Sintering device and method

Abstract

The invention relates to a sintering device (10) and a sintering method for simultaneously connecting components of a plurality of electronic assemblies (22) arranged next to each other by means of pressure sintering, the sintering device having an upper tool (12) and a lower tool (14) and comprising a plurality of first punches (16), which can be associated with the upper tool (12), and at least one, in particular a plurality of second punches (18), which can be associated with the lower tool (14), the assemblies (22) being accommodated therebetween. For this purpose, each of the first punches (16) and / or each of the at least one second punch (18) has a drive device (28, 28.1, 28.2), which is designed to apply a pressing force to one of the assemblies (22) by axially moving the associated first punch (16) and / or the associated second punch (18) along a direction of action of the pressing force (P). According to the invention, the first punches (16) are laid onto the assemblies (22) before the start of the pressing operation and, during the application of the pressing force, press the assemblies (22) against the at least one second punch (18).

Description

[0001] SINTERING DEVICE AND METHOD

[0002] The present invention relates to a sintering device and a method for simultaneously joining components of several adjacently arranged electronic assemblies by means of pressure sintering.

[0003] STATE OF THE ART

[0004] Pressure sintering allows two or more components, particularly electronic components and substrates, to be electrically and / or thermally bonded together using a joining material. The joining material is sintered. The components to be joined are pressed uniaxially between an upper and lower tool to provide joining pressure.

[0005] It has been found that producing a connection under a process atmosphere, in particular under reduced pressure or vacuum, is particularly advantageous, especially for preventing undesirable chemical reactions such as oxidation, preventing gas inclusions, and preventing contamination. The heat required for sintering is generally transferred to the components via the upper and lower tools, but can also be applied as radiant heat from the bottom and / or top. Often, several components are to be arranged on a common substrate. These components can differ from one another in terms of both their lateral extent and their height. To ensure even pressure transfer, several press punches can be provided on the upper and / or lower tools, the dimensions of which are tailored to the components to be joined.

[0006] If a system is to process various assemblies of different types, it is often necessary to adjust the press ram arrangement on the upper and lower tools. This adjustment is time-consuming and is made more difficult by the fact that the tools and / or press rams can be hot. Furthermore, the tools, especially the press rams, are usually made of metal because they must withstand high compressive forces. Therefore, such tools are heavy, cool slowly, and are costly. Furthermore, precise alignment of the tools or press rams with the components to be joined is required.

[0007] It is an object of the invention to provide a sintering device and a corresponding method which allows a quick and reliable adaptation of a press die arrangement to the components to be joined.

[0008] DISCLOSURE OF THE INVENTION

[0009] The object is achieved by a sintering device having the features of claim 1 and by a method having the features of the independent claims. Preferred embodiments are specified in the subclaims.

[0010] A sintering device according to the invention for simultaneously joining components of a plurality of adjacently arranged electronic assemblies by means of pressure sintering comprises an upper tool and a lower tool, wherein a plurality of first press dies can be assigned to the upper tool (12), and at least one, in particular a plurality of second press dies are assigned to the lower tool. The assemblies are accommodated between the first press die and the at least one, in particular a plurality of second press dies, wherein each of the first press dies and / or each of the at least one second press dies is assigned a drive device which is designed to exert a pressing force on one of the assemblies by axially displacing the assigned first press die and / or the assigned second press die along an effective direction of the pressing force (P).

[0011] It is proposed that the first pressing dies are placed on the assemblies before the start of the pressing process, ie they are also placed outside the sintering device before the sintering process, and that the assemblies are pressed against the at least one second pressing die during the application of the pressing force.

[0012] In contrast to conventional sintering devices, in which the press dies acting on the upper side of the assemblies are permanently or replaceably attached to an upper tool, the first press dies acting on the upper side of the assemblies are only loosely placed on the assemblies or their components. The first press dies are preferably placed on the assemblies or their components outside the sintering device, so that during the necessary step of introducing the components into the sintering device, the first press dies can be introduced together with the components. If the drive device(s) drive theWhen the second press rams are moved to exert the pressing force, the first press rams, together with the underlying components of the assemblies, are pressed against the pressure plate arranged above the assemblies, which is stationary, for example, attached to a frame of the sintering device, or against the respective drive devices of the upper tool. Alternatively, the second press ram(s) can be supported on a pressure plate of the lower tool, and the first press rams of the upper tool press the assemblies against the pressure plate or the second press rams of the lower tool. The pressure plate or the respective opposite drive device thus applies a counterforce that opposes the pressing force.The drive device, preferably of the lower tool and / or upper tool, can preferably be temperature-controlled by means of corresponding heating and / or cooling devices in order to effect heat transfer to or from the components through the first and / or second press dies. The heating and / or cooling device is preferably provided at least in the lower tool in order to heat a base body of the assembly, while the first press dies of the upper tool are thermally heated beforehand, e.g., before or after application, so that a separate heating or cooling device in the upper tool can be dispensed with if necessary.

[0013] Alternatively or in addition to placing the first press punches on the assemblies before the start of the sintering process, as described in EP 4 080 554 A2, at least some of the first press punches, in particular all of the first press punches, can be exchangeably fastened in the upper tool, in particular thermally clamped in a clamping device. This enables a flexible configuration of the first press punches. For example, the first press punches can be displaceably received on or in a holding plate of the upper tool at a first temperature along an effective direction of the pressing force in the upper tool and can be clamped on or in the holding plate or the upper tool at a second temperature which is higher than the first temperature. This enables rapid and precise adaptation to respective assemblies in which the various components have different heights.For example, at the first, i.e. low, temperature the first press punches can be brought close to the assemblies to be joined or a corresponding alignment gauge until all contact surfaces of the first press punches are in contact with the respective assigned components. In this case, those press punches that are in contact with relatively high components or parts are offset further than those press punches that are in contact with components or parts with a comparatively low height. Once the press punches have adapted their longitudinal position to the components or assemblies, the temperature of the first press punches and the holding plate of the upper tool increases. This clamps the first press punches on or in the holding plate and thus fixes them in their longitudinal or axial position. This clamping creates a frictional connection between the first press punches and the holding plate.

[0014] Advantageously, a definable temperature gradient can be provided between the upper and lower dies during the sintering process by separately operating heating or cooling devices in the lower and lower dies, particularly in the associated press dies. Typically, a heat-sensitive upper part of the assembly, e.g., a power semiconductor component, faces the upper die, while a heat-insensitive and, advantageously, highly thermally conductive lower part of the assembly, e.g., a heat sink, faces the lower die. A sintered joint is intended to be created between the underside of the upper part and the lower part of the assembly, usually with an intermediate layer of sintering paste.To avoid exceeding a limit temperature of the upper part, the upper punch can be heated or cooled along a temperature curve with lower temperature curves compared to a temperature curve with higher temperatures of the upper punch during the sintering process. For example, a temperature gradient of 50°C to 100°C can be set between the hotter, lower second press punches and the cooler, upper first press punches, at least until the sintering temperature is reached.

[0015] If a single drive device is used in the upper tool and / or the lower tool, this can be designed, for example, as a single-acting hydraulic cylinder for the respectively assigned individual or multiple first and / or second press rams. The single-acting hydraulic cylinder can have a large piston area that can essentially cover the arrangement area of ​​the assemblies on the support frame. The single-acting hydraulic cylinder can be reset, for example, via a spring means or via another reset element. In this respect, it is possible to dispense with hydraulically tensioned action on a press plane and the use of a complex, double-acting hydraulic cylinder; instead, the single-acting hydraulic cylinder can move freely as a cylinder block, so that the hydraulic pressing device can be provided cost-effectively and places low demands on the hydraulic control system.

[0016] In an advantageous embodiment, the first press rams can be supported against a pressure plate of the upper tool, wherein the at least one drive device of the lower tool, in particular a respective drive device assigned to each second press ram, applies an effective direction of the pressing force P in the direction of the upper tool via the at least one second press ram. Alternatively, the at least one second press ram can be supported against a pressure plate of the lower tool or can be formed therefrom, wherein the at least one drive device of the upper tool, in particular a respective drive device assigned to each first press ram, applies an effective direction of the pressing force P in the direction of the lower tool. In this embodiment, at least one drive device for applying a pressing force in the effective direction towards the lower tool orto the upper tool. If at least one drive device is provided in the upper tool, the pressing force can be transmitted, for example, via a pressure plate to the first press rams with the direction of action towards the lower tool. Alternatively, drive devices (multi-drives) separately assigned to each of the first press rams can be arranged in the upper tool, which can individually exert pressing forces on the first press rams. In this case, the second press ram can be designed, for example, as a pressure plate in the lower tool. Alternatively, a plurality of second press rams can statically support the assemblies in the lower tool relative to the lower tool. Alternatively, at least one drive device can be provided in the lower punch. This can, for example,the second press ram, designed as a pressure plate, or several second press rams statically connected to the drive device in the effective direction of the pressing force towards the upper ram. Nevertheless, each of the several second press rams, in particular each second press ram associated with a first press ram, can also be separately assigned to a respective drive device (multi-drive), which can individually exert pressing forces on the second press rams. In this respect, this embodiment provides a common drive device or multi-drives for the first or second press rams, either in the upper tool or in the lower tool.

[0017] As an alternative to the aforementioned embodiment, in a further advantageous embodiment, a respective drive device of the upper tool can be assigned to the plurality of first press dies and a drive device of the lower tool can be assigned to the plurality of second press dies, wherein each electronic module can be acted upon on both sides by the drive devices of the upper tool and the lower tool by opposing directions of action of the pressing forces P. In this embodiment, a sandwich-like, counter-rotating pressing of the modules by at least one drive device of the upper tool and the lower tool is proposed. The drive device of the upper tool can distribute pressing forces to the first press dies placed on the modules as an individual drive, for example via a pressure plate. Alternatively, a respective drive device can be provided, separately assigned to each first press die.The same applies to the drive device of the lower tool. This can be provided either as a single drive device that applies a pressing force in the effective direction of the upper tool, for example via a second press ram designed as a pressure plate, or via several second press rams arranged statically on the drive device. Alternatively, a separate drive device can be provided for each second press ram. In contrast to the aforementioned embodiment, by mutually pressing the assemblies using counter-rotating drive devices in the upper and lower tools, individual temperature and pressure parameters can be achieved on adjacent assemblies. This is particularly advantageous for parallel sintering of different assemblies.

[0018] According to a preferred embodiment, each drive device can be controlled individually, preferably hydraulically, electromotively, piezoelectrically or magnetostrictively, with regard to an offset path and / or an exerted pressing force. A respective first and / or second press ram is preferably assigned to a respective assembly or component. This makes it possible to apply a uniform pressing pressure to the various assemblies or individual components. In particular, it is ensured that each assembly can be individually subjected to a predetermined pressing pressure. This avoids, among other things, individual assemblies being subjected to too high or too low a pressing pressure, as is the case, for example, with conventional solutions in which several assemblies are only subjected to a single common press ram. A further advantage is that height tolerances of the assemblies orcomponents can be compensated or taken into account. The required pressing force can be set, for example, with the help of an assigned force or pressure sensor or even a position sensor, whereby the exerted pressing force can be set directly by setting a working pressure or indirectly by setting an offset path of the second press ram. A hydraulically controllable drive device can, for example, be formed by an arrangement of double-acting pistons, which can be fed by means of appropriate control valves from a common, pressurized fluid reservoir. In principle, however, each drive device can also have its own fluid source for generating pressure, which means that valves can be dispensed with. An electric motor control can, for example, be achieved with the help of a drive device having a spindle drive.Furthermore, piezoelectric or magnetostrictive drive devices can also be provided.

[0019] According to a further preferred embodiment of the invention, each of the first and / or second press rams is connected to the associated drive device. Advantageously, the second press rams are not superimposed, but rather form a unit with the associated drive device.

[0020] Alternatively or additionally, each of the first and / or second press rams can have a respective heating and / or cooling device. By means of the heating or cooling device, an individually controllable heat transfer to or from this assembly can take place individually for each second press ram and thus for each assembly in thermal contact therewith. The heating and / or cooling device can, for example, be electrically operated and / or comprise respective fluid channels provided in the second press rams, which are in fluid communication with a corresponding temperature-controlled fluid source. The heating and / or cooling device is preferably designed as a pin-contact heating and / or cooling device.Using highly thermally conductive, elastic pins, a heating or cooling temperature can be efficiently transferred even before the second press dies make full contact with the assemblies, and in particular, any alignment problems such as surface parallelism can be compensated for. Such thermal transfer pin contacts are described, for example, in WO 2016 / 091962 A1. These can be used in a heating chamber to heat the assembly, the second press die, and / or the printing plate. Preferably, in a combined temperature control of the heating and / or cooling device, the temperatures of the first and second press dies are controlled simultaneously and while maintaining a predefined temperature gradient between the respective first and associated second press die. This protects temperature-sensitive parts of the assemblies from thermal overload.Furthermore, identical temperature conditions can be maintained on the first and second press dies even after a large number of repeated sintering processes.

[0021] According to a further preferred embodiment, a support frame which can be introduced into the sintering device is provided, in which the components of the assemblies, preferably together with the applied first press dies, are held guided in the lateral direction, wherein the support frame preferably has openings assigned to the assemblies, through which openings the second press dies can come into mechanical and thermal contact with the assemblies. The assemblies are mounted by the support frame in a laterally aligned manner in accordance with an arrangement grid of the second press dies, wherein the lateral alignment refers to an alignment transverse to the pressing direction. While the support frame thus prevents lateral movement of the components, movement along a direction of action of the pressing force is permitted. The openings enable the second press dies to lift the components out of the support frame.

[0022] According to a further preferred embodiment, at least one guide frame is preferably detachably arranged on the carrier frame, which is designed to guide the first press punches in a lateral direction relative to the assemblies. The guide frame thus prevents any relative movement of the applied press punches relative to the components of the assemblies and / or the carrier frame. To facilitate the loading of the carrier frame or reconfiguration for different assembly and / or punch configurations, the at least one guide frame can be plugged onto the carrier frame or screwed to it. For example, the guide frames can only be arranged after the components have been inserted into the carrier frame, whereupon the first press punches can then be inserted into the guide frame.

[0023] Preferably, the guide frame has a higher thermal expansion coefficient than an upper part of the assembly. The assembly to be sintered can consist of individual, stacked parts, for example, power semiconductor components as the upper part and a heat sink as the lower part of the assembly, which can have different thermal expansions. For example, a power semiconductor component has a lower thermal expansion than a heat sink. Heating to sintering temperature can lead to undesirable relative displacement of the stacked assemblies.Since precise alignment of the individual stacked parts of the assembly relative to one another is important in the subsequent processing step, the guide frame can advantageously have a thermal expansion that compensates for the undesirable thermal relative displacement of the assembly parts relative to one another and, for example, thermally displaces the upper parts in the same way as the lower part(s). Advantageously, the guide frame can have a higher thermal expansion than the upper parts of the assemblies accommodated therein and can, in particular, be made of aluminum. The lower part of the assembly can, for example, be a heat sink and can be made of copper or a similarly thermally conductive material. This expands when heated, whereas an upper part of the assembly, for example a power semiconductor component, expands less when heated.To ensure the power semiconductor components are sintered correctly onto the heat sink, the guide frame can have a higher coefficient of thermal expansion to adjust the relative alignment of the upper and lower parts of the modules when heated. For example, aluminum is suitable for the guide frame, rather than copper for the lower part of the modules. For example, in subsequent process steps, an electrical supply board can be precisely connected to the terminals of the power semiconductor components, preferably converter components such as IGBTs for electrical energy conversion, sintered on a common heat sink or on individual heat sinks.

[0024] According to a further preferred embodiment, each of the first and / or second press punches has a punch body that is axially displaceable along a direction of action of the pressing force and a contact surface that can be contacted with a component of the assembly, wherein the contact surface is mounted such that it can be tilted relative to the punch body about at least one spatial axis. Preferably, however, the contact surface is tiltable about two Cartesian spatial axes, wherein the third spatial axis of this Cartesian spatial axis system runs along the direction of action of the pressing force. The contact surface is thus movable in a cardanic manner relative to the punch body, so that the contact surface can evenly contact the component in contact with it.In contrast to a rigidly aligned contact surface, which may under certain circumstances be tilted relative to the component it contacts, this prevents the occurrence of force peaks or force gradients within the components and distributes the pressing force evenly. The alignment of the contact surface takes place automatically. The tiltable mounting of the contact surface relative to the punch body can be achieved, for example, by an elastic compensating layer. A respective press punch can, for example, also be divided into two parts and, in addition to the aforementioned punch body, comprise another punch body which has the aforementioned contact surface, wherein both parts of the punch bodies are connected via the aforementioned elastic compensating layer or another mounting allowing tilting is provided.

[0025] According to a further preferred embodiment, a respective second press die is assigned a plurality of adjacently arranged first press dies. Alternatively, a respective first press die can be assigned a plurality of adjacently arranged second press dies. In particular, the first and second press dies assigned to a second and first press die can have different heights. This also makes it possible to sinter assemblies in which, for example, a plurality of components of different heights are to be arranged on a flat substrate. The height of the first and second press dies is dimensioned such that the contact surfaces of the first and second press dies facing the printing plate lie in a common plane.Advantageously, the first press dies can be transported in a flow production process by a transport device, in particular bypassing the sintering device after completion of the sintering process, from an unloading station downstream of the sintering device back to a loading station upstream of the sintering device, as described, for example, in WO 2021 / 069328 A1. This ensures a series production process that can sinter a large number of components to be joined at high cycle rates.

[0026] A method according to the invention for the simultaneous connection of components of several adjacently arranged electronic assemblies by means of pressure sintering in a sintering device, which is designed in particular according to one of the preceding inventive or preferred embodiments, wherein the sintering device comprises several first press dies and at least one, in particular several second press dies, between which the assemblies are accommodated, wherein each of the first press dies and / or the at least second press die is displaceable axially along an effective direction of the press force by means of an associated drive device for exerting a press force on one of the assemblies, comprises the steps

[0027] Placing the first press stamps on the assemblies,

[0028] Introducing the assemblies together with the first press dies into the sintering device in a position aligned with the second press dies, and carrying out the sintering process by actuating the drive device in order to move the first press dies and / or the at least second press die for generating the pressing pressure from a rest position into a working position in which the assemblies are pressed together between the first press dies and the at least second press die, which is arranged opposite the first press dies for applying a counterforce.

[0029] By placing the first press dies on the assemblies and jointly introducing the assemblies into the sintering device, the first press dies can be configured in a simple manner, which includes both the arrangement of first press dies of suitable size and their exact alignment relative to the assemblies or indirectly also to the arrangement geometry of the second press die(s).

[0030] The insertion of the assemblies together with the first press dies into the sintering device can advantageously be carried out with the aid of a support frame in which the components of the assemblies are held in a laterally guided manner together with the applied press die. The support frame can preferably have openings assigned to the assemblies, through which the second press dies can come into mechanical and thermal contact with the assemblies. The assemblies can be lifted out of the support frame during the movement of the second press die(s) into the working position.To prevent the first punches from slipping sideways or laterally during the lifting process before they come into contact with the pressure plate and are fixed in place by the building-up pressing force, the support frame can have a guide frame designed to guide the first pressing punches laterally relative to the assemblies. The guide frame ensures axial displacement of the first pressing punches in the effective direction of the pressing force.

[0031] Advantageously, the guide frame and / or the support frame have complementary alignment elements such as guide pins, guide grooves, guide recesses, or the like, which ensure a correct position of the guide frame on the support frame. When assembling the modules on the support frame, for example, a lower part of the module, such as a heat sink, which can also serve as the lower part for several attached upper parts of the module, can be placed on or in the support frame. The guide frame can then be placed on the support frame in a positionally aligned manner using alignment elements. The guide frame can have openings into which an upper part of the module, such as power semiconductor components with applied first press dies, can be inserted.

[0032] According to a preferred embodiment of the method, at least the step of carrying out the sintering process comprises heating and / or cooling the first press die and / or the at least one, in particular a plurality of second press dies. In this way, the heat required for sintering can be transferred to the assemblies via the press dies and, if necessary, targeted cooling can also take place. To protect against exceeding a critical temperature of an upper part of the assembly, for example a power semiconductor component, the first, upper press die can preferably maintain a lower temperature level during the sintering process than the second, lower press die, which faces, for example, a heat sink. Thermal transfer can preferably take place via an elastic thermal transfer device, as known from WO 2016 / 091962 A1. The second press die(s) is / are preferably heated orCooled, the first press dies are preheated before or after being placed on the assemblies, and their thermal storage capacity allows them to maintain a predeterminable temperature level. This may eliminate the need for a heating and / or cooling device in the upper tool.

[0033] According to a further preferred embodiment of the method, the actuation of various drive devices for moving the first and / or second press rams into the working position occurs at different times. The actuation of the various drive devices for moving the first and / or second press rams from the working position back to the rest position can occur in the same chronological sequence, simultaneously, or in the reverse chronological sequence.

[0034] According to a further advantageous embodiment of the method, the staggered actuation of various drive devices takes place in such a way that at least one drive device arranged in a central area is actuated first, and further outward drive devices are actuated at a time interval. For example, in an arrangement of nine press dies in three rows of three press dies each, the middle press die can be moved first, followed by the press dies further out surrounding it. By prematurely lifting the central component or central assemblies, the aforementioned guide frame can advantageously be lifted along with it, and all upper press dies or upper parts of the assemblies with the upper press die accommodated therein can also be lifted and centered before the other, peripheral press dies press.This allows for early alignment of the assemblies with respect to the upper and lower press rams or upper and lower drive devices. The guide frame advantageously comprises three groups of three assemblies each, or possibly four groups of three assemblies each, with the middle drive device within each group prematurely lifting the middle assembly with the upper press ram and guide frame out of the support frame.

[0035] Preferably, at least the sintering process takes place under a process atmosphere, in particular under an oxygen-free, oxidation-preventing process atmosphere, preferably at a negative pressure and in particular under vacuum.

[0036] Advantageously, a measuring support frame can be provided for calibration and / or verification of the sintering device and the sintering process, which may also include a measurement guide frame and geometrically simulated assemblies arranged in the correct position. Pressure sensors and / or temperature sensors can be provided in or on the simulated assemblies. These sensors, for example, are first passed through the sintering device during setup or calibration of the sintering device and subjected to the specified sintering pressures and temperatures to enable verification and calibration of the sintering process. The data from the pressure and / or temperature sensors can be used to adjust process parameters and to test the proper functioning of the sintering device.

[0037] Preferably, the heating and / or cooling temperature transfer takes place via mechanical contact pin cooling. If necessary, thermal radiation transfer, for example, via induction heating, infrared heaters, or convection temperature transfer through process gas circulation, can also be used.

[0038] DRAWINGS

[0039] Further advantages emerge from the drawings and the associated description of the drawings. The drawings illustrate exemplary embodiments of the invention. The drawings, the description, and the claims contain numerous features in combination. Those skilled in the art will expediently consider the features individually and combine them into further meaningful combinations. In particular, those skilled in the art will also utilize features described with reference to embodiments of the sintering device in embodiments of the method according to the invention, and vice versa.

[0040] They show:

[0041] Fig. 1 is a schematic longitudinal sectional view of a sintering device according to a first embodiment;

[0042] Fig. 2 is a schematic perspective view of a support frame of the sintering device of Fig. 1 with inserted components;

[0043] Fig. 3 is a perspective view of the support frame of Fig. 2 additionally with the first pressing dies and guide frames placed on it;

[0044] Fig. 4 to 7 are schematic cross-sectional views of the sintering device of

[0045] Fig. 1 in different operating positions;

[0046] Fig. 8 is a schematic longitudinal sectional view of a sintering device according to a second embodiment; and

[0047] Fig. 9 is a schematic longitudinal sectional view of a sintering apparatus according to a third embodiment.

[0048] Figs. 1 and 4 to 7 show a sintering device 10 according to a first exemplary embodiment, which comprises an upper tool 12 and a lower tool 14. In the first exemplary embodiment, a sintering device 10 is considered in which the first press rams 16 are statically supported against a pressure plate 20 of the upper tool 12, wherein a plurality of second press rams 18 of the lower tool 14, each displaceable by separate drive devices 28, 28.2, are displaceable. The sintering device 10 can comprise a solid press frame, which can define an evacuable process chamber, wherein the upper tool 12 and the lower tool 14 are supported on the press frame.

[0049] The upper tool 12 comprises a flat pressure plate 20, which may have a heating and / or cooling device (not shown). The lower tool 14 comprises an arrangement of second press rams 18, wherein each second press ram 18 is assigned a drive device 28. The drive devices 28 can, for example, each be configured as a hydraulically operated piston-cylinder arrangement, which is operated by means of a pressurized hydraulic fluid in order to raise or lower the associated second press ram 18. The second press rams 18 can also have heating and / or cooling devices, for example fluid channels through which temperature-controlled fluid flows, or IR-based, electrical, or inductive heating elements.

[0050] Between the second press punches 18 of the lower tool 14 and the pressure plate 20 of the upper tool 12, a working space 40 is defined, into which a support frame 30 can be inserted or pushed, on which the components of the assemblies 22 to be connected are mounted.

[0051] The operation of the carrier frame 30 is explained in more detail with reference to Figs. 2 and 3. The carrier frame 30 comprises an outer frame 34 with a central opening, in which an inner frame 36 is arranged. In the exemplary embodiment, a total of five substrates 24 are inserted into the inner frame 36 and held in a laterally guided manner, for example, heat sinks or carrier plates for a power semiconductor component, on each of which three components 26 are placed, for example, semiconductor units or so-called molds, in each of which several semiconductor components are pre-assembled and encapsulated. Respective first pressing dies 16 are in turn placed on the components 26, with three first pressing dies 16 assigned to a respective substrate 24 being mounted in a laterally guided manner in a guide frame 32. Each guide frame 32 accordingly extends over a respective substrate 24.The support frame 30 has openings or perforations covered by the substrates 24, through which the second press dies 18 can come into direct contact with the assemblies 22 or the substrates 24.

[0052] With the exemplary sintering device 10 shown, a total of five assemblies 22 can be joined by pressure sintering, wherein each assembly 22 comprises a common substrate 24 and three components 26 arranged in series thereon. Accordingly, the second press dies 18, including the associated drive devices 28, are arranged in a matrix with five rows of three second press dies 18 or three drive devices 28, respectively. The placed first press dies 16, the components 26, the second press dies 18, and the drive devices 28 are each aligned with one another, ie, the aforementioned components are arranged vertically one above the other in each of the fifteen stacks in plan view, ie, in the direction of action of a pressing force P.

[0053] The support frame 30 is preferably loaded with the assemblies 22, the guide frame 32, and the first press dies 16 outside the sintering device 10. After loading has been completed, the support frame 30, including the elements arranged thereon, is pushed into the sintering device 10. A corresponding rest position is shown in Fig. 1, in which the sintering device 10 is shown in a longitudinal section, so that a total of five press dies 16, 18 and, accordingly, five assemblies 22 and five drive devices 28 are visible. In contrast, the sectional views shown in Figs. 4 to 7 represent cross-sections, so that in each case only one assembly 22 with a substrate 24 and three components 26 placed on it is visible. Accordingly, only three press dies 16, 18 and three drive devices 28 are shown.

[0054] As can be seen in Fig. 4, the second press punches 18 can have a two-part punch body 42 with an upper punch body 44 facing the pressure plate 20 and a lower punch body 46 facing the associated drive device 28. The contact surface 48 between the upper punch body 44 and the lower punch body 46 is designed as a spherical surface and enables the upper punch body 44, which is in contact with the assembly 22, to automatically align itself on the underside of the assembly by a small sliding movement along the spherical surface. This prevents the occurrence of pressure peaks within the assembly 22.

[0055] According to one embodiment of an operating method for operating the sintering device 10, as shown in Fig. 4, initially only the middle second press rams 18 assigned to a respective assembly 22 are raised. As shown in Fig. 5, the outer second press rams 18 are raised with a time delay, so that a certain height offset can temporarily occur between the upper sides of the second press rams 18. As soon as the second press rams 18 come into contact with the underside of a respective substrate 24 of an assembly 22, this assembly 22 is lifted out of the support frame 30 in the direction of action of the pressing force, wherein the placed first press rams 16 are also lifted out of the assigned guide frame 32 at the same time.

[0056] According to Fig. 6, the first press rams 16 come into contact with the pressure plate 20 as they are progressively raised, building up a counterforce that opposes the pressing force P generated by the drive devices 28, resulting in a pressure increase within the assemblies 22. Heating the pressure plate 20 or the second press rams 18 provides the heat required for pressure sintering.

[0057] The working position of the sintering device 10 shown in Fig. 6 is held for a predetermined period of time until the formation of the sintering device between the components of the assemblies 22 is completed.

[0058] After the sintering process has been completed, the drive devices 28 are actuated again according to Fig. 7 in order to lower the second press punches 18 against the direction of action of the pressing force P. As a result, the assemblies 22, including the placed press punches 16, are also lowered and fall back into the support frame 30 or the guide frame 32. After the lowering process has been completed, the support frame 30 with the sintered assemblies 22 accommodated therein can be moved out of the sintering device 10 and a further support frame 30 with the assemblies 22 to be sintered can be pushed in in order to carry out another sintering process. The further Figs. 8 and 9 show alternative second and third embodiments of a sintering device 10 in which a multi-drive comprising a plurality of drive devices 28, 28.1, 28.2 is arranged both in the upper tool 12, see Fig. 8 with regard tothe second embodiment or in both the upper tool 12 and the lower tool 14, see Fig. 9 for the third embodiment. Basically, the second and third embodiments of Figs. 8, 9 are based on the design of the first embodiment, which is described in detail with reference to Figs. 1 to 7. Therefore, only the differing features will be described below.

[0059] The embodiment 10 shown in Fig. 8 differs from the embodiment shown in Fig. 1 in that separate drive devices 28.1 are assigned to the first press punch 16 and are arranged in the upper tool 12. A pressure plate 20 is provided in the lower tool and acts as a second press punch 18. The pressure plate 20 supports the assemblies 22 in the lower tool 14 during the sintering process. As soon as the support frame 30 with the assemblies 22 and guide frame 22 is introduced into the working space 40 with the first press punch 16 placed thereon, e.g. as part of a flow production by a transport device not shown, e.g. transported from a preheating chamber into a vacuumable process chamber of the sintering device 10, the drive devices 28.1 can be placed on the upper side of the first press punch 16 and provide a pressing force P to the assemblies 22 with the direction of action towards the lower tool 14.A suitable transport device is known, for example, from WO 2021 / 069328 A. The preheating chamber can preferably cause an inductive temperature increase, in particular of the lower part, of the assembly, preferably of a heat sink, and can thus comprise conductive induction coils that are at a short distance from induction-heatable regions of the assembly and / or the support frame 30.

[0060] Fig. 9 shows a third embodiment 10, which essentially represents a combination of the embodiments of Figs. 1 and 8. While according to Fig. 1 the first press ram 16 of the first embodiment is supported by a pressure plate 20 in the upper tool 12, and in Fig. 8 the second press ram 18 is designed as a pressure plate 20 in the lower tool 14, the third embodiment of Fig. 9 dispenses with a pressure plate. In the upper tool 12, several drive devices 28.1 are arranged, each associated with a first press ram 16. In the lower tool 14, several drive devices 28.2 are arranged, each displaceably driving a second press ram 18. For this purpose, the support frame 30 has openings 52 through which the second press rams 18 can act.The press dies 18 have resilient pin contact thermal transfer devices 50 to enable rapid heat transfer and to compensate for unevenness and non-parallelism between the surface of the press dies 18 and the underside of the assemblies 22.

[0061] Each assembly 22 is pressed together in a sandwich-like manner by a drive device 28.1 and a drive device 28.2, whereby temperature, pressure, travel distance, etc. can be adjusted separately for each assembly 22. The third embodiment is particularly suitable for parallel sintering of heterogeneous assemblies 22.

[0062] The process atmosphere in the sintering device 10 is preferably adjustable, so that rinsing with a cleaning gas such as formic acid is possible, and even the removal of oxygen to prevent oxidation is advantageously possible, up to a vacuum.

[0063] List of reference symbols

[0064] 10 Sintering device

[0065] 12 upper tool

[0066] 14 Lower tool

[0067] 16 first press stamp

[0068] 18 second press ram

[0069] 20 printing plate

[0070] 22 Assembly

[0071] 24 Substrat

[0072] 26 Component

[0073] 28, 28.1, 28.2 Drive device, drive device of the upper tool,

[0074] Drive device of the lower tool

[0075] 30 support frames

[0076] 32 guide frames

[0077] 34 outer frames

[0078] 36 inner frames

[0079] 40 workspace

[0080] 42 stamp bodies

[0081] 44 upper stamp body

[0082] 46 lower stamp body

[0083] 48 contact surface

[0084] 50 pin contact thermal transfer device

[0085] 52 openings in the support frame

[0086] P Direction of force

Claims

Sintering device (10) for the simultaneous connection of components of a plurality of electronic assemblies (22) arranged next to one another by means of pressure sintering, with an upper tool (12) and a lower tool (14), comprising a plurality of first press dies (16) which can be assigned to the upper tool (12), and at least one, in particular a plurality of second press dies (18) which are assigned to the lower tool (14), between which the assemblies (22) are accommodated, wherein each of the first press dies (16) and / or each of the at least one second press dies (18) is assigned a drive device (28, 28.1, 28.2).2) is assigned, which is designed to exert a pressing force on one of the assemblies (22) by axially displacing the assigned first press ram (16) and / or the assigned second press ram (18) along a direction of action of the pressing force (P), characterized in that the first press rams (16) are placed on the assemblies (22) before the start of the pressing process, and during the application of the pressing force, the assemblies (22) are pressed against the at least one second press ram (18). Sintering device (10) according to claim 1, characterized in that the first press rams (16) are supported against a pressure plate (20) of the upper tool (14), wherein the at least one drive device (28, 28.2) of the lower tool (14), in particular a respective drive device (28, 28.2) assigned to each second press ram (18),2), via which at least one second press ram (18) applies an effective direction of the pressing force (P) in the direction of the upper tool (12), or that the at least one second press ram (18) is supported against a pressure plate (20) of the lower tool (14) or is formed therefrom, wherein the at least one drive device (28, 28.1) of the upper tool (12), in particular a respective drive device (28, 28.1) assigned to each first press ram (16), applies an effective direction of the pressing force (P) in the direction of the lower tool (14). Sintering device (10) according to claim 1, characterized in that a drive device (28, 28.1) of the upper tool (12) is assigned to the plurality of first press dies (16), and a drive device (28, 28.2) of the lower tool (14) is assigned to the plurality of second press dies (18), wherein each electronic assembly (22) can be acted upon on both sides by the drive devices (28, 28.1, 28.2) of the upper tool (12) and the lower tool (14) by opposing directions of action of the pressing forces (P). Sintering device (10) according to one of claims 1 to 3, characterized in that each drive device (28, 28.1, 28.2) can be individually controlled, preferably hydraulically, electromotively, piezoelectrically, or magnetostrictively, with regard to an offset path and / or an exerted pressing force (P). Sintering device (10) according to one of the preceding claims, characterized in that each of the second press stamps (18) is connected to the associated drive device (28, 28.2) and / or has a respective heating and / or cooling device, preferably a pin-contact thermal transfer device. Sintering device (10) according to one of the preceding claims, characterized in that a support frame (30) which can be introduced into the sintering device (10) is provided, in which frame at least the components of the assemblies (22), preferably together with the placed first press dies, are held guided in the lateral direction, wherein the support frame (30) preferably has openings (52) assigned to the assemblies (22), through which openings the second press dies (18) can come into mechanical and thermal contact with the assemblies (22).Sintering device (10) according to claim 6, characterized in that at least one guide frame (32) is preferably detachably arranged on the support frame (30), which guide frame is designed to guide the first press punches (16) in the lateral direction relative to the assemblies (22), wherein preferably the guide frame (32) has a higher thermal expansion coefficient than an upper assemblies (22). Sintering device (10) according to one of the preceding claims, characterized in that each of the first and / or second pressing dies (18) has a die body (42) that can be axially displaced along a direction of action of the pressing force (P) and a contact surface (48) that can be contacted with a component of the assembly (22), wherein the contact surface (48) is mounted such that it can be tilted about at least one spatial axis relative to the die body (42). Sintering device (10) according to one of the preceding claims, characterized in that a respective second pressing die (18) is assigned a plurality of adjacently arranged first pressing dies (16), or a respective first pressing die (16) is assigned a plurality of adjacently arranged second pressing dies (18).Method for the simultaneous connection of components of a plurality of adjacently arranged electronic assemblies (22) by means of pressure sintering in a sintering device (10), in particular according to one of the preceding claims, wherein the sintering device (10) comprises a plurality of first press dies (16) and at least one, in particular a plurality of second press dies (18), between which the assemblies (22) are received, wherein each of the first press dies (16) and / or the at least second press die (18) is displaceable axially along an effective direction of the press force (P) by means of an associated drive device (28, 28.1, 28.2) in order to exert a press force on one of the assemblies (22), comprising the steps of a. placing the first press dies (16) on the assemblies (22), b. introducing the assemblies (22) together with the first press dies into the sintering device (10) in a position aligned with the second press die(s) (18), c.Carrying out the sintering process by actuating the drive devices (28, 28.1, 28.2) in order to move the first press dies (16) and / or the at least second press die (18) from a rest position to a working position for generating the pressing pressure, in which the assemblies (22) are pressed together between the first press dies (18) and the at least second press die (18), which is arranged opposite the first press dies (16) for applying a counterforce. The method according to claim 10, wherein at least the step of performing the sintering process comprises heating and / or cooling the first press ram (16) and / or the at least second press ram (18), wherein the first press ram (16) preferably maintains a lower temperature level than the second press ram (18). The method according to claim 10 or 11, wherein the actuation of various drive devices (28, 28.1, 28.2) for displacing the first press ram (16) and / or the second press ram (18) into the working position takes place at staggered times. Method according to claim 12, wherein the actuation of different drive devices (28, 28.1, 28.2) at different times is effected in such a way that at least one drive device (28, 28.1, 28.2) arranged in a central region is actuated first and drive devices (28, 28.1, 28.2) located further out are actuated at a time interval.

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