Sintering press, sintering press and pressing method

Abstract

The present invention relates to a pressing assembly (1) for applying pressure to an object or a region of an object, for example, for use in a sintering press (100) to perform sintering of electronic components (11) on a substrate (12). The pressing assembly includes: a multi-bar actuator (20) provided with a plurality of pressure bars (14); and a set of pressing elements (2), each pressing element being disposed between a pressure bar (14) and an object (11) to be pressed, for transmitting force applied by at least one pressure bar to the object to be pressed. The set of pressing elements includes two or more interchangeable pressing elements (2a, 2b, 2c) so that they can be engaged by different numbers of pressure bars (14).

Description

Technical Field

[0001] This invention relates to a pressing assembly for use in industrial or laboratory machinery. Background Technology

[0002] The pressing assembly can be used, for example, in a sintering press to press electronic components onto a substrate by inserting sintering material, or to press the housing of electronic components onto a dissipative element by inserting sintering material.

[0003] Generally speaking, this pressing component can be applied to all situations where pressure needs to be applied to a specific area of ​​a component or object.

[0004] In the example of a sintering press, the part to be sintered must be subjected to a given temperature of, for example, 250°C for a given time of, for example, 180 seconds, by applying a predetermined constant pressure of, for example, 15 MPa to a predetermined area.

[0005] Currently, different pressing component design schemes have been implemented to ensure the correctness of the process for each part to be pressed in the sintering press.

[0006] One of these solutions (e.g., described in the same applicant's WO2020008287A1) involves applying an independent pressing element to each object to be pressed. This structural solution allows for the processing of objects requiring different working pressures and / or having different thicknesses, where thickness refers to the geometric dimension along an axis orthogonal to the working plane of the press under consideration, within the same cycle. Summary of the Invention

[0007] The objective of this invention is to provide a pressing assembly of the type described above, but which is adaptable to different geometries of the object to be processed, and in particular, can utilize different ranges of available pressing forces.

[0008] This objective is achieved by the pressing assembly according to claim 1, the sintering press according to claim 9, and the pressing method according to claim 10. The dependent claims describe preferred embodiments of the invention. Attached Figure Description

[0009] However, the features and advantages of the pressing assembly and sintering press according to the invention will become apparent from the following description of preferred embodiments of the invention with reference to the accompanying drawings, which are given by way of non-limiting example, in which: - Figure 1 This is an elevation view of an example of a sintering press employing the pressing assembly according to the present invention; - Figure 2 and Figure 2aEnlarged partial axial cross-sectional views of the upper and lower portions of the closed press are shown, with the multi-bar actuator in a disabled and enabled configuration, respectively; and - Figure 3 and Figure 3a These are two views, namely an elevation view and a perspective view, of some pressure bars and related pressure elements of the pressing assembly according to the present invention. Detailed Implementation

[0010] In these figures, the pressing assembly used to apply pressure to an object or a region of an object is generally indicated by reference numeral 1. In the application example shown in the figures, the pressing assembly is used in a sintering press 100 to perform the sintering of electronic components 11 onto a substrate 12.

[0011] In a typical embodiment, the pressing assembly 1 includes a multi-bar actuator 20 provided with a plurality of parallel pressing rods 14.

[0012] The multi-bar actuator 20 is configured to apply pressure to each lever 14 in proportion to the thrust section of the lever 14.

[0013] In one embodiment, when subjected to pressurized fluid, the pressure bar 14 is movable along the pressing direction X between a non-activated retracted position and an activated extended position. It should be noted that the term "movable" means that under certain operating conditions, each pressure bar can perform a stroke along the pressing direction X, for example, due to the crushing of the sintered material during the pressing step. Therefore, this stroke can result in axial movement of the pressure bar, even imperceptible axial movement, such as axial movement on the order of millimeters or tenths of a millimeter.

[0014] The pressing assembly 1 includes a set of pressing elements 2 adapted to cooperate with the pressing rod 14. Each pressing element 2 in the set of pressing elements is prismatic in shape, for example, having a rectangular cross-section. Specifically, each pressing element 2 is adapted to be positioned between the pressing rod 14 and the object 11 to be pressed, for transmitting the force applied by at least one pressing rod 14 to the object 11 to be pressed.

[0015] In the following description, for ease of disclosure, the terms “upper” and “lower” (e.g., the ends of the pressure bar and the pressing element or parts of the press) are used with reference to conventional but non-limiting embodiments, wherein the pressing direction X is the vertical direction.

[0016] According to an aspect of the invention, a set of pressing elements 2 includes two or more interchangeable pressing elements 2a, 2b, 2c, which have at least an upper end surface 2' at their upper ends. The planar projection of the upper end surface (i.e., the planar projection in a plane orthogonal to the pressing axis X) is wide enough that when one of the interchangeable pressing elements 2a, 2b, 2c is positioned between the pressing rod and the object to be pressed 11, the planar projection of the upper end surface intersects with the planar projection of the lower end surface 14' of each of the at least two pressing rods 14a, 14b, 14c.

[0017] The end surfaces 2' (i.e., the upper surfaces) of the interchangeable pressing elements 2a-2c have different profiles along the pressing axis X, so that the interchangeable pressing elements can be joined by different numbers of pressing rods 14.

[0018] In other words, at least two pressure bars 14a-14c are stacked on each of the interchangeable pressure elements 2a-2c. However, due to the different profiles of the upper ends 2' of the interchangeable pressure elements, it can be ensured that when moving in the extended position, only one pressure bar, or in any case fewer than the number of pressure bars 14 stacked on the pressure element 2, contacts the upper surface 2' of the pressure element.

[0019] Therefore, different pressing forces can be obtained depending on which of the interchangeable pressing elements is used in the pressing assembly and because the pressing force is proportional to the thrust cross-section of the pressing rod. In fact, the total thrust cross-section of the pressing rod is given by the sum of the thrust cross-sections of the individual pressing rods capable of transmitting the thrust to the lower pressing element. Therefore, if one or more pressing rods move idling, i.e., when these pressing rods are in the extended position but do not engage the lower pressing element due to the contour of their upper surfaces, the total thrust cross-section will be proportionally smaller than the maximum thrust cross-section given by the sum of the thrust cross-sections of all pressing rods stacked on the pressing element.

[0020] exist Figure 2 and Figure 2a In the example of the pressing assembly 1 shown, three different interchangeable pressing elements 2a, 2b, and 2c are illustrated, but in this example, these interchangeable pressing elements are simultaneously installed in the press. Three pressure bars 14a, 14b, and 14c are associated with each pressing element 2a, 2b, and 2c.

[0021] Figure 3 and Figure 3a The enlarged view shows, for example, two interchangeable pressing elements 2a, 2b adjacent to each other at different heights, each of which is associated with three pressure bars 14a, 14b, 14c.

[0022] Therefore, it should be noted that the term "interchangeable" is used to indicate that the same set of pressure bars 14a, 14b, 14c, consisting of at least two adjacent pressure bars, can be associated with at least two different pressing elements 2a, 2b, 2c, that is, they have different axial profiles at least on the upper surface 2'. This does not preclude the possibility that such interchangeable pressing elements can also be used simultaneously in a single press.

[0023] In one embodiment, the first pressing element 2a in the interchangeable pressing elements has a planar pressing element end surface 2' so that it can be simultaneously engaged by all the pressing rods acting on this first pressing element 2a (i.e., axially stacked on the first pressing element).

[0024] At least one recess 2' is formed in the end surface 2' of at least the second pressing element among the interchangeable pressing elements 2b, 2c. The at least one recess is adapted to prevent contact between the end surface 2' of the pressing element and at least one pressing rod 14a, 14b, 14c that can act on the first pressing element or the second pressing element 2a, 2b, 2c (i.e., pressing rods stacked on the first pressing element or the second pressing element).

[0025] In other words, at least one recessed region 2” is formed in the upper end surface 2’ of at least one of the interchangeable pressing elements. For example, the depth of this recessed region is greater than the stroke of the pressure bar 14.

[0026] In the embodiment shown in the accompanying drawings, the multi-bar actuator 20 has a lower head 22 and an upper head 24 that commonly and fluid-tightly define the compression chamber 26.

[0027] An inlet channel 32 for introducing pressurized fluid into the compression chamber 26 is formed in the upper head 24.

[0028] The pressure rod 14 is slidably supported in the lower head 22. In one embodiment, the upper end 142 of the pressure rod 14 protrudes into the compression chamber 26.

[0029] The actuating diaphragm 30 extends into the compression chamber 26. When the compression chamber 26 is not pressurized, the actuating diaphragm 30 is in a deactivated configuration, in which the actuating diaphragm is substantially flat. Figure 2 In a preferred embodiment, the actuating diaphragm is spaced apart from the bottom wall 26a of the compression chamber 26, and the upper end 142 of the pressure rod 14 protrudes from the bottom wall.

[0030] When the compression chamber 26 is pressurized, the actuating diaphragm 30 deforms to act on the upper end 142 of the pressure rod 14, thereby transmitting the pressure in the compression chamber to each pressure rod 14. Figure 2a ).

[0031] If it is possible Figure 2a As can be seen, in one embodiment, when the actuating diaphragm 30 deforms, it also rests against the bottom wall 26a of the compression chamber 26. Therefore, the deformed actuating diaphragm 30 acts simultaneously on all the pressure rods 14, and the force acting on each pressure rod 14 is equal to the product of the fluid pressure in the pressurized chamber and the thrust surface of the pressure rod.

[0032] In one embodiment, each lever 14 is slidably accommodated in a corresponding lever cavity 144 in a form-fitting manner, the lever cavity being formed in the body of the multi-lever actuator 20, specifically in the portion of the head 22 formed in the body.

[0033] In one embodiment, each lever 14 is provided with a mechanical stop element adapted to restrict the movement of the lever 14 from the retracted position to the extended position.

[0034] In fact, under very high pressures acting on the actuating diaphragm 30, the actuating diaphragm 30 may deform to the extent that it penetrates the cavity 144 of the lever, causing the lever to move excessively in the extension direction and wear prematurely due to contact with the edge that defines the lever cavity 144 at the top. The presence of a mechanical stop prevents this from happening and makes the lever stroke deterministic and repeatable.

[0035] For example, a mechanical stop keeps the pressure rod 14 in place, so that the upper surface of the pressure rod is coplanar with the bottom wall 26a of the compression chamber 26.

[0036] For example, such as Figure 3 and Figure 3a As shown, the mechanical stop element consists of a rod head 146 that expands radially relative to the rest of the body of the pressure rod 14.

[0037] In other words, the pressure bar is shaped to resemble a mushroom or a nail with an enlarged head.

[0038] The cross-section of the upper portion of the pressure rod cavity 144 can be complementary to the cross-section of the pressure rod head 146; that is, the upper portion can have a larger diameter than the rest of the pressure rod cavity 144. When the pressure rod 14 is in the extended position, its head 146 is thus completely received within the upper portion of the corresponding rod cavity 144. For example, the upper surface of the pressure rod can be coplanar with the bottom wall 22a of the compression chamber 26.

[0039] It should be noted that, especially when the pressing assembly is used in a sintering press, the stroke of the pressure bar from the retracted position to the extended position is used to apply force to the corresponding object to be sintered by means of the corresponding pressing element, and therefore this stroke roughly corresponds to the height reduction experienced by the object to be sintered as it is pressed onto the substrate.

[0040] In other words, even when the pressure bars are in the retracted position, they may have already come into contact with the corresponding pressure element (other than the pressure bars stacked on the sunken area of ​​the corresponding pressure element), so that the pressurized fluid, through, for example, acting on the upper surface of the pressure bar via an actuating diaphragm, directly and immediately results in a force acting on the pressure element.

[0041] In such embodiments, it is the same pressing element 2 that holds the corresponding pressing rod(s) 14 in the retracted position, whereas in the case of vertical positioning, the pressing rod would be brought to the extended position by gravity.

[0042] Therefore, in the presence of a recess 2” or a sunken area formed in the upper end surface 2' of the pressing element 2, the overlying pressure bar 14 can be brought to the extended position without transmitting the force of the actuating member (e.g., the actuating diaphragm 30) to the pressing element 2, since it does not abut against the pressing element 2, because this force is transmitted to the mechanical stop formed by the housing seat 144 of the pressure bar itself.

[0043] In one embodiment, the pressing assembly 1 includes a heating unit 40 adapted to heat the pressing element 2 so as to press the object 11 under desired temperature conditions, for example for a sintering process.

[0044] In one embodiment, a through hole 42 suitable for accommodating the pressing element 2 is formed in the heating unit 40. This heating unit 40 is provided with a heating member, such as a resistor 44, for heating the pressing element 2 accommodated in the through hole 42.

[0045] In one embodiment, the lower end of the pressure bar 14 has a configuration adapted to minimize heat transfer from the pressure element to the pressure bar. For example, the lower end of the pressure bar 14 is hemispherical in shape.

[0046] In one embodiment, the pressing element 2 housed in the heating unit can be easily removed for replacement by pulling it out of the heating unit 40.

[0047] Please note that, in addition to allowing selection of pressing force, the interchangeability of pressing components offers other advantages, such as less invasive maintenance in the event of component failure or damage, and the ability to replace these pressing components to suit different operating heights. For example, different operating heights may be required when the height of the substrate needs to be changed without modifying the design of the product to be pressed, or when the thickness of one or more components involved in the pressing process varies, while maintaining the previously used pressure and geometry.

[0048] It should be noted that the proposed pressing assembly can have more pressure bars than the number of pressing elements. Using pressing elements that can be used with more or fewer pressure bars can expand the range of forces applicable to the object to be pressed.

[0049] By manufacturing two close-fitting pressure bars, a force equivalent to that of a single pressure bar (whose upper surface is equal to the sum of the upper surfaces of the first two pressure bars) can be obtained. Thus, by using a suitable pressure element, the force transmitted from one of the pressure bars, from the other pressure bar, or from both can be selectively utilized.

[0050] The present invention also relates to a sintering press 100, which includes the pressing assembly 1 as described above.

[0051] As explained above, the sintering press 100 can be used in certain electronic applications, such as when it is necessary to insert sintering paste to secure electronic power components like IGBTs, thermistors, and MOSFETs to a substrate. To ensure that each component is properly sintered, it must be pressed using a sintering press under controlled and suitable temperature conditions.

[0052] In other applications, the device to be sintered by a press can consist of a housing comprising an electronic board formed from electronic components and a substrate. Furthermore, the housing is pressed onto a dissipative element.

[0053] In other applications, the sintering press 100 can be used to perform the rolling process, wherein the object to be sintered does not contain any electronic components.

[0054] For ease of disclosure, in the following description of the sintering press, any electronic component, its housing, or object intended for rolling is referred to as the object to be sintered. Similarly, any element that serves as the sintering object and provides structural support is referred to as a substrate, for example, the base plate for an electronic component or, in the case of sintering an electronic housing onto a dissipative element, a block-shaped dissipative element.

[0055] In a typical embodiment, the press includes a mounting structure 80 that extends vertically and supports a base 90 at the lower part and an upper block 60 at the upper part.

[0056] The base 90 is adapted to support at least one substrate 12.

[0057] The upper 60 supports or embodies the suppression component 1.

[0058] The mounting structure 80 may be provided with a longitudinal guide 82, and at least one of the upper block 60 and the base 90 may be vertically translated relative to each other along the longitudinal guide between an open or inactive pressing position and a closed or active pressing position, for example by a hydraulic or electric actuator.

[0059] The base 90, the upper block 60, and the longitudinal guide 82 form the mold of the sintering press 100.

[0060] As described above, the pressing component 1 is configured to apply a preset pressure to the pressing region of the object 12 to be sintered. For example, the pressing region is the upper flat side of the main body of the object to be pressed.

[0061] The heating unit 40 may be located in the lower portion of the pressing assembly 1, in which a through hole 42 for accommodating the pressing element 2 is formed. For example, the heating unit 40 may be heated to up to 350°C.

[0062] The multi-bar actuator 20 is positioned above the heating unit 40.

[0063] In some embodiments, the body of the multi-bar actuator 20 is cooled by a suitable cooling circuit so that its body can be kept at a constant temperature even when the heating unit is at a high temperature.

[0064] The present invention also relates to a pressing method for applying desired pressure to an object or a specific area thereof.

[0065] The pressing method includes using the pressing assembly 1 described above in the press 100 to select the force to be applied to the pressing element 2, and then applying the force to the area of ​​one or more corresponding objects or objects 11 to be pressed.

[0066] Specifically, the selection of pressing force is performed using one of two or more interchangeable pressing elements 2, wherein the end surface 2' (i.e., the upper surface) of such interchangeable pressing elements 2 has a different profile along the pressing axis X, such that the interchangeable pressing elements can be engaged by different numbers of pressure bars 14.

[0067] After selecting the pressing element 2 from the interchangeable pressing elements 2a, 2b, and 2c and installing it in the press 100, the multi-bar actuator 20 can be actuated to actuate all the pressing rods 14.

[0068] Without departing from the scope of the appended claims, those skilled in the art can make changes and adjustments to embodiments of the pressing assembly, sintering press, and pressing method according to the invention, or replace some elements with functionally equivalent elements to meet occasional needs. Each of the features described as belonging to one possible embodiment can be implemented independently of the other described embodiments.

Claims

1. A pressing assembly (1) for applying pressure to an object or a region of an object, for example, said pressing assembly for use in a sintering press (100) to perform sintering of electronic components (11) on a substrate (12), said pressing assembly comprising: A multi-bar actuator (20) is provided with a plurality of parallel pressure bars (14), the multi-bar actuator (20) being configured to apply a pressing force to each of the pressure bars (14) in proportion to the thrust section of the pressure bar; A set of pressing elements (2), each of the pressing elements being prismatic in shape and adapted to be positioned between the pressing rod (14) and the object (11) to be pressed, for transmitting a force applied by at least one of the pressing rods to the object to be pressed, wherein the set of pressing elements comprises two or more interchangeable pressing elements (2a, 2b, 2c), the two or more interchangeable pressing elements having a pressing element end surface (2') at least at the end facing the pressing rod, the planar projection of the pressing element end surface being sufficiently wide such that when one interchangeable pressing element is positioned between the pressing rod and the object to be pressed, the planar projection of the pressing element end surface intersects the planar projection of the pressing rod end surfaces of at least two of the pressing rods (14a, 14b, 14c), and wherein the pressing element end surfaces (2') of the interchangeable pressing elements have different profiles such that the interchangeable pressing elements can be joined by different numbers of pressing rods (14).

2. The pressing assembly according to claim 1, wherein, The first pressing element (2a) of the interchangeable pressing elements has a planar pressing element end surface (2') so that it can be simultaneously engaged by all the pressing rods (14a, 14b, 14c) acting on the first pressing element, and wherein at least one recess (2") is formed in the pressing element end surface (2') of at least the second pressing element (2b, 2c) of the interchangeable pressing elements, the at least one recess being adapted to prevent contact between the pressing rod end surface and at least one of the pressing rods acting on the first pressing element or the second pressing element.

3. The pressing assembly according to claim 1 or 2, wherein, The multi-bar actuator is configured to act simultaneously on all pressure bars.

4. The pressing component according to any one of the preceding claims, wherein, The multi-bar actuator has a front head (22) and a rear head (24) that jointly and fluid-tightly define a compression chamber (26), wherein: An inlet channel (32) for introducing pressurized fluid into the compression chamber is formed in the rear head (24). The pressure rod (14) is slidably supported in the front head (22), and the rear end (142) of the pressure rod protrudes into the compression chamber (26). An actuating diaphragm (30) extends into the compression chamber (26), and when the compression chamber (26) is pressurized, the actuating diaphragm deforms to act on the rear end of the pressure bar, thereby transmitting the pressure in the compression chamber to each of the pressure bars (14).

5. The pressing assembly according to any one of the preceding claims, comprising a heating unit (40) for the pressing element, wherein a through hole (42) adapted to accommodate the pressing element is formed in the heating unit, and the heating unit is provided with a heating member (44) for heating the pressing element.

6. The pressing component according to any one of the preceding claims, wherein, Each of the levers (14) is slidably housed in a corresponding lever cavity (144) formed in the body of the multi-lever actuator in a form-fitting manner.

7. The pressing assembly according to the preceding claim, wherein, Each of the pressure bars is provided with a mechanical stop element suitable for restricting the movement of the pressure bar from the retracted position to the extended position.

8. The pressing assembly according to the preceding claim, wherein, The mechanical stop element consists of a rod head (146) that is radially enlarged relative to the rest of the body of the pressure rod.

9. A sintering press comprising a pressing assembly (1) according to any one of the preceding claims, and including a base (90) facing the pressing assembly (1) and adapted to support at least one substrate (12), wherein at least one of the pressing assembly (1) and the lower portion of the base (90) is axially translatable relative to each other between a retracted, inactive position and an extended pressing position, wherein, The object (11) to be sintered can be joined by the pressing element.

10. A pressing method for applying desired pressure to a specific area of ​​a component or object, the pressing method comprising the following steps: Provide a pressing assembly according to any one of claims 1 to 8; Select the force to be applied to the pressing element; Actuate the multi-bar actuator to activate all pressure bars; The selection of the force to be applied is performed using one of two or more interchangeable pressing elements, wherein the end surfaces of the interchangeable pressing elements have different profiles along the pressing axis, such that the interchangeable pressing elements can be engaged by different numbers of pressing rods.

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