Soldering aids for cable-to-circuit board connections, cables, circuit boards, assemblies and methods

Abstract

The invention relates to a soldering aid (100) for the connection of a cable (200) to a circuit board (300), comprising: an electrically insulating main body (190) having a first recess (110), a second recess (120) and a third recess (130); an electrically conductive contact structure (150) which is accommodated in the main body (190) in sections. The contact structure (150) is partially embedded in the main body (190) in order to connect the contact structure to a strand (210) of the cable (200) within the main body (190), and the contact structure is partially protruding from the main body (190) in order to connect the contact structure to a connection portion (310) of the circuit board (300).

Description

TECHNICAL FIELD

[0001] The invention relates to a soldering aid for the connection of a cable to a circuit board. The invention also relates to a cable, a circuit board and an assembly having such a soldering aid. Furthermore, the invention relates to a method for connecting a cable to a circuit board using such a soldering aid. BACKGROUND

[0002] Cables are used to couple electrical or electronic devices in signal technology and / or in energy technology to other devices. To this end, the circuit board with the electrical / electronic components of the device has a connection corresponding thereto, which can be coupled to the cable end in order to enable, for example, the transmission of electrical current and / or control signals and / or communication signals between the device and the device via the cable.

[0003] Various possibilities of forming an electrical connection by means of solder are known from the prior art.

[0004] DE 102008013226 A1 describes a soldering connection of a surface mounted device (SMD) to a solder paste via a contact surface, which is arranged in a recess of a circuit board. The circuit board must be correspondingly prepared at this point and provided with a recess.

[0005] US 5021630 describes the fixing of an electronic component on a substrate by means of a glass plate, which is heated under radiation by means of a laser in order to melt the solder.

[0006] EP 3477798 A1 describes a device for fixing a first strand of a cable in a housing by means of a pressing device, which pre-fixes the first strand of cable, whereby a second strand of cable can likewise be fixed in the housing.

[0007] DE 10046489 C1 describes an electrical conductor on a carrier film, which can be fixed on a contact surface by means of a connecting element by means of solder, wherein the additional piece comprises a solder reservoir and is configured as a crimping piece. The melting of the solder reservoir can be achieved by means of a laser by means of heat supply. SUMMARY

[0008] It is an object of the invention to simplify the formation of a solder joint between a strand of a cable and a connection of a circuit board.

[0009] According to a first aspect, a soldering aid for connecting a cable with a circuit board comprises an electrically insulating main body having a first recess, a second recess and a third recess, and an electrically conductive contact structure segmentedly accommodated in the main body, wherein the contact structure is segmentedly embedded into the electrically insulating main body so that the contact structure is connected with a strand of the cable within the main body, and the contact structure is segmentedly protruding from the main body so that the contact structure is connected with a connection portion of the circuit board. The first recess is configured for accommodating an end portion of the cable and has a first segment for an unstripped portion of the end portion of the cable and a second segment for a stripped portion of the end portion of the cable, wherein the stripped portion of the end portion of the cable comprises the strand, and the contact structure is adjacent to the second segment. The first recess is particularly preferably configured tapered, in particular conically tapered, so as to have a diameter which is reduced towards the second recess. The second recess is configured spatially offset with respect to the first recess and with an end portion of the second recess adjacent to the second segment of the first recess for enabling optical monitoring of the formation of the connection between the strand and the contact structure. The third recess is configured spatially offset with respect to the first recess and with respect to the second recess and with an end portion of the third recess adjacent to the second segment of the first recess, wherein the third recess is configured for accommodating and forwarding solder into the second segment of the first recess for forming the connection between the strand and the contact structure there.

[0010] According to a second aspect, a cable has a soldering aid according to the first aspect attached to an end portion of the cable.

[0011] According to a third aspect, a circuit board has a soldering aid according to the first aspect attached to a connection portion of the circuit board.

[0012] According to a fourth aspect, an assembly comprises a cable and a circuit board, wherein the cable and the circuit board are connected with each other by means of a soldering aid according to the first aspect.

[0013] According to a fifth aspect, a method for connecting a circuit board with a cable comprises forming an electrically conductive connection between a strand of the cable and a connection portion of the circuit board using a soldering aid according to the first aspect.

[0014] Some embodiments of the soldering aid are described in the following. The description applies analogously to the cable, the circuit board, the assembly and the method.

[0015] The main body of the soldering aid has for example an upper side, a lower side and an end side. The contact structure protrudes from the main body at the lower side for connecting with a connection portion, for example a pad, of the circuit board. The connection is generated for example by a soldering process, for example in the context of a so-called reflow soldering process.

[0016] The first recess is for example configured at the end side of the main body and extends into the main body parallel to the lower side of the main body.

[0017] The second and third recesses are for example configured at the upper side of the main body and extend into the main body offset to each other and perpendicular to the lower side of the main body.

[0018] The three recesses are for example formed by drilling and have a respective cylindrical shape.

[0019] According to one embodiment, the second and third recesses extend parallel to each other, for example from the upper side of the main body towards the lower side of the main body. Here, the second and third recesses are for example arranged offset to each other in the direction of extension of the first recess. The space between the second and third recesses is filled by the material of the main body.

[0020] The second and third recesses open into the second section of the first recess. The contact structure also adjoins this second section, for example by means of the contact structure protruding into the second section of the first recess to a small extent. In any case, the contact structure adjoins the second section of the first recess to enable the soldering aid to be in electrically conductive contact with the contact structure in the second section of the first recess.

[0021] According to one embodiment, the contact structure is configured as a profiled part, for example designed with a U-shaped or L-shaped cross-sectional profile, if necessary also with a Z-shaped or stepped cross-sectional profile, and the contact structure protrudes from the main body with a first leg to enable the first leg to be connected to the connection of the circuit board. Here, the contact structure adjoins the second section of the first recess with a second leg of the profiled part to enable the second leg of the profiled part to be electrically conductively connected to the strands of the cable by means of the soldering material located in the second section of the first recess.

[0022] According to one embodiment, the second section of the first recess has a smaller cross section than the first section, and a step corresponding to the difference in cross section is provided at the transition between the first section and the second section of the first recess. The positions and dimensions of the three recesses are determined such that, when the strands of the stripped part of the cable end adjoin both the end of the second recess and the end of the third recess in the second section of the first recess, the jacket of the unstripped part of the cable end adjoins the step.

[0023] The main body of the welding auxiliary component is made of an electrically insulating material. To withstand the welding process, the main body material is also preferably high-temperature resistant, such as a thermosetting plastic. In one embodiment, the first notch for receiving the cable end has a fastener, such as a clamping mechanism, which secures the cable end there after it is inserted into the first notch. To form the clamping mechanism, the first notch is configured to taper, particularly a tapered taper. To form the tapered taper, the diameter of the first notch decreases towards the direction of the second or third notch. Here, the fastener, particularly the tapered taper extension of the first notch, secures the unstripped portion of the cable end in the first section, for example, by clamping, engaging, locking, or otherwise securing the sheath of the cable end in the first section.

[0024] Conductive contact structures, for example, are made of bronze and can be constructed as monoliths.

[0025] Cables also include those used to transmit current or control or communication signals. Stranded wires are constructed and sized according to specific requirements. Welding aids, in particular, are permitted to have very small diameters (e.g., less than about 0.35 mm). 2 (The cross-sectional area of ​​the stranded wire)

[0026] The connections on a circuit board are formed, for example, by solder pads or the like. The concept of a circuit board is interpreted broadly here, thus encompassing the carrier of all electrical / electronic components, at least one of which is connected to a connection via a conductive coupling. This coupling can, for example, include integrated or laminated rails.

[0027] According to one embodiment, an arrangement having three notches extending into the body and contact structures is implemented in various ways in the body of the soldering aid to enable multiple strands (of different sizes) of one or more cables to be connected to the circuit board. For example, via the soldering aid, one or more data lines and one or more power lines of a single cable are connected to the corresponding connection portion of the circuit board.

[0028] By making the second and third gaps adjacent to the second section of the first gap at their ends, the stranded wire exposed by the stripped portion of the cable end in the second section of the first gap can be touched or seen through the second and third gaps.

[0029] The third notch is prepared with solder and thus forms, for example, a solder reservoir, into which the tip of the solder electrode can also extend. By inputting heat, the solder can be liquefied and thus connected to the contact structure in the second section of the first notch.

[0030] The input of heat is achieved, for example, by means of laser irradiation, wherein a laser beam is directed, for example, through the second gap in order to generate heat locally in the second section of the first gap as far as possible. The second gap thus allows optical monitoring in terms of time before the soldering process, in particular in terms of time before the heating of the solder. Whether the cable end with the stranded wire is positioned exactly in the first gap is monitored optically before the soldering process or in order to implement the soldering process. The second gap also enables the targeted coupling of the input of heat during the soldering process or in order to implement the soldering process, and the formation of the connection is monitored after the soldering process.

[0031] Instead of or in addition to the optical monitoring, the exact positioning of the stranded wire is optionally monitored using a pressure sensor, which detects, for example, the collision of the cable jacket at the step of the first gap during the introduction of the cable into the first gap.

[0032] According to one embodiment of the method, all the steps described above with regard to the formation of the soldered connection between the stranded wire and the contact structure and between the contact structure and the circuit board connection are carried out automatically by means of corresponding process automation.

[0033] According to one preferred embodiment of the method according to the application, in order to connect the circuit board with the cable, the soldered connection between the stranded wire and the contact structure is first generated within the body of the soldering aid, for example by means of an automated assembly device according to the previous positioning of the soldering aid in the context of a reflow soldering process at the connection of the circuit board provided with solder paste for pre-fixing (for example by "pick and place") and the connection between the contact structure and the circuit board connection is subsequently generated. In this way, the cable can be pre-assembled using the soldering aid and stored as an intermediate product, which is quickly and cost-effectively connected with the circuit board when required. The connection of the cable with the soldering aid can in particular be carried out in parallel with the process technology and less staggered in time with the fixing of the soldering aid on the circuit board. In an alternative embodiment, the connections are formed in reverse order, i.e. the soldering between the contact structure and the circuit board connection is first generated and the connection of the cable with the soldering aid is subsequently formed. In this alternative embodiment, it can be avoided that the soldered connection between the stranded wire and the contact structure within the body has to withstand any properties of the process (for example reflow soldering) for connecting the contact structure with the circuit board connection. Irrespective of the order of the process steps, it is in particular proposed to use a soldering aid having the features of claim 1.

[0034] Thus, the soldering aid described herein can advantageously fulfill multiple functions, such as the input of the wire, the fixation of the wire, the provision of solder for the connection between the wire and the contact structure in the body, and the optical inspection of the wire and the resulting connection. Thus, for example, an advantageous "wire-to-board" soldering aid is provided with which a durable, inseparable connection between a cable and a circuit board can be achieved.

[0035] Within the scope of the present application, known metal alloys can be used as soldering material. Alternatively, also electrically conductive adhesive materials can be used. BRIEF DESCRIPTION OF DRAWINGS

[0036] Further details and advantages of the present application are elucidated in the following description of multiple embodiments according to the drawings.

[0037] The accompanying drawings show:

[0038] Figure 1 A part of a cross-sectional view of an assembly with a soldering aid according to a first embodiment is shown exemplarily and schematically; and

[0039] Figure 2 A part of a cross-sectional view of an assembly with a soldering aid according to a second embodiment is shown exemplarily and schematically. DETAILED DESCRIPTION

[0040] Figure 1 An assembly with a circuit board 300 and a cable 200 is shown exemplarily and schematically. The wire 210 of the cable 200 is electrically conductively connected with a connection portion 310 of the circuit board 300.

[0041] A soldering aid 100 is provided for connecting the cable 200 with the circuit board 300.

[0042] The soldering aid 100 comprises an electrically insulating body 190 with a first recess 110, a second recess 120 and a third recess 130, and an electrically conductive contact structure 150.

[0043] The recesses 110, 120 and 130 are configured as bores, in particular blind bores.

[0044] The contact structure 150 is configured to be injection-molded by the body 190, for example, and is made of bronze or another material with good electrical conductivity, for example. The contact structure 150 is configured in both described embodiments as one piece.

[0045] The body 190 is made of a high-temperature-resistant material, such as a thermosetting plastic or another plastic.

[0046] The contact structure 150 is accommodated in the body 190 in sections, in particular inseparably connected by sectional injection-moulding encapsulation or sectional pouring of the material of the body 190, in order to be connected to the strands 210 of the cable 200 within the body 190. It is further proposed that the contact structure 150 projects in sections from the body 190, in order to be connected, in particular electrically conductively, to the connection portion 310 of the circuit board 300. Both connections, i.e. the connection of the strands 210 of the cable 200 to the contact structure 150 and the connection of the contact structure 150 to the connection portion 310 of the circuit board, can be realized by a soldering process, as will be described further below.

[0047] The first recess 110 accommodates the end of the cable 200 and has a first section 111 for the unstripped portion of the cable end and a second section 112 for the stripped portion of the cable end.

[0048] The stripped portion of the cable end points to the strands 210 of the cable 200, which are exposed by stripping of the insulation, wherein the strands 210 are accommodated in the second section 112 of the first recess 110. The contact structure 150 adjoins the second section 112, so that the soldering material obtained in the second section 112 is in electrically conductive contact with the contact structure 150.

[0049] The second recess 120 is configured to be spatially offset with respect to the first recess 110 and to adjoin the second section 112 of the first recess 110 with its end, in order to realize an optical monitoring of the formation of the connection between the strands 210 and the contact structure 150. Between the second recess 120, which is configured as a blind hole, and the third recess 130, which is likewise configured as a blind hole, a section 190a of the body 190 is left, which keeps the two recesses 120 and 130 at a distance. The material thickness of the body 190 is not reduced in the region of this section. The section 190a prevents a crossover of the scattered beam from one recess into the other. The two recesses 120, 130, which are each configured as a blind hole, terminate in or open into the first recess 110, which is also configured as a blind hole.

[0050] The third recess 130 is configured to be spatially offset with respect to the first recess 110 and the second recess 120 and to adjoin the second section 112 of the first recess 110 with its end, wherein the third recess is configured for accommodating solder 500 and forwarding it into the second section 112 of the first recess 110, in order to form a connection between the strands 210 and the contact structure 150 there.

[0051] The main body 190 of the soldering aid 100 has an upper side 191, a lower side 192 and an end side 193. The contact structure 150 projects from the main body 190 at the lower side 192 of the main body to be connected there to the connection portion 310 of the circuit board 300.

[0052] The first recess 110 is configured at the end side 193 of the main body and extends into the main body 190 parallel to the lower side 192 of the main body.

[0053] The second recess 120 and the third recess 130 are configured at the upper side 191 of the main body and extend into the main body 190 offset from one another and perpendicular to the lower side 192 of the main body.

[0054] The three recesses 110, 120 and 130 are configured as bores, for example, and have a substantially cylindrical profile shape and a substantially circular cross-sectional profile, respectively. The bores are configured as blind bores, respectively, or blind holes, wherein the hole walls completely surround the first recess and the second recess, respectively. An end of the second recess 120 or an end of the third recess 130 opens into a side wall of the first recess 110, so that the second recess 120 or the third recess 130 transitions into the first recess 110 in the region of the second portion 112. The transition from the second recess 120 into the first recess 110 is configured for enabling an optical control beam, for example a laser beam oriented along the axis of the second recess 120, to detect the stranded wire 210 accommodated in the first recess 110. The transition from the third recess 130 into the first recess 110 is also configured for enabling the solder 500 liquefied in the solder reservoir accommodated in the third recess 130 to enter into the first recess 110 in order to wet the stranded wire 210 in the first recess 110.

[0055] The second recess 120 and the third recess 130 are substantially parallel to one another and face from the upper side 191 of the main body toward the lower side 192 of the main body in the described embodiment. Here, the second recess 120 and the third recess 130 are arranged offset from one another and spaced apart from one another in the extension direction of the first recess 110 and are separated by a portion 190a of the main body 190. The remaining material of the main body 190 between the second recess 120 and the third recess 130 forms the portion 190a, which spatially separates the second recess 120 and the third recess 130 from one another so that the solder reservoir and the control beam provided for the measurement of the stranded wire 210 are spatially separated.

[0056] The second recess 120 and the third recess 130 open into the second section 112 of the first recess 110, that is to say, the second recess 120 and the third recess 130 transition into the second section 112 of the first recess 110, respectively. The contact structure 150 also adjoins this second section 112, such that the contact structure 150 bounds and encloses the second section 112 of the first recess 110 toward the lower side 192 of the main body 190. It can be proposed in particular that the contact structure 150 projects slightly into the second section 112 of the first recess 110.

[0057] By opening and transitioning the second recess 120 and the third recess 130 with their ends into the second section 112 of the first recess 110, the strands 210 of the cable, which are exposed by stripping the cable end, can be touched or optically seen in the second section 112 of the first recess 110 via the second recess 120 and the third recess 130.

[0058] The contact structure 150 is configured in the shape of a profile, for example in the shape of a U, as shown in Figure 2 or in the shape of an L, as shown in Figure 1 .

[0059] The contact structure 150 projects with a first arm 151 from the main body 190 and is connected to the connection portion 310 of the circuit board 300. The contact structure 150 adjoins the second section 112 of the first recess 110 with a second arm 152 and is connected there to the strands 210 of the cable 200.

[0060] In the embodiment according to Figure 1 , the second arm 152 is formed by a section of the L-shaped contact structure 150, and in the embodiment according to Figure 2 , the second arm 152 is formed by a section of the contact structure 150, which is here U-shaped, and is connected to the first arm 151 via a web 153.

[0061] In both embodiments, the second section 112 of the first recess 110 has a smaller cross section than the first section 111, and a step 113 corresponding to the difference in cross section is provided at the transition between the first section 111 and the second section 112 of the first recess 110. The positions and dimensions of the three recesses 110, 120 and 130 are determined such that, when the strands 210 of the stripped portion of the cable end adjoin both the end of the second recess 120 and the end of the third recess 130 in the second section 112 of the first recess 110, the sheath 220 of the unstripped portion of the cable end adjoins the step 113, as shown.

[0062] The first recess 110 also has a clamping device 115 (only schematically shown) for accommodating the cable end, which, after insertion into the first recess 110, fixes the sheath 220 of the cable end in the first section 111.

[0063] The connection 310 of the circuit board 300 is formed by a solder pad.

[0064] In the following, an exemplary method is set forth, which enables the connection of the strand 210 to the connection 310 (solder pad).

[0065] First, the cable 200 is inserted into the first recess 110. The exact positioning of the cable 200 is optically monitored. For the optical monitoring of the positioning, either the second recess 120 and the third recess 130 or only one of the recesses 120, 130 can be used.

[0066] After corresponding filling of the solder 500 (e.g. so-called solder preform), the third recess 130 is ready and thus forms, for example, a solder reservoir, into which the end of the soldering rod can also be inserted. The solder reservoir 500 is mechanically fixed, for example, by a clamping device before the introduction of the strand 210, alternatively, for this purpose, a solder reservoir can be provided which is, for example, known as a SMD assembly adhesive. The solder 500 is liquefied by the input of heat, flows to the soldering point and electrically conductively connects the strand 210 to the contact structure 150 in the second section 112 of the first recess 110. The solder 500 can also be increased in quantity depending on the flow, for example, in the second recess 120 by the action of capillary forces. The increase of the solder 500 in the second recess can be detected, for example, optically.

[0067] The input of heat is achieved, for example, by a laser beam, wherein the laser beam (400, see Figure 1 and Figure 2 is directed, for example, through the second recess 120 in order to generate heat in the second section 112 of the first recess 110 as locally as possible. The second recess 120 thus allows the optical monitoring before the soldering process: whether the cable end with the strand 210 is exactly positioned in the first recess 110, during the soldering process or in order to achieve the soldering process, the second recess also enables the targeted input of heat and after the soldering process the detection of the formation of the connection of the solder in the first recess 110 to the strand 210.

[0068] In order to avoid damage to the cable sheath 220 in the first section 111 of the first recess 110 due to the heat rise, it is proposed that the second recess 120 is positioned at a greater distance from the first section 111 of the first recess 110 than the third recess 130, as is shown in Figure 2 Correspondingly, it can be advantageous that the contact area of the elongated contact structure 150 is achieved by a U-shaped profile.

[0069] All steps described above with respect to forming the soldered connection between the stranded wire 210 and the contact structure 150 as well as between the contact structure 150 and the circuit board connection 310 can be automatically performed by corresponding process automation.

[0070] Advantageously, the connection between the contact structure 150 and the circuit board connection 310 is first generated, for example in the context of a reflow soldering process, by an automated assembly device according to the previous positioning of the soldering aid 100 at the connection 310 of the circuit board 300 provided with solder paste for pre-fixing (for example by "pick and place"), and the soldered connection between the stranded wire 210 and the contact structure 150 is subsequently generated within the main body 190 of the soldering aid 100. It is thus avoided that the soldering between the stranded wire 210 and the contact structure 150 within the main body 190 has to withstand the possibly high temperatures during the reflow soldering process for connecting the contact structure 150 with the circuit board connection 310.

Claims

1. A soldering aid (100) for the connection of a cable (200) to a circuit board (300), the soldering aid (100) comprising: an electrically insulating body (190) having a first recess (110), a second recess (120) and a third recess (130); and an electrically conductive contact structure (150) segmentally accommodated in the body (190), wherein the contact structure (150) is segmentally embedded into the body (190) so that the contact structure is connected to a strand (210) of the cable (200) within the body (190), and the contact structure is segmentally protruding from the body (190) so that the contact structure is connected to a connection portion (310) of the circuit board (300); wherein the first recess (110) is configured tapered for accommodating an end portion of the cable (200), and the first recess has a first segment (111) for an unstripped portion of the cable end portion and a second segment (112) for a stripped portion of the cable end portion, wherein the stripped portion of the cable end portion comprises the strand (210), and the contact structure (150) abuts the second segment (112); the second recess (120) is configured spatially offset with respect to the first recess (110) and abuts the second segment (112) of the first recess (110) with an end portion of the second recess for optically monitoring the formation of a connection between the strand (210) and the contact structure (150); and the third recess (130) is configured spatially offset with respect to the first recess (110) and with respect to the second recess (120) and abuts the second segment (112) of the first recess (110) with an end portion of the third recess, wherein the third recess (130) is configured for accommodating and forwarding solder (500) into the second segment (112) of the first recess (110) for forming a connection between the strand (210) and the contact structure (150) at the second segment. The first recess (110) is configured conically tapered for accommodating an end portion of the cable (200).

2. The welding aid (100) according to claim 1, wherein The body (190) has an upper side (191), a lower side (192) and an end side (193), and wherein 3. The welding aid (100) according to claim 1, wherein the contact structure (150) protrudes from the body (190) at the lower side (192) of the body for connecting to the connection portion (310) of the circuit board (300) at the lower side; the first recess (110) is configured at the end side (193) of the body and extends into the body (190) parallel to the lower side (191) of the body. ​ The second notch (120) and the third notch (130) are configured at an upper side (191) of the main body (190) and extend into the main body (190) perpendicular to a lower side (192) of the main body (190) and are staggered with respect to each other.

4. The welding aid (100) according to any one of claims 1 to 3, wherein The second notch (120) and the third notch (130) extend parallel to each other.

5. The welding aid (100) according to any one of claims 1 to 3, wherein The contact structure (150) is configured in a profiled manner and projects from the main body (190) with a first leg (151) and adjoins the second section (112) of the first notch (110) with a second leg (152).

6. The welding aid (100) according to claim 5, wherein The contact structure (150) is configured in a U-shaped or L-shaped or Z-shaped or stepped manner.

7. The soldering aid (100) according to any one of claims 1 to 3, wherein The second section (112) of the first notch (110) has a smaller cross section than the first section (111) and is provided with a step (113) corresponding to the cross section difference at a transition between the first section (111) and the second section (112) of the first notch (110); and The first notch (110), the second notch (120) and the third notch (130) are positioned and dimensioned such that, when the strands (210) of the stripped portion of the cable end abut both an end of the second notch (120) and an end of the third notch (130) in the second section (112) of the first notch (110), a sheath of the unstripped portion of the cable end abuts the step (113).

8. A cable (200) having a soldering aid (100) according to any one of the preceding claims attached to an end of the cable (200).

9. A circuit board (300) having a soldering aid (100) according to any one of claims 1 to 7 attached to a connection (310) of the circuit board (300).

10. An assembly comprising a cable (200) and a circuit board (300), wherein, The cable and the circuit board are connected to each other by means of a soldering aid (100) according to any one of claims 1 to 7.

11. A method for connecting a circuit board (300) with a cable (200), wherein, The method comprises: forming an electrically conductive connection between strands (210) of the cable (200) and a connection (310) of the circuit board (300) using a soldering aid (100) according to any one of claims 1 to 7. The method comprises:

Images