Inductive Soldering method and apparatus.

[0001] The invention relates to a method and a device for inductive soldering, in particular a automatable inductive method for soldering terminals of a car battery.

[0002] Inductive Soldering method are well known. Also for automated soldering of workpieces often used There will, since the soldering can be selectively heated by suitable shaping of the inductor. It will also be paid to the temperature at the measured location to be soldered and correspondingly the induction coil operated controlled.

[0003] in addition to the heating by inductive heating is also used in known methods the soldering point an air or gas stream, to cool rapidly after completion of soldering the soldering.

[0004] In a known soldering process according to EP 215,122 together with a suction device is used an air flow, so as to blow away by the molten solder to remove silt and by the suction device. In EP 364,422 is disclosed a soldering method, in which, in a closed and separated from the ambient air is introduced around the soldering space around a laminar gas stream, so as to keep smoke and other particles from the end of a glass fiber element serves, by means of the temperature measurement the infrared radiation.

[0005] The present invention is the task, a soldering process and a device for soldering of electrical cables provide electrical connections with, wherein the solder is prevented as far as possible by the open solder joint remains concentrated and that the solder during brazing and across the place of connection to the cable insulation along down-flowed.

[0006] This problem is solved according to the invention by a soldering process according to claim 1.

The method comprises the inductive heating a junction between a first electrical workpiece by means of a high-frequency generator and an induction coil and a second electrical workpiece,

familiarising of a braze alloy in the connecting point between the two electrical workpieces,

the melting of the solder at the junction,

hot air blowerhot-air stream on the molten solder and directing a in a direction opposite to the direction of flow of the solder by means of a.

[0007] Through a flow of hot air is directed at the soldering hot air blower a strong air flow at the soldering by means of a, the strikes there onto the flowing solder and prevents this from the flow over the edge of the solder joint between the two electrical workpieces. It is directed counter to the direction of flow of the solder, a back pressure, so that the air stream thus forms a kind of air embankment or aerodynamic dam, whereby the solder is prevented from thereto, via the soldered joint to flow away also. Instead, the solder on the solder joint remains concentrated and is able to flow more in the cavities between the two electrical workpieces. The resulting electrical connection is improved. Also there is no flow comes from the solder of undesirable locations outside the soldering point, the otherwise could lead to malfunctions during the operation of the electrical workpieces.

[0008] in an embodiment of the invention is directed from a direction slightly below the edge of the solder joint on the air flow this, whereby a pressure is created and the gravity counter to the direction of flow.

[0009] Depending on the shape of the workpieces to be soldered it may also be desirable, to direct the flow of air laterally at the soldering.

[0010] In an embodiment of the invention the method is applied to an electrical cable and a cable lug with electrical connecting element as first electrical workpiece as second electrical workpiece. The wires at the cable end is pressed, the cable lug This, the forms an edge at the level of the wire ends and encloses the wire ends. The two workpieces are disposed in the induction coil, so that it encloses the cable lug and the wire ends. The solder is then guided to the wire ends, where it is melted. During of melting of the solder to the wire ends the solder flows into the interstices between the individual wires and to the edge of the terminal and to the electrical contact member connected with the cable lug. The stream of hot air effected that the solder flows over the edge of the terminal and not on the cable insulation along. This the stream of hot air is directed from a direction at the edge of the terminal on the soldered joint.

[0011] In one design, the following additional process steps during the soldering process is also carried out:

the measurement of the temperature in the region of the soldered joint by means of a temperature gauge,

the conduction of at least one measured temperature value to a control unit of the high frequency power generator for the induction coil,

and the control of the high-frequency generator in accordance with the supplied measured temperature value.

In this way the control unit in accordance with the measured temperature values can be adapted the high-frequency induction coil, so as to reduce the temperature at the soldered joint on the basis of predetermined values by Optimize increase or the power of the generator. The temperature measurement is carried out, for example, by means of a pyrometer or infrared measuring instrument.

[0012] The temperature of the air stream from said hot-air fan is above the ambient temperature, so that, during the influent flow of the solder is caused no cooling is not affected, and the soldering process. Appropriate hot-air stream are for example temperatures of the 30 to 250 °C. It the temperature is selected so the flow of air that a flow of the solder between the individual electrical workpieces is ensured and no acceleration of the cooling of the solder is effected by early plumb bob procedure.

[0013] contained The invention has the advantage that the flow of the molten solder during the soldering process can be held in place and at a targeted and can be prevented from flow away. The quality of the solder joint is thereby improved and repeatable controlled.

[0014] The according to the invention is suitable for soldering by means of any soft solder soldering method, such as tin-copper-solder, Silver-containing solders and other soft solders.

In an embodiment of the invention a battery cable is soldered with a terminal by means of the method according to the invention.

[0015] According to the invention, a device for soldering of workpieces is disclosed comprising:

A high-frequency induction generator and a high-frequency induction generator connected with the induction coil,

a device for holding a first and a second [...][...], wherein the induction coil is disposed between the first and second workpiece about a provided soldered joint,

an apparatus for introducing a soft solder to the intended braze pad, and a hot-air fan with a nozzle, the the direction of flow of the solder at the soldering of the soldering point away is directed against a.

[0016] In one design device has also a temperature-measuring device on the according to the invention is connected to the high-frequency induction generator.

[0017] Additional advantages of the invention follow from the dependent claims and from the following description, in which the invention is explained on the basis of a design embodiment illustrated in the schematic drawings in more detail. It shows:

[0018]

Fig. 1 shows a schematic representation of a overall view of a device for carrying out the soldering process with hot-air fan the invention inductive.

2 shows a more detailed view of the soldering point of the device with hot-air fan Fig. from Fig. 1.

3 shows a plan view of the soldering point according to III from Fig. Fig. 2.

Fig. 4 shows a side view of a soldered joint according to the state of the art, in which no hot-air fan is used and wherein the solder flows over the edge of the braze pad.

Fig. 5 shows a side view of a soldered joint 2 and 3 according to the invention and according to V from Fig., wherein the hot-air fan is used remains over the edge of the braze pad and the solder.

[0019] In the figures, for the same elements in each case and first-time explanations relate to all Figures the same reference symbols have been used, unless otherwise mentioned.

[0020] The method is based on a device for soldering of two electrical workpieces as in 1 Fig., 2,3 and 5 described represented. There a device 1 is shown with a high-frequency generator for induction soldering of two electrical workpieces 2,3 are connected with the electrical conductor 4 with an induction coil. The coil 4 is so shaped that it encloses two workpieces 5 and 6. In the shown example a cable is 5 workpiece The, for example a car battery cable, a cable lug 6 is pressed at the wire ends. An electrical terminal element 6 is arranged on the cable lug 7. When according to the invention by means of a control unit 2a is set in operation 2 the high-frequency generator Soldering method, 5 and 6 whereby the two electrical workpieces, the cable lug and the wire ends of the cable, by means of the induction coil as well as a heated solder advanced be 8. Depending on the workpiece may, for example, having a melting point of 260 280 °C for this purpose a suitable solder or 350 °C are used or to. During the solder melts is formed on the wire ends of the cable 8a 5 molten solder, fills the area within the rim 6a of the terminal 6 the down-flowed and in the spaces between the individual wires of the cable and between the wires and the cable lug 6. During of melting is operating and its strong 9 in a hot-air fan set, hot air stream 9' 8a directed to the molten solder. The blower 9 is here so aligned that the solder within the rim 6a and it will not be over the edge and on the insulation of the cable 5 down-flowed. This the blower 9 is at an angle below the horizontal H aligned, so that the air flow flows from below to the molten solder. The air stream and forms there a air embankment thuds the solder, of a back pressure to the flow of the solder effected. In the Fig. 2,3 and 5 is the direction of the fan 9 with respect to the horizontal, and the angle between the horizontal H H α below the horizontal and the longitudinal axis or the axis of the airflow represented. Α is, for example, between 0 and 85° The angle, between 50 and 80° or 20° in further examples between 40° and.

[0021] is, for example, between 50 and 100 °C hot-air stream The temperature in the. This temperature is sufficiently high, to avoid a premature cooling of the solder to ensure a sufficient connection of the electrical contact surfaces, bearing in mind the to effect. A higher temperature would also be applicable.

The blower 9 is arranged, a strong air stream and to generate a back pressure on the flowing solder. It the blower so in its starch is used that the flowing solder [...] 8a is held by the, it is blown away but not from the soldered joint. The [...] differs from a weak air stream as such air stream used for cooling a surface or a laminar air flow, such as for the supplying a gas.

The Blower for the method according to the invention has for this purpose, for example, a narrow round nozzle on, generates a targeted air flow from the smaller cross-sectional area. In another construction of the invention, for example, a nozzle with elongated opening on, which may be straight or rounded is carried out also. Depending on the shape and size of the soldering point, at which the solder is to be held and maintained by a concentrated flow away 8a, the nozzle may be shaped accordingly. Depending on the shape of the nozzle can also be adapted to the strength of the fan.

[0022] 4 and 5 in a side view the action of the is In Fig. hot-air stream 9' 8a represented on the flowing solder. Fig. 8b 4 shows as in a conventional soldering process the solder over the edge of the terminal 5 down-flowed 6a of time and along the cable. Fig. hot-air stream 8a due to the action of the 5 shows how the solder 9' 6a remains in the region of the terminal.

[0023] 1 also comprises, for example, the method shown in the use as Fig. temperature gauge such as a pyrometer 10 a, the infrared radiation 10' temperature measuring signal generated by the induction coil 4 and feeds back a. This signal is passed to the control unit 11 via a line 2a, where it is used to control the high-frequency generator 2.

[0024]

1 Soldering device

2 high-frequency generator

2a control unit for high-frequency generator

3 electrical conductors

4 induction coil

5 cable

6 connecting element, cable lug

7 electrical contact element

8 solder

8a molten solder

9 Hot air machine

9' hot-air current

10 pyrometer

10' infrared ray

11 electric line for sensor signal transmission

12 electrical lead

H Horizontal at the level of the solder joint

α angle between horizontal and axis of the fan