SOLDERING TOOL FOR INDUCTIVE SOLDERING

Abstract

A soldering tool for inductive soldering, includes an induction loop and an induction generator that is electrically conductively connected to the induction loop, wherein the induction loop consists of a metal profiled element, has at least one U-shaped region or two U-shaped regions, and each U-shaped region has in each case two legs and an end region connecting the legs, the at least one U-shaped region has a length L of at least 3 mm to 500 mm and a width B of 2 mm to 30 mm.

Claims

1. Soldering tool for inductive soldering, comprising an induction loop and an induction generator that is electrically conductively connected to the induction loop, wherein the induction loop consists of a metal profiled element, has at least one U-shaped region or two U-shaped regions, and each U-shaped region has in each case two legs and an end region connecting the legs, the at least one U-shaped region has a length L of at least 3 mm.

2. The soldering tool according to claim 1, wherein the end region is rounded.

3. The soldering tool according to claim 1, wherein the end region has a first arcuate section, a rectilinear section, and a second arcuate section.

4. The soldering tool according to claim 1, wherein the induction loop has no soft magnetic material in its active area.

5. The soldering tool according to claim 1, wherein the induction loop contains or is substantially made of copper or silver-plated copper, aluminum, or metallic sintered materials.

6. The soldering tool according to claim 1, wherein the induction loop has, at least in sections, a non-magnetic enclosure.

7. The soldering tool according to claim 1, wherein the induction loop is a hollow profiled element.

8. Device for inductive soldering of at least one contact element to at least one conductor structure on a nonmetallic plate, comprising means for fastening a plate during the soldering operation, at least one soldering tool (13) according to claim 1 having at least one induction loop suitable for radiating a magnetic field, means for mutually positioning the soldering tool and a contact element such that the switched-on magnetic field of the soldering tool heats the contact element and thus the solder joint.

9. The device according to claim 8, wherein the induction loop is arranged such that, in the end region, the induction loop has a minimum distance from the contact element.

10. The device according to claim 8, wherein the soldering tool or the contact element is equipped with an electrically insulating intermediate layer for applying the induction loop on the contact element.

11. The device according to claim 8, wherein the device includes at least one counterholder for pressing the contact element onto the plate.

12. The device according to claim 11, wherein the counterholder and, optionally, the gripping tool have no components for directing and guiding the field lines of the magnetic field.

13. Method for inductively soldering at least one ferromagnetic contact element to at least one conductor structure on a nonmetallic plate, the method comprising: providing a nonmetallic plate having at least one conductor structure arranged thereon and at least one first solder connection surface, providing at least one contact element made of a ferromagnetic stainless steel and having at least one second solder connection surface, arranging at least one solder deposit, at least in sections, on the first solder connection surface or the second solder connection surface or on both, arranging the second solder connection surface on the first solder connection surface, wherein the solder deposit is arranged, at least in sections, between the first solder connection surface and the second solder connection surface, radiating a magnetic field with a predefined frequency by a soldering tool according to claim 1 including an electrically supplied induction loop into the contact element, in order to heat it by induction and to melt the solder deposit positioned thereon.

14. The method according to claim 13, wherein the end region of the induction loop is applied to the contact element directly or via an electrically insulating intermediate layer or with a narrow air gap.

15. The method according to claim 13, wherein a first solder connection surface of the conductor structure on the plate or a second solder connection surface of the contact element or both are provided with a lead-containing or lead-free solder deposit.

16. The soldering tool according to claim 1, wherein the length L is from 3 mm to 500 mm, and the width B is from 4 mm to 25 mm.

17. The soldering tool according to claim 2, wherein the end region is semicircular with a radius R of 2 mm to 20 mm.

18. The soldering tool according to claim 3, wherein the first arcuate section and the second arcuate section have a curvature angle R1 of 0.5 mm to 5 mm.

19. The soldering tool according to claim 6, wherein the non-magnetic enclosure is a non-soft-magnetic enclosure made of a thermally resistant plastic or a ceramic.

20. The soldering tool according to claim 1, wherein the induction loop has at least two tube connections that are connected to a hollow space arranged in the interior of the induction loop.

Description

[0107] They depict, schematically and not to scale:

[0108] FIG. 1 a schematic representation of a device according to the invention with a soldering tool according to the invention and an enlarged detail of a solder joint according to the invention,

[0109] FIG. 2 a view of a pane with contact elements according to the invention,

[0110] FIG. 3A a detailed representation of the exemplary induction loop 13I of FIG. 1 in plan view,

[0111] FIG. 3B a detailed representation of the exemplary induction loop 13I of FIG. 3A in a side view from the left,

[0112] FIG. 3C a cross-sectional representation along the section plane spanned by the section line X-X′ of FIG. 3A and the section line Y-Y′ of FIG. 3B,

[0113] FIG. 4 a cross-sectional representation of an alternative induction loop made of a hollow profiled element with a rectangular cross-section,

[0114] FIG. 5 a perspective representation of an induction loop according to the invention having an exemplary contact element in the form of a bridge,

[0115] FIG. 6A a detailed representation of another exemplary embodiment of an induction loop according to the invention with a U-shaped region rotated by 90° in plan view,

[0116] FIG. 6B a detailed representation of the induction loop of FIG. 6A in a side view from the left,

[0117] FIG. 7 a detailed representation of another exemplary embodiment of an induction loop according to the invention with a straight reversal region,

[0118] FIG. 8 a detailed representation of another exemplary embodiment of a double-U-shaped induction loop according to the invention, and

[0119] FIG. 9 a perspective representation of an induction loop according to the invention having a rotated double-U-shape and an exemplary contact element in the form of a bridge.

[0120] FIG. 1 depicts a schematic representation of a device 100 according to the invention having a soldering tool 13 according to the invention during the soldering of a contact element 14 to a conductor structure 3. FIG. 1 depicts a detail of the pane 1 shown in FIG. 2 based on a cross-sectional representation along the dotted line in the region Z.

[0121] FIG. 2 depicts a trapezoidal pane 1 made of glass or plastic, whose upper surface in the viewing direction is provided along its edge with an opaque and, for example, black, electrically nonconductive coating (not shown here, for the sake of simplicity). This is, for example, a rear wall pane of a motor vehicle, shown here simplified without curvature. On its surface, electrical conductor tracks or structures 3, for example, heating conductors 5 and antenna conductors 5′ are also provided, which extend over the field of vision of the pane and/or at the edge all the way to the opaque coating. Busbars 4 are provided along the left and right edge of the pane 1. Also, multiple first solder connection surfaces 6 are provided for the electrical contacting of the conductor structures 3 via the busbars 4, which will be discussed in more detail later. Here, a simplified identical mirror-image configuration of busbars and first solder connection surfaces 6 is indicated. However, in reality, the configurations of the busbars and solder connection surfaces can be different depending on the side of the pane. The first solder connection surfaces 6 can also be arranged on the long sides of the pane shape depicted here.

[0122] The layout of the heating conductors 5 and antenna conductors 5′ in the central field of vision of the pane 1 is shown in simplified form only and absolutely does not restrict the invention. It is, in any case, irrelevant for the present description because this is intended only to discuss the establishing of the electrical connections (at the edges, in this case) of the conductor structures 3 by soldering with inductive heat generation.

[0123] The conductor structures 3, the busbars 4, and the first solder connection surfaces 6 are usually produced by printing an electrically conductive printing paste in thick-film technology and subsequent firing. The firing on glass panes is preferably done during the heating of the glass pane during bending. The printing is advantageously done by screen printing. The electrically conductive printing paste is advantageously silver-containing.

[0124] The pane 1 is inserted into the device 100 that includes, among other things, the soldering tool 13 and means 11 for placing the pane 1 and, optionally, further stops and positioning aids. Here, the support means 11 are, for example, positioned behind/under the pane 1 in the viewing direction; and the soldering tool 13, in front of/above the pane 1. It can, in particular, be seen that the soldering tool 13, which is fixed in the device, is arranged above the first solder connection surface 6 in the vertical projection onto the pane surface.

[0125] Also, contact elements 14 are shown. The contact elements 14 have in each case a second solder connection surface 7. This is arranged in the vertical projection onto the pane surface above the first solder connection surface 6. A solder deposit 9 is arranged between the first solder connection surface 6 of the conductor structure 3 of the pane 1 and the second solder connection surface 7 of the contact element 14. After soldering, the solder connection is created between the first solder connection surface 6 and the second solder connection surface 7. Function-appropriate electrical supply lines 19, such as supply lines or connection lines or antenna cables, are connected to the contact elements 14, for example, by crimping, spot welding, screwing, or other connection techniques.

[0126] The contact elements 14 contain, for example, a ferromagnetic stainless steel and are substantially made of this material. In other words, the contact element 14 contains at least a core of the ferromagnetic stainless steel. The contact element 14 can, for example, additionally have a sheathing on the surface facing away from the second solder connection point 7, preferably made of a suitable (electrically insulating) plastic. In addition, the contact element 14 can also have, on the surface of the core, thin layers of other metals, not necessarily ferromagnetic, for example, for improved corrosion protection. The special role of the ferromagnetic property of the contact element 14 is discussed further below.

[0127] The solder deposit 9 consists of a thin layer of a lead-containing or lead-free solder, optionally with integrated or subsequently applied flux. It can, optionally, suffice to apply a solder deposit 9 on only one of the two surfaces to be soldered in each case, i.e., either on the first solder connection surface 6 or the second solder connection surface 7, if it is ensured that the energy inputted can heat all components sufficiently for good soldering on both sides and the non-tinned surface can be wetted by solder.

[0128] The contact element 14, the solder deposit 9, the conductor structure 3, and the pane 1 are depicted here only schematically. This means, in particular, that the thicknesses shown are not to scale.

[0129] Here, for example, the contact element 14 is pressed onto the pane 1 by one or a plurality of counterholders 18 and positioned. The counterholders 18 can, for example, and also advantageously, be remotely controlled gripping and positioning tools in an automated production line. They remove the initially loosely movable contact elements 14 from the respective supply magazines, position them on the associated first solder connection surfaces 6, and hold them fixedly during the soldering operation until the solder solidifies.

[0130] As shown in FIG. 1, the soldering tool 13 according to the invention is arranged directly above the contact element 14 and, in particular, above the second solder connection surface 7 and the solder deposit 9.

[0131] Here, the soldering tool 13 contains an induction loop 13I that is supplied with an alternating voltage with adjustable frequency and power by a commercial induction generator 13G. Furthermore, a switch 13S, with which the operation of the induction loop 13I can be controlled, is indicated symbolically in the connection between the induction generator 13G and the induction loop 13I. Finally, the soldering tool 13 can, if need be, be cooled via tube connections 13C. In deviation from the schematic representation, the supplying of coolant and the electrical supply line are, optionally, combined. For example, the induction loop 13I can consist of a metal profiled element in the form of a metal or metallic hollow profiled element with, for example, a circular cross-section through which the coolant flows and which acts at the same time as a high-frequency induction loop. The hollow profiled element can, for example, be made of silver-plated copper.

[0132] Compared to prior art high-frequency induction loops or coils, the soldering tool 13 used here contains a hollow profiled loop whose dimensions correspond substantially to the length and width of the soldering tool. The filling of the intermediate spaces in a manner known per se using bodies made of ferrite or other similarly suitable materials is unnecessary. Such ferrite-free soldering tools 13 can be used in particular in combination with ferromagnetic contact elements 14 in a particularly simple, flexible, and energy-saving manner.

[0133] As a result of the arrangement of the soldering tool 13 directly above the ferromagnetic material of the contact element 14, the magnetic field radiated by the induction field is concentrated in or through the contact element 14 and optimized such that it is directed and acts as intensively and concentrated as possible on the solder joints 2. It is thus less important to achieve high homogeneity over large areas than to direct the magnetic field into the specially designed contact element 14. The heating of the contact element 14 results, via the second solder connection surface 7, in a quick and intense heating of the solder deposit 9 and the adjacent first solder connection points 6.

[0134] The soldering tool 13 requires no special elements, such as ferrite elements or functionally identical components for shaping and guiding the field lines, as is the case in prior art induction soldering tools. Even the counterholders 18 and other possible components in the vicinity of the soldering tool 13 contain no ferrites or ferromagnetic materials or the like. The concentration of the magnetic field on the solder joint 2 is done only via the ferromagnetic contact element 14. This is particularly efficient and energy-saving. At the same time, the soldering tool 13 is particularly flexibly suitable for a variety of connection configurations and does not have to be adapted to the respective contact element 14 as is required in the prior art.

[0135] In order to achieve consistently high soldering quality, it is advantageous to keep the distance between the soldering tool 13 and the contact element 14 as nearly the same as possible for each pane. Here, according to the invention, a very narrow, well-defined air gap 17 of, for example, 0.5 mm is provided between the soldering tool 13 and the contact element 14. Such an air gap 17 reliably avoids contact and electrical short circuits completely.

[0136] Alternatively, the induction loop 13I of the soldering tool can have an enclosure with which the contact element 14 can be pressed onto the plate and positioned (not shown here). The enclosure is made, for example, of a thermally stable plastic or a ceramic and is in particular not soft magnetic.

[0137] Alternatively, the contact element 14 can also have an electrically insulating intermediate layer or enclosure on its surface facing the soldering tool 13, made, for example, of a thermally resistant plastic or a ceramic.

[0138] The compact soldering tool 13 according to the invention can be implemented to be movable without problems and, for example, can, using robots, be placed with reproducible positions on a pane to be processed. This will be preferred, for example, if no large numbers of always consistent panes are to be processed, or if frequent model changes are to be processed on the same device.

[0139] Of course, the soldering tool 13 can also be arranged in a fixed position/stationary in the device 100. The respective pane 1 to be processed is then placed by means of conveyors (not shown) on the support means 11 and moved to the soldering tool 13 with interposition of the contact element 14.

[0140] To establish the solder connections, the induction loop 13I is supplied with current of the desired frequency (for example, 900 kHz) by switching on its power supply (closing the switch 13S). A typical power in the range from 0.2 kW to 15 kW is set, which can be varied depending on the distance from the loop, (total) area of the solder joints, and the masses to be heated. The magnetic field penetrates the air gap 17 or any possible intermediate layers without excessive damping. The less air gaps or intermediate layer material, the less damping.

[0141] Heat that heats the adjacent solder deposit 9 is generated in the metallic and, in particular, ferromagnetic components of the contact element 14.

[0142] A high frequency according to the invention of the induction voltage of, for example, 900 kHz results in a magnetic field with only a small penetration depth. This has the particular advantage that although the contact element 14, the solder deposit 9 positioned on the second solder connection surface 7, and, thus, indirectly, also the first solder connection surface 6 of the conductor structure 3 are reliably heated, the conductor structure 3 in the vicinity of the first solder connection surface 6 is heated only slightly. Thus, damage to the conductor structure 3 and detachment of the conductor structure 3 from the pane 1 are reliably prevented.

[0143] The required ON-time of the magnetic field until the complete melting of the solder deposit 9 and the best frequency range can be determined simply and quite reproducibly by tests and also simulated by suitable software. After the soldering operation, the magnetic field is switched off (opening the switch 13S). The pane 1 is still held in place for a short time, as are the counterholders, until the solder has solidified and the electrical connections are held in place even without additional mechanical fixation. After that, the pane 1 is fed for further processing.

[0144] To optimize the soldering operation and to avoid stresses in the pane 1 and the conductor structure 3, it can be advantageous to preheat the pane 1 together with the conductor structure 3 in the region of the first solder connection point 6 and its vicinity. For this, for example, a heater 20 can be arranged below the pane 1 (i.e., on the side facing away from the soldering tool 13 and the contact element 14).

[0145] FIG. 3A, 3B, and 3C depict in each case detailed representations of the exemplary induction loop 13I of FIG. 1. FIG. 3A depicts a plan view of a region of the induction loop 13I; and FIG. 3B, a side view from the left relative to the plan view of FIG. 3A.

[0146] In this example, the induction loop 13I is semicircular at an end region 13E. The semicircular end region 13E is connected to two parallel legs 13P. The two legs 13P and the end region 13E arranged between them form a U-shaped region 13U.

[0147] The radius of curvature R of the induction loop 13I in the end region 13E is, for example, 3 mm. The radius of curvature R is relative to the center of the hollow profiled element.

[0148] The length L of the induction loop 13I here is, for example, 20 mm; however, it can also be shorter or longer. Here, the length L includes the length of the legs 13P plus the length of the end region 13E. It goes without saying that the hollow profiled element can be longer in the further region and can then be connected via tube connections 13C and, optionally, other connections to the cooling unit (supply region 13Z). The induction loop 13I is made of a metal and thus also serves simultaneously as an electrical conductor which is supplied with the induction signal from the induction generator 13G.

[0149] The width B of the induction loop 13I (relative in each case to the center of the hollow profiled element) equals the distance between the legs 13P and is, for example, 6 mm.

[0150] The U-shaped region 13U is connected to the two tube connections 13C via the two parallel legs 13P, via which a coolant can be fed through the induction loop 13I. For this purpose, the induction loop 13I is made of a continuous hollow profiled element that is closed, apart from the tube connections 13C. For this, the hollow spaces of the legs 13P and of the end region 13E are connected to one another. A coolant can be passed through the interior of one leg 13P into the inner hollow space of the end region 13 and, through this, into the interior of the second leg 13P, thereby cooling the induction loop 13I.

[0151] FIG. 3C depicts a cross-sectional representation along the section plane, which is spanned by the section line X-X′ of FIG. 3A and the section line Y-Y′ of FIG. 3B. The induction loop 13I consists, in this example, of a hollow profiled element with a circular cross-section with an inner diameter Di of 1 mm and an outer diameter Da of 1.8 mm.

[0152] FIG. 4 depicts a cross-sectional representation of an alternative induction loop 13I consisting of a hollow profiled element with a rectangular cross-section. The inner diameter Di1 in the shorter dimension of the rectangular cross-section is, for example, 1 mm; the corresponding outer diameter Da1 is, for example, 1.8 mm. The inner diameter Di2 in the longer dimension of the rectangular cross-section is, for example, 2 mm; the corresponding outer diameter Da2 is, for example, 2.8 mm.

[0153] FIG. 5 depicts a perspective representation of another exemplary embodiment of an induction loop 13I according to the invention with an exemplary contact element 14 in the form of a bridge. The reversal region of the induction loop 13I is arranged above one of the two (second) solder connection surfaces 7 of the contact element 14.

[0154] FIG. 6A and 6B depict a detailed representation of another exemplary embodiment of an induction loop 13I according to the invention with a U-shaped region 13U rotated by 90° relative to the supply region 13Z. FIG. 6A depicts a plan view; and FIG. 6B, a side view from the left.

[0155] FIG. 7 depicts a detailed representation of another exemplary embodiment of an induction loop 13I according to the invention with a straight end region 13E.

[0156] The length L of the U-shaped region is, for example, 20 mm.

[0157] The width B of the induction loop 13I is, for example, 6 mm.

[0158] The end region 13E that connects the legs 13P is substantially rectilinear here. The radius of curvature at the transition between the end region 13E and the legs 13P is limited by the technical possibilities of the bending of the hollow profiled element and is, for example, 0.5 mm.

[0159] FIG. 8 depicts a detailed representation of another exemplary embodiment of an induction loop 13I according to the invention with a double-U-shape. Here, the induction loop 13I has two U-shaped regions 13U. The U-shaped regions 13U have, for example, in each case, a semicircular end region 13E with a radius of curvature R of, for example, 4 mm. The width B of the U-shaped regions 13U is, for example, 8 mm. Here, the two U-shaped regions 13U are, for example, connected to one another by a semicircular connection region 13V. Here, the distance A between the center lines of the U-shaped regions 13U is, for example, 16 mm.

[0160] FIG. 9 depicts a perspective representation of another exemplary embodiment of an induction loop 13I according to the invention with a rotated double-U-shape and an exemplary contact element 14 in the form of a bridge. This induction loop 13I is a further development of the induction loop 13I of FIG. 8. Here again, the induction loop 13I is made from two particularly advantageous U-shaped regions 13U, which, unlike the arrangement in one plane of FIG. 8, are rotated and thus aligned parallel to one another. As a result of this design, two (second) solder connection surfaces 7 of a bridge-shaped contact element 14 with an intermediate structure (in this case, a standard plug connection element) can be heated and soldered simultaneously. Here, the width B is, for example, 6 mm, the length L=20 mm, and the distance A=16 mm.

[0161] It goes without saying that in all exemplary embodiments presented here, the induction loop 13I can also be made of a solid metal profile, in particular if the induction voltage is applied for only a short time or pulsed and, consequently, cooling can be dispensed with.

[0162] It further goes without saying that all induction loops 13I depicted here by way of example can have metal profiled elements and in particular hollow profiled elements with any cross-section, for example, circular, oval, rectangular, square, or triangular cross-sections.

[0163] It further goes without saying that all induction loops 13I according to the invention depicted here can be adapted in their dimensions, such as length L, width B, and radius of curvature R, and in their shapes to the conditions of the individual case. The U-shape or the double-U-shape with the dimensions according to the invention is particularly universal and can be used for a large variety of connection elements.

REFERENCE CHARACTERS

[0164] 1 plate/pane

[0165] 2 solder joint

[0166] 3 conductor structure

[0167] 4 busbar

[0168] 5 heating conductor,

[0169] 5′ antenna conductor

[0170] 6 first solder connection surface

[0171] 7 second solder connection surface

[0172] 9 solder deposit

[0173] 11 support means

[0174] 13 soldering tool

[0175] 13C tube connections

[0176] 13E end region, reversal region

[0177] 13G induction generator

[0178] 13I induction loop

[0179] 13P leg

[0180] 13S switch

[0181] 13U U-shaped region

[0182] 13V connection region

[0183] 13Z supply region

[0184] 14 contact element

[0185] 17 air gap

[0186] 18 counterholder

[0187] 19 electrical supply line

[0188] 20 heater

[0189] 100 device

[0190] A distance

[0191] B width

[0192] L length

[0193] Di, Di1, Di2 inner diameter

[0194] Da, Da1, Da2 outer diameter

[0195] R, R1 radius

[0196] X-X′, Y-Y′ section line

[0197] Z region