Filling device for filling a bubbler, filling system and soldering or sintering system equipped with the filling system, and method for operating the filling device

Abstract

The invention relates to a filling device (10) for filling at least one bubbler (12) with a process fluid (14), in particular formic acid, which can be or is installed in a brazing or sintering system, wherein the filling device (10) comprises a fluid reservoir (20), which can be or is fluidically connected to the bubbler (12) by means of at least one filling valve (26), to which the process fluid (14) can be supplied controllably, and which is designed for controlled filling of the process fluid (14) to the bubbler (12). It is provided that the filling device (10) comprises a make-up reservoir (22), which is fluidically connected upstream of the fluid reservoir (20), to which the process fluid (14) can be supplied from a fluid source (24); wherein the make-up reservoir (22) and the fluid reservoir (20) can be connected controllably by means of at least one supply valve (28); wherein, when the supply valve (28) is open, the make-up reservoir (22) is atmospherically isolated from the fluid reservoir (20) by means of a siphon effect, so that the process fluid (14) can always be supplied controllably from the make-up reservoir (22) to the fluid reservoir (20) via the at least one supply valve (28) in an oxygen-free manner, and the fluid reservoir (20) always remains in an oxygen-free state.

Description

[0001] The present invention relates to a filling device for filling at least one bubbler, a filling system, a brazing or sintering system equipped with said filling system, and a method for operating said filling device. Existing technology

[0002] Brazing and sintering systems are a key component of many industrial manufacturing processes and value chains. A well-known example is the manufacture of electronic components and assemblies containing semiconductor elements, particularly for the automotive, power generation, and industrial electronics sectors, where high-quality intermetallic compound connections are created between or on top of electronic components through properly designed and configured brazing and / or sintering systems.

[0003] In brazing and sintering processes, it is typically necessary to reliably remove metal oxides from at least the surface of the component to be processed. In low-pressure sintering, diffusion brazing, and low-pressure and vacuum brazing as subgroups of reflow brazing techniques, for example, the removal or reduction of oxide layers is considered a standard process. Oxide layers have a strong inhibitory effect on the brazing process and therefore must be reliably removed to ensure a stable and controllable process.

[0004] Brazing systems are specifically understood as systems used to perform vacuum brazing and diffusion brazing processes.

[0005] To remove surface metal oxides, a process fluid mixed with a process gas is typically used. Formic acid (HCOOH) is commonly used here, and it is usually mixed with nitrogen (N2) as the process gas. Reducing and thus removing the oxide layer on the component surface using nitrogen-rich formic acid (HCOOH) is a stable and economical method in brazing technology, proven in industry for many years. Formic acid has a reducing effect, thus cleaning the oxides on the surface to ensure high quality in subsequent processes (brazing, sintering, bonding, welding). No flux is required using this method.

[0006] In the reduction process, the use of formic acid-rich nitrogen gas is typically accomplished using a so-called bubbler. A bubbler, also known as a vapor pressure saturator, is a device commonly used to generate a process gas, either in vapor form or rich in process fluid, which carries the liquid starting material (in this case, formic acid in saturated vapor form) through bubbles of a carrier gas (typically nitrogen, N2) into the sintering or brazing chamber. A bubbler typically consists primarily of a closed container into which the liquid or process fluid to be evaporated, typically formic acid, is added, usually from a fluid reservoir such as a replaceable container or a fillable tank. The process gas, typically N2, is then injected into the bottom of the bubbler container via a bubbler gas supply source and through a spray gun or nozzle tube with multiple openings. The process gas (N2) then rises as bubbles through the process fluid (HCOOH) within the bubbler, carrying away some of the vaporized process fluid. The resulting process gas / process fluid vapor mixture, typically nitrogen rich in formic acid vapor, is then fed through a gas pipe from the bubbler outlet into the vacuum chamber, which serves as the process chamber for brazing and / or sintering systems, and is used as a reducing agent for the components.

[0007] For example, a bubbler device of this type is disclosed in US 7,025,337 B2. This bubbler device includes a standard bubbler 12, which is filled with fluid and fluidly connected to a fluid reservoir via a piping system with multiple valves. Furthermore, process gas and purge gas sources, a vacuum source, and an outlet are each fluidly connected to or disconnected from the bubbler via multiple valves through the piping system. The key functional principle is to maintain a constant fluid level by varying the gas pressure and the amount of fluid present in or supplied to the bubbler. This aims to prevent harmful chemical reactions between the fluid and sensitive components of the bubbler system. However, this patent only includes a fluid reservoir that is directly connected to the outside atmosphere via valves.

[0008] Due to the continuous consumption of process fluid, it is inevitable to replenish the bubbler with fresh process fluid periodically. Refilling is typically performed using a filling device, which is designed to deliver process fluid from a fluid reservoir, which is in particular part of the filling device, into the bubbler.

[0009] Regarding filling devices, it is known that process fluid is either filled directly into the bubbler or replenished from a fluid reservoir connected to the bubbler via at least one filling valve. In the latter case, the fluid reservoir must be replenished after a certain period of time. For example, in the case where the fluid reservoir is designed as a replaceable container that can be connected to the bubbler, once the container is emptied, it must be disconnected and replaced, and a new full container must be reconnected.

[0010] For example, this type of filling device for a bubbler is known from publications such as DE 10 2007 024 266 A1, EP 0 949 212 A1, and US 4 276 243 A. These publications each disclose a bubbler system having a bubbler and a filling device, wherein process fluid from a fluid reservoir can be filled into the bubbler via the filling device.

[0011] When replenishing or filling the bubbler with process fluid, it is crucial to remember that the reduction process of the process gas / process fluid vapor mixture generated by the bubbler on the component surface requires the absence of oxygen in the process atmosphere. Otherwise, oxidizing oxygen will significantly limit or directly negate the reducing power of the process gas / process fluid vapor mixture, thus failing to effectively and adequately remove the oxide layer. To ensure an oxygen-free environment within the bubbler system, the container into which the process fluid is introduced (i.e., the bubbler itself or the fluid reservoir) must be oxygen-free.

[0012] In existing replenishment methods, the required pressure inside the container must be atmospheric during replenishment, compromising the container's integrity to allow for the filling of process fluids. As a result, oxygen may enter the container and must be removed again before the process can begin, for example, by purging with an inert gas. During both the filling and oxygen removal processes, the internal process is halted.

[0013] For known bubbler systems, this situation results in the recurring problem that the bubbler and / or the entire system must be periodically interrupted for intended operation to fill the bubbler, replenish or replace fluid reservoirs, and to purge the entire bubbler system with inert gas to eliminate oxygen before resuming operation. The disadvantages of this interruption are decreased operating efficiency and thus increased operating costs, as well as the potential for contamination due to the need to open containers, particularly when oxygen is present during improper purging. This could reduce the quality of the finished product or disrupt the entire manufacturing process, especially by damaging the system.

[0014] The object of this invention is to provide an improved filling device and method in this regard, which advantageously solves the aforementioned problems, particularly enabling automatic filling of the bubbler and replenishment of process fluid to the bubbler and / or fluid reservoir without interrupting bubbler operation and / or the intended operation of the system. A further object of this invention is to improve the efficiency and productivity of process gas supply in brazing or sintering systems.

[0015] This objective is achieved by the filling device, bubbler system, brazing or sintering system, and method according to the independent claims. Advantageous embodiments of the invention are the subject of the dependent claims. Summary of the Invention

[0016] The present invention relates to a filling device for filling at least one bubbler (or multiple bubblers) with a process fluid, particularly formic acid or other reducing agents such as formic acid (CH2O2) or citric acid, said bubbler being mounted or attached to a brazing or sintering system, particularly a vacuum brazing or diffusion brazing system, wherein said filling device includes a fluid reservoir which is fluidly connected or is fluidly connected to said bubbler by means of at least one filling valve, said process fluid being controllably supplied to said fluid reservoir, and said fluid reservoir being designed for controllably filling said process fluid into said bubbler.

[0017] According to the present invention, the filling device includes a replenishment reservoir fluidly connected upstream of the fluid reservoir, wherein the process fluid can be supplied from a fluid source to the replenishment reservoir; wherein the replenishment reservoir and the fluid reservoir are controllably connected by means of at least one supply valve; wherein when the supply valve is open, the replenishment reservoir is isolated from the atmosphere of the fluid reservoir by a siphon effect, such that the process fluid can always be controllably supplied from the replenishment reservoir to the fluid reservoir via the at least one supply valve in an oxygen-free state, and the fluid reservoir is always kept in an oxygen-free state.

[0018] By creating an atmosphere isolation between the fluid reservoir and the replenishment reservoir through the siphon effect generated by opening the supply valve, the filling device is designed to, on the one hand, automatically and / or continuously replenish the bubbler with the oxygen-free process fluid present in the fluid reservoir via the filling valve; on the other hand, the fluid reservoir can be filled with process fluid in an oxygen-free manner, and fluidly independent of the replenishment filling of the bubbler, without interrupting the operation of the bubbler during the intended operation of the brazing or sintering system (i.e., operating independently of the bubbler).

[0019] In the context of this invention, atmospheric decoupling caused by the siphon effect must be understood as follows:

[0020] The shape of the connecting pipelines between reservoirs, their design, the operation of valves, filling devices, and / or the periodic filling of the replenishment reservoirs (structurally) ensure that, when the reservoirs are connected, some fluid is always retained or can be retained in the replenishment reservoir, even as fluid is transferred from the replenishment reservoir to the fluid reservoir, thus creating or presenting a siphon effect. The process fluid retained in the replenishment reservoir acts as a barrier (siphon) to any gas (i.e., oxygen) present in the replenishment reservoir.

[0021] Due to the siphon effect, fluid transfer between the supply reservoir and the fluid reservoir is always oxygen-free, meaning that oxygen from the supply reservoir will never enter or reach the fluid reservoir or its associated connections. Therefore, it is impossible to introduce oxygen into the bubbler.

[0022] Due to the atmosphere isolation caused by the siphon effect, a certain amount of residual process fluid is always present in the replenishment reservoir, preventing any oxygen from entering the fluid reservoir. This allows the replenishment reservoir to be fluidly decoupled from the oxygen-free supply of the fluid reservoir to the bubbler while replenishing the process fluid to the replenishment reservoir.

[0023] This advantageously achieves fluid independence between the "reservoir replenishment" and "bubbler filling" processes, making system interruptions for replenishment unnecessary. In this regard, using the solution according to the invention, one or more bubblers can be filled automatically during breaks in the brazing system's operation (particularly during the transfer of components processed by the system between process chambers). Its advantage lies in the fact that during bubbler operation, i.e., during system operation, the fluid reservoir can already be continuously replenished oxygen-free, thereby ensuring a constant and, most importantly, oxygen-free supply of process fluid. Due to the atmosphere isolation achieved through the siphon effect, the supply is always ensured to be oxygen-free, so that system operation, in principle, never needs to be interrupted for replenishment—contrary to solutions known in the prior art.

[0024] The replenishment reservoir can be replenished at any time, independently of the operation of the bubbler, and even under ambient air conditions. It is not a problem for the oxygen generated by the replenishment to enter the replenishment reservoir, because the siphon effect of the atmosphere isolation ensures that oxygen is prevented from entering the fluid reservoir.

[0025] Therefore, the solution according to the present invention advantageously and significantly improves operational efficiency and saves manpower, time and costs.

[0026] According to a preferred improvement, the replenishment reservoir and the fluid reservoir are fluidly connected or already fluidly connected via the supply valve, allowing pressure equalization between the fluid reservoir and the replenishment reservoir to be achieved through the supply valve. Therefore, the supply valve can be a combination valve (pressure equalization / fluid flow), such as a fluid and pressure valve with check valve characteristics. The resulting advantage is that the filling device requires fewer components.

[0027] According to an alternative preferred improvement, at least one pressure equalizing valve is provided between the supply reservoir and the fluid reservoir, wherein the supply valve (particularly designed as a bellows valve) is designed as a fluid flow valve to allow fluid flow, and the pressure equalizing valve (particularly designed as a bellows valve or check valve) is designed to allow pressure equalization. In this respect, the provided supply valve is not a combined valve as described above; rather, the function of such a combined valve is achieved by two independent valves, namely a fluid flow valve and a pressure equalizing valve. This advantageously simplifies the structure of the filling device and allows for easy replacement in case of failure of a single valve.

[0028] Generally, the positive pressure valve in the replenishment reservoir can be omitted, and the reservoir can be directly connected to the exhaust gas. Evaporation losses are negligible in practice. According to a preferred improvement, the replenishment reservoir may include a positive pressure valve for releasing positive pressure, particularly designed as a bellows valve or check valve, and / or a fluid connection, particularly a fluid connection to the fluid replenishment valve, for supplying process fluid from the fluid source, particularly in a controlled manner, to the replenishment reservoir. Therefore, the replenishment reservoir is always at atmospheric pressure or a definable positive or negative pressure. It can advantageously be opened and filled at any time, or in principle, process fluid can be supplied without requiring (large) pumping capacity.

[0029] The fluid connection can be a valve (fluid supply valve) or a simple opening in a supply reservoir, such as an open upper side that can be closed with a cap. The fluid source can be an external piping system / network, a (large) storage tank, etc., especially located in a different location from the filling device.

[0030] According to a preferred improvement, at least the fluid reservoir, and preferably the replenishment reservoir, is designed as a closed, preferably pressure-resistant, and particularly openable container as needed. The replenishment reservoir is positioned above the fluid reservoir relative to the ground, allowing process fluid to be supplied from the replenishment reservoir to the fluid reservoir by gravity. The replenishment reservoir is preferably positioned above or higher than the fluid reservoir, allowing process fluid to flow out from the replenishment reservoir by gravity. Advantageously, fluid flow can be achieved without pumping capacity, or at least with only a relatively low pumping capacity, making the delivery of process fluid both economical and reliable.

[0031] Alternatively, it is conceivable to place the two containers at the same height and transport the process fluid via a pump. Even when the two containers are placed at different heights, pumping capabilities can be provided in addition to gravity, for example, to achieve particularly rapid transport of the process fluid.

[0032] According to a preferred improvement, the replenishment reservoir and / or the fluid reservoir is configured to have at least one level sensor. The level sensor is designed to monitor the level of the existing process fluid in the respective reservoir. In particular, monitoring ensures the previously discussed siphon effect and allows for (periodic) replenishment as needed.

[0033] Preferably, monitoring and / or supplementation are performed automatically by at least one control unit using adapted operating software.

[0034] According to a preferred improvement, at least the filling valve is configured to be automatically controllable, allowing the bubbler to be automatically and / or continuously replenished with process fluid from the fluid reservoir. Preferably, at least another valve of the filling device is automatically controllable, particularly all valves, i.e., the supply valve, equalizing valve, positive pressure valve, and / or other valves. This advantageously ensures uninterrupted operation.

[0035] A fluid replenishment valve between the fluid source and the replenishment reservoir is not automatically necessary, as the supply of process fluid can be controlled by a suitable pump or directly by gravity pressure, depending on the design. According to a preferred improvement, a fluid replenishment valve is arranged between the replenishment reservoir and the fluid source to controllably supply process fluid from the fluid source to the replenishment reservoir. This advantageously and reliably ensures a controlled, on-demand replenishment supply of process fluid.

[0036] According to a preferred improvement, the system includes a higher-level control unit connected to the filling valve and at least to the supply valve, preferably to the level sensor of the fluid reservoir and / or to the level sensor of the replenishment reservoir and / or to the equalizing valve. This control unit is configured to provide a controllable supply of process fluid from the fluid reservoir to the bubbler and from the replenishment reservoir to the fluid reservoir. This advantageously automates the operation of the filling device, allowing for particularly efficient management. The control unit can advantageously be part of a system-wide overall control unit, or it can be independent of it, using the interface of the overall control unit to match or synchronize the various programs of the system with the filling operation.

[0037] The present invention also relates to a bubbler system for a brazing or sintering system, comprising at least one bubbler for supplying a process fluid, particularly formic acid, formic acid, or citric acid, mixed with a process gas, particularly nitrogen, to at least one process chamber of the brazing or sintering system, and having a filling device for filling the at least one bubbler with the process fluid. The bubbler system is characterized in that the filling device is designed according to the present invention as described above. This results in the aforementioned advantages.

[0038] The present invention also relates to a brazing or sintering system having a bubbler system for supplying a process fluid, particularly formic acid, formic acid, or citric acid, mixed with a process gas, particularly nitrogen, to at least one process chamber of the brazing or sintering system. The system is characterized in that the bubbler system is designed according to the present invention as described above. This results in the aforementioned advantages.

[0039] The present invention also relates to a method for operating a filling device, particularly a filling device according to the invention as described above.

[0040] In this method, process fluid is controlledly filled into at least one bubbler, which can be installed or is already installed in a brazing or sintering system, by means of the filling device. The bubbler is fluidly connected to a fluid reservoir of the filling device via at least one filling valve, to which the process fluid is supplied. Using the filling device, two or more bubblers can also be advantageously filled, which has the benefit of increasing system productivity at the same acid concentration.

[0041] According to the present invention, the method is characterized in that a replenishment reservoir with a filling device is connected upstream of the fluid reservoir, the process fluid is supplied from a fluid source to the replenishment reservoir, wherein the replenishment reservoir and the fluid reservoir are controlled atmospherically isolated by means of at least one supply valve through a siphon effect, such that the process fluid is always supplied from the replenishment reservoir to the fluid reservoir in a controlled, oxygen-free manner, and the fluid reservoir is always kept in an oxygen-free state.

[0042] This results in the advantages already stated above.

[0043] Therefore, the present invention includes a method for operating the aforementioned filling device, the aforementioned bubbler system, and the aforementioned brazing or sintering system, wherein the device has at least one control unit configured to perform the method according to the invention. In other words, the present invention includes a method for operating the aforementioned bubbler system or the aforementioned brazing or sintering system according to the invention, wherein the bubbler device is operated accordingly.

[0044] According to a preferred improvement, the bubbler can be configured to replenish the oxygen-free fluid reservoir via the filling valve with the oxygen-free process fluid present in the reservoir on demand and / or continuously in a controlled manner. This replenishment preferably occurs during periods when no brazing or sintering process is taking place in the brazing or sintering system, particularly during the workpiece transfer time within the system. Here, the filling of the bubbler and the replenishment of the fluid reservoir can be synchronous or asynchronous. This advantageously improves the operating efficiency of the bubbler.

[0045] According to a preferred improvement, the fluid reservoir can be configured such that, during the operation of the brazing or sintering system as intended, the fluid reservoir is filled with the process fluid in an oxygen-free manner, the filling being independent of the replenishment filling of the bubbler without interrupting the operation of the bubbler, wherein the fluid reservoir is preferably filled with the process fluid while the bubbler is operating as intended.

[0046] The bubbler is preferably replenished during the transfer or movement of components to be processed within the system (from one processing chamber to the next). For replenishment, the filling device, particularly its filling valve, operates automatically or is controlled by logic. Furthermore, system operation is not interrupted during the filling of the fluid reservoir. The replenishment reservoir can advantageously be filled at any time, thus independent of the operation / filling of the fluid reservoir, bubbler, and system, because the siphon effect prevents any oxygen from entering, thereby ensuring atmospheric isolation. This further advantageously improves operational efficiency.

[0047] According to a preferred improvement, the fluid reservoir and the replenishment reservoir can be connected via the supply valve (particularly designed as a bellows valve) and the equalizing valve (particularly designed as a bellows valve) to address atmosphere isolation caused by the siphon effect. The process fluid is supplied from the replenishment reservoir to the fluid reservoir in a controlled manner via the supply valve, and the equalizing valve balances the pressure between the replenishment reservoir and the fluid reservoir. A certain amount of residual process fluid is always maintained in the replenishment reservoir to prevent any oxygen from entering the fluid reservoir. The bellows valve is preferably controlled and can be replaced by a passive check valve where applicable. This results in the previously stated advantages.

[0048] Specifically, the positive pressure present in the fluid reservoir (relative to the pressure in the replenishment reservoir), i.e., the positive pressure from the fluid reservoir, is released into the replenishment reservoir via the supply valve (or equalizing valve). Optionally, after pressure equalization between the fluid reservoir and the replenishment reservoir, the positive pressure now present in the replenishment reservoir (relative to atmospheric pressure) is released via a positive pressure valve (as associated with the replenishment reservoir). The retained residual process fluid volume ensures that gaseous fluids, particularly oxygen, never enter the fluid reservoir via the supply valve, thus keeping the reservoir oxygen-free (siphon effect).

[0049] According to a preferred improvement, the process fluid can be supplied from the replenishment reservoir to the fluid reservoir and / or from the fluid reservoir to the bubbler by means of gravity and / or positive pressure. The process fluid is transferred by gravity, alternatively or additionally by pressure equalization between the reservoir and the bubbler. Specifically, in each transfer step of the process fluid, a pressure difference exists between the fluidly continuous volumes (reservoir / bubbler), wherein process fluid from the volume with higher pressure (positive pressure) is transferred to the volume with relatively lower pressure. This advantageously ensures efficient and economical fluid flow or transfer.

[0050] Alternatively or additionally, the process fluid may be actively pumped (by consuming energy) between volumes to counteract gravity and pressure generated by the (spatial) arrangement and / or (pressure-related) connection of the volumes, i.e., to transfer the process fluid from one volume (initial volume, such as a replenishment reservoir) to another (fluidly downstream) volume (target volume, such as a fluid reservoir) despite the counteracting forces.

[0051] According to a preferred improvement, the level of process fluid present in the replenishment reservoir and / or the fluid reservoir can be detected by means of a level sensor. If the process fluid level in the fluid reservoir drops below a preset first threshold, a controlled supply of process fluid from the replenishment reservoir to the fluid reservoir is triggered. If the process fluid level in the replenishment reservoir drops below a preset second threshold, a controlled supply of process fluid from the fluid source to the replenishment reservoir is triggered, or at least an instruction is issued to the operator to replenish the replenishment reservoir from the fluid source. This advantageously and effectively prevents potential operational shutdowns due to a lack of process fluid.

[0052] According to a preferred improvement, the following steps can be performed to fill the bubbler during continuous operation of the brazing or sintering system:

[0053] a) In the first step, the process fluid is filled from the fluid source into the replenishment reservoir;

[0054] b) In the second step, the pressure equalization valve is opened to equalize the pressure between the fluid reservoir and the replenishment reservoir, which are under positive pressure. The positive pressure can preferably be discharged to the atmosphere via the positive pressure valve of the replenishment reservoir, or the positive pressure can be discharged directly to the atmosphere, since the evaporation loss is negligible.

[0055] c) In the third step, the supply valve is opened to supply the process fluid from the replenishment reservoir to the fluid reservoir;

[0056] d) In the fourth step, close the supply valve and the pressure equalization valve;

[0057] e) In the fifth step, the fill valve between the fluid reservoir and the bubbler is opened to perform pressure equalization between the respective pressures in the bubbler and the fluid reservoir;

[0058] f) In the sixth step, preferably during the period when the bubbler is inactive, preferably during a period when there is no brazing or sintering process in the brazing or sintering system, especially during the time when the workpiece is being transferred in the brazing or sintering system, the gas pressure in the bubbler is reduced and the filling valve is opened to supply process fluid from the fluid reservoir to the bubbler.

[0059] g) In the seventh step, positive pressure is restored in the bubbler and the filling valve is closed again.

[0060] According to a preferred improvement, the following steps can be performed sequentially to remove oxygen from the filling device, particularly during initial commissioning, for maintenance purposes, and / or to initially fill the filling device with process fluid, and preferably repeated when a minimum amount of process fluid (preferably 2.5 liters) is reached:

[0061] I. Reduce the corresponding air pressure in the bubbler, preferably to below 10 mbar within 10 seconds;

[0062] II. Reduce the gas pressure in the fluid reservoir, preferably to below 10 mbar within 10 seconds;

[0063] III. Open all valves between the supply reservoir, the fluid reservoir, and the bubbler;

[0064] IV. The bubbler is subjected to pressure while being purged with process gas for at least 2 minutes, wherein the positive pressure is discharged via the positive pressure valve of the replenishment reservoir;

[0065] V. Close all valves between the supply reservoir, the fluid reservoir, and the bubbler.

[0066] In the prior art, the typical filling level is between a minimum of 127 mm and a maximum of 191 mm, and the standard flushing flow rate of the process gas enriched by the bubbler is ≤15 l / min. The internal pressure within the bubbler drops to 400 mbar or lower. According to a preferred improvement of the filling method, the bubbler can be filled to a preset filling level, preferably greater than 500 mm, and particularly greater than 650 mm. The filling level should be at least 30% greater than the maximum filling level, preferably 50%, and particularly 70% of the maximum filling level. The advantage is that the bubbler can be flushed at a flow rate greater than 30 l / min, preferably stably operating at 35 l / min or higher. This allows for a significant reduction in process time and completion speed, and the system's production efficiency is higher than that achievable without an automatic bubbler filling system.

[0067] Experiments show that a stable process gas supply can be maintained for an extended period at a flow rate of 35 L / min. At flow rates greater than 40 L / min, a flow rate decrease will occur over a prolonged period if the bubbler pressure drops below 250 mbar. At even higher flow rates, the flow rate decrease will occur even at higher bubbler pressures. Therefore, when a flow rate greater than 35 L / min, and preferably greater than 40 L / min, is required, it is recommended to use two bubblers in parallel and / or the intermediate process gas reservoir described below to maintain a stable high process gas flow rate over an extended period.

[0068] The filling device can be advantageously used to fill two or more bubblers to increase the concentration of process gases or control system productivity.

[0069] However, the filling device can also be used in the filling system of an alternative process gas enrichment unit that operates similarly to a bubbler, to prevent oxygen from entering the system.

[0070] Furthermore, it is advantageous to envision providing a process gas storage tank downstream of the bubbler, i.e., between the bubbler and the process chamber, for storing the process gas enriched by the bubbler. Thus, the process gas can be enriched by the bubbler and initially stored in the process gas storage tank at a higher quantity. Using the gas stored in the process gas storage tank, the process chamber can be flushed at a much higher flushing rate than the process gas flow rate available from the bubbler to meet demand. Therefore, the process gas enriched by the bubbler at a relatively low bubbler rate can be stored in the process gas storage tank and suddenly released into the process chamber to achieve a higher flushing rate. This makes it possible to improve productivity or increase the process gas concentration, as an alternative to or supplement to the parallel operation of multiple bubblers. Attached Figure Description

[0071] The following description with accompanying drawings illustrates further advantages. The drawings illustrate examples of the invention. The drawings, description, and claims contain numerous features in combination. Those skilled in the art will also readily consider these features individually and combine them into meaningful further combinations.

[0072] In the attached diagram:

[0073] Figure 1 An embodiment of a filling device or filling system in its initial state is illustrated in schematic diagram;

[0074] Figures 2A-2D It shows Figure 1 The embodiments, each at different times during the advantageous method for operating the filling device, and

[0075] Figure 3 It shows Figure 1 The state of the implementation during initial debugging;

[0076] Figure 4 Further embodiments of the filling device are shown;

[0077] In the accompanying drawings, the same elements are denoted by the same reference numerals. The drawings are merely illustrative and should not be construed as limiting.

[0078] Figure 1 A simplified schematic diagram of an advantageous filling device 10 for filling a bubbler 12 is shown. The filling device 10 is designed to fill the bubbler 12 with process fluid 14 at regular intervals and / or continuously to ensure its intended operation. In this example, the bubbler 12 may be installed or has been installed in a brazing or sintering system (not shown for clarity) and, together with the filling device 10, constitutes a filling system 16 for the brazing or sintering system.

[0079] In this regard, the filling device 10 and the bubbler 12, or the filling system 16 formed therefrom, are installed in the brazing or sintering system during operation for the intended purpose in this example.

[0080] The bubbler 12 is used or designed to mix the process fluid 14 with the process gas and supply the resulting gaseous process mixture via the bubbler outlet 18 to the brazing or sintering system, more precisely, to the process chamber of the system, typically a vacuum chamber. In this example, the process fluid 14 is formic acid (HCOOH), and the process gas is nitrogen (N2). The purge gas process mixture (typically with a formic acid concentration between 0.5% and 1.5%) formed by the process fluid 14 and the process gas introduced through the bubbler gas supply source 40 is used to reduce the oxide layer on the workpiece processed in the brazing or sintering system, particularly on semiconductor devices, to ensure further processing of the workpiece under oxide-free conditions.

[0081] To replenish the process fluid 14 that is continuously consumed during the operation of the bubbler 12 as intended, the filling device 10 is provided, which ensures a stable supply of process fluid 14 to the bubbler 12.

[0082] In this example, the filling device 10 has a fluid reservoir 20 and a replenishment reservoir 22 located upstream of and connected to the fluid reservoir 20, wherein the process fluid 14 can be supplied from the fluid source 24 via the reservoirs 20 and 22 to the bubbler 12.

[0083] To supply process fluid 14 to the bubbler 12, the bubbler may be fluidly connected to the fluid reservoir 20 via a switchable fill valve 26, or fluidly connected when the fill valve 26 is open. The fill valve 26 may be an electrically driven, electromagnetically controlled, and / or pneumatically controlled valve, particularly a bellows valve. In this example, the fill valve 26 is automatically controlled, allowing the bubbler 12 to be automatically and continuously replenished with the process fluid 14.

[0084] The fluid reservoir 20 may be fluidly connected to the replenishment reservoir 22 via two valves (in this example, a supply valve 28 and a pressure equalization valve 30), or fluidly connected when valves 28 and 30 are open. In this example, the supply valve 28 is designed as a fluid flow valve 28 for allowing process fluid 14 to flow from the replenishment reservoir 22 into the fluid reservoir 20 when it is open. The supply valve 28 is preferably designed to be magnetically and / or pneumatically controllable, and in particular, can also be automatically controlled, especially as a bellows valve. The pressure equalization valve 30 is used for or designed to achieve pressure equalization between the fluid reservoir 20 and the replenishment reservoir 22 when it is open. The pressure equalization valve is preferably designed to be magnetically and / or pneumatically controllable, and in particular, can also be automatically controlled, especially as a bellows valve or a check valve.

[0085] In this example, the fluid reservoir 20 and the replenishment reservoir 22 are designed as closed and pressure-tight containers. Figure 1 As schematically shown, further configured, the replenishment reservoir 22, located upstream of the fluid reservoir 20, is positioned higher than the fluid reservoir 20 relative to the ground, and thus spatially above the fluid reservoir 20. This ensures that when the supply valve 28 and / or the fluid flow valve 28 are open, the process fluid 14 can flow from the replenishment reservoir 22 into the fluid reservoir 20 by gravity. Alternatively or additionally, the process fluid 14 may be actively transported from the replenishment reservoir 22 to the fluid reservoir 20 by consuming energy, for example, through a pumping device.

[0086] Furthermore, in this example, both the fluid reservoir 20 and the replenishment reservoir 22 have a level sensor 32, such as... Figure 1 As illustrated in the diagram, it is used to monitor the current liquid level of the process fluid 14 in the corresponding storage tanks 20 and 22, i.e., the amount of process fluid 14 present in the corresponding container.

[0087] While the fluid reservoir 20 or the container constituting the fluid reservoir 20 is preferably always closed and designed to be pressure-tight, it may be configured that the replenishment reservoir 22 or the container constituting the replenishment reservoir 22 is optionally openable, such that the process fluid 14 can be filled into the replenishment reservoir 22, for example, by simply removing the lid of the closed container.

[0088] In this example, the replenishment reservoir 22 or its container is also enclosed and designed to be pressure-tight. To fill the replenishment reservoir 22 with the process fluid 14, the replenishment reservoir 22 is fluidly connected to a fluid replenishment valve 34, through which the replenishment reservoir 22 can be fluidly connected to the fluid source 24, or fluidly connected when the fluid replenishment valve 34 is open. The fluid replenishment valve 34 is preferably designed to be controllable, particularly automatically controlled, especially magnetically and / or pneumatically controlled, for supplying the process fluid 14.

[0089] Furthermore, the supply reservoir 22 has a positive pressure valve 36 for releasing positive pressure present in the supply reservoir 22 under certain conditions. By releasing the positive pressure as needed, the supply reservoir 22 can be ensured to be continuously, or at least at a normal pressure level when needed, so that the process fluid 14 can be filled into it without actively overcoming the reaction positive pressure by consuming energy (e.g., by pumping).

[0090] Furthermore, the filling device 10 or filling system 16 includes a control device, not shown here for clarity, designed to control the filling of the filling device 10 for the process fluid 14 filling the reservoirs 20, 22 and the bubbler 12. In this example, control specifically includes the opening and closing of valves of the filling device 10 or the filling system 16, including at least the filling valve 26, the supply valve 28, the equalizing valve 30, and the fluid replenishment valve 34, and optionally the positive pressure valve 36. The control device is configured to provide at least a controllable supply of process fluid from the fluid source 24 to the replenishment reservoir 22 and thus to the fluid reservoir 20, and preferably also from the fluid reservoir 20 to the bubbler 12.

[0091] As previously described, the process fluid 14, mixed with the process gas supplied by the bubbler gas supply source 40, is used to remove oxide layers from workpieces processed in the brazing or sintering system. For this purpose, it is crucial that the process atmosphere be completely free of oxygen, thereby ensuring that the process chamber of the system is oxygen-free. To ensure oxygen-free conditions, it is advantageous that the mixture of process gas and process fluid 14 is already oxygen-free when supplied to the system via the bubbler outlet 18.

[0092] In this regard, in order to ensure that the process fluid 14 fills the bubbler 12 without oxygen and thus ensures that the process mixture is supplied to the system without oxygen, the filling device 10 is designed such that the fluid reservoir 20 and the replenishment reservoir 22 can achieve atmosphere isolation through the siphon effect.

[0093] To address the atmosphere isolation caused by the siphon effect, a defined amount of residual process fluid 14 is always maintained in the replenishment reservoir 22, which is ensured in particular by continuously monitoring the current liquid level using the level sensor 32. When the supply valve 28 is open, the continued presence of the defined amount of residual process fluid 14 creates a siphon effect through the gas barrier effect of this residual process fluid. This ensures that the process fluid 14 is always supplied from the replenishment reservoir 22 to the fluid reservoir 20 in a controlled, oxygen-free manner, and that the fluid reservoir 20 is always kept oxygen-free.

[0094] Since the fluid reservoir 20 is always kept oxygen-free, it also means that the bubbler 12 is always kept oxygen-free during the filling of the process fluid 14, thus ultimately ensuring that the process mixture supplied to the system is also oxygen-free.

[0095] Since the aforementioned replenishment reservoir 22 is arranged upstream of the fluid reservoir 20, and the design and control of the supply valve 28 and the equalizing valve 30 ensure that a certain amount of residual process fluid 14 is continuously present in the replenishment reservoir 22, the siphon effect can be structurally ensured to cause atmosphere isolation.

[0096] Now based on Figures 2A to 2D Advantageous methods for operating the filling device 10 or filling system 16 are described. For this purpose, Figures 2A to 2D Each showed the previous basis Figure 1 The filling device 10 or filling system 16 described refers to different time points during the method.

[0097] The method preferably starts from Figure 2A The first state shown in the diagram begins, in which state, as Figure 2A As clearly shown, only a very small amount of process fluid 14 is present in the fluid reservoir 20 and the replenishment reservoir 22. The presence of the minimum amount of process fluid 14 and the drop in level below a predetermined first threshold (fluid reservoir 20) or second threshold (replenishment reservoir 22) are detected by level sensors 32 associated with the control device, thereby initiating replenishment with the process fluid 14.

[0098] Therefore, the fluid supply valve 34 is opened, such as... Figure 2A As shown, the process fluid 14 (such as...) Figure 2A (As shown in the corresponding droplets) fluid is replenished from the fluid source 24 into the replenishment reservoir 22. Replenishment from the fluid source 24 continues until the reservoir 22 reaches a certain level. Figure 2A The dashed line indicates the determined fluid level. The level sensor 32 of the replenishment reservoir 22 detects that the determined fluid level has been reached.

[0099] Once the determined fluid level is reached, the equalizing valve 30 is opened in the second step to ensure pressure equalization between the fluid reservoir 20, which is under positive pressure, and the replenishment reservoir 22, which is under lower pressure. The opening of the equalizing valve 30 and the resulting pressure equalization... Figure 2A The pressure equalization valve 30 is schematically shown against a light-colored background and with multiple bubbles 38. The positive pressure flowing into the supply reservoir 22 can then be released from the supply reservoir 22 into the atmosphere via the positive pressure valve 36.

[0100] Figure 2B This shows that the filling device 10 or filling system 16 is now in a second state, which immediately follows the first state in the process of the method. After pressure equalization, in a third step, the supply valve 28 to the fluid reservoir 20 is opened, as shown... Figure 2B The light-colored background of the supply valve 28 is shown in the image. This allows the process fluid 14 (such as...) to... Figure 2B(As shown in the corresponding droplets) flows from the replenishment reservoir 22 into the fluid reservoir 20 or is supplied to the fluid reservoir. The supply valve 28 remains open until the fill level of the replenishment reservoir 22 drops to a minimum amount of process fluid 14 required to ensure the siphon effect, which is detected by the level sensor 32.

[0101] Alternatively, the supply valve 28 remains open until a significant amount of process fluid 14 flows into the fluid reservoir 20 and reaches the desired fluid level in the fluid reservoir 20, such as... Figure 2B The dashed lines and arrows indicate, implicitly, that a predetermined minimum amount of process fluid 14 retained in the replenishment reservoir 22 will not drop below the amount required to ensure the siphon effect, and this is monitored by the level sensor 32. The achievement of the expected fluid level in the fluid reservoir 20 is also detected by the level sensor 32 of the fluid reservoir 20.

[0102] In this regard, at all times a minimum amount of process fluid 14 is always maintained in the replenishment reservoir 22, such that the latter is isolated from the atmosphere of the fluid reservoir by the siphon effect, and the process fluid is supplied to the fluid reservoir 20 only in an oxygen-free manner.

[0103] After the fluid reservoir 20 has been filled, the supply valve 28 and the equalizing valve 30 are closed in the fourth step. This third state of the filling device 10 or filling system 16 is shown in... Figure 2C The closure of the supply valve 28 and the equalizing valve 30 is schematically indicated here by the dark background of the two valves 28 and 30.

[0104] After closing the supply valve 28 and the equalizing valve 30, in the fifth step, the filling valve 26 between the fluid reservoir 20 and the bubbler 12 is opened, as follows: Figure 2C The light-colored background of the filling valve 26 is shown. This results in positive pressure equalization between the pressure in the bubbler 12 and the pressure in the fluid reservoir 20, as... Figure 2C The corresponding bubble 38 in the middle indicates this again schematically.

[0105] Figure 2D This shows that the filling device 10 or filling system 16 is now in a fourth state, which immediately follows the third state in the course of the method. Figure 2DAs shown, after pressure equalization between the fluid reservoir 20 and the bubbler 12, the gas pressure in the bubbler 12 is reduced in a sixth step while the fill valve 26 remains open. This sixth step is preferably performed during periods when the bubbler 12 is inactive, particularly during times when no brazing or sintering processes are being performed in the brazing or sintering system, i.e., especially when the currently processed workpiece or component is moving between process chambers within the system. After pressure equalization and pressure reduction in the bubbler 12 are completed, the fill valve 26 is opened to allow the process fluid 14 to flow into or be supplied to the bubbler 12, as shown. Figure 2D The corresponding droplets are shown in the diagram. Alternatively or additionally, the process fluid 14 can be actively delivered to the bubbler, for example, by a pump. The fill valve 26 remains open until the process fluid 14 reaches a fixed level again within the bubbler 12.

[0106] After a sufficient fluid level is reached in the bubbler 12, the fill valve 26 is closed again in the seventh step, and the positive pressure in the bubbler 12 is restored. Thereafter, the process fluid 14, mixed with the process gas, can be supplied back to the system via the bubbler outlet 18 as intended.

[0107] Figure 3 Finally, a special case is shown of the previously discussed filling device 10 or filling system 16, wherein the filling device 10 or filling system 16 (i.e., particularly the replenishment reservoir 22 and the fluid reservoir 20) is initially filled with process fluid 14. During this initial filling, oxygen is present at least in the fluid reservoir 20, making it impossible to ensure the atmosphere isolation caused by the siphon effect of the previously discussed advantageous replenishment reservoir 22 and fluid reservoir 20 at this point in time.

[0108] In this regard, it precedes the previous one based on time. Figures 2A to 2D In step zero of steps one through seven discussed, it is necessary to remove at least the initially present oxygen from the bubbler 12 and the fluid reservoir 20. In step zero or... Figure 3 In the special state shown, the initial commissioning, maintenance, or initial filling of the process fluid 14 of the filling device 10 is performed. Furthermore, deoxygenation can be performed if necessary, for example, whenever a certain amount of residual process fluid 14 present in the replenishment reservoir 22 inadvertently drops below the required amount, making it impossible to ensure the siphon effect.

[0109] During step zero, the gas pressure in both the bubbler 12 and the fluid reservoir 20 is reduced, preferably to below 10 mbar within 10 seconds. Then, all valves between the replenishment reservoir 22, the fluid reservoir 20, and the bubbler 12 are opened, namely, in this example, the filling valve 26, the supply valve 28, and the equalizing valve 30. Figure 3 The corresponding valves 26, 28, and 30 are shown against a light-colored background.

[0110] The bubbler 12 is then pressurized and purged with process gas introduced through the bubbler gas supply source 40 for at least 2 minutes. The purging is performed using process gas (nitrogen in this example). Figure 3 The image is illustrated by arrows and corresponding bubbles 38 introduced by the bubbler gas supply source 40. The process gas introduced into the bubbler 12 via the bubbler gas supply source 40 flows through the open valves 26, 28, 30, enters the fluid reservoir 20 from the bubbler 12 and then enters the replenishment reservoir 22, before being discharged into the atmosphere via the positive pressure valve 36.

[0111] As the process gas is introduced into the bubbler 12 under positive pressure via the bubbler gas supply source 40, and thus logically flows under pressure through the two reservoirs 20, 22, the oxygen present in the system, particularly in the fluid reservoir 20, is gradually squeezed out of the respective containers by the process gas supplied by the bubbler gas supply source 40 and expelled into the atmosphere via the positive pressure valve 36.

[0112] Simultaneously, during the purging process, the process fluid 14 from the fluid source 24 is introduced into the replenishment reservoir 22 until a certain level is reached. Figure 3 The dashed line indicates the expected minimum fill level of process fluid 14, i.e., reaching a predetermined residual amount. Due to the introduction of positive-pressure process gas during purging, the flow of process fluid 14 from the replenishment reservoir 22 into the fluid reservoir 20 via the supply valve 28 is reliably prevented, as the gas pressure opposes the inflow of process fluid 14. Therefore, after a certain point in time, the fixed residual or minimum amount of process fluid 14 in the replenishment reservoir 22 is again reached, thus ensuring the siphon effect for atmosphere isolation. During further purging, oxygen present in the fluid reservoir 20 is continuously expelled, and the siphon effect, i.e., through the process fluid 14 now present in the replenishment reservoir 22, further reliably prevents any new oxygen from entering the fluid reservoir 20.

[0113] After purging the system and thereby displacing any present oxygen for a sufficiently short time, all valves between the replenishment reservoir 22, the fluid reservoir 20, and the bubbler 12 are closed again, particularly the supply valve 28, the equalizing valve 30, and the filling valve 26, so that the oxygen-free state of the system is restored, and the previous state can be restored based on... Figures 2A to 2D The expected operation is described.

[0114] As explained in the foregoing description, the advantageous filling device 10 or filling system 16 discussed in this application, in conjunction with the discussed operating method, advantageously ensures that replenishment of the bubbler 12 and the fluid reservoir 20 does not require interruption of the bubbler 12 and / or the brazing or sintering system to operate as intended, since the process fluid 14 is always supplied to the fluid reservoir 20 and thereby to the bubbler 12 in an oxygen-free manner.

[0115] By providing the replenishment reservoir 22 and combining it with the atmosphere isolation caused by the siphon effect, continuous oxygen-free filling of the fluid reservoir 20 and the bubbler 12 can be advantageously ensured. Therefore, preferably, the process fluid 14 is oxygen-freely filled from the replenishment reservoir 22 into the fluid reservoir 20, while the bubbler 12 operates as intended with the remaining process fluid 14 therein, supplying the process mixture to the system. During periods when the bubbler 12 is paused, particularly during the time the currently processed workpiece is moving within the system, preferably, the process fluid 14 is again oxygen-free replenished from the fluid reservoir 20 into the bubbler 12.

[0116] Therefore, there is no need to interrupt the operation of the bubbler 12 or the brazing or sintering system at any time, thus significantly improving the process efficiency of the system by avoiding downtime.

[0117] Figure 4 It shows the basis Figure 3 A further embodiment of the filling device having a bubbler. It is related to... Figure 3 The difference in the illustrated embodiment is that the two bubblers 12 can be filled individually and independently by the filling device 10. Furthermore, it is conceivable that two or more bubblers 12 can be controllably connected to the fluid reservoir 20 via filling valves 26, thereby significantly improving the productivity and efficiency of the process gas supplied within the system.

[0118] The form of the replenishment reservoir and the filling reservoir can be adapted in their position and shape to specific system requirements. Their relative positions to each other, especially their height difference, can also be customized, and the replenishment reservoir and the filling reservoir, as well as possible bubblers, can be horizontally adjacent and possibly at the same height, wherein fluid flow can be set by utilizing the relative height difference of the liquid level via valves 26, 28 and 30.

[0119] In other words, the filling device according to the invention consists of a replenishment container, an intermediate container, and a bubbler connected to each other. A reducing fluid, such as formic acid, citric acid, or formic acid, is filled into the replenishment container via a supply side (supply of a medium such as compressed air or nitrogen). The reducing fluid acts as a gas barrier and prevents oxygen from entering the brazing or sintering system. If the level monitoring indicates that the reducing fluid needs to be replenished, formic acid is transferred from the replenishment container into the intermediate container. The intermediate container ensures pressure equalization. If necessary, the reducing fluid is transferred from the intermediate container to the bubbler, wherein the reducing fluid can be transferred from the replenishment container to the intermediate container independently of this transfer. This operation is performed completely automatically and in parallel without affecting the brazing process. This achieves the following advantages:

[0120] - Increased system availability (no downtime due to adding or replacing the bubbler)

[0121] - Proven and extremely high process quality

[0122] - Higher process reliability (due to oxygen-free filling)

[0123] Acid-free treatment in cleanrooms

[0124] - Self-gout system

[0125] List of reference numerals

[0126] 10 Filling device

[0127] 12 Bubbler

[0128] 14 Process fluids

[0129] 16 Filling System

[0130] 18 Bubble outlet

[0131] 20 Fluid Storage

[0132] 22 Supply Storage

[0133] 24 Fluid Source

[0134] 26. Filling valve

[0135] 28 Supply valve / fluid flow valve

[0136] 30 equalizing valve

[0137] 32 Liquid Level Sensor

[0138] 34 Fluid supply valve

[0139] 36 Positive pressure valve

[0140] 38 bubbles

[0141] 40. Bubble blower gas supply source.

Claims

1. A filling device (10) for filling at least one bubbler (12) with a process fluid (14), particularly formic acid, formic acid (CH2O2), or citric acid, said bubbler being installable or already installed in a brazing or sintering system, said filling device (10) comprising a fluid reservoir (20), said fluid reservoir being fluidly connected or already fluidly connected to said at least one bubbler (12) by means of at least one filling valve (26), said process fluid (14) being controllably supplied to said fluid reservoir, and said fluid reservoir being designed for controllably filling said process fluid (14) into said bubbler (12), characterized in that, The filling device (10) includes at least one replenishment reservoir (22) fluidly connected upstream of the fluid reservoir (20), to which the process fluid (14) can be supplied from a fluid source (24); wherein the replenishment reservoir (22) and the fluid reservoir (20) are controlled to be connected by means of at least one supply valve (28); wherein when the supply valve (28) is open, the replenishment reservoir (22) is isolated from the atmosphere of the fluid reservoir (20) by a siphon effect, such that the process fluid (14) can always be controlled to be supplied from the replenishment reservoir (22) to the fluid reservoir (20) in an oxygen-free state via the at least one supply valve (28), and the fluid reservoir (20) is always kept in an oxygen-free state.

2. The filling device according to claim 1, characterized in that, The replenishment reservoir (22) and the fluid reservoir (20) are fluidly connected or have been fluidly connected by means of the supply valve (28), so that pressure equalization between the fluid reservoir (20) and the replenishment reservoir (22) can be achieved through the supply valve (28).

3. The filling device according to claim 1, characterized in that, At least one equalizing valve (30) is provided between the supply reservoir (22) and the fluid reservoir (20), wherein the supply valve (28), which is specifically designed as a bellows valve, is designed as a fluid flow valve (28) to allow fluid flow, while the equalizing valve (30), which is specifically designed as a bellows valve or a check valve, is designed to allow pressure equalization.

4. The filling device according to any one of the preceding claims, characterized in that, The replenishment reservoir (22) includes a positive pressure valve (36) for releasing positive pressure, particularly designed as a check valve, and / or a fluid connection, particularly a fluid connection connected to the fluid replenishment valve (34), for supplying process fluid (14) from the fluid source (24) to the replenishment reservoir (22) in a controlled manner.

5. The filling device according to any one of the preceding claims, characterized in that, At least the fluid reservoir (20), and preferably the replenishment reservoir (22), is designed as a closed, preferably pressure-resistant and particularly openable container as needed, wherein the replenishment reservoir (22) is arranged above the fluid reservoir (20) relative to the ground, such that process fluid (14) can be supplied from the replenishment reservoir (22) to the fluid reservoir (20) by means of gravity.

6. The filling device according to any one of the preceding claims, characterized in that, The replenishment reservoir (22) and / or the fluid reservoir (20) have at least one level sensor (32).

7. The filling device according to any one of the preceding claims, characterized in that, At least the filling valve (26) is automatically controlled so that the bubbler (12) can be automatically and / or continuously replenished with process fluid (14) from the fluid reservoir (20).

8. The filling device according to any one of the preceding claims, characterized in that, A fluid supply valve (34) is arranged between the supply reservoir (22) and the fluid source (24) for controllably supplying process fluid (14) from the fluid source (24) to the supply reservoir (22).

9. The filling device according to any one of the preceding claims, characterized in that, The device includes a control unit connected to the filling valve (26) and at least to the supply valve (28), preferably also to the level sensor (32) of the fluid reservoir (20) and / or to the level sensor (32) of the replenishment reservoir (22) and / or to the equalizing valve (30), and the control unit is configured to provide a controlled supply of process fluid from the fluid reservoir (20) to the bubbler (12) and from the replenishment reservoir (22) to the fluid reservoir (20).

10. A bubbler system (16) for a brazing or sintering system, comprising a bubbler (12) for supplying a process fluid, particularly formic acid, mixed with a process gas, particularly nitrogen, to at least one process chamber of the brazing or sintering system, and comprising a filling device (10) for filling the bubbler (12) with the process fluid (14), characterized in that... It has a filling device (10) according to any one of claims 1 to 9.

11. A brazing or sintering system comprising a bubbler system (16) for supplying a process fluid, particularly formic acid, mixed with a process gas, particularly nitrogen, to at least one process chamber of the brazing or sintering system, characterized in that... It has a bubbler system (16) according to claim 10.

12. A method for operating a filling device (10), particularly a filling device (10) according to any one of claims 1 to 9, wherein process fluid (14) is controlledly filled by means of the filling device (10) to at least one bubbler (12) that can be installed or has been installed in a brazing or sintering system, wherein the bubbler (12) is fluidly connected to a fluid reservoir (20) of the filling device (10) by means of at least one filling valve (26), the process fluid (14) being supplied to the fluid reservoir, characterized in that, A replenishment reservoir (22) of the filling device (10) is connected upstream of the fluid reservoir (20), and the process fluid (14) is supplied from the fluid source (24) to the replenishment reservoir; wherein the replenishment reservoir (22) and the fluid reservoir (20) are controlled atmosphere isolated by means of at least one supply valve (28) through a siphon effect, such that the process fluid (14) is always supplied from the replenishment reservoir (22) to the fluid reservoir (20) in a controlled, oxygen-free manner, and the fluid reservoir (20) is always kept in an oxygen-free state.

13. The method according to claim 12, characterized in that, The bubbler (12) is replenished from the oxygen-free fluid reservoir (20) via the filling valve (26) with oxygen-free process fluid (14) present in the fluid reservoir as needed and / or continuously in a controlled manner, preferably during periods when there is no brazing or sintering process in the brazing or sintering system, particularly during the time when the workpiece is being transferred within the brazing or sintering system.

14. The method according to claim 13, characterized in that, During the operation of the brazing or sintering system as intended, the fluid reservoir (20) is filled with the process fluid (14) in an oxygen-free manner by the replenishment reservoir (22), the filling being independent of the replenishment filling of the bubbler (12) without interrupting the operation of the bubbler (12), wherein the fluid reservoir (20) is preferably filled with the process fluid (14) when the bubbler (12) is operating as intended.

15. The method according to any one of claims 12 to 14, characterized in that, For the atmosphere isolation caused by the siphon effect, the fluid reservoir (20) and the replenishment reservoir (22) are connected via the supply valve (28), which is specifically designed as a bellows valve, and via the equalizing valve (30), which is specifically designed as a bellows valve, wherein the process fluid (14) is supplied from the replenishment reservoir (22) to the fluid reservoir (20) in a controlled manner via the supply valve (28), and the equalizing valve (30) is used to equalize the air pressure between the replenishment reservoir (22) and the fluid reservoir (20), wherein a certain amount of residual process fluid (14) is always maintained in the replenishment reservoir (22) to prevent any oxygen from entering the fluid reservoir (20).

16. The method according to any one of claims 12 to 15, characterized in that, The process fluid (14) is supplied from the replenishment reservoir (22) to the fluid reservoir (20) by means of gravity and / or by means of positive pressure and / or from the fluid reservoir (20) to the bubbler (12).

17. The method according to any one of claims 12 to 16, characterized in that, The level of process fluid (14) present in the replenishment reservoir (22) and / or the fluid reservoir (20) is detected by means of a level sensor (32), wherein if the level of process fluid in the fluid reservoir (20) drops below a preset first threshold, a controlled supply of process fluid (14) from the replenishment reservoir (22) to the fluid reservoir (20) is triggered, and if the level of process fluid in the replenishment reservoir (22) drops below a preset second threshold, a controlled supply of process fluid (14) from the fluid source (24) to the replenishment reservoir (22) is triggered, or at least an instruction is issued to the operator to replenish the replenishment reservoir (22) from the fluid source (24).

18. The method according to any one of claims 12 to 17, characterized in that, During continuous operation of the brazing or sintering system, the following steps are performed to fill the bubbler (12): a) In the first step, the process fluid (14) is filled from the fluid source (24) into the replenishment reservoir (22); b) In the second step, the equalizing valve (30) is opened to equalize the pressure between the fluid reservoir (20) and the replenishment reservoir (22) which are under positive pressure, wherein the positive pressure can preferably be discharged to the atmosphere via the positive pressure valve (36) of the replenishment reservoir (22); c) In the third step, the supply valve (28) is opened to supply the process fluid (14) from the replenishment reservoir (22) to the fluid reservoir (20). d) In the fourth step, the supply valve (28) and the equalizing valve (30) are closed. e) In the fifth step, the fill valve (26) between the fluid reservoir (20) and the bubbler (12) is opened to perform pressure equalization between the respective pressures in the bubbler (12) and the fluid reservoir (20); f) In the sixth step, preferably during the period when the bubbler (12) is inactive, preferably during the period when there is no brazing or sintering process in the brazing or sintering system, especially during the time when the workpiece is being transferred in the brazing or sintering system, the gas pressure in the bubbler (12) is reduced and the filling valve (26) is opened to supply process fluid (14) from the fluid reservoir (20) to the bubbler (12). g) In the seventh step, positive pressure is restored in the bubbler (12) and the filling valve (26) is closed again.

19. The method according to any one of claims 12 to 18, characterized in that, To remove oxygen from the filling device, particularly during initial commissioning, for maintenance purposes, and / or to initially fill the filling device with process fluid (14), and preferably repeated when a minimum amount of process fluid, preferably 2.5 liters, is reached, the following steps are performed in sequence: I. Reduce the corresponding air pressure in the bubbler (12), preferably to below 10 mbar within 10 seconds; II. Reduce the gas pressure in the fluid reservoir (20), preferably to below 10 mbar within 10 seconds; III. Open all valves between the supply reservoir (22), the fluid reservoir (20), and the bubbler (12); IV. The bubbler (12) is subjected to pressure while being purged by process gas for at least 2 minutes, wherein the positive pressure is discharged via the positive pressure valve (36) of the replenishment reservoir (22); V. Close all valves between the supply reservoir (22), the fluid reservoir (20), and the bubbler (12).

20. The method according to any one of claims 12 to 19, characterized in that, The bubbler (12) is filled to a preset filling level, preferably to a filling level greater than 500 mm, and particularly to a filling level greater than 650 mm.

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