Device for connecting a component to a substrate

Abstract

The invention relates to a device for connecting a component (5) to a substrate, comprising a chamber divisible into at least two parts. A punch (11, 111) is provided on a first part (1), and a counter-punch (31) is provided on a second part (3). The counter-punch (31) can be loaded with starting materials when the chamber is open. The first part (1) has a wall with an edge that can be brought into contact with an opposite edge of a wall of the second part (3) to close the chamber. When the chamber is closed, pressure can be exerted on the starting materials located between the punch (11) and the counter-punch (31) via the punch (11, 111). In an unloaded state, the counter-punch (31) is spaced apart from the heating element (33). Due to the pressure exerted by the punch (11, 111), the counter-punch comes into contact with the heating element (33).

Description

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

[0002] With the increasing demand 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 popularity.

[0003] Sintering is known, among other things, as a process for the production of metal or ceramic parts. The compression of a powdered starting material creates a fine- or coarse-grained green body, which acquires its final shape during subsequent heat treatment, thus becoming a solid workpiece.

[0004] Sintering according to the application and in the manufacture and processing of components such as semiconductor chips is understood here to be a similar process of pressing a component and a substrate together for a certain period of time using a predetermined pressure and a predetermined temperature, thereby creating a bond between the two elements. The current state of the art is the use of pasty materials such as silver or copper paste or nanostructured platelets, which serve as a bond between chip and substrate and are sintered by the application of pressure and temperature. Such sintering as a process for connecting a component to a substrate is known and has proven advantageous over previously used tin- or lead-based soldering processes.

[0005] For such a sintering process, specific parameters such as a set temperature, pressure, and holding time must be defined for effective attachment of the component to the substrate. These parameters can be determined based on tests, depending on requirements. In such sintering processes, a binder can also be advantageously used, which is applied between the component and the substrate. Accordingly, the layer thickness of the binder can represent a further parameter. A silver paste can preferably be used as such a binder.

[0006] Preferably, a phase transition of the binder, e.g., a silver paste, does not occur during the sintering process, as is the case in tin- and lead-based soldering processes. By applying appropriate temperature and pressure, particles of the binder diffuse into the surface of the substrate and the component to be attached. This creates a surface-to-surface bond rather than a phase-change bond.

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

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

[0009] The principle of the process does not involve a phase transition of the bonding agent (e.g., silver paste), as is the case with tin- and lead-based soldering processes. By applying appropriate temperature and pressure, silver components diffuse into the surface of the substrate and the component to be attached. This creates 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] The publication DE 10 2013 101 124 describes a device and a method for producing a sintered product. The sintered product comprises a component and a substrate. To bond them, the sintered product is placed in a device with a press table and a press die. Increasing the temperature using a heating device causes a pressure body in the press die to expand, exerting pressure on the sintered product. The component is thus bonded to the substrate.

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

[0013] In order to protect the component to be sintered as much as possible, it is desirable to adjust the heat supply to the component as precisely as possible during a sintering process.

[0014] There is a need for an apparatus and method for bonding a component to a substrate that allows for precise control of heat supply to a component to be sintered.

[0015] 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 stamp is provided on a first part. A counter-stamp is provided on a second part. A heating device is provided on a side of the counter-stamp facing away from the first part. The first part can be moved towards the second part to close the chamber. When the chamber is open, the counter-stamp can be loaded with starting materials, and when the chamber is closed, pressure can be exerted via the stamp on the starting materials provided between the stamp and the counter-stamp. In an unloaded state, the counter-stamp is spaced from the heating device and is configured to come into contact with the heating device due to the pressure exerted by the stamp.

[0016] Because the counter-punch acts as a product holder and is spaced apart from the heating device, no direct heat transfer occurs. Therefore, the raw materials on the counter-punch are not exposed to excessive heat before the sintering process begins. Only when pressure is exerted by the punch does the gap between the counter-punch and the heating device become bridged, and the heat is then transferred directly to the counter-punch, the raw materials, and the punch.

[0017] The heating device can be designed in the form of a heating plate, the surface of which is directed towards the counter-stamp and is configured to come into contact with a surface of the counter-stamp facing away from the first part.

[0018] The flat contact between the surfaces of the heating device and the counter-stamp enables rapid and even heat transfer.

[0019] The counter-punch can be spaced from the heating device by means of preloading elements, whose preload is overcome by the pressure exerted by the punch. After the pressure exerted by the punch is terminated, the preload is restored.

[0020] Thus, even after the sintering process has ended, as soon as the stamp is retracted to its starting position, direct heat transfer is prevented.

[0021] In a load-free state, the counter-punch can be spaced from the heating device by means of springs.

[0022] Spiral springs or leaf springs can be used preferably here.

[0023] In a load-free state, the counter-punch can be spaced from the heating device by means of an air cushion. The air supply to the air cushion can be provided via air ducts that are at least partially guided through the heating device.

[0024] An air cushion can be used as a preload element instead of or in addition to the springs. The air supply also makes it possible to improve the effectiveness of the invention. For example, the supply of cold air after the sintering process allows for faster cooling. Likewise, the counter-punch can be preheated using hot air before the sintering process, if necessary.

[0025] 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 can be moved toward the second part to close the chamber. When the chamber is open, the counter-punch can be loaded with starting materials, and when the chamber is closed, pressure can be exerted via the punch on the starting materials provided between the punch and the counter-punch. 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 a side of the punch guide plate facing away from the counter punch.

[0026] The vacuum device makes it possible to suck the die back to its original position after the sintering process is complete by creating a vacuum. Since the die's pressure body has a larger cross-sectional area than the shaft, this prevents the pressure body from being drawn into the die guide plate.

[0027] 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 can reciprocate in a cylinder bore. The piston has a guide rod on a side facing the punch, which is configured to engage the end face of the shaft when pressure is applied to the piston and to exert pressure on the punch.

[0028] Since the guide rod only comes into contact with the end face of the punch shaft when the piston is actuated, a gap is created between the guide rod and the shaft in the initial or retracted position of the piston and punch. This allows heat transfer from the punch to the guide rod and the piston.

[0029] The end face of the shank of the punch may be flat and a tip of the guide rod to be brought into contact with the end face of the shank may be rounded.

[0030] This structure allows the punch to be tilted in the event of a possible non-planar alignment of the starting materials, thereby improving the quality of the sintered product.

[0031] The vacuum device may be an intermediate control chamber formed between the punch guide plate and a cylinder plate located on a side of the punch guide plate facing away from the counter punch. This chamber can be subjected to either a negative pressure or an overpressure.

[0032] The design as an intermediate control chamber, which can be pressurized with either overpressure or negative pressure, has the advantage that if a piston or plunger becomes stuck, its mobility can be restored by applying positive pressure. By creating the negative pressure, the plunger is returned to its starting or retracted position.

[0033] Since the piston is also brought into its retracted position by means of negative pressure from another vacuum source, there is no risk of the piston extending again due to the excess pressure. Further advantageous features and effects of the invention are described below.

[0034] The invention provides an adaptable tool for developing surface mount technology by joining surfaces of different materials by applying pressure and temperature to the top surface of a component through a positive sealing / locking mechanism of the tool.

[0035] There is no need to provide counterforce through an external system.

[0036] The tool can be designed as a sealed pressure chamber (negative or positive pressure). The joining process can take place in a high-pressure gas or vacuum atmosphere. This chamber is enclosed by the shape of the chamber itself. A portion of the chamber—preferably the lower part of the chamber—can be moved into position by drive means such as motors, or by hydraulic or pneumatic means.

[0037] 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.

[0038] The substrate can be made of directly bonded copper or a similar ceramic substrate.

[0039] The pressure can be predefined, e.g., 40 MPa. The bonding process can take place at a temperature setting between e.g., 20°C and 330°C for a defined time of e.g., 70-120 seconds.

[0040] The temperature can be maintained by a heating device in the chamber, preferably provided directly at the stamps. Additionally, multiple heating devices can advantageously be used in the system. Insulating layers and / or materials can be used in the chamber to thermally insulate sensitive components.

[0041] In the bonding process, a protective film, e.g. made of PTFE material, can additionally be used to protect the semiconductor stamps, which is preferably arranged with the aid of a roller mechanism.

[0042] The chamber can consist of several parts and be designed to accommodate multiple components (chips) in the form of multiple levels. Simultaneous processing can also be carried out on one level or on several levels arranged one above the other.

[0043] The size of the stamp, especially of its surface facing the counter surface, can exactly correspond to the size of the component (chip). SHORT DESCRIPTION OF THE CHARACTERS

[0044] 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. 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 form-locking mechanism according to a first embodiment of the invention, and Fig. 2b shows a sectional view of the Fig. 2a. Fig. 3a shows a sectional view of the form-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 provided with a seal, and Fig. 4b shows the modification according to Fig. 4b. Fig. 5 shows an alternative form-locking mechanism. Fig. 6 shows a detail of a stamp for connecting a component to a substrate. Fig. 7a shows a view of a stamp viewed from a bottom side of the stamp, Fig. 7b shows a side view of the punch, the shaft of which is guided in a punch guide plate, and Fig. 7c shows a view of the punch shaft guided in the punch guide plate viewed from a top side. Fig. 8 shows a detailed view of a lower part of the device with a thermal separation device. Fig. 9 shows an alternative thermal separation device.

[0045] Embodiments of the invention are described with reference to Fig. 1 to 9. The figures are schematic, and described details may be omitted.

[0046] The device according to the invention is described with reference to Fig. 1 is designed in the form of a chamber comprising an upper part 1 (first part) and a lower part 3 (second part). The chamber is essentially shaped like a hollow cuboid with four side walls, a base, and a lid wall. By separating the lower part 3 from the upper part 1, the chamber can be opened into two parts, whose openings face each other.

[0047] A press plate 31, also referred to as a product holder, is provided in the lower part 3 and functions as a counter-punch. The press plate 31 serves to position starting materials such as a substrate, a sintering paste, and a component prior to a sintering process. A heating plate (heating device) 33 is arranged below the press plate 31. The heating plate 33 serves to transfer heat to the press plate 31 during a sintering process, thereby warming it up.

[0048] The top is made using the Fig. 1, Fig. 6 and Fig. 7. A cylinder plate 19 is provided on the upper part 1 of the chamber at an uppermost 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 a 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.

[0049] 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. Upon actuation, the pistons 117 move, together with a guide rod 113 provided on a side of the piston facing the lower part 3, in the direction of the lower part 3 of the chamber. This direction is also referred to below as the "downward direction" or simply "downward" and, in the figures, corresponds to a direction from the upper side of the blade to the underside of the blade.

[0050] While it is preferred to actuate all pistons simultaneously by applying a predetermined pressure to the fluid in the pressure supply line, it is alternatively possible to provide means to control the pistons 117 individually. The pistons 117 are reset by applying a negative pressure to the pressure supply line 115, thereby returning the pistons 117 with the guide rods 113 to their initial position.

[0051] Each piston 117 can be brought into contact with a shaft 111 of a punch via the guide rod 113. This is achieved by actuating the piston 117, which guides a rounded end of the guide rod 113 facing away from the piston 117 downward against a flat end face of the shaft 111 facing the piston 117.

[0052] As can be seen in particular from the Fig. 6, the guide rod 113 is guided through a hole in an upper plate 16 arranged above a punch guide plate 15. The upper plate 16 also bears against the inner walls of the upper part 1 in such a way that a space between the upper plate 16 and the cylinder plate 19 can be subjected to an overpressure or underpressure independently of the pressure in the pressure supply line 115. For this purpose, a seal 8 is preferably provided between the inner walls of the upper part 1 and the upper plate 16. The space between the upper plate 16 and the cylinder plate 19 is referred to as the intermediate control chamber 119.

[0053] 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., this represents a clearance fit with interference. The gap is between 8 and 12 µm. A gap of 10 µm is preferred.

[0054] On the side of the shaft 111 facing away from the piston there is a pressure body 11 of the punch, which is directed towards the pressure plate 31. In the Fig. Seven stamps are shown in Figure 1, but the number of stamps is not limited in any way; any number can be chosen. In particular, only a single stamp may be used, although a larger number is preferred.

[0055] Each punch is manufactured from a single piece and consists of the shaft 111 and the pressure body 11. The cylindrical shaft 111 is guided by the punch guide plate 15 and can be tilted slightly due to the interference fit. The maximum possible degree of tilting can be adjusted by the precise gap between the shaft 111 and the hole through the punch guide plate 15.

[0056] 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. The fact that the shaft 111, and thus the punch 11, can tilt makes it possible to compensate for any inclined position of the components to be sintered. This means that when the punch is brought close to a component that is not exactly level, it can adapt to the inclination of the component by tilting.

[0057] The pressure body 11 of the die is cuboid-shaped. Its surface on the underside facing away from the piston is referred to as the pressure surface. The dimensions of the pressure surface slightly exceed those of the product to be sintered in order to reliably completely cover the component to be sintered in the event of minor positional deviations, such as a slight rotation of the die and thus of the pressure body 11.

[0058] The pressure body 11 of the punch is accommodated in a recess 141 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 escape from the recess when pressure is applied by the pistons 117. The total height of the starting materials and thus the required travel distance of the punch are in the micrometer range, while the height of the pressure body and also of the recess is a few millimeters.

[0059] The distance between the sides of the pressure body 11 and the inner walls of the recess 141 is larger than the distance between the shaft 111 and the inner wall of the hole. For this reason, the possibility of the pressure body 11 becoming jammed in the recess 141 due to the previously described possible tilting of the punch is ruled out.

[0060] Since the punch merely comes into contact with the guide rod 113 or the piston 117, but is not firmly connected to it, the punch remains in an extended position after pressure is applied, although the piston 117 and the guide rod 113 are returned to their initial position by applying a negative pressure to the pressure supply line. This state is shown schematically in the Fig. 6 shown.

[0061] To release the punch from the sintered product and return it to its original position, the intermediate control chamber 119 is subjected to a negative pressure, and the punch is sucked back to its original position due to the pressure difference now prevailing between the area of ​​the pressure body 11 and the intermediate control chamber. However, this creates a slight air flow 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.

[0062] However, this slight air flow is negligible and ceases as soon as the upper surface of the pressure body 11 surrounding the shaft 111 comes into contact with the punch guide plate 15. Since the upper surface of the pressure body 11 of the punch comes into contact with the underside of the punch 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 punch, which is hot after the sintering process, and the piston.

[0063] A contribution to the return of the stamp is also made by air sucked from a gap 151 between the front side of the shaft 111 and the upper plate 16, as can be seen from Fig. 6. The air present in the intermediate space 151 is already amplified by the return of the guide rod 113 by creating the negative pressure in the intermediate control chamber 119.

[0064] This design makes it possible to replace a defective punch at any time without great effort, or, depending on the component to be sintered, to completely replace all punches. To do so, it is only necessary to remove the punches and the punch base plate 14 with the recesses 141 from the chamber and replace them with other punches with a punch base plate with matching recesses.

[0065] If, despite the thermal separation, the piston 117 jams and cannot be retracted 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, whereby the jamming is released and the piston 117 can return to its starting position.

[0066] It should also be noted here 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.

[0067] In a possible design of the stamp with a square pressure surface, the side length of the square is "a." In both cases, the piston 117 has a circular cross-section with a radius "a." In this case, where the cross-section of the stamp surface is square, the ratio of input to output area is smallest. This means that the pressure exerted on the component is maximized, as can be seen from the equation P=F / A In the equation, “P” stands for pressure, “F” for force, and “A” for cross-sectional area.

[0068] For a square with a side length of "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 with diameter "a" inscribed within the square.

[0069] Thus, it is necessary to apply a pressure to piston 117 that is higher than the pressure exerted on the starting materials. In the above example, the inlet pressure would need to be approximately 51 MPa to achieve a desired discharge pressure of 40 MPa.

[0070] In the case of a non-square, but, for example, rectangular pressure area, the ratio must be determined analogously. Required input pressures for different stamping surfaces can be provided, for example, in the form of a table or, for different output pressures, in the form of a characteristic map.

[0071] Details of the lower part 3 are shown in particular on the basis of the Fig. 1, Fig. 8 and Fig. 9 described in more detail.

[0072] On the lower part 3 of the chamber, a cooling plate 37, thermal insulation in the form of an insulating plate 35, a heating plate 33, and a product holder 31 are provided in a sequence from bottom to top. The product holder 31 serves as a counter-stamp and is used to support a substrate onto which components are to be sintered.

[0073] To improve the quality of the sintered product, it is necessary to apply heat to the raw materials as simultaneously as possible with the pressure exerted by the stamp. For this purpose, a thermal separation is provided between the heating plate 33 and the product holder 31 located above it, as can be seen from the Fig. 8 is shown schematically.

[0074] To achieve the thermal separation, pre-tensioning elements 32 are provided between a bottom side of the product holder 31 and a bottom wall of the lower part 3, which pre-tension the product holder 31 upwards at a distance from the heating plate 33. The pre-tensioning elements 32 can be designed in the form of springs, such as spiral springs, as shown in the Fig. 8 is shown schematically, but are not limited thereto.

[0075] For example, instead of the spiral springs shown schematically, other types of springs such as leaf springs, hydraulic or pneumatic pistons or mechanical means such as racks are possible as preload elements.

[0076] Due to the preload elements 32, the product holder 31 is located at a distance from the heating plate 33, in which heat transfer occurs at most to a reduced extent, since an air gap acts as an insulator between the product holder 31 and the heating plate 33. As soon as the stamps are actuated and begin to exert pressure on the starting 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 further to the starting materials.

[0077] Thus, the starting materials are simultaneously exposed to pressure and heat until the pressure load from the plunger is released by returning the piston 117. Simultaneously with the release of the pressure load, the product holder 31 is again removed from the heating plate 33 by the preload force of the preload elements 32, preventing further heating of the product holder 31 and the starting materials by the still-hot heating plate 33.

[0078] It should be noted that the presentation of the Fig. 8 only shows the components important for thermal separation, but the overall structure can be designed as shown in the Fig. 1. For example, thermal insulation, cooling, etc., may be present between the heating plate 33 and the bottom wall of the lower part 3.

[0079] The Fig. Figure 9 schematically shows an alternative for thermally separating the product holder and the heating plate. According to the alternative, the heating plate is provided with a plurality of through-holes (air channels) directed from its underside to its top side, which are connected to an air supply channel 36 leading through the bottom wall of the lower part 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 pressure is activated by the piston 117 on the plunger. After this air has passed through the numerous air channels in the heating plate 33, it forms an air cushion between the heating plate 33 and the product holder, which, in addition to thermal separation, provides additional insulation against radiant heat.

[0080] 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 plunger.

[0081] To carry out the sintering process, the device is closed by bringing together the upper part 1 and the lower part 3. This process is particularly described by the Fig. 1 to 5 described.

[0082] The side walls of the upper part 1 have a recess 131 at their edge facing the lower part 3. Corresponding projections 137a and 137b are located adjacent to the recess 131. 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 from the external environment.

[0083] 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, respectively. Their cross-sections overlap each other in the contact 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 of 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.

[0084] In the figures, the proportions of the holes are exaggerated. In fact, it is sufficient if the lengths l1 and l2 exceed the widths b of the holes 133a, 133b, and 391 by approximately 0.5 mm.

[0085] The holes, for example, 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 selected larger than the pins, automatic centering is advantageously achieved via the upper pressure point (i.e., where the pin comes into contact with the wall of the hole), thus eliminating the need for high-precision fits.

[0086] Due to the proportions of the holes 133a, 133b, and 391, a cylindrical pin 135 can easily be guided through all the holes in the abutting state due to the clearance created by the elongated hole shape. As soon as the piston 117 exerts a compressive load on the plunger and, via this, on the lower part 3 of the chamber, a situation arises as shown in Fig. 3a shown.

[0087] Due to the pressure load, a downward force F acts, causing the lower part 3 of the chamber to shift downward from its initial position until further displacement is no longer possible due to the now-blocking 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.

[0088] After the chamber is locked, the plunger 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.

[0089] In 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 bonding process in between 70 and 120 seconds. Advantageously, the heating plate is arranged so that the heat is transferred directly to the product holder 31.

[0090] The required pressure is created by applying a gas under high pressure to pistons 117 in cylinders of the cylinder plate 19.

[0091] 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 to promote the bonding process or a reaction gas can be supplied.

[0092] If this state is maintained for a predetermined time, a sintering process occurs, i.e. a connection of the silver molecules with the component and the substrate.

[0093] As soon as the pressure load on the stamp ends, the lower part 3 can again come into contact with the upper part 1, as can be seen from the Fig. 3b. In this state, the pin 135 can be easily removed from the holes 133a, 133b, and 391, and the chamber opened to remove the finished sintered components.

[0094] 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 capable of sealing the interior of the chamber not only in the installed state (see Fig. 4b) but also in the pressure load state (see Fig. 4a) to seal fluid-tight.

[0095] All compressive forces generated during the sintering process are absorbed by the chamber itself due to the mold closure. Therefore, no additional structural measures are required to absorb or dissipate high compressive forces.

[0096] An alternative to the design of the form closure is shown schematically in the Fig.5. Here, instead of the design 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 bevel on their surfaces facing away from each other. To create the positive connection, a C-shaped clamp 435 is guided over the projections. The clamp 435 has a corresponding bevel on its inner leg surfaces facing the beveled surfaces of the projections, so that surface contact between the inner leg surfaces of the clamp 435 and the beveled 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 has ended due to the bevels.

[0097] Instead of the cylindrical pin described above, the positive locking can also be realized with tapered pins and correspondingly conical holes.

[0098] Advantageously, this process described above can be automated.

[0099] According to the current state of the art, the counterforces required by the pressing process must be applied by external structures. A mechanism that moves a support assembly upwards to hold the substrate provides the external force required 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.

[0100] Due to the positive locking mechanism according to the invention, the present invention creates an internal counterforce mechanism. Therefore, an external power source to provide the counterforce is not required.

[0101] To prepare for the bonding process, the paste is printed onto the substrate, and the components (chips) are placed on the paste, i.e., the substrate is populated with the chips. The printed and chip-populated substrate is then placed into the chamber.

[0102] Because the tool is adjustable, the positions of the stamp correspond to the corresponding positions of the chips on the substrate. Advantageously, a film can be placed over the chips, for example, using rollers attached to the sides of the tool. The film can be replaced 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 done by pulling the film wound on a roller further, thereby changing the position of the film. The film material can be, for example, PTFE or a similar plastic, but is not limited to this.

[0103] The bonding process takes place over a predetermined period of time at a predetermined temperature and pressure to effectively sinter the component onto the substrate. Advantageously, the component and / or the other starting materials, such as the substrate and silver paste, can be preheated or cooled using a preheating or cooling device before and after the bonding process.

[0104] While the invention has been described with reference to a presently preferred embodiment, it is to be understood that this description of the embodiment is for illustrative purposes only and is not intended to limit the scope of the invention. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2013 101 124

[0011] DE 10 2015 120 156 A1

[0012]

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), and a heating device (33) is provided on a side of the counter-stamp (31) facing away from the first part (1), wherein the first part (1) is displaceable towards the second part (3) to close the chamber, wherein the counter-stamp (31) can be loaded with starting materials when the chamber is open, and in a closed state of the chamber, pressure can be exerted via the stamp (11, 111) on the starting materials provided between the stamp (11, 111) and the counter-stamp (31), wherein the counter-stamp (31) is spaced apart from the heating device (33) in an unloaded state and is configured to come into contact with the heating device (33) due to the pressure exerted by the stamp (11, 111). [2] Device according to claim 1, wherein the heating device (33) is designed in the form of a heating plate, the surface of which directed towards the counter-stamp (31) is configured to come into contact with a surface of the counter-stamp facing away from the first part (1). [3] Device according to claim 1 or 2, wherein the counter-punch (31) is spaced from the heating device by means of prestressing elements, the prestressing of which is overcome due to the pressure exerted by the punch (11, 111) and is restored after the end of the pressure exerted by the punch (11, 111). [4] Device according to one of claims 1 to 3, wherein the counter-stamp (31) is spaced from the heating device (33) by means of springs (32) in a load-free state. [5] Device according to one of claims 1 to 4, wherein the counter-stamp (31) is spaced from the heating device (33) in a load-free state by means of an air cushion, wherein the air supply to the air cushion takes place via air ducts (34, 36) guided at least partially through the heating device. [6] 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 displaceable towards the second part (3) to close the chamber, wherein the counter-stamp (31) can be loaded with starting materials when the chamber is open, and in a closed state of the chamber, pressure can be exerted via the stamp (11, 111) on the starting materials provided between the stamp (11, 111) and the counter-stamp (31), 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 an interference fit, and a pressure body (11) of the stamp (11, 111) has a larger cross-sectional area than the shaft (11) of the stamp (11, 111), wherein a vacuum device (119) is provided on a side of the punch guide plate (15) facing away from the counter punch (31). [7] Device according to claim 6, wherein on the side of the punch guide plate (15) facing away from the counter punch (31) a cylinder plate (19) is provided, which has a piston (117) which is movable back and forth in a cylinder bore and which has a guide rod (113) on a side directed towards the punch (11, 111) which is configured to come into contact with the end face of the shaft (111) when pressure is applied to the piston (117) and to exert pressure on the punch (11, 111). [8] Device according to claim 7, wherein the end face of the shaft (111) of the punch (11, 111) is flat, and a tip of the guide rod (113) which is to be brought into contact with the end face of the shaft (111) is rounded. [9] Device according to one of claims 6 to 8, 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 intermediate control chamber can be subjected to a negative pressure or an overpressure. [10] Device according to one of claims 7 to 9, 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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