Mechatronic curtain for process chamber for performing thermal processes in the manufacture of electronic assemblies

Abstract

The invention relates to a process chamber (10) for performing thermal processes in the manufacture of an electronic assembly (30), comprising the following: at least one orifice (20) for inserting and / or removing the electronic assembly (30); a device (40) for supplying a gas; a controllable protective device (50) that is placed in the orifice (20) for the purpose of reducing gas escape from the process chamber, wherein the controllable protective device (50) comprises a first movable element (50A) as an integral piece that covers the width between the total width of the orifice and the width of the electronic assembly; a device for detecting data relating to the dimensions of the electronic assembly (30);and a controller (60) that can control the protective device (50) based on data relating to the dimensions of the electronic assembly (30) so that when the electronic assembly (30) passes through the hole (20), a defined separation is constantly defined between the electronic assembly and the first movable element (50A).;

Description

Mechatronic curtain for process chamber for performing thermal processes in the manufacture of electronic assemblies Field of invention The present invention relates to devices for performing thermal processes in the manufacture of electronic assemblies. The present invention relates, in particular, to a process chamber according to the preamble of claim 1. Previous technique In the manufacture of electronic assemblies, various thermal processes are performed, such as soldering, drying, and functional testing at high and low temperatures. To prevent oxidation or ice formation during the thermal process, the process chamber is flooded, continuously or intermittently, with a shielding gas, an inert gas such as nitrogen. In typical electronic assembly manufacturing systems, the assemblies are transported from one processing station to the next. For example, a printed circuit board (PCB) is supplied with solder butt lacquer and dried at one processing station. Subsequently, the PCB is coated with solder paste at another processing station and filled with components at a subsequent station. The filled PCB is then conveyed to a reflow soldering station and then to a station where the electronic assembly is coated with a protective lacquer. Functional tests, for example, at low and high temperatures, can then be performed. The individual stations are not hermetically sealed regions where the shielding gas atmosphere is permanently maintained.This means that the process stations are left open to avoid obstructing the workflow. It also means that the shielding gas atmosphere volatilizes, and the concentration of this gas at the process site can only be maintained if it is supplied continuously. In a system operating on the intermittent principle, and specifically on the continuous flow principle, workpieces must be fed into and removed from the process chamber. For this purpose, the process chamber must have corresponding openings. Through these openings, leakage occurs, resulting in the loss of inert gas. To prevent this, the cross-section of these openings is reduced by a suitable device, such as curtains, bellows, sliding flaps, etc. Here, for example, fin curtains are used with a plurality of fins that hang downwards and are supported upwards from bottom to top. These fins consist of a fabric laminated with conductive plastic that is stable at temperatures up to, for example, 260°C. The fins are rigid so that they do not collapse when supported from bottom to top. The fins at the process chamber inlet are designed to reduce the cross-sectional area of ​​the process chamber opening along its longest cross-sectional area. A / nAnn / eznz / e / Yi of the assemblies to be supplied. At the process chamber outlet, the upper and lower fins are positioned one above the other, i.e., they overlap. However, the fins are flexible enough to bend to the side when the assembly is guided through the orifice. One disadvantage of this method at the inlet and outlet is that it only reduces the cross-section with a certain separation to the passing workpieces, which means that a relatively high amount of shielding gas can still escape. If the separation is selected to be too long, too much shielding gas escapes. If the separation is selected to be too short, the components in the assembly can shift, and there can also be excessive friction and wear, resulting in significant staining or fouling when the components make contact or the fins bend. In this way, a compromise is sought between the loss of shielding gas and the protection of the assemblies against component displacement and wear. The term "safety clearance" refers to the area between the assembly surface and the fins. The net orifice area remains, through which the shielding gas can escape. This corresponds to the difference between the orifice area reduced by the fins and the cross-sectional area of ​​the assembly. If no assembly is passing through the orifice, the orifice area through which the shielding gas can escape corresponds to the net orifice area, which is larger than the difference in area. This means that during the heating process, when no assembly is passing through the orifice, more shielding gas escapes. Therefore, an objective of the present invention is to provide a device for a process chamber that can flexibly and efficiently adapt the cross-section of the orifice to the given conditions (i.e., that no assembly is passing through, that a large component of the assembly is passing through, that a small component of the assembly is passing through), so that less shielding gas can escape. Overview of the invention The present objective is achieved by means of a process chamber according to claim 1. The process chamber is designed to perform thermal processes in the manufacture of an electronic assembly, wherein the process chamber comprises: at least one orifice for inserting and / or removing the electronic assembly and a device for supplying a gas, in particular a shielding gas.The process chamber is characterized by a controllable protective device that is placed in the orifice for the purpose of reducing leakage or escape of the protective gas from the process chamber, wherein the controllable protective device comprises a first movable element as an integral part that covers a width between the total width of the orifice and the width of the electronic assembly; a device for detecting data relating to the dimensions of the electronic assembly; and a controller that can control the protective device based on the data relating to the dimensions of the electronic assembly so that, when the electronic assembly passes through the orifice, a defined separation becomes constant between the electronic assembly and the first movable element. R / nRnn / eznz / e / Yi This means that, as the assembly passes through the hole, the gap between the mounting surface and the edge of the first movable element that guides the assembly is permanently readjusted. This ensures that the gap between the edge of the element and the highest part of the assembly remains almost constantly small when the current is flowing through the hole. In the prior art, fin curtains are used to reduce the cross-section of the hole. However, fin curtains cannot be controlled. While flexible fins allow for some variation in the cross-section of the assembly, they cannot individually minimize the cross-section of the hole depending on the assembly and carry the risk of contact with and damage to components.A movable element as an integral part will be understood in the present context, for example, as a strip of material made from one piece; however, these can also be several strip-type parts that are connected together, either firmly or loosely, and that are coupled with a common assembly and that are moved together (this means that they are not independent). According to embodiments of the present invention, the electronic assembly consists of a plurality of electronic components which are fixed to an upper and / or lower side of a printed circuit board. To better accommodate assemblies filled on both sides in the hole control, the controllable protective device may comprise a second movable element as an integral part covering a width between the full width of the hole and the width of the electronic assembly, wherein the first movable element and the second movable element can be individually controlled and are positioned so as to be above and below the electronic assembly when the electronic assembly passes through the hole. In order to keep the cross-section of the hole as small as possible during the passage of printed circuit boards filled on both sides, the controllable protection device (50) can control the second movable element (50A) so that, when the electronic assembly (30) passes through the hole (20), a defined separation between the components on the lower side of the electronic assembly and the second movable element (50A) can be kept constant. In an additional embodiment, the device for detecting data relating to the dimensions of the electronic assembly further comprises a measuring device that detects the topography or three-dimensional structure of the electronic assembly, respectively. The measuring device is advantageously positioned within the processing chamber where the topography of the electronic assembly can be detected before it passes through the hole. In certain configurations, the measuring device uses 2D imaging and / or 3D measurement methods, and / or optical measurement methods, and / or mechanical measurement methods, and / or acoustic measurement methods to detect the topography of the electronic assembly. To determine the height information dependent on the position of the electronic assembly, one or more cameras can be used, for example, to establish a three-dimensional model of the assembly. As an alternative R / nRnn / eznz / e / Yi or in support of the evaluation of camera images, height information can also be obtained by interferometry with a laser or a series of lasers. As an alternative and in support of the methods mentioned above, mechanical sampling methods or acoustic methods, such as the generation and evaluation of a sound field, can also be used to obtain height information. As an alternative and in support of the methods mentioned above, 2D / 3D data of the assembly geometry can be taken from previous processes, for example, the assembly development and / or filling process. In one embodiment, the processing chamber also includes a drive device by which the first and / or second movable elements can be moved simultaneously and independently in the vertical direction. In this way, the movable elements can be used flexibly to maintain constant separations between the assembly and the first or second movable element. As an alternative or complement to the previous design, the processing chamber also includes a drive device by which the first and / or second movable elements can be rotated simultaneously and independently around a horizontal axis, such that a rotation axis is located at one end of the movable element opposite the assembly, perpendicular to the transport direction of the assembly. If, for the modernization of the processing chamber, sufficient space is not provided for vertical movement, the separation can be maintained constant by means of an oscillating, rotating, or flapping motion. The drive device may comprise an electric or pneumatic drive device. In certain configurations, the moving parts are made of stainless steel. Stainless steel is a robust and inert material that is only slightly prone to corrosion, so moving parts designed with this material require minimal maintenance and do not affect the processes. Furthermore, stainless steel is conductive and thus able to conduct static electricity, which can negatively impact electronic assemblies. Because stainless steel is also dimensionally very stable, stainless steel moving parts allow for precise positioning relative to the surface of the electronic assembly and the process chamber. Alternatively, the moving parts can be made of a conductive plastic that is stable up to 240°C, such as PEEK, if the costs of the device must be considered. Brief description of the figures The present invention will now be described with reference to the following figures, where Figure 1 shows a cross-sectional view of a process chamber with a protective device according to the present invention. Detailed description The present invention relates to a process chamber for carrying out thermal processes in the R / nRnn / eznz / e / Yi Electronic assembly manufacturing. In electronic assembly manufacturing, individual process stages, such as coating, filling, soldering, lacquering, and operation, are not hermetically sealed. Electronic assemblies are transported between processing stages using a conveyor system between processing stations / processing chambers. The processing chambers include openings to allow electronic assemblies to be moved in and out. This means that the manufacturing process takes place in an open environment, facilitating workflow. However, thermal processes are performed under a protective gas atmosphere to prevent oxidation. For this purpose, a localized protective gas atmosphere is created by supplying the gas locally.Due to the open nature of the process sequences, a dynamic equilibrium exists for the concentration of shielding gas at the process site, where a sufficient quantity of shielding gas is supplied constantly and locally for discharge through the compensated orifices. Smaller orifices reduce the amount of shielding gas that needs to be replenished to maintain a certain concentration at the process site. The present invention was developed to maintain the open nature of the process sequences and to keep the required orifices as small as possible. This reduces shielding gas consumption, creates a more stable process environment, and allows for reproducible process results. To reduce the cross-sectional area of ​​the bore around the workpiece, depending on the assembly, and thus minimize the loss of inert shielding gas, the bore's cross-section is actively adapted to the workpiece's topography. For this purpose, the workpiece's topography can first be determined using 2D and / or 3D imaging, optical, mechanical, and / or acoustic measurement methods. Alternatively, and / or in support of the aforementioned methods, 2D / 3D data of the assembly geometry can be obtained from previous processes, such as the assembly development and / or filling process.Based on this data, a pneumatically, electrically, or mechanically controlled moving element can minimize the separation between an edge of the moving element and the mounting surface, so that the cross-section of the hole is minimized depending on the topography of the workpiece in the direction of passage. Figure 1 shows a schematic cross-sectional view of a process chamber according to the present invention. In the cross-section of Figure 1, reference number 10 designates a process chamber, reference number 20 an opening, reference number 30 an electronic assembly, reference number 30A the assembly components, reference number 40 a device for supplying a shielding gas, reference number 50 a controllable shielding device, reference number 50A a movable element, reference number 50B an actuating device, reference number 60 a controller, and reference number 70 a measuring device. In Figure 1, the process chamber 10 is depicted with two openings 20 provided for inserting or removing the electronic assembly 30, respectively. R / nRnn / eznz / e / Yi movable element 50A is represented as the first and second movable elements, each of which covers an upper section and a lower section of the hole, respectively. In the arrangement shown in Figure 1, an assembly 30 is introduced into the process chamber 10. Figure 1 shows a condition at time ti where the assembly 30 passes through the inlet hole 20. At this point in time ti, the controller 60 has already caused the drive device 50B of the protective device 50 to retract the first and second movable elements 50A of the protective device 50 to an extension where the electronic assembly 30 is positioned through the hole, taking into account the height of component 30A, which remains in the protective device's location. Here, the safety clearance between the movable element 50A and the surface of component 30A is maintained. On the one hand, achieving an effective reduction in gas leakage from the process chamber, while on the other hand only involving slight structural stresses, is advantageous for designing the movable elements with a width greater than the width of the individual components in the assembly. In this way, the clearance width is kept consistently small only between the component with the greatest extension at the top and the edge of the movable element as a single, integral part—that is, at a minimum adjustable value. This also reduces the number of movable elements, preferably providing only a single movable element on one side of the assembly. It is particularly advantageous to configure the movable element with a width that corresponds to the clearance width for the passage of the assemblies.On the other hand, the width of the movable element can correspond to the width of the assembly, meaning approximately the width of a printed circuit board on which the components are mounted, or it could be larger, up to the width of the gap. In the latter case, an additional arrangement is advantageously provided to reduce gas leakage, for example, one or more fixed or even laterally movable board elements, which are joined laterally to the movable elements. Each of the movable elements can be an individual strip-type element made from a single piece of material. However, they can also be composed of several partial pieces, which are connected to each other either firmly or loosely. In one embodiment, the movable elements have a straight edge on the side that orients the respective assembly. Alternatively, this edge can already be adapted to the typical topography of the assemblies. Although the protective device 50 has been previously depicted with the movable element moving in the vertical direction (i.e., retracting), the movable element and the corresponding drive devices 50B can be designed so that the movable element can be rotated about a horizontal axis, with a rotation axis located at one end of the movable element opposite the assembly, perpendicular to the transport direction of the assembly. This is shown schematically in the outlet hole in Figure 1. Here, Figure 1 shows a rotation axis DA that is perpendicular to the image plane and to the transport direction of the assembly. Figure 1 also shows an arrow P1 indicating the direction of rotation of the element. R / nRnn / eznz / e / Yi movable. In the inlet hole, an arrow P2 shows the alternative vertical direction of movement. Both of the movement mechanisms can be implemented, individually or in combination, in the process chamber. In the arrangement shown in Figure 1, at time point ti, no electronic assembly passes through the hole at the outlet of the process chamber 10. Correspondingly, the first and second movable elements 50A are positioned so that they almost close the process chamber 10 or leave an open hole corresponding to a safety clearance between the first and second movable elements 50A with respect to each other or to adjacent structures. At a final point in time ta (not shown), when a subsequent component 30A is placed in the location of the protective device 50, the controller 60 causes the drive device 50B of the protective device 50 to adapt the position of the first and second movable elements 50A of the protective device 50 to the height of the subsequent component 30A. Here, the first and second movable elements can move simultaneously and independently so that the second movable element can follow the height profile on the lower side of the assembly. The height information of the components 30A can be determined, for example, with a measuring device 70 at a point in time t0 (not shown) before the electronic assembly 30 passes through hole 20. Alternatively, a 3D model of the electronic assembly 30 can be created using imaging methods, such as a camera, from which the height data of the components 30A can be read. The position and height information can also be obtained from component data generated during the assembly of the printed circuit board without requiring measurements. Data files are generated in this process and transmitted to the controllers.Together with the position and speed data of the electronic assembly 30 relative to the process chamber 10, the controllers 60 can calculate the time it takes for a certain component of a certain height to pass through the hole 20 at the location of the protective device 60. Correspondingly, the controller 60 can activate the drive device 50B to position the movable element 50A that corresponds to the height of component 30A. As an alternative or in combination, the height information of the 30A components can be detected with a mechanical sensor and / or interferometric sensors directly at the entrance of hole 20. Preferably, the 50A moving parts (i.e., the first moving part and the second optional moving part) are made of stainless steel, resulting in durable, dimensionally stable, and conductive moving parts. Corrosion and wear are low, so less maintenance is required. Furthermore, the conductivity is designed to mitigate the conductance of static electricity generated, for example, during transport in electronic assembly. Improved static conductivity can be achieved, for example, by applying soft conductive brushes to the ends of the individually controllable moving parts, which can dissipate frictional electricity. Because the stainless steel moving parts are Because the components are dimensionally stable and can be manufactured with high precision, safety gaps in the components or other parts of the process chamber can be minimized, thus also minimizing the net orifice through which the shielding gas can escape. The net orifice is understood as the net orifice area through which the shielding gas can escape. The net orifice area corresponds to the difference between the orifice area reduced by the individually controllable moving parts and the cross-sectional area of ​​the assembly. If less emphasis is placed on precision and minimizing consumables and wear, a temperature-stable conductive plastic can also be used as the material for the moving parts, thereby reducing manufacturing costs for the process chamber. For the drive mechanism, electrical, electromechanical, or pneumatic means are preferably used. For example, a stepper motor with a defined stage size, a pneumatic piston with position sensing, an electric motor with position sensing of the moving element, etc., can be used. The controller 60 can communicate with the measuring device 70 and the drive device 50B wirelessly or in a wired mode. CAD data or 2D / 3D assembly data can be entered, for example, wirelessly into the measuring device 70 or the controller 60.

Claims

1. A process chamber (10) for performing thermal processes in the manufacture of an electronic assembly (30), comprising: at least one opening (20) for inserting and / or removing the electronic assembly (30); a device (40) for supplying a gas; characterized in that a controllable protective device (50) is placed in the opening (20) for the purpose of reducing gas leakage from the process chamber, wherein the controllable protective device (50) comprises a first movable element as an integral part (50A) covering a width between the total width of the opening and the width of the electronic assembly; a device for detecting data relating to the dimensions of the electronic assembly (30);and a controller (60) that can control the protective device (50) based on data relating to the dimensions of the electronic assembly (30) so that, when the electronic assembly (30) passes through the hole (20), a defined separation is constantly defined between the electronic assembly and the first movable element (50A).; 2. The process chamber (10) according to claim 1, wherein the controllable protective device comprises a second movable element (50A) covering a width between the total width of the hole and a width of the electronic mounting, wherein each of the first movable element and the second movable element can be moved as integral parts and can be controlled individually and are positioned so as to be located above and below the electronic mountings when the electronic mountings pass through the hole.

3. The processing chamber (10) according to claim 2, wherein the controllable protective device (50) can control the second movable element (50A) so that, when the electronic assembly (30) passes through the hole (20), a defined separation between the components on the lower side of the electronic assembly and the second movable element (50A) can be maintained.

4. The processing chamber (10) according to one of the preceding claims, wherein the device for detecting data relating to the dimensions of the electronic assembly (30) comprises a measuring device (70) that detects the topography or the three-dimensional structure of the electronic assembly, respectively.

5. The processing chamber (10) according to claim 4, wherein the measuring device (70) uses 2D imaging methods and / or 3D measurement methods, and / or optical measurement methods, and / or mechanical measurement methods, and / or acoustic measurement methods to detect the topography of the electronic assembly.

6. The processing chamber (10) according to any of the preceding claims, wherein the data sensing device is designed to adopt the provided 2D and / or 3D data from the assemblies. R / nRnn / eznz / e / Yi 7. The processing chamber (10) according to one of the preceding claims, further comprising a drive device (50B) by means of which the first and / or the second movable elements can be moved simultaneously and independently in the vertical direction.

8. The processing chamber (10) according to one of the preceding claims, further comprising a drive device (50B) by means of which the first and / or second movable elements can be rotated simultaneously and independently about a horizontal axis, such that a rotation axis (DA) is located at one end of the movable element opposite the assembly perpendicular to the transport direction of the assembly.

9. The process chamber (10) according to claim 7 or 8, wherein the drive device comprises an electric or pneumatic drive means.

10. The processing chamber (10) according to one of the preceding claims, wherein the first and / or second movable elements are made of stainless steel.

11. The processing chamber (10) according to one of the preceding claims, wherein the first and / or second movable elements are made of a conductive plastic that is stable up to 280°C.

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