pressure pad

[0140] solid core

[0141] Pillow material

[0142] Mounting side

[0143] Fastener

[0144] Stamp page

[0145] rim lip

[0146] Prison section

[0147] rejuvenation

[0148] Barbs

[0149] Mold

[0150] Casting device

[0151] Cast iron plate

[0152] Negative recess

[0153] Filler neck

[0154] Cast iron cover

[0155] Fixing elements

[0156] Boundary element

[0157] Receptacle cylinder

[0158] printing plate

[0159] piston ring

[0160] Fasteners

[0161] Fastening device surface profiling

[0162] Survey

[0163] opening

[0164] Core profiling Core insert

[0165] Core stamp area

[0166] workpiece

[0167] Pressure plate seal, piston ring seal

[0168] Piston ring guide element

[0169] Injection channel in the solid core

[0170] Compressed air connection in pressure cushion unit

[0171] Contour profile with conical tapered section of the pressure stamp; piston ring extraction aid

[0172] Piston ring fastening device

[0173] Positive form of the solid core for subsequent insertion

Claims

Patent claims 1. Pressure pad (22) for a diffusion soldering device and / or sintering device (10), wherein the pressure pad (22) can be inserted into a tool (12, 14), in particular an upper tool (12), of the diffusion soldering device and / or sintering device (10) having at least one axially displaceable pressure punch (16) and is designed to transmit an equilibrated pressure force to the at least one pressure punch (16), characterized in that the pressure pad (22) is manufactured as a prefabricated replacement element, in particular by means of a separate mold (42), wherein the pressure pad (22) comprises at least one solid core (24), in particular a metal core, which is attached, in particular cast in or at least partially encased or inserted, to a pressure-elastic and castable pad material (26), wherein the solid core (24) is designed and connected to the pad material (26) in such a way as toin particular embedded in the cushion material (26), the pressure cushion (22) can be inserted into and removed from a pressure cushion unit (20) of a pressure stamp (16) of the tool (12, 14) by means of the solid core (24), in particular without tools.

2. Pressure cushion according to claim 1, characterized in that the solid core (24) has at least one force-, form- and / or material-locking adhesive section (36), in particular a taper (38), incision, undercut, barb (40) or the like, for adhesion of the solid core (24) in or to the cushion material (26).

3. Pressure cushion according to one of the preceding claims, characterized in that the cushion material (26) is made of a high-temperature-resistant elastomer material, in particular silicone.

4. Pressure pad according to one of the preceding claims, characterized in that the pad material (26) has a circumferential edge lip (34) on a side facing the solid core (24), and / or tapers conically in a stamp side (32) opposite the solid core (24).

5. Pressure pad according to one of the preceding claims, characterized in that the solid core (24) is made of, in particular magnetic or magnetizable, metal, in particular stainless steel, and / or plastic, and / or tapers towards a punch side (32) opposite a fastening side (28) of the solid core.

6. Pressure cushion according to one of the preceding claims, characterized in that the pressure cushion (22) and the solid core (24) are designed for a high temperature range of 180°C to 380°C, preferably between 220°C and 260°C.

7. Pressure pad according to one of the preceding claims, characterized in that the pressure pad (22) has a square or rectangular shape, in particular with rounded corners, a circular or elliptical shape or a polygonal shape.

8. Pressure pad according to one of the preceding claims, characterized in that the pressure pad (22) and / or the solid core (24) has a surface profile (68) with at least one protrusion (70) or a core profile (74) for transferring the equilibrated pressure force to the pressure punch (16) on a punch side (32) attributable to the at least one pressure punch (16), wherein preferably a core insert (76) with a Shore hardness than the pad material (26) is inserted in the core profile (74).

9. Pressure pad according to one of the preceding claims, characterized in that the protrusion (70) of a pressure plate (60) can be assigned to a pressure pad unit (20) receiving the pressure pad (22), wherein the protrusion (70) is formed essentially complementary to an opening (72) of the pressure plate (60), so that the protrusion (68) can be inserted into the opening (72) and the equilibrated pressure force can be transmitted indirectly via the pressure plate (60) through the opening (72) to the pressure stamp (16).

10. Pressure pad unit (20) for a tool (12, 14), in particular upper tool (12), a diffusion soldering device and / or sintering device (10), comprising at least one pressure pad (22), at least one pressure plunger (16) associated with the pressure pad (22) and a limiting element (56) encompassing the pressure pad (22) at least partially, into which the pressure pad (22) can be inserted or is inserted, wherein the limiting element (56) is designed to limit deformation of the pressure pad (22) and to seal the pressure pad (22) against a component exerting a pressure force on the pressure pad (22), characterized by a design of the pressure pad (22) according to one of claims 1 to 9.

11. Pressure cushion unit (20) according to claim 10, characterized in that the limiting element (56) comprises a receiving cylinder (58) for the pressure cushion (22) and a pressure plate (60) receiving and guiding the pressure punch(es) (16), as well as a piston ring (62), wherein the piston ring (62) causes the pressure cushion (22) to be compressed, preferably by a stop against an opposing tool (14, 12), in particular a lower tool (14), and further preferably compresses the edge lip (34) of the cushion material (26).

12. Pressure cushion unit (20) according to claim 10 or 11, characterized in that the limiting element (56) is made of a material that is more rigid than the pressure cushion (22), in particular non-deformable, preferably metal, in particular steel, or plastic, and / or the pressure cushion (22) is connected to the limiting element (56), preferably detachably, by means of a material, force and / or form-fitting connection, preferably by means of a quick-release device, in particular inserted into the receiving cylinder (58).

13. Pressure cushion unit (20) according to one of claims 10 to 12, characterized in that the limiting element (56) has at least one force- and / or form-locking fastening device (66), in particular a quick-release unit or clamping device, for fastening the pressure cushion unit (20) to the tool (12, 14), in particular upper tool (12) and / or lower tool (14), preferably without tools.

14. Pressure cushion unit (20) according to one of claims 10 to 13, characterized in that the pressure cushion (20) is inserted at least partially into a pressure plate (60) of the boundary element (56) with a protrusion (70) of a surface profile (68).

15. Pressure pad unit (20) according to claim 14, characterized in that the pressure plate (60) has at least one opening (72) into which, in particular instead of the pressure stamp (16), the projection (70) of the pressure pad (22) is inserted, so that the equilibrated pressure force can be transmitted indirectly via the pressure plate (60) to the pressure stamp (16) by means of the projection (70).

16. Mold (42), in particular a die, for producing a pressure pad (22) for a tool (12, 14) of a diffusion soldering device and / or sintering device (10), characterized in that the mold (42) is designed for producing a pressure pad (22) according to one of claims 1 to 9 for a pressure pad unit (20) according to one of claims 10 to 15, in particular wherein the mold (42) has a profiling section for generating a surface profiling (68) of the pressure pad (22).

17. Casting device (44) for producing a pressure cushion (22) according to claims 1 to 9, at least comprising a mold (42) according to claim 16.

18. Casting device according to claim 17 characterized in that the casting device (44) has a material supply device, in particular an injection pump, for supplying a material, in particular silicone, for the pressure cushion into the mold, and / or a handling device for handling the mold, and / or control and / or sensor means, in particular a control unit, sensors and / or actuators, for automating the production of the pressure cushion (22) by the mold (42).

19. Method for manufacturing a pressure pad (22), in particular a pressure pad (22) according to any one of claims 1 to 9, for a diffusion soldering device and / or sintering device (10), wherein the pressure pad (22) can be inserted into a tool (12, 14) having at least one axially displaceable pressure die (16), in particular an upper tool (12), of the diffusion soldering device and / or sintering device (10) in order to transmit a pressure force to the at least one pressure die in an equilibrating manner, characterized in that the pressure pad (22) is prefabricated separately as an exchange element before being inserted into the tool (12, 14) using a mold (42), in particular a mold (42) according to claim 16, and / or a casting device (44) according to any one of claims 17 to 18, wherein the pressure pad (22) with at least one solid core (24), in particular a metal core, is manufactured by a casting step becomes,wherein the solid core (24) is attached at least section by section to or within a pressure-elastic and castable cushion material (26), in particular cast in or at least partially encased or inserted, wherein the solid core (24) is arranged in the cushion material (26) and connected to the cushion material (26), in particular embedded, such that the pressure cushion (22) can be inserted into and removed from the tool (12, 14), preferably into a pressure cushion unit (20) of the tool (12, 14), by means of the solid core (24), in particular without tools, wherein in particular the pressure cushion (22) is produced with a surface profile (68) having at least one projection (70) and / or a core profile (76) of the solid core (24) receiving a core insert (78).

20. Method for using a pressure cushion (22) according to one of claims 1 to 9 and a pressure cushion unit (20) according to one of claims 10 to 15, characterized in that in a pressure cushion unit (20) the pressure cushion (22) is inserted in a limiting element (56) which at least partially encompasses the pressure cushion (22), and is, in particular detachably, connected to the limiting element (56) by material, force and / or form-fitting means, so that the pressure cushion (22) inserted in the pressure cushion unit (20) forms an interchangeable insert for insertion into a pressure die (16) of the tool (12, 14).

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