DE19741557C1 - Applying solder to electromechanical precision components made of electroconductive materials - Google Patents

Abstract

Two electrodes (3, 4) are pressed against one another by pneumatic, hydraulic or mechanical means, and via a strip shaped component (1) and a soldering agent supplied in the form of a welding wire (2), an electric contact is established between. As result of a controllable electric current passing through the contact, the solder is melted so that it forms an adhesive joint with the component.

Description

The present invention relates to a method in which the known Wi derstandslötverfahren is applied with the electrically conductive, an electri electromechanical components that represent resistance, with solder be seen by heating them by an electric current so that supplied solder partially or completely by contact with the workpiece Melting is brought and a surface connection with the heated Component arrives.

The problem of electro-mechanical components or other conductive materials using order soldering, in particular tinning, can be solved with various known soldering methods such as solder bath soldering, wave soldering and drag soldering. It is also known to apply smaller soldering agent deposits by means of Kolbenlötverfah ren or by tacking and gluing onto conductive materials in order to be able to process them further by subsequent reflow melting processes. See also:

• - Schmidtke: "Soldering technology in electronics", specialist publication Aargauer Tagblatt, 1976
• - DVS reports: "Soldering Brazing and Welding in Electronics", DVS GmbH 1976
• - Neumann, Richter: "Table book welding and soldering technology", DVS Verlag 1989
• - Wuich: "Gluing, soldering, welding", Leuchtturm Verlag 1977.

Furthermore, a method is based on the American patent US 52 86 945 for applying solder to electrically conductive materials, especially electro Precise mechanical components, in which the solder by two against each other ge pressed electrodes is melted to connect two workpieces. In Ge Contrary to the inventive method described here, heating the compressed workpieces and electrodes via contact resistance testifies and only added solder later, which is due to the heating thus generated and not caused to melt by its own electrical resistance becomes. The device presented there has the additional disadvantage of being complex Cooling devices for regulating the temperatures of the electrodes and workpieces  and the associated setting of the melting and curing range of the having to install subsequently added solder.

It has also been shown that soldering, in particular the tinning of elec trofeinomechanical components with the help of solder bath, wave soldering and drag soldering leads to strong heating of the components to be soldered goes, which sometimes leads to the destruction of sensitive components and thus strong failure shot quantities generated.

Furthermore, the constructive measures for applying solder deposits are very expensive with the help of soldering or tacking in series production.

The method according to the invention presented here is used with the aid of the known ten resistance soldering process both differently shaped, electrically conductive, elec Solder trofine mechanical components, in particular to be able to tin-plate as well Solder depots on differently shaped electrically conductive, electro-fine mechanics attaching components.

The current I required for resistance soldering and the duration of the current supply t is to be regulated in the method according to the invention with a device on the one hand so that the solder involved can melt completely in order to solder, in particular to, workpieces on the surface involved tinning, the electrical current I heating both the workpiece and the solder to temperatures above the liquidus temperature T _Li .

On the other hand, the electrical current I and the duration of the current supply t can be regulated so that the solder only partially melts due to the heating of the workpiece to the temperature T _W , whereby T _{W must be} above the liquidus temperature T _{Li of} the solder .

The workpiece is supplied with that thermal energy that it is the contact area due to the increased temperature of the workpiece to Adhäsi ons and diffusion processes with the solder, and at the same time the heat meergy in the solder, due to its own electrical resistance, ent it is not sufficient to melt it or not to use it is sufficient. In addition, the evaporation process also becomes one in the solder existing flux regulated by the supplied thermal energy.

In the method according to the invention, the solder is first fed to the workpiece. The solder is then deformed by a pressure caused by the force and pressed against the workpiece. In the subsequent soldering process, the electrodes are increased to the temperature T _E , the solder to the temperature T _L and the material to the temperature T _W by the electrical current I supplied. The thermal energy Q supplied in each case obeys the dependency Q ∝ I ² .Rt, where I is the current, R is the electrical resistance and t is the length of time during the electr. Represents current flowing through the workpiece. If the solder should only partially melt, T _W <T _Li and T _L <T _W or T _L <T _{Li must} apply, as already mentioned.

With reference to the accompanying drawings in Fig. 1 to Fig. 6, the inventive method to the example of preferred embodiments of a method according to the apparatus will be explained in more detail and schematically illustrated.

It means:

Fig. 1 starting position of the components involved in the soldering process according to the invention;

Fig. 2 position of the components involved in the soldering position;

Fig. 3 starting position analogous to Figure 1 with shaped electrodes.

Fig. 4 position of the components involved in Figure 3 is in the soldering position.

Fig. 5 shows the upper press plate ( 6 ) and the lower press plate ( 7 ) required for the pressing process. Together with the upper electrode ( 3 ) and the lower electrode ( 4 ), the pressure plates with the working cylinders ( 8 ) are moved and exert a force on the solder wire ( 2 ) so that it can be deformed in shear and pressing processes . A device for supplying material ( 11 ) controls the feed V _{W of} the material, a device for supplying solder ( 12 ) controls the feed V _{L of} the solder through the supply of solder ( 5 ). In general, this solder is designed as a flux-containing solder wire ( 2 ). When the press plates ( 6 ) and ( 7 ) are closed, the electrodes ( 3 ) and ( 4 ) are in electrical contact with the solder wire ( 2 ) and the workpiece ( 1 ). Upon application of egg ner electrical voltage to the electrodes (3) and (4) and the resulting verbun which current I from the current source (10), it comes to the already mentioned soldering processes which are outlined in FIG. 1 to FIG. 4. The regulating and control unit ( 13 ) coordinates the previously named variables V _L , V _W , F, I and the duration of the power supply t. In this exemplary embodiment of a method according to the device, the workpiece is a metallic strip pre-punched from the press ( 14 ), which can be further processed in a subsequent press ( 15 ) after the soldering operation carried out in the method according to the method.

FIG. 6 shows a detail from FIG. 5, which is intended to illustrate the soldering process according to the invention with the device according to the method.

Reference list

1

Workpiece, in this case pre-punched metallic tape

2nd

Starting wire in portions and portioned

3rd

upper electrode

4th

lower electrode

5

Solder wire feed

6

upper press plate

7

lower press plate

8th

Working cylinder of the press plate and electrodes

9

Power supply

10th

Power source

11

Tape feed

12th

Solder wire feed

13

control

14

Press

15

Follow-up press

Claims (3)

1. A method for applying solder to primarily electro-mechanical components made of electrically conductive materials, characterized in that two electrodes are pressed together by pneumatic, hydraulic or mechanical pressing pressure and thus via a workpiece present in tape form, fed by a feed and also fed by a feed Solder in the form of solder wire get electrical contact, where the components involved are heated by a feedable, controllable, electrical current and there is a controlled melting of the solder and its adhesive connection to the workpiece. 2. The method according to claim 1, wherein the supplied electric current and the time period during which the electric current flows is set so that the supplied solder to a temperature above its liquidus temperature is warmed and it melts completely and thus becomes a Belo ten, especially tinning of the workpiece involved. 3. The method of claim 1, wherein the electrical current supplied is turned on is that the supplied solder to a temperature below its Li temperature and the workpiece to a temperature above the liquidu temperature of the solder is heated and it partially melts of the solder only comes on the contact surface of the workpiece involved.