Device for connecting a component to a substrate

Abstract

Device for connecting a component to a substrate, with a chamber divisible into at least two parts, wherein a stamp (11, 111) is provided on a first part (1), and a counter-stamp (31) is provided on a second part (3), wherein the first part (1) is movable towards the second part (3) in order to close the chamber, wherein the counter-stamp (31) can be loaded with starting materials in an open state of the chamber, and in a closed state of the chamber, pressure can be exerted on the starting materials provided between the stamp (11, 111) and the counter-stamp (31) via the stamp (11, 111), wherein a shaft (111) of the punch (11, 111) is received in a punch guide plate (15) provided on the first part (1) by means of a clearance fit with interference, and a pressure body (11) of the punch (11, 111) has a larger cross-sectional area than the shaft (11) of the punch (11, 111), characterized in that a vacuum device (119) is provided on a side of the punch guide plate (15) facing away from the counter-punch (31).

Description

[0001] The invention relates to a device for connecting a component to a substrate. BACKGROUND OF THE INVENTION

[0002] With the increasing need of the electronics industry for the development of efficient and high-temperature resistant components such as chips, the sintering of a bonding layer between the component and the substrate is gaining in popularity.

[0003] Sintering is known, among other things, as a process for manufacturing metal or ceramic parts. In this process, a fine- or coarse-grained green body is created by compressing a powdered starting material. This green body then undergoes a subsequent heat treatment to achieve its final shape and become a solid workpiece.

[0004] Sintering, as defined in the application and used in the manufacturing and processing of components such as semiconductor chips, refers to a similar process of pressing a component and a substrate together under predetermined pressure and temperature for a specific period of time, thereby creating a bond between the two elements. The current state of the art involves the use of pasty materials such as silver or copper paste, or even nanostructured platelets, which serve as a connection between the chip and the substrate and are sintered by the application of pressure and temperature. Such sintering as a method for bonding a component to a substrate is known and has proven advantageous compared to previously used tin- or lead-based soldering processes.

[0005] For such a sintering process, certain parameters, such as a set temperature, pressure, and holding time, must be defined to ensure effective bonding of the component to the substrate. These parameters can be determined based on experiments, depending on the requirements. In such sintering processes, a bonding agent can also be advantageously used, applied between the component and the substrate. The thickness of the bonding agent layer can then be another parameter. A silver paste is preferably used as such a bonding agent.

[0006] Preferably, during a sintering process, the binder, e.g., a silver paste, does not undergo a phase transformation, as is the case in tin- and lead-based soldering processes. Through appropriate temperature and pressure application, particles of the binder diffuse into the surface of the substrate and the component to be bonded. This creates a surface-to-surface bond instead of a phase-change bond.

[0007] Effective fastening requires a parallel, uniform force distribution across the component's surface, and this must be ensured. Therefore, a custom force application component is a preferred solution for modern electronics manufacturers, guaranteeing a high-quality connection. Custom force application means a separate tool for each component-substrate pairing, which can result in high tooling costs.

[0008] The application of temperature and pressure is necessary to achieve an effective bond between the component and the substrate; otherwise, the quality of the bond could be poor or too slow for practical purposes.

[0009] The principle of this process does not involve a phase change of the bonding agent (e.g., silver paste), as is the case with tin- and lead-based soldering processes. Through appropriate temperature and pressure application, silver components diffuse into the surface of the substrate and the component being bonded. This results in a surface-to-surface connection, rather than a phase change contact.

[0010] The terms "die attach" or "die packaging" are also commonly used for this type of process.

[0011] German patent application DE 10 2013 101 124 A1 discloses a device and a method for sintering a product. The sintered product comprises a component and a substrate. To join these, the sintered product is placed in a device with a press table and a press ram. By increasing the temperature using a heating device, a pressure element in the press ram expands, thereby exerting pressure on the sintered product. This bonds the component to the substrate.

[0012] German patent application DE 10 2015 120 156 A1 discloses a device for the material-locking connection of connection partners of a power electronics component. Here, a dimensionally stable frame acts on one of the connection partners, while an elastic cushion acts on a second connection partner to build up the pressure required for joining.

[0013] Both publication JP 2002 - 110 744 A and publication DE 10 2021 126 716 B3 describe a two-part device with a lower chamber in which a sintering process takes place. According to both publications, pressure is exerted on a plunger via a diaphragm by applying a vacuum to the lower chamber. The exact position of the vacuum device is not specified, but it must naturally be located within the lower chamber.

[0014] According to JP 2002 - 110 744 A, springs provide the return. DE 10 2021 126 716 B3 does not describe a return. The return is achieved by restoring pressure in the lower chamber, thereby reversing any bulging of the diaphragm.

[0015] In order to protect the component being sintered as much as possible, it is desirable to adjust the heat supply to the component as precisely as possible during a sintering process.

[0016] The object of the invention is to provide a device for connecting a component to a substrate, which makes it possible to precisely control the heat input to a component to be sintered.

[0017] The problem is solved by a device for connecting a component to a substrate according to claim 1. Advantageous embodiments are the subject of the dependent claims.

[0018] A device for connecting a component to a substrate according to the invention is provided with a chamber that can be divided into at least two parts. A punch is provided on a first part. A counter-punch is provided on a second part. A heating device is provided on a side of the counter-punch facing away from the first part. The first part is slidable towards the second part to close the chamber. The counter-punch can be loaded with starting materials when the chamber is open, and pressure can be exerted on the starting materials located between the punch and the counter-punch when the chamber is closed. A shank of the punch is received in a punch guide plate provided on the first part by means of an interference fit, and a pressure body of the punch has a larger cross-sectional area than the shank of the punch.A vacuum device is provided on one side of the punch guide plate facing away from the counter-punch.

[0019] The vacuum device makes it possible to draw the punch back into its starting position after a sintering process has finished by creating a vacuum. Since the punch's pressure body has a larger cross-sectional area than the shaft, it is prevented from being pulled into the punch guide plate.

[0020] On the side of the punch guide plate facing away from the counter-punch, a cylinder plate may be provided, which has a piston that moves back and forth in a cylinder bore. The piston has a guide rod on one side facing the punch, which is configured to contact the end face of the shank when the piston is pressurized and exert pressure on the punch.

[0021] Since the guide rod only comes into contact with the end face of the ram's shaft when the piston is actuated, a gap is created between the guide rod and the shaft in both the starting and retracting positions of the piston and ram. This allows heat to be transferred from the ram to the guide rod and the piston.

[0022] The end face of the shank of the punch can be flat, and a tip of the guide rod to be brought into contact with the end face of the shank can be rounded.

[0023] This structure allows the stamp to tilt in case of uneven alignment of the raw materials, thereby improving the quality of the sintered product.

[0024] The vacuum device can be an intermediate control chamber formed between the punch guide plate and a cylinder plate located on the side of the punch guide plate facing away from the counter-punch. This chamber can be pressurized with either a vacuum or a positive pressure.

[0025] The design as an intermediate control chamber, which can be pressurized with positive or negative pressure, has the advantage that if a piston or plunger becomes stuck, its mobility can be restored by applying positive pressure. Applying negative pressure returns the plunger to its starting or retracted position.

[0026] Since the piston is also brought into its retracted position by means of a vacuum from another vacuum source, there is no risk that the piston will extend again due to the overpressure.

[0027] Further advantageous features and effects of the invention are described below.

[0028] The invention provides an adaptable tool for developing a surface mounting technology by joining surfaces made of different materials through pressure and a specific temperature acting on the upper surface of a component, by means of a form-fitting sealing / locking mechanism of the tool.

[0029] It is not necessary to provide a counterforce through an external system.

[0030] The tool can be designed as a sealed pressure chamber (under negative or positive pressure). The joining process can take place in a high-pressure gas or vacuum atmosphere. The chamber is closed by its own shape. A portion of the chamber—preferably the lower part—can be moved into position by means such as motors, or by hydraulic or pneumatic means.

[0031] The resulting compressive force exerted by the tool is balanced by a form-fitting mechanical internal element and / or a geometric shape, so that the force reaction takes a shorter path.

[0032] The substrate can consist of directly bonded copper or a similar ceramic substrate.

[0033] The pressure can be predefined, for example, at 40 MPa. The connection process can take place at a temperature setting between, for example, 20°C and 330°C for a defined time of, for example, 70-120 seconds.

[0034] The temperature can be maintained by a heating device in the chamber, preferably supplied directly at the dies. Advantageously, several heating devices can be used in the system. Insulating layers and / or materials can be used in the chamber for thermal insulation of sensitive components.

[0035] In the joining process, a protective film, e.g. made of PTFE material, can also be used to protect the semiconductor dies, which is preferably arranged using a roller mechanism.

[0036] The chamber can consist of several parts and be designed for multiple components (chips) in the form of multiple levels. Simultaneous processing on one level or on different, superimposed levels is also possible.

[0037] The size of the stamp, especially of its surface facing the opposite surface, can correspond exactly to the size of the component (chip). BRIEF DESCRIPTION OF THE FIGURES

[0038] Further advantages of the invention will also become clear from the following description with reference to the figures, which show a currently preferred embodiment. Fig. Figure 1 shows a device according to the invention for connecting a component to a substrate in an open state. Fig. 2a shows a side view of a positive locking mechanism according to a first embodiment of the invention, and Fig. 2b shows a sectional view of the Fig. 2a. Fig. Figure 3a shows a sectional view of the positive locking mechanism according to the first embodiment in a closed state of the device under load, and Fig. 3b shows a sectional view according to Fig. 3a in a closed state of the device without load. Fig. 4a shows a modification according to Fig. 3a, which is fitted with a seal, and Fig. 4b shows the modification according to Fig. 4b. Fig. Figure 5 shows an alternative form-locking mechanism. Fig. Figure 6 shows a detail of a stamp for joining a component to a substrate. Fig. Figure 7a shows a view of a stamp from the underside of the stamp. Fig. Figure 7b shows a side view of the punch, the shank of which is guided in a punch guide plate, and Fig. Figure 7c shows a view of the die shank guided in the die guide plate from a top view. Fig. Figure 8 shows a detailed view of a lower part of the device with a thermal separation device. Fig. Figure 9 shows an alternative device for thermal separation.

[0039] Embodiments of the invention are described by reference to the Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig. 7, Fig. 8 to Fig. 9 described. The figures are schematic, and some described details may have been omitted.

[0040] The device according to the invention is with reference to the Fig. The chamber is formed in the form of a chamber comprising an upper part 1 (first part) and a lower part 3 (second part). The chamber is essentially in the shape of a hollow cuboid with four side walls, a base, and a top wall. By separating the lower part 3 from the upper part 1, the chamber can be opened into two parts, the openings of which face each other.

[0041] The lower part 3 contains a press plate 31, also referred to as a product holder, which functions as a counter-punch. The press plate 31 serves to arrange raw materials such as a substrate, a sintering paste, and a component before a sintering process. A heating plate (heating device) 33 is located below the press plate 31. The heating plate 33 serves to transfer heat to the press plate 31 during a sintering process, thereby heating it.

[0042] The top will be based on the Fig. 1, Fig. 6 and Fig. 7 is described in more detail. A cylinder plate 19 is provided on the upper part 1 of the chamber at a top position, i.e., a position furthest from the opening of the upper part 1. The cylinder plate 19 has cylindrical bores in which pistons 117 are received. The cylindrical bores on the side of the cylinder plate 19 facing away from the respective piston 117 are connected to a pressure supply line 115. This piston-cylinder arrangement serves as a pneumatic adjustment device.

[0043] To actuate the pistons 117, a pressurized fluid, such as air, is introduced into the cylindrical bores in the cylinder plate 19 via the pressure supply line, thereby actuating the pistons 117. This actuation causes the pistons 117, together with a guide rod 113 provided on one side of the piston facing the lower part 3, to move towards the lower part 3 of the chamber. This direction is hereinafter also referred to as the "downward direction" or simply "downwards" and corresponds in the figures to a direction from the upper surface of the leaf to the lower surface.

[0044] While it is preferred to actuate all pistons simultaneously by pressurizing the fluid in the pressure supply line to a predetermined pressure, it is alternatively possible to provide means for actuating the pistons 117 individually. The pistons 117 are reset by applying a vacuum in the pressure supply line 115, which returns the pistons 117 and the guide rods 113 to their initial position.

[0045] Each piston 117 can be brought into contact with a shaft 111 of a punch via the guide rod 113. This is achieved by moving a rounded end of the guide rod 113, facing away from the piston 117, downwards against a flat end face of the shaft 111 facing the piston 117, through the actuation of the piston 117.

[0046] As can be seen in particular from the Fig. As can be seen in Figure 6, the guide rod 113 is guided through a hole in an upper plate 16 arranged above a piston guide plate 15. The upper plate 16 is also in contact with the inner walls of the upper part 1 such that a space located between the upper plate 16 and the cylinder plate 19 can be pressurized with overpressure or underpressure independently of the pressure in the pressure supply line 115. Preferably, a seal 8 is provided between the inner walls of the upper part 1 and the upper plate 16 for this purpose. The space between the upper plate 16 and the cylinder plate 19 is designated as the intermediate control chamber 119.

[0047] The shank 111 of the punch is cylindrical and guided through a hole in a punch guide plate 15. The diameter of the hole is dimensioned such that it slightly exceeds the diameter of the shank 111 of the punch, i.e., a clearance fit with interference is present. The clearance dimension is between 8 and 12 µm. A clearance dimension of 10 µm is preferred.

[0048] On the side of the shaft 111 facing away from the piston is a pressure body 11 of the ram, which is directed towards the pressure plate 31. In the Fig. Figure 1 shows seven stamps; however, the number of stamps is in no way limited and can be chosen arbitrarily. In particular, only a single stamp may be provided, although a larger number of stamps is preferred.

[0049] Each punch is manufactured from a single piece and consists of the shank 111 and the pressure body 11. The cylindrical shank 111 is guided by the punch guide plate 15 and, due to the clearance fit, can be tilted slightly. The maximum possible tilting angle can be adjusted by precisely defining the gap between the shank 111 and the hole in the punch guide plate 15.

[0050] Tilting is made possible by the fact that the guide rod 113 has a rounded end that can roll on the flat end face of the shaft 111 facing the piston 117. Because the shaft 111, and thus the punch 11, can tilt, it is possible to compensate for any inclination of the components to be sintered. This means that when the punch is brought into contact with a component that is not perfectly flat, it is able to adjust to the inclination of the component by tilting.

[0051] The pressure body 11 of the punch is cuboid in shape. Its underside surface, facing away from the piston, is called the pressure surface. The dimensions of the pressure surface slightly exceed those of the product to be sintered in order to reliably cover the component to be sintered completely even in the event of minor positional deviations, such as a slight rotation of the punch and thus of the pressure body 11.

[0052] The pressure body 11 of the punch is received in a recess 141, which is provided on the underside of a punch base plate 14 located below the punch guide plate 15. The thickness of the punch base plate 14, and thus of the recess 141, is dimensioned such that the pressure body 11 of the punch cannot completely dislodge from the recess during pressure application by the pistons 117. This is because the total height of the starting materials, and thus the required travel of the punch, is in the micrometer range, while the height of the pressure body and the recess is several millimeters.

[0053] The distance between the sides of the pressure body 11 and the inner walls of the recess 141 is greater than the distance between the shaft 111 and the inner wall of the hole. Therefore, it is impossible for the pressure body 11 to become jammed in the recess 141 due to the previously described possible tilting of the punch.

[0054] Since the plunger merely comes into contact with the guide rod 113 or the piston 117, but is not rigidly connected to it, the plunger remains in an extended position after pressurization, even though the piston 117 and the guide rod 113 are returned to their initial position by applying a vacuum to the pressure supply line. This condition is shown schematically in the Fig. 6 shown.

[0055] To detach the punch from the sintered product and return it to its starting position, the intermediate control chamber 119 is pressurized, and the punch is drawn back into its starting position due to the resulting pressure difference between the pressure body 11 and the intermediate control chamber. However, this creates a slight airflow between the shaft 111 and the inner wall of the hole, as well as between the walls of the pressure body 11 and the inner walls of the recess 141.

[0056] This slight airflow is negligible and ceases as soon as the upper surface of the pressure body 11 surrounding the shaft 111 comes into contact with the piston guide plate 15. Since the upper surface of the piston pressure body 11 is in contact with the underside of the piston guide plate 15, the end face of the shaft 111 is prevented from striking the guide rod 113 of the retracted piston 117. This has the advantage of creating a thermal separation between the hot piston (after the sintering process) and the piston.

[0057] Air drawn from a space 151 between the end face of the shaft 111 and the upper plate 16 also contributes to the resetting of the stamp, as shown from Fig. 6 is evident. The air present in the space 151 is already increased on the one hand by resetting the guide rod 113 by creating the negative pressure in the intermediate control chamber 119.

[0058] This design allows for the easy replacement of a defective punch at any time, or, depending on the component being sintered, the complete replacement of all punches. This simply requires removing the punches and the punch base plate 14 with the recesses 141 from the chamber and replacing them with other punches that have a punch base plate with matching recesses.

[0059] Should the piston 117 become jammed despite the thermal separation and be unable to retract solely due to the negative pressure in the pressure supply line 115, pressure can be exerted on the underside of the piston by increasing the pressure in the intermediate control chamber 119, thereby releasing the jam and allowing the piston 117 to return to its starting position.

[0060] It should also be mentioned that, due to the different cross-sections of the piston 117 and the plunger with the pressure surface of the pressure body 11, a minimum ratio of the input pressure exerted by the piston 117 on the guide rod 113 and the shaft 111 to the output pressure of the plunger surface must be maintained. The input pressure is applied to a circular cross-section of the piston 117.

[0061] In a possible configuration of the piston with a square pressure surface, let the side length of the square be "a". The piston 117 has a circular cross-section with radius "a" in both cases. In this case, where the cross-section of the piston surface is square, the ratio of inlet to outlet area is smallest. That is, the pressure exerted on the component is maximized, as can be seen from the equation P=F / A This results in the following equation: "P" represents pressure, "F" represents force, and "A" represents cross-sectional area.

[0062] For a square with a side length "a", the ratio of pressure area to piston area is approximately 1.273. This corresponds to the ratio of the area of ​​a square with side length "a" to that of a circle inscribed in the square with diameter "a".

[0063] Therefore, it is necessary to pressurize piston 117 to a pressure higher than the pressure exerted on the starting materials. In the example above, the inlet pressure would need to be approximately 51 MPa to achieve the desired outlet pressure of 40 MPa.

[0064] In the case of a non-square, but for example rectangular, printing surface, the ratio is determined analogously. Required input pressures for different die areas can be provided, for example, in the form of a table, or for different output pressures in the form of a characteristic curve.

[0065] Details of subsection 3 will be explained in particular by reference to the Fig. 1, Fig. 8 and Fig. 9 described in more detail.

[0066] The lower part 3 of the chamber is equipped, in order from bottom to top, with a cooling plate 37, thermal insulation in the form of an insulating plate 35, a heating plate 33, and a product holder 31. The product holder 31 serves as a counter-mold and is used to support a substrate onto which components are to be sintered.

[0067] To improve the quality of the sintered product, it is necessary to apply heat to the raw materials as simultaneously as possible with the application of pressure by the die. For this purpose, a thermal break is provided between the heating plate 33 and the product holder 31 positioned above it, as shown in the Fig. 8 can be seen schematically.

[0068] To achieve thermal separation, preload elements 32 are provided between an underside of the product holder 31 and a bottom wall of the lower part 3. These preload elements 32 tension the product holder 31 upwards, spacing it away from the heating plate 33. The preload elements 32 can be in the form of springs, such as...

[0069] coil springs should be designed as in the Fig. The schematic representation in section 8 is not limited to this.

[0070] For example, instead of the schematically indicated coil springs, other types of springs such as leaf springs, hydraulic or pneumatic pistons, or mechanical means such as racks are possible as preload elements.

[0071] Due to the preload elements 32, the product holder 31 is positioned at a distance from the heating plate 33, in which heat transfer is at most reduced because an air gap acts as an insulator between the product holder 31 and the heating plate 33. As soon as the pistons are actuated and begin to exert pressure on the raw materials and the product holder supporting them, the preload force of the preload elements 32 is overcome and the product holder 31 is brought into contact with the heating plate 33. In this state, direct heat transfer occurs from the heating plate 33 to the product holder 31 and then to the raw materials.

[0072] Thus, the raw materials are simultaneously exposed to pressure and heat until the pressure load is released by the piston 117 being reset. Simultaneously with the release of the pressure load, the preload force of the preload elements 32 removes the product holder 31 from the heating plate 33, preventing further heating of the product holder 31 and the raw materials by the still-hot heating plate 33.

[0073] It should be noted that the presentation of the Fig. Figure 8 shows only the components important for thermal separation, but the overall structure can be designed as shown in the Fig. Figure 1 shows that, for example, thermal insulation, cooling, etc., may be present between the heating plate 33 and the bottom wall of the lower part 3.

[0074] The Fig. Figure 9 schematically shows an alternative for the thermal separation of the product holder and the heating plate. According to this alternative, the heating plate is provided with numerous through-holes (air channels) oriented from its underside to its top surface, which are connected to an air supply channel 36 that runs through the bottom wall of the base 3 and the thermal insulation 35 of the heating plate 33. To thermally separate the product holder 31 from the heating plate 33, air or another suitable fluid is supplied through the air supply channel 36 until the piston 117 applies pressure to the plunger. After passing through the numerous air channels in the heating plate 33, this air forms an air cushion between the heating plate 33 and the product holder, providing not only thermal separation but also additional insulation against radiant heat.

[0075] By interrupting the air supply at the moment the piston 117 is actuated, the air cushion between the heating plate 33 and the product holder 31 is eliminated. The product holder 31 comes into contact with the heating plate and is thus immediately heated. This heat is simultaneously transferred to the starting materials, which are then under pressure from the piston.

[0076] To carry out the sintering process, the device is closed by bringing the upper part 1 and the lower part 3 together. This process is described in particular by the Fig. 1, Fig. 2, Fig. 3, Fig. 4 to Fig. 5 described.

[0077] The side walls of the upper part 1 have a recess 131 at their edge facing the lower part 3. Next to the recess 131 are corresponding projections 137a and 137b. The side walls of the lower part 3 have a corresponding projection 39, which is inserted into the recess 131 between the projections 137a and 137b when the edge of the upper part 1 is brought into contact with the edge of the lower part 3. Additionally, a seal is arranged outside the projection 39 of the lower part 3, which, when the chamber is closed, seals its interior fluid-tight against the external environment.

[0078] In each of the projections 137a, 137b, 39, holes 133a, 133b and 391 are provided transversely to an opening or closing direction of the chamber, the cross-sections of which overlap each other in the closed state, i.e., when the chamber is closed. The holes 133a, 133b and 391 are designed as elongated holes. This means that a length l1 of the holes 133a, 133b in the upper part and a length l2 of the hole 391 in the lower part 3 exceed a width b of the holes 133a, 133b and 391.

[0079] The figures exaggerate the proportions of the holes. In reality, it is sufficient if the lengths l1 and l2 exceed the widths b of holes 133a, 133b and 391 by approximately 0.5 mm.

[0080] The holes can have a diameter of 5 to 40 mm, depending on their number. The same diameter range applies to the pin(s). Tolerances from H7 to 2 mm are possible. If the holes are chosen to be larger than the pins, an advantageous automatic centering is achieved via the upper contact point (i.e., where the pin contacts the wall of the hole), thus eliminating the need for high-precision fits.

[0081] Because of the proportions of holes 133a, 133b, and 391, a cylindrical pin 135, in its installed position, can easily be guided through all the holes due to the clearance created by the elongated hole shape. As soon as the piston 117 exerts a pressure load on the plunger and, via the plunger, on the lower part 3 of the chamber, a situation arises as described in Fig. 3a shown.

[0082] Due to the pressure load, a downward force F acts, causing the lower part 3 of the chamber to move downwards from its in-place position until further movement is prevented by the now-locking pin 135. This positive locking mechanism thus makes it possible to absorb the force acting on the lower part without the need for complex hydraulic tables, etc.

[0083] After the chamber is locked, the piston is actuated, exerting pressure on the starting materials. This creates a predetermined pressure on the starting materials placed on the product holder 31, such as a substrate, a layer of silver paste as a bonding agent, and a chip as a component. According to the invention, a pressure of 40 to 50 MPa can be achieved.

[0084] Within the chamber, a temperature between 20 °C and 330 °C can be reached in the area between the product holder 31 and the stamp base plate 14. This makes it possible to complete a joining process in 70 to 120 seconds. A key advantage is that the heating plate is positioned so that the heat is transferred directly to the product holder 31.

[0085] The required pressure is generated by pressurizing pistons 117 in cylinders of the cylinder plate 19 with a gas under high pressure.

[0086] If necessary, an overpressure or underpressure can also be created in the chamber by introducing or removing gas, and / or a gas such as nitrogen can be supplied to promote the joining process, or a reaction gas can be added.

[0087] Holding this state for a predetermined time results in a sintering process, i.e., a bonding of the silver molecules with the component and the substrate.

[0088] As soon as the pressure on the piston ends, the lower part 3 can again come into contact with the upper part 1, as shown in the Fig. 3b is evident. In this state, the pin 135 can easily be removed again from the holes 133a, 133b and 391 and the chamber opened to remove the finished sintered components.

[0089] In the Fig. 4a and Fig. Figure 4b shows a variant in which additional seals 311 are provided inside and outside the projection 39. These seals 311 are able to protect the interior of the chamber not only in the installed state (see Figure 4b). Fig. 4b) but also in the pressure load state (see Fig. 4a) to seal fluid-tight.

[0090] All compressive forces generated during the sintering process are absorbed by the chamber itself due to the form-fit. Therefore, it is not necessary to implement further structural measures to absorb or dissipate high compressive forces.

[0091] An alternative design for the positive locking mechanism is schematically derived from the Fig.Figure 5 shows that, instead of the configuration described above, each side wall of the upper part 1 and the lower part 3 is provided with a flange-like projection 431, 433. The projections 431, 433 have a chamfer on their surfaces facing away from each other. To create the positive fit, a C-shaped clamp 435 is guided over the projections. The clamp 435 has a corresponding chamfer on the inner surfaces of its legs facing the chamfered surfaces of the projections, so that a surface contact between the inner surfaces of the clamp 435 and the chamfered surfaces of the projections 431, 433 is possible. In the case of the alternative described here, the compressive forces are absorbed by the C-shaped clamp 435, which can be easily removed again after the sintering process is complete due to the chamfered surfaces.

[0092] Instead of the cylindrical pin described above, the positive locking mechanism can also be achieved, for example, with tapered pins and correspondingly conical bores.

[0093] The process described above can be advantageously automated.

[0094] According to the current state of the art, the counterforces required for the pressing process must be applied using external structures. In this case, a mechanism that moves a support assembly upwards to hold the substrate provides the external force necessary to lock the substrate in position and generate the counterforce required for the process. However, this results in a machine structure that is heavy and very complex.

[0095] Due to the positive locking mechanism according to the invention, the present invention creates an internal counterforce mechanism. Therefore, an external force source is not required to provide the counterforce.

[0096] To prepare for the bonding process, the paste is printed onto the substrate and the components (chips) are arranged on the paste; that is, the substrate is populated with the chips on the paste. Afterwards, the printed and chip-populated substrate is placed into the chamber.

[0097] Since the tool is adjustable, the positions of the punch correspond to the positions of the chips on the substrate. A film can be advantageously placed over the chips, for example, using rollers mounted on the sides of the tool. The film can be renewed after each bonding process. This can be done by replacing the rollers with the film or by changing the position of the existing film. The latter can be achieved by advancing the film wound on a roller, thereby changing its position. PTFE or a similar plastic can be used as the film material, but this is not the only option.

[0098] The joining process takes place over a predetermined period at a predetermined temperature and pressure to effectively sinter the component onto the substrate. Advantageously, the component and / or other starting materials such as the substrate and silver paste can be preheated or cooled by a preheating or cooling device before and after the joining process.

Claims

[1] Device for connecting a component to a substrate, with a chamber divisible into at least two parts, wherein a stamp (11, 111) is provided on a first part (1), and a counter-stamp (31) is provided on a second part (3), wherein the first part (1) is movable towards the second part (3) in order to close the chamber, wherein the counter-stamp (31) can be loaded with starting materials in an open state of the chamber, and in a closed state of the chamber, pressure can be exerted on the starting materials provided between the stamp (11, 111) and the counter-stamp (31) via the stamp (11, 111), wherein a shaft (111) of the punch (11, 111) is received in a punch guide plate (15) provided on the first part (1) by means of a clearance fit with interference, and a pressure body (11) of the punch (11, 111) has a larger cross-sectional area than the shaft (11) of the punch (11, 111), characterized by , that a vacuum device (119) is provided on a side of the punch guide plate (15) facing away from the counter-punch (31). [2] Device according to claim 1, wherein a cylinder plate (19) is provided on the side of the punch guide plate (15) facing away from the counter punch (31), which has a piston (117) movable back and forth in a cylinder bore, which has a guide rod (113) on a side facing the punch (11, 111) which is configured to come into contact with the end face of the shaft (111) when the piston (117) is pressurized and to exert pressure on the punch (11, 111). [3] Device according to claim 2, wherein the end face of the shaft (111) of the punch (11, 111) is planar, and a tip of the guide rod (113) which is to be brought into contact with the front surface of the shaft (111) is rounded. [4] Device according to one of claims 1 to 3, wherein the vacuum device (119) is an intermediate control chamber formed between the punch guide plate (15) and a cylinder plate (19) provided on a side of the punch guide plate (15) facing away from the counter punch (31), which can be pressurized with a vacuum or a positive pressure. [5] Device according to one of claims 2 to 4, wherein in a retracted position of the piston (117) and the punch (11, 111) there is a distance between the tip of the guide rod (113) and the end face of the shaft (111) of the punch (11, 111).

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