Flux module for applying flux to solder, method for operating a flux module, and soldering system for soldering with a flux module.

Abstract

Flux module (12) for applying flux (42) to solder (11), with a movable spray head and with a cleaning device (60) for cleaning the spray head (38), wherein the flux module (12) is designed such that the spray head (38) can be moved into a cleaning area (78) and, wherein the cleaning device (60) is designed to dispense cleaning fluid (72) onto the spray head (38) located in the cleaning area (78), wherein the cleaning device (60) comprises a metering needle (66), and wherein the arrangement is such that the metering needle (66) is located vertically above the spray head (38) when the spray head (38) is located in the cleaning area (78).

Description

[0001] The invention relates to a flux module for applying flux to soldering material, comprising a movable spray head and a cleaning device for cleaning the spray head. The invention further relates to a method for operating the flux module and a soldering system for soldering material with the flux module.

[0002] Fluxes are essential in soldering technology and in any selective or wave soldering process because they perform several crucial functions. First, they clean the surface of the materials to be soldered of oxide layers, allowing for better solder adhesion. Furthermore, fluxes promote wetting by facilitating the formation of solder droplets on the surface and their subsequent wetting. This improves solder distribution and enables the formation of stable, electrically conductive solder joints. Despite their vital role, fluxes can leave residues that must be removed after soldering.

[0003] For high-volume production, automated flux modules are used. These modules apply the flux to the workpieces to be soldered within a work area using a movable spray head, prior to the actual soldering process. The spray heads precisely meter the flux onto the areas to be soldered using flux nozzles.

[0004] The advantage of this method is that precise control of the flux application is possible, resulting in minimal flux waste. However, if the flux is not applied correctly, is applied unevenly, or not at all, this can negatively affect the subsequent solder joints. Therefore, precise alignment, adjustment, and careful calibration of the flux nozzle are essential. If the flux nozzle is not correctly aligned, this can lead to uneven flux distribution.

[0005] The flux nozzle can wear down over time, especially when processing high volumes. This wear can affect the precision of the flux application and necessitates regular maintenance. To ensure consistent performance, it is essential to clean the nozzles regularly. Flux has a sticky consistency and can quickly become lodged on the nozzle due to small splashes. In particular, the flux can rebound off the solder and splash back onto the spray head. There, it hardens and is difficult to remove. Depending on the type of flux, the consistency when dried can also be sticky-viscous to crystalline. Cleaning the entire process requires additional maintenance and downtime, not only for the flux module but for the entire production line in electronics manufacturing.

[0006] It is known to blow off excess flux from the flux nozzle using a compressed air nozzle. This has the disadvantage of contaminating further areas of the flux module with flux. Additionally, not all flux residues can be removed with a compressed air nozzle, as the residues can be sticky and crystalline and remain on the spray head. Consequently, manual cleaning of the spray head, requiring system downtime, becomes necessary.

[0007] From DE 691 10 824 T2 a flux application device for applying flux to solder is known, which has a cleaning system with a brush for cleaning the spray head.

[0008] The object of the present invention is to improve the soldering process.

[0009] The problem is solved by a flux module for applying flux to solder according to claim 1. The flux module comprises a movable spray head and a cleaning device for cleaning the spray head. The flux module is further configured such that the spray head can be moved into a cleaning area. The cleaning device is configured to dispense cleaning fluid onto the spray head located in the cleaning area. The cleaning area is preferably located outside the working area within which the spray head can be moved to apply flux to the solder, and in particular to a printed circuit board. Within the cleaning area, there is preferably an application area for applying the cleaning fluid and a removal area for removing the cleaning fluid and the flux residues dissolved in the cleaning fluid.

[0010] Furthermore, the cleaning device includes a metering needle, arranged such that the metering needle is positioned vertically above the spray head when it is within the cleaning area. This arrangement offers the advantage of a defined application area for the cleaning fluid. This ensures that the cleaning fluid is only applied within a specific area. Additionally, the metering needle, preferably with a small diameter, allows for precise and accurate dispensing of the cleaning fluid, particularly by dripping, thus conserving resources and increasing efficiency.

[0011] The spray head is preferably movable in a plane. This plane is preferably defined by an X-direction and a Y-direction. It is conceivable that the spray head can move along one of the X- or Y-directions, or along both X- and Y-directions.

[0012] It is conceivable that the spray head could also be moved in a Z-direction. Furthermore, it is conceivable that the spray head could have a nozzle plate with a flux nozzle on its upper surface for applying the flux. It is also conceivable to provide more than one spray head and / or more than one cleaning device in the flux module.

[0013] Designating a cleaning zone has the advantage of preventing further areas from being contaminated by dirt removed by the spray head during cleaning. This keeps the flux module clean in the working area and ensures better flux application. This also reduces subsequent maintenance and cleaning efforts.

[0014] Applying the cleaning fluid has the advantage that it makes it easier to remove contaminants, especially those caused by the flux on the spray head. The cleaning fluid loosens contaminants, allowing them to be removed without significant external mechanical stress. Preferably, no mechanical stress is required during cleaning, as is the case with manual intervention. This largely eliminates the risk of damage to the spray head and flux nozzle caused by external mechanical stress. Furthermore, the necessary precise alignment, adjustment, and careful calibration of the spray head remain unaffected.

[0015] Another advantage of such a cleaning device is that multiple spray heads can be used in a single flux module. For example, one spray head can apply flux to the workpiece in the working area while the other is being cleaned in the cleaning area. This ensures uninterrupted production with little to no downtime.

[0016] It is advantageous if the cleaning device is fixedly positioned within the flux module. It is further advantageous if the cleaning device is positioned above the cleaning area. "Fixedly positioned" here means fixed within the flux module and fixed relative to the spray head, so that the cleaning device is largely immobile within the flux module. This allows for a simple design with few moving parts and reduces the risk of kinking of the cleaning fluid lines.

[0017] Advantageously, a control unit and at least one metering valve for dispensing the cleaning fluid, a tank for the cleaning fluid, and / or a pump for pumping the cleaning fluid from the tank to the cleaning device are provided, wherein the control unit is configured to control the metering valve and / or the pump. It is further advantageous if the tank is located above the metering valve and the metering needle. This allows the cleaning fluid to be dispensed by gravity from the tank located above the metering needle and metering valve. With this arrangement, a pump can advantageously be omitted. If a higher pressure of the cleaning fluid is required, or if the tank cannot be located above the metering needle, a pump can be provided, in which case the cleaning fluid is dispensed from the cleaning device by means of pump pressure.Overall, such an arrangement can further improve the precise dosage and dispensing of the cleaning fluid.

[0018] It is conceivable that the flux module includes a removal device for removing cleaning fluid present on the spray head. This removal device can be located in conjunction with the cleaning device within the cleaning area. It is further advantageous if the removal device is located in a designated removal zone within the cleaning area. Another advantage is if the removal device can be used to dry the cleaning fluid on the flux nozzle and the spray head.

[0019] The removal device can be designed as a nozzle, a suction device, a brush, or by wiping with a textile / sponge or a scraper, or various combinations thereof. This ensures the effective removal of dirt dissolved by the cleaning fluid and the cleaning fluid itself from the spray head.

[0020] If necessary, the removal device is arranged on the spray head and can be moved with it, so that no movement of the spray head is necessary for removal.

[0021] It is advantageous if the removal device is fixed in place within the flux module. Fixed in place means that the removal device cannot be moved with the spray head.

[0022] It has proven advantageous if the removal device is designed as a nozzle through which a removal gas flows. The removal gas is preferably compressed air or nitrogen. In particular, the nozzle is designed as a fan nozzle to cover as wide an area as possible, and especially the entire spray head, with the removal gas. This enables fast and reliable removal.

[0023] The nozzle can be arranged such that the removal gas flows at an angle of 45° to 90° to a horizontal top surface of the spray head, and preferably at an angle of 60° to 80°. This flow pattern ensures particularly effective removal of the cleaning fluid. Furthermore, it allows even stubborn contaminants such as flux residue to be removed from the spray head and flux nozzle. Another advantage of this arrangement is that the cleaning fluid and contaminants are predominantly removed downwards rather than horizontally, thus preventing contamination of the flux module or the soldering workpiece.

[0024] It is conceivable to provide a flow control valve for the removal gas, with the control unit then actuating the flow control valve. It is also conceivable that the control unit actuates the flow control valve in such a way that the flow of removal gas pulsates at a specific frequency. Pulsating flow allows for particularly effective removal of the cleaning fluid. In particular, adhering contaminants that are not yet, or not completely, dissolved by the cleaning fluid can be loosened by the pulses of the pulsating flow. It is further advantageous if the control unit and the flow control valve are configured so that the frequency can be variably adjusted.

[0025] It is advantageous to have an imaging sensor configured to detect the degree of contamination of the spray head and provide data to the control unit accordingly. The imaging sensor is, in particular, a camera that provides image data or already processed image data via object recognition. This arrangement can, for example, signal to an operator that cleaning should be initiated using the cleaning device, or automatically start spray head cleaning using the cleaning device.

[0026] It is further advantageous if the control unit is configured such that, when a limit value is exceeded, control signals are provided based on the contamination level data to move the spray head and activate the cleaning device. When cleaning is due, the spray head is then moved into the cleaning zone, specifically into the dispensing zone below the metering needle. The metering valve and / or the pump are then activated to dispense the cleaning fluid and apply it to the spray head. After a short exposure time, the spray head is preferably moved into the removal zone, and the flow valve is activated. The spray head is then moved in such a way that the removal gas reaches the spray head and, in particular, the flux nozzle, in order to remove and dissolve the cleaning fluid and the contaminants.

[0027] It is advantageous if a collection device is provided for collecting cleaning fluid removed by the removal device, wherein the collection device is removable from the flux module. The collection device is preferably provided below the cleaning area and covers it at least partially.

[0028] The cleaning fluid is advantageously a mixture of water and alcohol; isopropanol is particularly advantageous. This is beneficial because this type of cleaning fluid can evaporate if any residue remains on the spray head. Furthermore, this type of cleaning fluid is gentle on the other materials and components in the flux module.

[0029] Depending on the flux used, a cleaning fluid with other components that dissolve residues more effectively can also be employed. If different fluxes are applied simultaneously with two spray heads, two dosing systems with different cleaning fluids for spray head cleaning are also conceivable.

[0030] The problem is also solved by a method according to claim 14 for operating a flux module according to the invention.

[0031] This method allows the spray head in a flux module according to the invention to be cleaned particularly effectively of contaminants. It is also conceivable to repeat the steps depending on the degree of contamination.

[0032] It is conceivable that steps a) to d) are repeated until the dirt adhering to the spray head is largely removed. A particularly good cleaning effect can be achieved by repeatedly dispensing and allowing the cleaning fluid to take effect, followed by removal using the removal device.

[0033] Advantageously, the inventive method is started in an inventive flux module depending on the provided data. It is further advantageous if steps a) to d) of the inventive method are repeated depending on the provided data. Automatic and demand-driven starting and repetition of the method minimizes downtime of the inventive flux module, particularly since manual intervention for cleaning the spray heads is reduced.

[0034] The problem is also solved with a soldering system according to claim 18. The soldering system is designed for soldering components. The soldering system comprises a flux module according to the invention and / or a flux module that is operable according to the method according to the invention and / or has a control unit for carrying out the method according to the invention. Advantageously, the control unit of the soldering system is connected or connectable to the control unit of the flux module, or the control units are integrated with each other. With such a soldering system, the application of the flux before the soldering process can be better controlled, and the cleaning process of the spray head can be coordinated with the soldering task.

[0035] The soldering process is improved by the flux module, the method and the soldering system according to the invention.

[0036] Further details and advantageous embodiments of the invention can be found in the following description, which provides further description and explanation of exemplary embodiments of the invention.

[0037] They show: Fig. 1: a soldering system with a flux module; Fig. 2: a schematic soldering process of a soldering system according to Fig. 1; Fig. 3: a cleaning device in a flux module, viewed obliquely from the side; Fig. 4: the cleaning device according to Fig. 3 from diagonally above; Fig. 5 to 7: a section of the cleaning device according to Fig. 3 and Fig. 4. A cleaning area with a spray head in different positions; and Fig. 8: a schematic flowchart of a procedure for operating the flux module according to the Fig. 1 and 3 to 7.

[0038] The Fig. Figure 1 shows a soldering system 10 for soldering components 11. The soldering system 10 can be either a selective soldering system with individual solder pots or a wave soldering system. The components 11 are placed in the Fig. Figure 2 shows an example. The soldering system 10 comprises various modules, the first being a flux module 12, the second a heating module 14, and the third a soldering module 16. The soldering system 10 is enclosed in a housing 18. Depending on the soldering process, the soldering system 10 can also include more or fewer than the three modules 12, 14, 16 shown. For example, two flux modules 12, several heating modules 14, or several soldering modules 16 are conceivable, but not shown. An operating element and control unit 20 is, for example, located in the middle module 14. The modules 12, 14, 16 are interconnected and are preferably controlled by a central control unit. It is also conceivable to provide the modules 12, 14, 16 individually and spatially separated, for example, at different stations in a production line.

[0039] The casing 18 can enclose a process channel (cf. wave soldering systems) that extends through all modules 12, 14, 16. The soldering system includes a transport system 24 which is located in the Fig. 3 and Fig. Figure 4 shows the transport of solder material 11 along a transport direction along the X-direction through the flux module 12 and the soldering system 10.

[0040] The in Fig. The diagram shown is intended to illustrate the basic sequence of a soldering process 26 for soldering a component 11 using the soldering system 10. The soldering process 26 has three steps 28, 30, and 32. In all steps 28, 30, and 32, the component 11 is schematically shown as a through-hole resistor 34 inserted into a printed circuit board 36. The component 11 moves through the process 26 from left to right.

[0041] In the first step 28, which is carried out in the soldering system in the flux module 12, flux 42 is applied to the circuit board 36 on the areas 44 to be soldered using a movable spray head 38, which has a flux nozzle 40 for applying flux 42. In this case, the areas 44 to be soldered are, firstly, the two terminals of the resistor 34, which are inserted through the circuit board 36, and secondly, the corresponding contact pads on the circuit board 36. As indicated by the arrows, the spray head 38 is movable in the X and Y directions, so that different areas of the solder joint 11 can be sprayed within a working area 62. It is important that the flux 42 is dispensed precisely. The problem, however, is that the flux 42 can bounce off or drip down from the circuit board 36 and then adhere to the spray head 38 due to its resinous and sticky consistency.This results in the flux nozzle 40 becoming contaminated or even clogged, so that the application of the flux 42 no longer functions correctly. Incorrectly or not at all applied flux 42 can lead to solder joints of inferior quality and ultimately to the rejection of the solder 11.

[0042] In the second step 30 of the soldering process 26, the workpiece 11 is heated in preparation for the subsequent selective wave soldering or wave soldering in step 32. Two heating cassettes 46 are shown schematically for heating, with one heating cassette 46 positioned as a top heater above the workpiece 11 and the other heating cassette 46 as a bottom heater below the workpiece 11. The heating cassettes 46 emit thermal radiation 48, which is shown schematically as arrows. In the soldering system shown, step 30 of the heating process can be carried out in the second module 14.

[0043] After heating, the soldering element 11 is soldered in step 32. The areas 44 of the soldering element to be soldered are brought into contact with liquid solder 50 from a standing wave expelled from a soldering nozzle 52 on the underside of the circuit board 36. A movable selective wave soldering nozzle, which solders specific areas of the soldering element, is shown as an example; however, any other soldering technology can also be used. In step 32, it is also conceivable to use a top heating element in the form of a heating cassette 46, as shown in step 30. Step 32 can be described in the Fig. The soldering system shown in 1 is carried out in the third module 16.

[0044] To avoid the previously mentioned problems of unintentionally contaminating the spray head 38 and its flux nozzle 40 with the flux 42, a cleaning device 60 for cleaning the spray head 38 is provided in the flux module 12, as described in the following Fig. 3 to 7 are shown.

[0045] The cleaning device 60 is in the Fig. 3 shown from the side, looking out from work area 62 of the flux module 12 and in Fig. 4 shown from above. In this working area 62, the spray head 38 moves, which is in the Fig. Figures 5 to 7 show the spraying of the soldering material 11. The transport system 24 is also shown, which conveys the soldering material 11 through the flux module 12, the soldering system 10, and the process channel. The X-direction runs in Fig. 3 in the plane of the drawing and the Y-direction into the plane of the drawing. The cleaning device 60 has a metering needle 66, a metering valve 68 and a tank 70 containing cleaning fluid 72. The tank 70 is connected by means of a line 73 to the metering valve 68 and finally to the metering needle 66, which is also in the Fig. 5 and Fig. Figure 6 shows a removal device 75, comprising a nozzle 74 through which a gas can flow and a flow valve 76. A schematic diagram of the control unit 20 for controlling the flux module 12, the cleaning device 60, and the removal device 75 is also shown.

[0046] Below the cleaning device 60 and in particular below the metering needle 66 and the nozzle 74 lies a cleaning area 78 in which the spray head 64 can be cleaned.

[0047] The Fig. Figures 5 to 6 show a section of the cleaning device 60 with the spray head 38 in the cleaning area 78. Contamination 80 on the spray head 38 is indicated by black dots. This contamination 80 consists primarily of flux residue. The metering needle 66 and the nozzle 74 are also shown. The metering valve 68, the tank 70, the flow valve 76, and the control unit 20 are shown schematically.

[0048] In the Fig. In step 5, the spray head 38 is moved into the cleaning area 78 below the metering needle 66. The metering needle 66 is arranged vertically above the spray head 38 and its flux nozzle 40. The metering valve 68 is actuated by the control unit 20, causing cleaning fluid 72 to exit the metering needle 66 and be dispensed onto the spray head 38. A drop of cleaning fluid 72 is indicated on the metering needle 66.

[0049] In Fig. 6. The spray head 38 is moved to the left in the X direction within the cleaning area 62 into the removal area. No cleaning fluid 72 is dispensed from the metering needle 66. The dispensed cleaning fluid 72 is located on a horizontal upper surface 81 of the spray head 38 in the area of ​​the flux nozzle 40. The time required to move from the dispensing area below the metering needle 66 to the removal area may already be sufficient as the contact time of the cleaning fluid 72. However, the spray head 38 can also remain in this position or previously below the metering needle 66 to extend the contact time.

[0050] The nozzle 74 is supplied with removal gas 82, so that the removal gas 82 flows out of the nozzle 74 with a flow direction 84. The control unit 20 controls the flow valve 76 accordingly. The removal gas 82 originates from a compressed air source (not shown) and is primarily nitrogen or compressed air, which is required for other steps in the soldering process. The flow 84 does not yet reach the spray head 38 in this position.

[0051] Fig. Figure 7 shows the spray head 38 being moved below the nozzle 74 so that the removal gas 82 flows with the flow 84 at an angle α to the horizontal top surface 81 of the spray head 38. The angle α is in a range of 45° to 90° and preferably at an angle of 60° to 80°. The cleaning fluid 72 and the dissolved contaminants 80 are removed from the top surface 81 of the spray head 38. A collection device 86 is provided for the cleaning fluid 72 and the contaminants 80. The spray head 38 can remain statically below the nozzle 74 or be moved from left to right by the flow. Repeating the movement is also conceivable.

[0052] To operate the flux module 12 with the cleaning device 60, the following is required: Fig. The eight illustrated procedures of procedure 90 are provided for, including optional steps. However, procedure 90 specifically includes the following steps: a) Moving the spray head 38 into the cleaning area 62 below the cleaning device 60; b) Dispensing the cleaning fluid 72 onto the spray head 38 by means of the cleaning device 60; and c) Wait a period of time so that the cleaning fluid 72 dissolves the dirt 80 on the spray head 38.

[0053] After step c), a further step d) is carried out in which the cleaning fluid 72 with the flux residues is removed. In this step, the spray head 38 is moved into the area of ​​the nozzle 74, so that the removal device 75 largely removes the cleaning fluid 72 from the spray head 38.

[0054] Steps a) to d) can also be repeated in a loop 92 until the contaminants 80 adhering to the spray head 38 are largely dissolved and removed.

[0055] Furthermore, it is possible to start the procedure 90 depending on data provided by a sensor, in particular an imaging sensor 94 and / or that steps a) to d) of the procedure 90 are repeated in loop 92 depending on the data provided.

Claims

[1] Flux module (12) for applying flux (42) to solder (11), with a movable spray head and with a cleaning device (60) for cleaning the spray head (38), wherein the flux module (12) is designed such that the spray head (38) can be moved into a cleaning area (78) and, wherein the cleaning device (60) is designed to dispense cleaning fluid (72) onto the spray head (38) located in the cleaning area (78), wherein the cleaning device (60) comprises a metering needle (66), and wherein the arrangement is such that the metering needle (66) is located vertically above the spray head (38) when the spray head (38) is located in the cleaning area (78). [2] Flux module (12) according to claim 1, wherein the cleaning device (60) is arranged in a fixed position in the flux module (12). [3] Flux module (12) according to one of claims 1 or 2, wherein a control unit (20) and at least one metering valve (68) for metering the cleaning fluid (72), a tank (70) for the cleaning fluid (72) and / or a pump for pumping the cleaning fluid (72) from the tank (70) to the cleaning device (60) are provided, wherein the control unit (20) is configured to control the metering valve (68) and / or the pump. [4] Flux module (12) according to one of the preceding claims, wherein a removal device (75) is provided for removing cleaning fluid (72) present on the spray head (38). [5] Flux module (12) according to claim 4, wherein the removal device (75) is designed as a nozzle through which a removal gas (82) can flow. [6] Flux module (12) according to claim 5, wherein the nozzle is arranged such that the removal gas (82) flows at an angle (α) in a range of 45° to 90° to a horizontal top surface (81) of the spray head (38), and preferably at an angle (α) of 60° to 80°. [7] Flux module (12) according to one of claims 3 to 6, wherein a flow valve (76) is provided for controlling the removal gas (82) and wherein the control unit (20) controls the flow valve (76). [8] Flux module (12) according to claim 7, wherein the control unit (20) controls the flow valve (76) such that the flow (84) pulsates at a frequency. [9] Flux module (12) according to one of the preceding claims, wherein an imaging sensor is provided which is configured to detect the degree of contamination of the spray head (38) and to provide data corresponding to the degree of contamination to the control unit (20). [10] Flux module (12) according to claim 9, wherein the control unit (20) is configured such that, when a limit value is exceeded, control signals are provided based on the data of the degree of contamination for the movement of the spray head (38) and for the control of the cleaning device (60). [11] Flux module (12) according to one of the preceding claims, wherein a collecting device (86) is provided for collecting cleaning fluid (72) removed by the removal device (75), wherein the collecting device (86) is removable from the flux module (12). [12] Flux module (12) according to one of the preceding claims, wherein the cleaning fluid (72) is a mixture of water and alcohol, in particular isopropanol. [13] Method (90) for operating a flux module (12) according to any one of claims 1 to 12, comprising the following steps: a) Moving the spray head (38) into the cleaning area (78) below the cleaning device (60); b) Dispensing the cleaning fluid (72) onto the spray head (38) by means of the cleaning device (60); and c) Wait a period of time so that the cleaning fluid (72) dissolves the dirt (80) on the spray head, and d) Moving the spray head (38) into the area of ​​a removal device (75) and activating the removal device (75) to remove the cleaning fluid (72) from the spray head (38). [14] Method (90) according to claim 13, wherein steps a) to d) are repeated until the contaminants (80) adhering to the spray head (38) are largely removed. [15] Method (90) for operating a flux module (12) according to claim 9, wherein the method (90) according to claim 13 is started depending on the data provided and / or steps a) to d) of the method (90) according to claim 14 are repeated depending on the data provided. [16] Soldering system (10) for soldering material (11), comprising a flux module (12) according to one of claims 1 to 13 and / or a flux module (12) that is operable according to a method (90) of claims 13 to 15 and / or has a control unit (20) for carrying out the method (90) according to one of claims 14 to 15.

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