CYLINDER PLATE OF A DEVICE FOR CONNECTING A BUILDING ELEMENT TO A SUBSTRATE

Description

[0001] The invention relates to a cylindrical plate of a device for connecting a component to a substrate and to such a device. 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 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] Publication JP H11 - 121 532 A discloses a sintering device in which pistons are pneumatically actuated to exert pressure on a product to be sintered.

[0014] The publication EP 2 954 550 B1 discloses a sintering device in which several pistons are housed in cylinder bores of a cylinder plate. The pistons can be pneumatically actuated to transmit pressure via plungers to a product to be sintered.

[0015] To actuate the pistons, a pressure medium must be supplied to the cylinder bores via pressure supply lines. According to the state of the art, these pressure supply lines are manufactured by drilling holes from outside the cylinder plate. In the case of more extensive piping systems, it is necessary to produce a large number of holes, all of which, except for one connection for the pressure medium, must be sealed. Furthermore, if several pistons are to be actuated independently, the pressure supply lines must be arranged at different heights, as there must be no overlap or crossing of the different pressure supply lines. It is conceivable, for example, that individual pistons or groups of pistons may be subjected to different pressures.

[0016] Since the arrangement of the pressure supply lines and cylinder bores depends on the design of the components to be manufactured, the location and diameter of the cylinder bores, as well as the routing of the pressure supply lines, vary considerably. According to current technology, each new cylinder plate requires different tooling setup and machine reprogramming for its production. Furthermore, due to the strength limitations of the drilling tool, it is not possible to produce boreholes with a minimum diameter. This is because the pressure supply lines have a length-to-diameter ratio that is unfavorable for drilling.

[0017] Manufacturing small-diameter horizontal pressure supply lines, in particular, is very demanding and often leads to defective cylinder plates, i.e., scrap. Therefore, rigorous quality control is essential.

[0018] Examples of this undocumented state of the art are taken from the Figs. 10 bis 12 and the Figs. 19 , 20 , 20a bis 20c evident. The Figs. 10 bis 12 a cylinder plate 190 with a single pressure supply line 191 for supplying all cylinder bores 118. The pressure medium is introduced into the pressure supply line via a connection 193.

[0019] The Figs. 19, 19 , 20 , 20a bis 20c Figure 1 shows a cylinder plate 190 in which cylinder bores 118a, 118b, and 118c are each supplied in groups via their own pressure supply line 191a, 191b, and 191c with connections 193a, 193b, and 193c. To prevent the individual lines from crossing, the different pressure supply lines 191a, 191b, and 191c are each arranged in their own plane, as shown in the figure 191a. Fig. 20 as is evident.

[0020] There is a need for an improved cylindrical plate that is easier to manufacture and more flexible in design compared to the state of the art, and for a device for connecting a component to a substrate using such a cylindrical plate.

[0021] A cylindrical plate according to the invention is provided for a device for connecting a component to a substrate, which has a chamber divisible into at least two parts. The cylindrical plate is provided on a first part of the chamber. The cylindrical plate includes: a cylinder bore for receiving a reciprocating piston, which, when pressurized with a gaseous pressure medium, can be brought into contact with a plunger to transmit pressure and press the plunger against a counter-plunger provided on a second part; and a pressure supply line through which a pressure medium can be supplied to the cylinder bore to actuate the piston. The cylindrical plate is manufactured using additive manufacturing.

[0022] Surprisingly, it has been found that despite the inferior material properties of a cylindrical plate manufactured using additive manufacturing, the material characteristics such as tensile strength, modulus of elasticity, etc., are sufficient for the intended application, even with the required input pressure between 50 MPa and 60 MPa. Therefore, an additively manufactured cylindrical plate represents a cost-effective and, above all, flexible alternative to a conventional cylindrical plate.

[0023] The inferior material properties of printed metal, such as lower tensile strength and lower modulus of elasticity, can be compensated for by the fact that smaller pipe diameters and thus thinner wall thicknesses are possible compared to conventionally manufactured cylindrical plates. Furthermore, the very high degree of design freedom for the pressure supply lines represents a further advantage of the cylindrical plate according to the invention.

[0024] Advantageously, the cylinder plate according to the invention can be provided with a plurality of cylinder bores, each containing a reciprocating piston. Each cylinder bore can be supplied with a pressure medium via a pressure supply line formed in the cylinder plate.

[0025] This makes it possible to supply each individual cylinder bore with the pressure medium independently of the other cylinder bores. However, it is equally possible to supply all cylinder bores simultaneously with the pressure medium via the pressure supply line formed in the cylinder plate.

[0026] The cylinder plate according to the invention can have a plurality of cylinder bores, and individual cylinder bores can be grouped together. Cylinder bores of a group can be supplied with a pressure medium via their own pressure supply line formed in the cylinder plate.

[0027] Thus, depending on the requirements of the components to be sintered, individual groups can be defined, and the components can be subjected to different pressures.

[0028] Advantageously, several pressure supply lines can be provided in a single plane of the cylinder plate according to the invention. Intersections or crossings of two different pressure supply lines are avoided by the second pressure supply line bypassing the first pressure supply line via a second plane.

[0029] Accordingly, it is possible to design the cylinder plate with a smaller thickness compared to the state of the art, since it is not necessary to provide each pressure supply line in its own plane.

[0030] At least one section of the pressure supply line may deviate from a straight shape.

[0031] Additive manufacturing makes it possible to produce not only straight pressure supply lines, but also lines with any desired curvature in three-dimensional space. This allows for the shortest possible connection between a pressure medium and a corresponding cylindrical bore.

[0032] Preferably, the pressure supply lines can have a circular cross-section. However, it is equally possible to manufacture a cross-section other than circular, such as square, polygonal, elliptical, or even star-shaped.

[0033] The pressure supply line can advantageously have a diameter between 0.1 mm and 4 mm. Preferably, the diameter is between 0.1 mm and 1 mm.

[0034] Additive manufacturing makes it possible to produce pressure supply lines with much smaller diameters than is possible with conventional methods. This is highly advantageous because the reduced surface area of ​​a thin pressure supply line decreases the pressure force acting on the cylinder plate. Consequently, the overall wall thickness can be reduced, saving both installation space and material.

[0035] Advantageously, the cylinder plate can be made of aluminum or an aluminum alloy.

[0036] Advantageously, the cylinder plate can comprise several parts.

[0037] This simplifies manufacturing, as a printing device for additive manufacturing can be smaller. But even for non-additively manufactured cylindrical plates according to the state of the art, such a division is advantageous, as the bores can be manufactured more easily.

[0038] Four parts are preferred, however the number of multiple parts can be chosen to be any size from two upwards.

[0039] Advantageously, the cylindrical plate can have holes in its edge areas for mounting via pins on a top part of a device for connecting a component to a substrate.

[0040] Advantageously, the cylindrical plate can be connected to the chamber and / or the stamping plate at its connection surfaces via pins or other positive-locking connection techniques. In this case, a one-dimensional displacement in the plane of the corresponding connection surface is provided on one side of the respective connection mechanism. For a cylindrical pin, this could, for example, be designed as an elongated hole.

[0041] The contact surface is defined as the area of ​​the cylinder plate where it comes into contact with or is connected to adjacent elements such as the upper part of the chamber or the stamp plate.

[0042] This allows for precise positioning of the cylinder plate via the holes and pins. This is particularly advantageous with a multi-part cylinder plate, as the individual parts can be fixed in place.

[0043] Advantageously, the holes can be designed as elongated holes whose longitudinal axis lies on a line that connects the respective connecting surface of the cylinder plate with a zero point (A) of the cylinder plate or a joint point of several parts of the cylinder plate.

[0044] The point of contact is defined here as the point where, in the case of a multi-part cylindrical plate, the several parts abut each other. The zero point is defined as a point that corresponds to the center point of the cylindrical plate or a part thereof. The zero point has the property that, due to the mounting of the cylindrical plate via the holes, it is not subject to any change in position in the event of thermal expansion.

[0045] The longitudinal axes of the one-dimensional displacement mechanisms in the case of elongated holes or slots define a zero point of the respective connection system at their intersection. The direction of the longitudinal axes in the connection surface can be freely chosen. It must be ensured, however, that at least one longitudinal axis is not parallel to the others.

[0046] An inventive device for connecting a component to a substrate has a chamber that can be divided into at least two parts. A first part has a plunger, and a second part has a counter-plunger. The first part can be brought into contact with the second part to close the chamber. The counter-plunger can be loaded with starting materials when the chamber is open. When the chamber is closed, pressure can be exerted on the starting materials located between the plunger and the substrate via the plunger. A cylindrical plate, as described above, is provided on the first part. The pressure of the pressure medium in the pressure supply line is transmitted to the plunger by means of a piston.

[0047] The pressure medium is preferably a gas.

[0048] The invention also relates to a method for manufacturing a cylinder plate having cylinder bores connected to a port via a pressure supply line. The cylinder plate is additively manufactured by applying a material that hardens after application layer by layer onto a manufacturing surface. The cylinder bores and the pressure supply lines are recessed during the material application.

[0049] Advantageously, the pressure supply lines can lie in a single plane of the cylinder plate, and cuts or crossings of two different pressure supply lines are made by bypassing one pressure supply line through the other pressure supply line via a second plane.

[0050] Accordingly, it is possible to provide several cylinder groups, each subjected to different pressures and / or at different times. Because all lines, except at the intersections of two lines where a second plane is used, lie in a single plane, the cylinder plate can be designed with a reduced thickness. BRIEF DESCRIPTION OF THE FIGURES

[0051] 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 positive 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 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 equipped 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 joining a component to a substrate. Fig. 7a shows a view of a stamp from the underside of the stamp, Fig. 7b shows a side view of the punch, the shank of which is guided in a punch guide plate, and Fig. 7c shows a view of the die shank guided in the die guide plate from a top view. Fig. 8 shows a detailed view of a lower part of the device with a thermal separation device. Fig. 9 shows an alternative device for thermal separation. Fig. 10 shows a cylindrical plate according to the state of the art. Fig. 11 shows a front view of the cylinder plate of the Fig. 10 . Fig. 12 shows a sectional view of the cylinder plate of the Fig. 10 along line AA in the Fig. 11 . Fig. 13 shows a perspective view of a cylindrical plate according to the invention. Fig. 14 shows a front view of the cylinder plate of the Fig. 13 . Fig. 15 shows a sectional view of the cylinder plate of the Fig. 13 along line AA in the Fig. 14 . Fig. 16 shows a perspective view of another embodiment of a cylindrical plate according to the invention. Fig. 17 shows a front view of the cylinder plate of the Fig. 16 . Fig. 18 shows a sectional view of the cylinder plate of the Fig. 16 along line AA in the Fig. 17 . Fig. 19 shows another cylindrical plate according to the state of the art. Fig. 20 shows a front view of the cylinder plate of the Fig. 19 . Figs. 20a , 20b und 20c show sectional views of the cylinder plate of the Fig. 19 along lines AA, BB or CC of the Fig. 19 . Fig. 21 shows a perspective view of another embodiment of a cylindrical plate according to the invention. Fig. 22 shows a front view of the cylinder plate of the Fig. 21 . Fig. 23 shows a sectional view of the cylinder plate of the Fig. 21 along line AA in the Fig. 22 . Fig. 24 shows a perspective view of a multi-part cylinder plate and a stamp plate according to an embodiment of the invention. Fig. 25 shows a front view of the cylinder plate with stamp plate according to Fig. 24 . Fig. 26 shows a top view of the cylinder plate of the Fig. 24 Fig. 27 shows a top view of a stamping plate corresponding to line AA of the Fig. 25 .

[0052] Embodiments of the invention are described by reference to the Figs. 1 bis 23 described. The figures are schematic, and some described details may have been omitted.

[0053] The Figs. 13 bis 15 show a first embodiment of a cylindrical plate according to the invention.

[0054] The cylinder plate is manufactured using additive manufacturing. For this process, a liquid material is applied layer by layer to a work surface. After application, the liquid material solidifies, allowing further layers to be applied to the existing solidified material layers. The application process is such that areas remain unfilled in the finished cylinder plate. These areas include, in particular, the cylinder bores 118 and a pressure supply line 115. As can be seen in Figures 13 to 5, the pressure supply line 115 runs from a connection 116 on the side of the cylinder plate 19 to the cylinder bores 118.

[0055] It should also be noted that, for the sake of clarity, not every element in the figures is labelled with a reference symbol. For example, in the Fig. 13 A cylinder bore is designated with the reference numeral 118. The remaining cylinder bores are identical to the cylinder bore designated with the reference numeral, except for their position.

[0056] Since the pressure supply line 115 is manufactured by leaving the areas occupied by it free, it, unlike the pressure supply line 191, according to the state of the art (see e.g. Fig. 10 ) does not take up unnecessary space in places where it is not needed. For this reason, not only is the strength of the cylindrical plate 19 improved, but the need to reseal the parts of the pipes created by drilling that protrude to the edge of the cylindrical plate 19 is also eliminated.

[0057] According to the prior art cylinder plate, the bores must be sealed again, which is only partially possible. For this reason, parts of the bores remain, even though a pressure supply line is not required at these points. These remaining open areas, as well as the additional material used to seal the bores, can negatively affect the strength of the cylinder plate according to the prior art. These disadvantages are avoided according to the invention.

[0058] From the Figs. 16 bis 18 Another embodiment of a cylinder plate according to the invention is shown. Here, a pressure supply line 115' is shown, deviating from the straight design of the first embodiment. Figs. 13 bis 15 The pressure supply line 115' is designed in a curved manner. This reduces the volume occupied by the pressure supply line 115' in the cylinder plate 19, thereby further improving the strength of the cylinder plate 19.

[0059] From the Fig. 21 and the Figs. 22 und 23 A third embodiment of the cylinder plate 19 according to the invention is shown. Here, the cylinder bores are divided into three groups of cylinder bores 118a, 118b, and 118c. Each of these individual groups is supplied with a pressure medium via its own pressure supply line 115a, 115b, or 115c, from connections 116a, 116b, and 116c. The pressure supply lines 115a, 115b, and 115c are all located in the same plane. Only at intersections and points where two lines cross, such as line 115a and line 115b, is one of the pressure supply lines routed over the other. Fig. 21 It is shown that, for example, the pressure supply line 115a is routed over both the pressure supply line 115b and the pressure supply line 115c in order to supply the cylinder bores 118a, 118a, located furthest from the connection in the drawing above and to the right. Similarly, at intersections with the pressure supply line 115b, the pressure supply line 115c is routed over it.

[0060] In addition to allowing for arbitrarily curved pressure supply lines in 3D space, additive manufacturing also enables the production of significantly thinner pressure supply lines than is possible with conventional methods. For example, diameters of 0.1 mm to 1 mm are achievable. Due to these reduced cross-sectional areas of the pressure supply lines, the surface area of ​​the lines is considerably smaller than in conventional methods. Consequently, a lower compressive force acts on the structure of the cylinder plate itself. This is known to be caused by F = p * A Expressed in this way, F represents the force, p the pressure, and A the area on which the pressure acts. Here, A is the lateral surface area of ​​the pipe. Consequently, thinner walls can be used, which means that, despite the reduced strength due to additive manufacturing, the material required for the cylinder plate can be lower than for cylinder plates manufactured using state-of-the-art methods.

[0061] Since both the surface area and the volume of the pressure supply lines are smaller compared to the prior art, the energy required to introduce the preferably gaseous pressure medium into the pressure supply lines is reduced. The technical work required to achieve a specific pressure depends on the volume in which the pressure must be achieved. This is illustrated by the equation A t 12 = V p 2 − p 1 Expressed in the equation above, A t12 represents the technical work required to move from a first state to a second state, V represents the volume, and p 1 and p 2 represent the pressures in the first and second states, respectively, i.e., before and after the pressure is applied.

[0062] Since the pressure supply lines are arranged in only one plane, and the plane only needs to be briefly left when lines cross, the cylinder plate according to the invention can be manufactured with a much smaller thickness by additive manufacturing than is possible according to the prior art.

[0063] A further advantage is that it is not necessary to seal the externally drilled pressure supply lines, for example by plugging or welding, according to current best practices. Screwing plugs into the boreholes not only means more complex manufacturing, as it requires threading the boreholes to insert the plugs, and additional manufacturing steps, but also increases the risk of failure and wear. Welding the externally open boreholes, on the other hand, places thermal stress on the component, which can cause it to warp. Furthermore, the heat generated during welding can locally alter the material properties, potentially impairing the strength of the cylinder plate in certain areas.

[0064] Since it is not possible to completely seal the boreholes that are no longer needed after the pressure supply lines have been manufactured, along their entire length not required for the pressure supply line, an unnecessary volume of pipe remains according to the prior art. This volume must be pressurized with unnecessary energy expenditure, as can be seen from equation (2) above. Furthermore, there is a risk of damaging the structure of the cylinder plate due to the increased pressure force.

[0065] In the following, a device according to the invention for connecting a component to a substrate is described, which is provided with one of the additively manufactured cylindrical plates described above.

[0066] The device according to the invention is with reference to the Fig. 1 The chamber is designed in the form of 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.

[0067] 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.

[0068] The top will be based on the Figs. 1 , 6 und 7 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 is additively manufactured and has cylinder bores 118, 118a, 118b, 118c in which pistons 117 are received. The cylinder bores 118, 118a, 118b, 118c on a side of the cylinder plate 19 facing away from the respective piston 117 are connected to a pressure supply line 115, 115', 115a, 115b, 115c. This piston-cylinder arrangement serves as a pneumatic adjustment device. Examples of different arrangements of one or more pressure supply lines are shown in the Figs. 13 bis 18 and 21 bis 23 as can be seen and is described above in connection with the cylinder plate 19 according to the invention.

[0069] To actuate the pistons 117, a pressurized fluid, such as air, is introduced into the cylinder bores 118, 118a, 118b, 118c in the cylinder plate 19 via the pressure supply line 115, 115', 115a, 115b, 115c, thereby actuating the pistons 117. This actuation causes the pistons 117, together with a guide rod 113 provided on a side of the piston 117 facing the lower part 3, to move towards the lower part 3 of the chamber. This direction is hereinafter also referred to as "downward direction" or simply "downwards" and corresponds in the figures to a direction from the upper surface of the leaf to the lower surface.

[0070] 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, 115', 115a, 115b, 115c, which returns the pistons 117 and the guide rods 113 to their initial position.

[0071] 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.

[0072] As can be seen in particular from the Fig. 6 As can be seen, 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, 115', 115a, 115b, 115c. 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.

[0073] 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.

[0074] On the side of the shaft 111 facing away from the piston, there is a pressure body 11 of the ram, which is directed towards the pressure plate 31. In the Fig. 1 Seven stamps are shown; 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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 punch, as shown from Fig. 6 This 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.

[0084] 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.

[0085] 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, 115', 115a, 115b, 115c, 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.

[0086] 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.

[0087] 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.

[0088] 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".

[0089] 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.

[0090] 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.

[0091] Details of subsection 3 will be explained in particular by reference to the Figs. 1 , 8 und 9 more precisely described.

[0092] 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.

[0093] 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 as can be seen schematically.

[0094] 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 coil springs, as shown in the Fig. 8 The schematic representation is used, but they are not limited to this.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] It should be noted that the presentation of the Fig. 8 It only shows the components important for thermal separation, but the overall structure can be designed as shown in the Fig. 1 is shown. For example, thermal insulation, cooling, etc. may be present between the heating plate 33 and the bottom wall of the lower part 3.

[0099] The Fig. 9 Figure 1 schematically shows an alternative to 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. These air channels 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. This air cushion provides thermal separation and additional insulation against radiant heat.

[0100] 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.

[0101] 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 Figs. 1 bis 5 described.

[0102] 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.

[0103] In each of the projections 137a, 137b, 39, holes 133a, 133b, and 391 are provided transversely to the opening and closing directions of the chamber, respectively. Their cross-sections overlap when the chamber is in its closed position. The holes 133a, 133b, and 391 are elongated. This means that the length l1 of the holes 133a, 133b in the upper part and the length l2 of the hole 391 in the lower part 3 exceed the width b of the holes 133a, 133b, and 391. The inner hole 133b is a blind hole.

[0104] 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.

[0105] 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.

[0106] 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 depicted one.

[0107] 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.

[0108] As from the Fig. 2a As can be seen, several series of holes 133a, 133b and 391 are provided, across which the resulting force F is distributed. Thus, requirements regarding the material properties of the pins can be met.

[0109] 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.

[0110] 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.

[0111] The required pressure is generated by pressurizing pistons 117 in cylinders of the cylinder plate 19 with a gas under high pressure.

[0112] 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.

[0113] 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.

[0114] 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 This is evident. In this state, pin 135 can easily be removed from holes 133a, 133b and 391 and the chamber opened to remove the finished sintered components.

[0115] In the Figs. 4a und 4b A variant is shown 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). Fig. 4b ) but also in the pressure load state (see Fig. 4a ) to seal fluid-tight.

[0116] 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.

[0117] An alternative design for the positive locking mechanism is schematically derived from the Fig. 5 As can be seen, 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.

[0118] Instead of the cylindrical pin described above, the positive locking mechanism can also be achieved, for example, with tapered pins and correspondingly conical bores.

[0119] The process described above can be advantageously automated.

[0120] 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.

[0121] 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.

[0122] 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.

[0123] 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.

[0124] 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.

[0125] Figs. 24 bis 27 Figure 1 shows an advantageous embodiment of the cylindrical plate 19. The cylindrical plate 19 is made up of four parts 19a, 19b, 19c, and 19d. Each part 19a, 19b, 19c, and 19d has a rectangular shape. All four parts 19a, 19b, 19c, and 19d are arranged such that they abut each other at a point of contact A. The point of contact A corresponds to the center of the cylindrical plate 19 and also to a zero point.

[0126] For connection to an upper part of a device for joining a component to a substrate, pins 20a, 20b, 20c, 20d are provided, which are received in holes 195a, 195b, 195c, 195d provided at the corners of the cylindrical plate 19. The holes 195a, 195b, 195c, 195d are designed as elongated holes whose longitudinal axis lies on a line connecting the respective corner of the cylindrical plate 19 or of the respective part 19a, 19b, 19c, 19d with the joint point A. Thus, the longitudinal axes of the elongated holes intersect at the joint point A, which in this embodiment also corresponds to the zero point.

[0127] This arrangement ensures that, in the event of heating of the cylindrical plate 19, the zero point (impact point A) remains in place, while the outer corners of the cylindrical plate 19 or each part 19a, 19b, 19c, 19d can be displaced along the axis of the corresponding elongated hole 195a, 195b, 195c, 195d with the respective pin 20a, 20b as a guide due to thermal expansion.

[0128] To compensate for thermal expansion of the punch guide plate 15, it is also provided with elongated holes 155a, 155a' and 155a" as shown in the Fig. 27 as can be seen, and are connected to the four parts 19a, 19b, 19c, 1519c', 1519c" of the cylinder plate 19 via pins 1519a, 1519a', 1519a", 1519b, 1519b', 1519c", 1519d, 1519d', 1519d". Thus, each part 19a, 19b, 19c, 19d is connected to the die guide plate at three of its corners. Only the corners at the joint A do not have pins. In the Fig. 27Only the elongated holes 155a, 155a' and 155a" whose longitudinal axes define point B1 are marked with reference symbols. For the sake of clarity, the elongated holes of the other three sections are not marked with reference symbols.

[0129] The pins 1519a to 1519d" are arranged in the elongated holes 155a, 155a' and 155a" of the punch guide plate 15, which are aligned such that their longitudinal axes intersect at a zero point B1, B2, B3 or B4. In the cold state, these points B1, B2, B3, B4 correspond to the center points of parts 19a, 19b, 19c, 19d of the cylinder plate 19. The arrangement of the elongated holes 155a, 155a', and 155a" and pins 1519a to 1519d" of the punch guide plate 15 enables excellent compensation for the different thermal expansions between the cylinder plate 19 (the four parts 19a, 19b, 19c, 19d) and the punch guide plate 15. Because the zero points B1, B2, B3, and B4 of the punch guide plate 15 are defined, it is ensured that the zero points do not shift relative to their corresponding points on the cylinder plate. This allows for precise pressure to be applied to the punch 11, regardless of thermal expansion.

[0130] This ensures that even if the individual plates 15, 19 expand thermally during operation, the positions of the punches 11 always correspond sufficiently accurately to the corresponding positions of the components on the substrate, thus preventing defects.

[0131] While the invention has been described using a currently preferred embodiment, it is noted that this description of the embodiment serves as an explanation for better understanding, but does not limit the scope of protection.

[0132] For example, the zero point defined by the elongated holes and the cylindrical pins is freely selectable. While, according to the embodiment, it lies in the center of the cylindrical plate, it can also be defined elsewhere if necessary.

[0133] This is easily achieved by changing the orientation of the slots so that their longitudinal axes intersect at a different point. In some applications, it can be advantageous to position the tool's zero point at a specific point on the component being pressed. In this case, the longitudinal axes of the slots do not lie on a line connecting a corner to the center of the cylinder plate.

[0134] In this embodiment, the pins and holes are arranged as elongated slots in the corner of the cylinder plate. However, it can be advantageous to arrange them at other locations along the edge of the cylinder plate, for example, in the middle of each side or even with several holes on each side of the cylinder plate.

Claims

1. A cylinder plate (19) for a device for connecting a component to a substrate, comprising a chamber that can be divided into at least two parts, wherein the cylinder plate (19) is provided on a first part (1) of the chamber, and formed in the cylinder plate (19) are: a cylinder bore (118; 118a, 118b, 118c) for receiving a reciprocating piston (117) which, when pressurized with a gaseous pressure medium, can be brought into abutment with a punch (11, 111) for pressure transmission so as to press the punch against a counter-punch (31) provided on a second part (3), and a pressure supply line (115; 115a, 115b, 115c) via which a pressure medium can be supplied to the cylinder bore (118; 118a, 118b, 118c) to actuate the piston (117), characterized in that the cylinder plate (19) is manufactured by additive manufacturing.

2. The cylinder plate according to claim 1, wherein a plurality of cylinder bores (118) are provided in the cylinder plate (19), with reciprocating pistons (117) received therein, and each cylinder bore can be supplied with a pressure medium via a pressure supply line (115; 115a, 115b, 115c) formed in the cylinder plate.

3. The cylinder plate according to claim 1 or 2, wherein a plurality of cylinder bores (118a, 118b, 118c) are provided in the cylinder plate (19), and individual cylinder bores (118a, 118b, 118c) are grouped together, and the cylinder bores (118a, 118b, 118c) of a group can be supplied with a pressure medium via a separate pressure supply line (115a, 115b, 115c) formed in the cylinder plate (19).

4. The cylinder plate according to any one of claims 1 to 3, wherein multiple pressure supply lines (115a, 115b, 115c) are provided in a single plane of the cylinder plate (19), and intersections or crossings (115a:115b, 115a:115c, 115c:115b) of two different pressure supply lines are avoided by bypassing the first pressure supply line (115b; 115c) by the second pressure supply line (115a; 115c; 115a) via a second plane of the cylinder plate (19).

5. The cylinder plate according to any one of claims 1 to 4, wherein at least one portion of the pressure supply line (115; 115a, 115b, 115c) is formed in a shape deviating from a straight shape.

6. The cylinder plate according to any one of claims 1 to 5, wherein the pressure supply line (115) has a circular cross-section or a cross-section deviating from a circular shape.

7. The cylinder plate according to any one of claims 1 to 6, wherein the pressure supply line (115) has a diameter between 0.1 mm and 1 mm.

8. The cylinder plate according to any one of claims 1 to 7, wherein the cylinder plate (19) is made of aluminum or an aluminum alloy.

9. The cylinder plate according to any one of claims 1 to 8, wherein the cylinder plate comprises multiple parts (19a, 19b, 19c, 19d).

10. The cylinder plate according to any one of claims 1 to 9, wherein the cylinder plate (19; 19a, 19b, 19c, 19d) includes holes (195a, 195b, 195c, 195d) in corner regions for supporting via pins (20a, 20b, 20c, 20d) on an upper part (1) of a device for connecting a component to a substrate.

11. The cylinder plate according to claim 10, wherein the holes (195a, 195b, 195c, 195d) are designed as elongated holes the longitudinal axes of which have an intersection point that defines a zero point.

12. The cylinder plate according to claim 11, wherein each longitudinal axis lies on a line connecting the respective corner of the cylinder plate (19; 19a, 19b, 19c, 19d) to a center point (A) of the cylinder plate (19) or a contact point (A) of multiple parts (19a, 19b, 19c, 19d) of the cylinder plate.

13. Device for connecting a component to a substrate, comprising a chamber which can be divided into at least two parts, wherein a punch (11, 111) is provided on a first part (1), and a counter-punch (31) is provided on a second part (3), wherein the first part (1) can be brought into abutment with the second part (3) to close the chamber, wherein the counter-punch (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 via the punch (11) on the starting materials provided between the punch (11, 111) and the counter-punch (31), wherein a cylinder plate according to any one of claims 1 to 12 is provided on the first part, and the pressure of the gaseous pressure medium in the pressure supply line (115; 115a, 115b, 115c) is transmitted to the punch (11, 111) by means of a piston (117).

14. A method for manufacturing a cylinder plate (19) having cylinder bores (118) that are connected via a pressure supply line (115) to a port (193), wherein the cylinder plate (19) is additively manufactured by applying a material that solidifies after application in layers onto a manufacturing surface, wherein the cylinder bores (118) and the pressure supply lines (115) are left out during the application of the material.

15. The method according to claim 14, wherein the pressure supply lines (115, 115a, 115b, 115c) lie in a single plane of the cylinder plate, and intersections or crossings of two different pressure supply lines (115a:115b; 115a, 115c; 115c; 115b) are formed by bypassing one pressure supply line (115b; 115c) by the other pressure supply line (115a; 115a, 115c) via a second plane.