Nozzle system, cover element, soldering system and process for selective wave soldering

Abstract

Nozzle system (18) for a soldering system (10), in particular for a selective soldering system, for soldering components (12) onto a printed circuit board (14), wherein components (13) are present on the printed circuit board (14), the nozzle system (18) comprising: - a soldering nozzle (20) with at least one nozzle opening (48) for forming at least one soldering wave (50) extending along a soldering direction (42), and - a cover element (22) with at least one cover opening (62) through which the solder wave (50) emerges, and with at least one wall (66) that covers the solder flowing out of the solder wave (50), wherein the cover element (22) has at least one pocket (64) for receiving the components (13).

Description

[0001] The invention relates to a nozzle system for a soldering system, in particular for a selective soldering system, a cover element for a nozzle system, a soldering system, in particular a selective soldering system, and a method for selectively wave soldering components on a printed circuit board, wherein components are already installed on the printed circuit board.

[0002] In the field of contacting electronic components, which are attached, for example, using Through Hole Technology (THT) from the top side of a printed circuit board through a hole in the board, it is known to contact the components from the underside of the board. For contacting individual pins, rows of pins, or groups of pins by soldering, the so-called selective wave soldering process is known, in which a stationary wave of liquid solder running along a soldering direction is positioned precisely under a component or a pin to be contacted.

[0003] Soldering systems with nozzle systems are known from US 2010 / 0 264 197 A1, US 11 059 119 B2 and EP 2 101 949 B1.

[0004] From DE 43 14 241 C2 a selective soldering system with a soldering nozzle and a solder bath is disclosed, wherein the soldering nozzle is surrounded by a protective gas guide channel in order to circulate a protective gas around the solder wave formed at the soldering nozzle.

[0005] For example, in printed circuit board (PCB) manufacturing for the automotive industry, large and small electronic components are mounted on the PCB. First, large electronic components (hereinafter referred to as "components") are attached to the PCB, for example, by soldering or mechanical connections. Subsequently, smaller electronic components (hereinafter referred to as "parts") must be placed on the PCB in the spaces between the already mounted components. This is where the selective wave soldering process described above is used.

[0006] Due to the dimensions of components required, for example, in the automotive industry, the spaces in which the components must be mounted are constantly decreasing. The distance between two components (parallel to the x- and y-axes) and also the depth between the free end of the component and the circuit board (parallel to the z-axis) present a challenge when mounting the components.

[0007] The invention is based on the objective of enabling the selective soldering of components in small and deep gaps, whereby in particular neighboring components on the printed circuit board should not be affected.

[0008] The problem underlying the invention is solved by a nozzle system with the features of claim 1. The nozzle system serves for a soldering system, in particular for a selective soldering system, for soldering components onto a printed circuit board extending parallel to the x- and y-axes, wherein components are already present on the printed circuit board. The components preferably form a space in which the components on the printed circuit board are to be soldered by means of the nozzle system, in particular the soldering system. The nozzle system has a soldering nozzle with at least one nozzle opening for forming at least one solder wave extending along a soldering direction parallel to the z-axis. The at least one solder wave serves to contact the solder pin or the row or group of solder pins and to form the solder joint, so that the at least one component is electrically and mechanically connected to the printed circuit board.Furthermore, the nozzle system comprises a cover element with at least one cover opening. The solder wave can emerge through the cover opening, preferably being formed by the cross-section of the nozzle opening. Preferably, the cover opening surrounds the solder wave along its circumference, and preferably, the solder wave emerges from the cover opening without contact.

[0009] Furthermore, the cover element has a wall that covers the solder flowing from the solder wave. The wall preferably extends parallel to the z-axis and / or perpendicular to the z-axis. It also preferably extends parallel to the soldering nozzle and / or perpendicular to the circuit board and / or parallel to the components. Consequently, the components surrounding the solder joint are protected during wave soldering and / or when the solder flows from the solder wave. In addition, the cover element has at least one pocket for receiving a component.

[0010] Wave soldering of components requires the soldering nozzle to be moved from below along the z-axis towards the circuit board. Due to the height of solder waves, which ranges from approximately 1 mm to 5 mm, the nozzle is positioned so that the solder wave contacts the desired solder joint between the component and the circuit board. However, adjacent components prevent the nozzle from moving towards the circuit board. Therefore, the cover element has at least one pocket to accommodate at least one component. Consequently, the soldering nozzle can move towards the circuit board, with the components engaging in the pockets of the cover element.

[0011] Consequently, components can be soldered to a printed circuit board using the nozzle, even if other components are already mounted on the board. The design of the cover element holds the components in pockets and protects them from solder due to the wall's thickness.

[0012] An advantageous further development provides that the cover element has a base housing. On the component side of the base housing, at least one pocket and / or a nozzle chamber for receiving the soldering nozzle are provided, and preferably on the nozzle side. Furthermore, at least one cover opening and / or at least one wall are preferably provided on or in the base housing. By arranging the cover element between the pocket and the nozzle chamber, the components are separated from the other components for soldering, or at least substantially fluidically separated.

[0013] Advantageously, the soldering nozzle can be inserted into the nozzle chamber of the cover element along the soldering direction, i.e., parallel to the z-axis. For this purpose, an insertion opening can be provided on the underside of the cover element on the housing opposite the pocket, into which the soldering nozzle can be inserted during assembly and / or operation. This results in simple assembly of the soldering nozzle and the cover element.

[0014] It is advantageous if the at least one nozzle opening and the at least one cover opening are formed at least substantially coaxially along the soldering direction. Consequently, a stable solder wave can form, with the cover element protecting the surrounding components.

[0015] Furthermore, it is advantageous if the soldering nozzle and the cover element are formed as a single piece or monolithically and / or cannot be separated from each other without damage. This results in a defined nozzle chamber and a defined distance between the soldering wave and the wall, thus reliably protecting the surrounding components. It is conceivable that the soldering nozzle and the cover element could be manufactured using an additive manufacturing process.

[0016] Alternatively, it is advantageous if the soldering nozzle and the cover element are designed in two parts. The soldering nozzle can then be inserted into the cover element along the soldering direction and / or removed from the cover element in a detachable or reversible manner against the soldering direction. This allows for individual adjustment between the soldering nozzle and the cover element depending on the circuit board and / or the components. Furthermore, this facilitates cleaning and enables the replacement of individual elements, as opposed to replacing the entire nozzle system.

[0017] An advantageous embodiment provides that a solder drain channel, preferably annular and / or surrounding the solder nozzle, is provided between the soldering nozzle and the cover element to allow the solder flowing from the soldering wave to drain away. The solder drain channel is preferably bounded by at least one wall and the outer surface of the soldering nozzle. The cover element, particularly the wall, separates the draining solder from the adjacent components.

[0018] To compensate for manufacturing tolerances, particularly those of components mounted on the printed circuit board (PCB), it is advantageous for the cover element to be floatingly mounted in or on a solder mask. The solder mask preferably extends perpendicular to the z-axis and / or parallel to the PCB. The solder mask preferably covers the PCB from below. Due to the floating mounting, the cover element can be inserted into the gap even if the components are in a different position. Furthermore, the nozzle system, especially the cover element, preferably compensates for deviations of the PCB, the components, and / or the drive system along the z-axis. It is conceivable that the soldering nozzle is also displaced in accordance with the displacement of the cover element. Alternatively, it is conceivable that the soldering nozzle has play in the cover element, particularly in the nozzle chamber, so that displacement of the cover element does not result in displacement of the soldering nozzle.This has the advantage that the solder joint is created at the defined point between the circuit board and the component.

[0019] It is advantageous if the floating mounting is achieved by means of at least one mounting receptacle and at least one fastening element that can be inserted into the mounting receptacle. The mounting receptacle can have an internal thread. The fastening element can have a threaded section, a collar section, and a head section. Preferably, the mounting receptacle is provided in the cover element.

[0020] To attach the cover element and the solder mask, the fastener is passed through a receiving bore in the solder mask and inserted into the mounting recess. The internal thread and the threaded section interact in such a way that the cover element and the fastener are securely connected. Preferably, the outer diameter of the collar section is smaller than the inner diameter of the receiving bore, allowing the cover element to be displaced relative to the solder mask according to the size difference. The ratio between the outer diameter of the collar section and the inner diameter of the receiving bore is preferably between 1:1.2 and 1:2, more preferably between 1:1.4 and 1:1.6. The outer diameter of the collar section is preferably 4 mm. The inner diameter of the receiving bore is preferably 6 mm. Furthermore, the collar height of the collar section is preferably greater than the thickness of the solder mask.This also achieves play along the z-axis. Elastic buffers are provided in the solder mask and / or in the cover element to center the cover element on the solder mask. The elastic buffers can, for example, be designed as rubber buffers. It is conceivable that the elastic buffers are hollow cylindrical and / or arranged radially between the fastener and the inner diameter.

[0021] The problem underlying the invention is also solved by a cover element with the features of claim 10. The cover element serves for a nozzle system, in particular for a nozzle system as previously described, preferably for or in a selective soldering system. The cover element has at least one cover opening through which a solder wave can emerge. The cover element further has at least one wall that covers the solder flowing from the solder wave and thus protects adjacent components provided on a printed circuit board. Furthermore, the cover element has at least one pocket for receiving the components. Consequently, the nozzle system, in particular the soldering nozzle, can approach the printed circuit board from below. The cover element preferably has a nozzle chamber for receiving the soldering nozzle.A wall is provided between the nozzle chamber and at least one pocket, so that the nozzle chamber and components are separated from each other, particularly fluidically. It is conceivable that excess solder from the soldering wave can flow away from the nozzle side via this wall. Thus, it does not come into contact with the components.

[0022] The problem underlying the invention is also solved by a soldering system, in particular a selective soldering system, with the features of claim 11. The soldering system comprises a solder pot that can be moved along the z-axis and a nozzle system as previously described. The soldering nozzle of the nozzle system is arranged on the solder pot, in particular in a manner that prevents movement. The solder pot is movable such that the soldering nozzle can be inserted into the cover element. Using the soldering system, components can also be soldered onto the printed circuit board in gaps formed between components without affecting the adjacent components.

[0023] It is advantageous if the cover element and / or the solder mask can be displaced parallel to the z-axis, particularly independently of the solder pot and the soldering nozzle. This allows the cover element and / or the solder mask to be moved relative to the circuit board, and at least one component can be inserted into at least one pocket of the cover element.

[0024] The problem underlying the invention is also solved by a method for selective wave soldering of components on a printed circuit board, wherein components are provided on the printed circuit board, with the features of claim 13. The method comprises the following steps, in particular in the order mentioned: a) Arranging a soldering nozzle in a nozzle chamber of a cover element to form a nozzle system, b) Arranging the nozzle system on the printed circuit board, wherein the components are accommodated in pockets of the cover element, and c) Forming a solder wave for soldering the component, wherein the solder wave protrudes from a nozzle opening of the soldering nozzle and from a cover opening of the cover element.

[0025] The nozzle system is preferably arranged perpendicular to the z-axis next to one or more components, in particular in a space formed by the components, as per step b).

[0026] Furthermore, it is conceivable that the cover element is arranged on a solder mask, in particular in a floating manner, before step a).

[0027] An advantageous further training procedure includes a further step, in particular after step c): d) Drainage of the solder flowing from the soldering wave in a solder drainage channel formed by the soldering nozzle and by at least one wall of the cover element, so that the components are protected from the draining solder. Further details and advantageous embodiments of the invention can be found in the following description, which further describes and explains exemplary embodiments of the invention.

[0028] They show: Fig. 1 a perspective exploded view of a plumbing system according to the invention with a nozzle system according to the invention; Fig. 2 a perspective underside view of a cover element according to the invention with a solder mask; Fig. 3 a perspective bottom view of a nozzle system according to Fig. 1; Fig. 4 a perspective side view of a soldering nozzle; Fig. 5 a perspective top view of a nozzle system; and Fig. 6 a schematic sectional view of a nozzle system according to the invention.

[0029] In Fig. Figure 1 shows a selective soldering system 10 according to the invention for the selective wave soldering of components 12 on a printed circuit board 14. The selective soldering system 10 comprises a solder pot 16 and a nozzle system 18 according to the invention, wherein the nozzle system 18 has a soldering nozzle 20 and a cover element 22 designed separately from the soldering nozzle 20. The soldering nozzle 20 is arranged on the solder pot 16, which is movable along the z-axis Z and preferably also along the x-axis X and y-axis Y. The cover element 22 is arranged on a solder mask 24 extending parallel to the printed circuit board 14, wherein the solder mask 24 is preferably also movable along the z-axis Z and preferably along the x-axis X and y-axis Y.

[0030] Using the selective soldering system 10, the components 12 are soldered to the printed circuit board 14, with the components 12 being inserted from above through the printed circuit board 14. On the underside 26 of the printed circuit board 14, facing the nozzle system 18, according to Fig. Six solder pins 28 protrude, which are soldered to the circuit board 14 by a solder wave 30 generated by the soldering nozzle 20. The circuit board 14 is held in a defined position by a clamping device 32. In addition to the components 12 to be soldered, components 13 already connected to the circuit board 14 are provided, which makes soldering the components 12 onto the circuit board 14 more difficult due to the limited space.

[0031] The soldering nozzle 20 has according to Fig. 4 and Fig. 6 A nozzle housing 34 with a nozzle underside 36 facing the solder pot 16, a nozzle upper side 38 facing the circuit board 14, and a nozzle jacket side 40 arranged between the nozzle underside 36 and the nozzle upper side 38. A solder channel 44 extends within the nozzle housing 34 between the nozzle underside 36 and the nozzle upper side 38, particularly parallel to the z-axis, along a soldering direction 42. The solder channel 44 fluidically connects a pot connection 46 arranged on the nozzle underside 36 and a nozzle opening 48 arranged on the nozzle upper side 38. The solder is supplied at the pot connection 46 and conveyed through the solder channel 44 along the soldering direction 42 to the nozzle opening 48, forming the solder wave 30 above the nozzle opening 48. The solder nozzle 20 and / or the solder channel 44 are preferably cylindrical. The nozzle opening 48 preferably protrudes parallel to the z-axis opposite the nozzle top 38.

[0032] The cover element 22 has according to Fig. 6 a basic housing 52 with a housing top 54 facing the circuit board 14, a housing bottom 56 facing the solder pot 16 and a housing jacket side 58 arranged between the housing top 54 and housing bottom 56. The cover element 22 has according to Fig. 2 and Fig. The housing 52 has a nozzle chamber 60 on its underside 56 for receiving the soldering nozzle 20. The housing 52 also has cover openings 62, which are preferably arranged coaxially with the nozzle openings 48 when the soldering nozzle 20 is located in the cover element 22, particularly in the nozzle chamber 60. The nozzle opening 48 and / or the cover opening 62 are preferably arranged such that they are centered below a solder pin 28, a row of solder pins, or a group of solder pins.

[0033] The cover element 22 further exhibits according to Fig. 5 and Fig. The housing 52 has 54 pockets 64 on its upper surface for receiving the components 13. During wave soldering, the components 13 are held by the pockets 64, which protect them by preventing solder from reaching them and / or by providing thermal insulation. For this purpose, the base housing 52 has walls 66, which are preferably arranged between at least one component 13 and the solder.

[0034] The cover element 22 further protects the components 13 from solder flowing off the soldering wave 50. In the prior art, the excess solder from the soldering wave 30 flows back into the soldering pot 16 via the nozzle opening 48 on the soldering nozzle 18, as is the case with a soldering nozzle 20 according to Fig. 4 without the cover element 22. Due to the proximity of the components 13 to the soldering nozzle 20, contact occurs between the solder and the components 13. The cover element 22, in particular the walls 66, is arranged between the components 13 and the excess solder. The cover element 22, in particular the walls 66, and the soldering nozzle 20, in particular the nozzle casing side 40, form a solder drain channel 68 on the underside 56 of the housing, by allowing the excess solder to flow away along a solder drain direction 69. The solder drain channel 68 is preferably annular and / or surrounds the soldering nozzle 20 along its circumference.

[0035] The cover element 22 is preferably trough-shaped, in particular with elevations for forming the nozzle chamber 60 and recesses for forming the pockets 64.

[0036] To compensate for tolerances of the gap formed by the components 13, the cover element 22 is preferably designed according to Fig. 5 and Fig. 6. The cover element 22 is floatingly mounted. This allows the cover element 22 to compensate for an offset parallel to the z-axis and preferably also to the x- and y-axes. It is conceivable that the cover element 22 is floatingly mounted on the solder mask 24 by means of at least one bearing 70. The bearing 70 comprises a fastening element 72, a fastening receptacle 74, and a receiving bore 76. The fastening receptacle 74 is preferably arranged in the cover element 22 along the z-axis. The receiving bore 76 is preferably arranged in the solder mask 24. The fastening element 72 has a head section 78, a collar section 80 adjacent to the head section 78, and a threaded section 82 adjacent to the collar section 80. For connection, the fastening element 72 is screwed into the receiving bore 76, the collar section 80 having an outer diameter that is smaller than the receiving bore 76.Furthermore, the flange section 80 has a flange height that is greater than the thickness of the solder mask 24. Consequently, the mask 22 has the necessary clearance to compensate for the tolerances on the printed circuit board 14.

[0037] To center the cover element 22 relative to the soldering nozzle 20, the cover element 22 has according to Fig. 2 preferably a centering pin 84 which can engage in a centering bore 86 of the soldering nozzle 20. It is advantageous if an elastic, and in particular cylindrical, buffer is arranged between the fastening means 72 and the receiving bore 76 and / or between the centering pin 84 and the centering bore 86.

[0038] For wave soldering, the circuit board 14 with the attached components 13 and the components to be soldered 12 is attached to the hold-down device 32 and positioned. The solder pot 16 with the soldering nozzle 20 moves along the z-axis in the soldering direction 42 according to Fig.3 into the cover element 22, in particular into the nozzle chamber 60, thus forming the nozzle system 18. The nozzle system 18 is moved further along the z-axis towards the circuit board 14, so that the solder pins 28 to be soldered are in the engagement area of ​​the solder wave 30, the components 13 are arranged in the pockets 64, and the walls 66 are essentially positioned between the solder, in particular the flowing solder, and the components 13. Thus, the components 12 can be soldered to the circuit board 14, with the components 13 being protected by the cover element 22.

Claims

[1] Nozzle system (18) for a soldering system (10), in particular for a selective soldering system, for soldering components (12) on a printed circuit board (14), wherein components (13) are present on the printed circuit board (14), the nozzle system (18) comprising: - a soldering nozzle (20) with at least one nozzle opening (48) for forming at least one soldering wave (50) running along a soldering direction (42), and - a cover element (22) with at least one cover opening (62) through which the soldering wave (50) emerges, and with at least one wall (66) which covers the solder flowing out of the soldering wave (50), wherein the cover element (22) has at least one pocket (64) for receiving the components (13). [2] Nozzle system (18) according to claim 1, wherein the cover element (22) has a base housing (52), wherein the at least one pocket (64) is provided on the component side of the base housing (52) and / or a nozzle chamber (60) is provided on the nozzle side for receiving the soldering nozzle (20). [3] Nozzle system (18) according to claim 2, wherein the soldering nozzle (20) can be inserted into the nozzle chamber (60) along the soldering direction (42). [4] Nozzle system (18) according to claim 2 or 3, wherein the components (13) can be inserted into the at least one pocket (64) counter to the soldering direction (42). [5] Nozzle system (18) according to one of the preceding claims, wherein the nozzle opening (48) and the cover opening (62) are formed at least substantially coaxially along the soldering direction (42). [6] Nozzle system (18) according to one of the preceding claims, wherein the soldering nozzle (20) and the cover element (22) are formed in one piece or are irreversibly connected. [7] Nozzle system (18) according to one of claims 1 to 5, wherein the soldering nozzle (20) and the cover element (22) are formed in two parts, and wherein the soldering nozzle (20) can be inserted into the cover element (22) along the soldering direction (42) and / or can be detachably removed from the cover element (22) counter to the soldering direction (42). [8] Nozzle system (18) according to one of the preceding claims, wherein a solder drainage channel (68) is provided between the soldering nozzle (20) and the cover element (22) for draining away the solder flowing out of the soldering wave (50). [9] Nozzle system (18) according to one of the preceding claims, wherein, in order to compensate for tolerances on the circuit board (14) and / or the components (13), the cover element (22) is mounted in a floating manner in or on a solder mask (24). [10] Cover element (22) for a nozzle system (18), in particular according to one of the preceding claims, the cover element (22) comprising: - at least one cover opening (62) through which a soldering wave (50) can emerge, - at least one wall (66) which covers the solder flowing out of the soldering wave (50), and - at least one pocket (64) for receiving components (13) provided on a printed circuit board (14). [11] Soldering system (10), in particular a selective soldering system, with a soldering pot (16) which can be displaced along a z-axis running parallel to the soldering direction (42), with a nozzle system (18) according to one of claims 1 to 9, wherein the soldering nozzle (20) is arranged on the soldering pot (16), and wherein the soldering pot (16) is displaceable such that the soldering nozzle (20) can be inserted into the cover element (22). [12] Soldering system (10) according to claim 11, wherein the cover element (22) is displaceable parallel to the z-axis such that a component (13) of the printed circuit board (14) can be received in at least one pocket (64) of the cover element (22). [13] Method for selective wave soldering of components (12) on a printed circuit board (14), wherein components (13) are provided on the printed circuit board (14), comprising the following steps: a) arranging a soldering nozzle (20) in a nozzle chamber (60) of a cover element (22) to form a nozzle system (18), b) arranging the nozzle system (18) on the circuit board (14), wherein the components (13) are received in pockets (64) of the cover element (22), and c) forming a soldering wave (50) for soldering the component (12), wherein the soldering wave (50) protrudes from a nozzle opening (48) of the soldering nozzle (20) and from a cover opening (62) of the cover element (22). [14] A method according to claim 13, comprising the further step of: d) flowing out of the soldering wave (50) into a solder flow channel (68) formed by the soldering nozzle (20) and by at least one wall (66) of the cover element (22), so that the components (13) are protected from the flowing out solder.

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