Cylinder plate of a device for connecting a component to a substrate

Abstract

A cylinder plate (19) according to the invention is provided for a device for connecting a component to a substrate, said device having a chamber that can be divided into at least two parts (1, 3). The cylinder plate (19) is provided on a first part (1) of the chamber. Formed in the cylinder plate (19) are: a cylinder bore (118a, 118b, 118c) for receiving a reciprocating piston (117), which, when acted upon by a gaseous pressure medium for pressure transmission, can be brought into contact with a stamp (11, 111) in order to press the stamp (11, 111) against a counter-stamp (31) provided on a second part (3), and a pressure supply line (115a, 115b, 115c), via which a pressure medium can be supplied to the cylinder bore (118a, 118b, 118c) for actuating the piston (117). The cylinder plate (19) is manufactured by additive manufacturing.

Description

[0001] The invention relates to a cylinder plate of a device for connecting a component to a substrate and to such a device. 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] The document 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] EP 2 954 550 B1 discloses a sintering device in which several pistons are accommodated in cylinder bores of a cylinder plate. The pistons can be pneumatically actuated to transfer pressure to a product to be sintered via plungers. This document shows the features of the preamble of claim 1.

[0015] A similar cylinder plate is known from the document DE 10 2017 216 545 A1.

[0016] 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, the pressure supply lines are created by drilling holes from outside the cylinder plate. In the case of more extensive piping systems, it is necessary to create a large number of drill holes, all of which, except for one, must be closed again for the pressure medium connection. In the case of several pistons to be actuated in different ways, it is also necessary to arrange the pressure supply lines at different heights, as there must be no overlaps or crossings between the different pressure supply lines. This is because it is conceivable to apply different pressures to individual pistons or groups of pistons.

[0017] Since the arrangement of the pressure supply lines and cylinder bores depends on the design of the components to be produced, the location and diameter of the cylinder bores, as well as the routing of the pressure supply lines, vary considerably. According to the state of the art, manufacturing each new cylinder plate requires setting up different tools and reprogramming the machine. Furthermore, due to the strength of the drilling tool, drilling holes below a certain minimum diameter is not possible. The pressure supply lines have an unfavorable length-to-diameter ratio for drilling.

[0018] The manufacturing of small-diameter horizontal pressure supply lines in particular is very demanding and often leads to defective cylinder plates, i.e., scrap. Therefore, extensive quality assurance is essential.

[0019] Examples of this undocumented state of the art can be found in the Fig. 10 to 12 and the Fig. 19, 20, 20a to 20c. The Fig. 10 to 12 a cylinder plate 190 with a single pressure supply line 191 to supply all cylinder bores 118. The pressure medium is introduced into the pressure supply line via a connection 193.

[0020] The Fig. 19, 19, 20, 20a to 20c show a cylinder plate 190 in which cylinder bores 118a, 118b, and 118c are supplied in groups via their own pressure supply lines 191a, 191b, and 191c with connections 193a, 193b, and 193c. To prevent crossings of the individual lines, the different pressure supply lines 191a, 191b, and 191c are each arranged in a separate plane, as can be seen from the Fig. 20 is evident.

[0021] The object is to provide an improved cylinder plate which is easier to manufacture and more flexible in design compared to the prior art and to provide a device for connecting a component to a substrate having such a cylinder plate.

[0022] The object of the invention is achieved by a cylinder plate according to claim 1, a device according to claim 13 and a method according to claim 14.

[0023] A cylinder plate according to the invention is provided for a device for connecting a component to a substrate, said device having a chamber that can be divided into at least two parts. The cylinder plate can be arranged on a first part of the chamber. Formed in the cylinder plate are: a cylinder bore for receiving a reciprocating piston that, when actuated by a gaseous pressure medium for pressure transmission, can be brought into contact with a stamp in order to press the stamp against a counter-stamp provided on a second part, and a pressure supply line via which a pressure medium can be supplied to the cylinder bore to actuate the piston. The cylinder plate is additively manufactured by layer-by-layer application of a material that solidifies after application to a production surface.

[0024] Surprisingly, it has been found that, despite the inferior material properties of a cylinder plate produced using additive manufacturing, the material parameters such as tensile strength, elastic modulus, etc., are sufficient for the intended application, despite the required input pressure between 50 MPa and 60 MPa. Therefore, an additively manufactured cylinder plate represents a cost-effective and, above all, flexible alternative to a cylinder plate manufactured using state-of-the-art technology.

[0025] The inferior material properties of printed metal, such as lower tensile strength, lower modulus of elasticity, etc., can be compensated for by allowing smaller line diameters and thus thinner wall thicknesses than with conventionally manufactured cylinder plates. Furthermore, the very high degree of design freedom for the pressure supply lines represents a further advantage of the cylinder plate according to the invention.

[0026] Advantageously, the cylinder plate according to the invention can be provided with a plurality of cylinder bores with reciprocating pistons accommodated therein. Each cylinder bore can be supplied with a pressure medium via a pressure supply line formed in the cylinder plate.

[0027] 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 with the pressure medium simultaneously via the pressure supply line formed in the cylinder plate.

[0028] The cylinder plate according to the invention can be provided with a plurality of cylinder bores, and individual cylinder bores can be combined into groups. Cylinder bores of a group can be supplied with a pressure medium via a dedicated pressure supply line formed in the cylinder plate.

[0029] 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.

[0030] Advantageously, the cylinder plate according to the invention can provide multiple pressure supply lines in a single plane of the cylinder plate. Intersections or crossings between two different pressure supply lines are avoided by bypassing the first pressure supply line with the second pressure supply line via a second plane.

[0031] Accordingly, it is possible to design the cylinder plate with a small thickness compared to the prior art, since it is not necessary to provide each pressure supply line in a separate plane.

[0032] At least one section of the pressure supply line may be designed in a manner deviating from a straight line.

[0033] Additive manufacturing makes it possible to produce not only straight pressure supply lines, but also any curved lines in three-dimensional space. This makes it possible to connect a pressure medium port to a corresponding cylinder bore via the shortest possible route.

[0034] Preferably, the pressure supply lines have a circular cross-section. However, it is equally possible to produce a cross-section other than circular, such as square, polygonal, elliptical, or even star-shaped.

[0035] 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.

[0036] Additive manufacturing makes it possible to make the diameters of the pressure supply lines much smaller than is possible with the current state of the art. This is very advantageous because the reduced surface area of ​​a thin pressure supply line reduces the compressive force acting on the cylinder plate. This allows for thinner wall thicknesses overall, saving space and material.

[0037] Advantageously, the cylinder plate can be made of aluminum or an aluminum alloy.

[0038] Advantageously, the cylinder plate can comprise several parts.

[0039] This simplifies production, as a printing device for additive manufacturing can be designed smaller. However, even for non-additively manufactured cylinder plates according to the state of the art, such a pitch is advantageous, as the holes can be manufactured more easily.

[0040] Four parts are preferred, but the number of multiple parts can be any size from two upwards.

[0041] Advantageously, the cylinder plate can have holes in edge regions for mounting via pins on an upper part of a device for connecting a component to a substrate.

[0042] Advantageously, the cylinder plate can be connected to the chamber and / or the stamping plate at its connecting surfaces via pins or other positive connection techniques. A one-dimensional displacement is provided on one side of the respective connecting mechanism, in the plane of the corresponding connecting surface. For a cylinder pin, this could be implemented, for example, as an elongated hole.

[0043] The connection surface is defined as the area of ​​the cylinder plate in which it comes into contact with adjacent elements such as the upper part of the chamber or the stamping plate or is connected to the adjacent elements.

[0044] This allows for precise positioning of the cylinder plate using the holes and pins. This is particularly advantageous for multi-part cylinder plates, as the individual parts can be secured in place.

[0045] Advantageously, the holes can be designed as elongated holes whose longitudinal axis lies on a line that connects the respective connection 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.

[0046] The butt point is defined here as a point where, in the case of a multi-part cylinder plate, the multiple parts abut each other. The zero point is defined as a point corresponding to a center point of the cylinder plate or a part of the cylinder plate. The zero point has the property that, due to the cylinder plate's support via the holes, it is not subject to any change in position in the event of thermal expansion.

[0047] 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 the intersection point of their axes. The direction of the longitudinal axes in the connection surface can be freely chosen. It is important to ensure that at least one longitudinal axis is not parallel to the others.

[0048] A device according to the invention for connecting a component to a substrate has a chamber that can be divided into at least two parts. A stamp is provided on a first part, and a counter-stamp is provided on a second part. The first part can be brought into contact with the second part to close the chamber. The counter-stamp can be supplied with starting materials when the chamber is open. When the chamber is closed, pressure can be exerted via the stamp on the starting materials provided between the stamp and the object. A cylinder plate, as described above, is provided on the first part. The pressure of the pressure medium in the pressure supply line is transferred to the stamp by means of a piston. The pressure medium is preferably a gas.

[0049] The invention also relates to a method for manufacturing a cylinder plate having cylinder bores connected to a connection via a pressure supply line. The cylinder plate is additively manufactured by applying a material that solidifies after application in layers to a production surface.

[0050] Advantageously, the pressure supply lines can be located in a single plane of the cylinder plate, and cuts or intersections of two different pressure supply lines are made by bypassing one pressure supply line through the other pressure supply line via a second plane.

[0051] Accordingly, it is possible to provide multiple cylinder groups, each of which is pressurized at different pressures and / or at different times. Because all lines are located on a single plane, except for the intersections of two lines, where a second plane is used, the cylinder plate can be designed with a reduced thickness. SHORT DESCRIPTION OF THE CHARACTERS

[0052] 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. Fig. 10 shows a cylinder plate according to the prior 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 cylinder 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 cylinder 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 cylinder plate according to the prior art. Fig. 20 shows a front view of the cylinder plate of the Fig. 19. Fig. 20a, Fig. 20b and Fig. 20c show sectional views of the cylinder plate of the Fig. 19 along lines AA, BB and CC of the Fig. 19. Fig. 21 shows a perspective view of another embodiment of a cylinder 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 stamping 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 plan view of the cylinder plate of the Fig. 24 Fig. 27 shows a plan view of a stamp plate along the line AA of the Fig. 25.

[0053] Embodiments of the invention are described with reference to Fig. 1 to 23. The figures are schematic, and described details may be omitted.

[0054] The Fig. 13 to 15 show a first embodiment of a cylinder plate according to the invention.

[0055] The cylinder plate is manufactured using additive manufacturing. A liquid material is applied layer by layer to a work surface. After application, the liquid material solidifies, allowing additional layers to be applied to the already existing solidified material layers. The application takes place in such a way that areas remain uncoated in the finished cylinder plate. These include, in particular, cylinder bores 118 and a pressure supply line 115. As can be seen from the Fig. As can be seen from Figures 13 to 5, the pressure supply line 115 is led from a connection 116 on the side of the cylinder plate 19 to the cylinder bores 118.

[0056] It should be noted that in the figures, for the sake of clarity, not every element is provided with a reference symbol. For example, in the Fig. 13, a cylinder bore is provided with the reference number 118. However, apart from their position, the remaining cylinder bores are identical to the cylinder bore provided with the reference number.

[0057] Since the pressure supply line 115 is manufactured by leaving the areas occupied by it free, it takes up, in contrast to the pressure supply line 191 according to the prior 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 cylinder plate 19 improved, but it also eliminates the need to reseal the drilled portions of the lines that extend to the edge of the cylinder plate 19.

[0058] According to the prior art cylinder plate, the holes must be closed again, which is only possible to a limited extent. For this reason, parts of the holes remain, even though a pressure supply line is not required at these locations. These exposed areas, as well as the additional material introduced to close the holes, can negatively impact the strength of the prior art cylinder plate. These disadvantages are avoided by the invention.

[0059] From the Fig. 16 to 18 shows a further embodiment of a cylinder plate according to the invention. Here, a pressure supply line 115' is deviating from the straight design of the first embodiment of the Fig. 13 to 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, further improving the strength of the cylinder plate 19.

[0060] From the Fig. 21 and the Fig. 22 and Fig. Figure 23 shows a third embodiment of the cylinder plate 19 according to the invention. 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 through 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 of intersection of two lines, such as line 115a with line 115b, is one of the pressure supply lines routed over the other. Fig. 21 shows that, for example, the pressure supply line 115a is routed over both the pressure supply line 115b and the pressure supply line 115c to supply the cylinder bores 118a, 118a, which are remote from the connection in the top and right-hand part of the figure. Similarly, the pressure supply line 115c is routed over the pressure supply line 115b at intersections with the latter.

[0061] In addition to the arbitrarily curved design of the pressure supply lines in 3D space, additive manufacturing also enables the pressure supply lines to be manufactured much thinner than in the prior art. For example, diameters of 0.1 mm to 1 mm are possible. Due to this reduced pressure supply line cross-section, the outer surface of the pressure supply lines is significantly smaller than in the prior art. For this reason, a lower compressive force acts on the structure of the cylinder plate itself. This is known to be F=p*A In the equation, F represents the force, p represents the pressure, and A represents the area on which the pressure acts. Here, A is the outer surface of the pipe. Consequently, thinner walls can be used, which means that the material requirements for the cylinder plate can be lower than in state-of-the-art cylinder plates, despite the reduced strength due to additive manufacturing.

[0062] Since not only the surface area of ​​the pressure supply lines but also the volume of the pressure supply lines is 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 certain pressure depends on the volume in which the pressure is to be achieved. This is expressed by the equation At12=V(p2−p1) In the above equation, A t12for the technical work to reach a second state from a first state, V stands for the volume and p1 and p2 stand for the pressures in the first and second states respectively, ie before and after the introduction of the pressure.

[0063] Since the pressure supply lines are arranged only in one plane, and only when lines cross the plane does the plane have to be left briefly, the cylinder plate according to the invention can be made by additive manufacturing with a much smaller thickness than is possible according to the prior art.

[0064] Another advantage is that it is no longer necessary to reseal the pressure supply lines, which are drilled from the outside according to the state of the art, e.g., by plugging or welding. Screwing plugs into the drilled holes not only makes production more complex, as it is necessary to create threads in the drilled holes to screw in the plugs, along with other manufacturing steps, but also increases the risk of failure and wear. Welding the drilled holes that are open to the outside, in turn, puts thermal stress on the component, which can warp due to the thermal stress. In addition, the heat applied during welding can lead to local changes in the material properties, which can locally impair the strength of the cylinder plate.

[0065] Since it is not possible to completely seal the boreholes no longer required after the pressure supply lines have been manufactured, the current state of the art leaves an unnecessary line volume that must be pressurized with unnecessary energy expenditure, as can be seen from equation (2) above. Furthermore, there is a risk of damage to the structure of the cylinder plate due to the increased pressure force.

[0066] 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 cylinder plates described above.

[0067] 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.

[0068] 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.

[0069] 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 is additively manufactured and has cylinder bores 118, 118a, 118b, 118c, in which pistons 117 are accommodated. 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 Fig. 13 to 18 and 21 to 23 and described above in connection with the cylinder plate 19 according to the invention.

[0070] 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. Upon actuation, the pistons 117 move, together with a guide rod 113 provided on a side of the piston 117 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.

[0071] 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, 115', 115a, 115b, 115c, thereby returning the pistons 117 with the guide rods 113 to their initial position.

[0072] 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.

[0073] 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 existing 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, 115', 115a, 115b, 115c. 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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 in fact already amplified by the resetting of the guide rod 113 by creating the negative pressure in the intermediate control chamber 119.

[0085] 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.

[0086] 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, 115', 115a, 115b, 115c, a pressure increase in the intermediate control chamber 119 can exert pressure on the underside of the piston, whereby the jamming is released and the piston 117 can return to its starting position.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] 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.

[0101] 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.

[0102] 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.

[0103] 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.

[0104] In each of the projections 137a, 137b, 39, holes 133a, 133b, and 391 are provided transversely to an opening or closing direction of the chamber, the cross-sections of which overlap one another in the abutting 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. The inner hole 133b is a blind hole.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] As from the Fig. As can be seen in Figure 2a, several series of holes 133a, 133b and 391 are provided, to which the resulting force F is distributed. Thus, requirements regarding the material properties of the pins

[0110] 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.

[0111] 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.

[0112] The required pressure is created by applying a gas under high pressure to pistons 117 in cylinders of the cylinder plate 19.

[0113] 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.

[0114] 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.

[0115] 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.

[0116] 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.

[0117] 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.

[0118] 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.

[0119] Instead of the cylindrical pin described above, the positive locking can also be realized with tapered pins and correspondingly conical holes.

[0120] Advantageously, this process described above can be automated.

[0121] 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.

[0122] Due to the positive locking mechanism according to the invention, the present invention creates an internal counterforce mechanism. Therefore, an external power source for providing the counterforce is not required.

[0123] 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.

[0124] 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.

[0125] 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.

[0126] Fig. Figures 24 to 27 show an advantageous embodiment of the cylinder plate 19. The cylinder plate 19 is constructed in several parts, consisting 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 one another at a joint point A. The joint point A corresponds to the center of the cylinder plate 19 and also to a zero point.

[0127] For connection to an upper part of a device for connecting 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, the longitudinal axes of which lie on a line connecting the respective corner of the cylindrical plate 19 or the respective part 19a, 19b, 19c, 19d with the abutment point A. Thus, the longitudinal axes of the elongated holes intersect at the abutment point A, which in this embodiment also corresponds to the zero point.

[0128] This arrangement ensures that, in the event of heating of the cylinder plate 19, the zero point (shock point A) remains in place, while the outer corners of the cylinder 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.

[0129] To compensate for thermal expansion of the punch guide plate 15, it is also provided with elongated holes 155a, 155a' and 155a'', as can be seen from the Fig. 27, and is connected to the four parts 19a, 19b, 19c, 19d of the cylinder plate 19 via pins 1519a, 1519a', 1519a'', 1519b, 1519b', 1519b'', 1519c, 1519c', 1519c'', 1519d, 1519d', 1519d''. Thus, each part 19a, 19b, 19c, 19d is connected to the punch guide plate at three of its corners. Only the corners at the abutment point A have no pins. Fig.27, only the elongated holes 155a, 155a', and 155a'' are provided with reference symbols, whose longitudinal axes define point B1. The elongated holes of the remaining three sections are not provided with reference symbols for the sake of clarity.

[0130] The pins 1519a to 1519d'' are arranged in the elongated holes 155a, 155a' and 155a'' of the punch guide plate 15, which are aligned so 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, respectively. 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. Determining the zero points B1, B2, B3, B4 of the punch guide plate 15 ensures that the zero points do not shift relative to their corresponding point on the cylinder plate. This enables precise pressure to be applied to the punch 11, regardless of the thermal expansion.

[0131] This ensures that, even in the event of thermal expansion of the individual plates 15, 19 during operation, the positions of the stamps 11 always correspond sufficiently precisely to the corresponding positions of the components on the substrate, thus preventing defective products. The zero point, defined by the elongated holes with the cylindrical pins, can be freely selected. While it is located in the center of the cylindrical plate according to the embodiment, it can also be defined elsewhere if necessary.

[0132] This is easily achieved by changing the orientation of the slots so that their longitudinal axes intersect at a different location. In some applications, it may be useful to set the tool's zero point at a specific point on the component to be pressed. In this case, the longitudinal axes of the slots do not lie on a line connecting a corner with the center of the cylinder plate.

[0133] In this design, the pins and holes are arranged as elongated holes in the corner of the cylinder plate. However, it may be useful to arrange them elsewhere along the edge of the cylinder plate, e.g., in the center of each side or even with multiple holes on each side of the cylinder plate.

Claims

[1] Cylinder plate (19) for a device for connecting a component to a substrate, with a chamber which can be divided into at least two parts, wherein the cylinder plate (19) can be arranged on a first part (1) of the chamber, and formed in the cylinder plate (19): a cylinder bore (118; 118a, 118b, 118c) for receiving a reciprocating piston (117) which, when acted upon by a gaseous pressure medium for pressure transmission, can be brought into contact with a plunger (11, 111) in order to press the plunger against a counter-plunge (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) for actuating the piston (117), characterized by , that the cylinder plate (19) is additively manufactured by applying a material which solidifies after application to a production surface in layers. [2] Cylinder plate according to claim 1, wherein a plurality of cylinder bores (118) with reciprocating pistons (117) accommodated therein are provided in the cylinder plate (19), and each cylinder bore is capable of being supplied with a pressure medium via a pressure supply line (115; 115a, 115b, 115c) formed in the cylinder plate. [3] 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] Cylinder plate according to one of claims 1 to 3, wherein a plurality of pressure supply lines (115a, 115b, 115c) are provided in one plane of the cylinder plate (19), and intersections or crossings of two different pressure supply lines (115a; 115c) are avoided by bypassing the first pressure supply line (115c) with the second pressure supply line (115a) via a second plane of the cylinder plate (19). [5] Cylinder plate according to one of claims 1 to 4, wherein at least a portion of the pressure supply line (115; 115a, 115b, 115c) is formed deviating from a rectilinear shape. [6] Cylinder plate according to one of claims 1 to 5, wherein the pressure supply line (115) has a circular or non-circular cross-section. [7] Cylinder plate according to one of claims 1 to 6, wherein the pressure supply line (115) has a diameter between 0.1 mm and 1 mm. [8] Cylinder plate according to one of claims 1 to 7, wherein the cylinder plate (19) is made of aluminum or an aluminum alloy. [9] Cylinder plate according to one of claims 1 to 8, wherein the cylinder plate comprises a plurality of parts (19a, 19b, 19c 19d). [10] Cylinder plate according to one of claims 1 to 9, wherein the cylinder plate (19; 19a, 19b, 19c, 19d) has holes (195a, 195b, 195c, 195d) in corner regions for mounting via pins (20a, 20b, 20c, 20d) on an upper part of a device for connecting a component to a substrate. [11] Cylinder plate according to claim 10, wherein the holes (195a, 195b, 195c, 195d) are designed as elongated holes whose longitudinal axes have an intersection point defining a zero point. [12] 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) with a center point (A) of the cylinder plate (19) or a butt point (A) of several parts (19a, 19b, 19c, 19d) of the cylinder plate. [13] 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) can be brought into contact with the second part (3) in order to close the chamber, whereby 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) on the starting materials provided between the stamp (11, 111) and the counter stamp (31), wherein a cylinder plate according to 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] Method for manufacturing a cylinder plate (19) for a device for connecting a component to a substrate, which has cylinder bores (118) for receiving a reciprocating piston (117), wherein the cylinder bores (118) are connected to a pressure supply line (115) and are connected via the pressure supply line (115) to a connection (193), wherein the cylinder plate (19) is additively manufactured by applying a material which solidifies after application layer by layer onto a production surface. [15] Method according to claim 14, wherein a plurality of pressure supply lines (115a, 115b, 115c) lie in a plane of the cylinder plate (19), and cuts or intersections of two different pressure supply lines are made by bypassing a first pressure supply line (115c) by a second pressure supply line (115a) via a second plane.

Images