EP0130902B1 - Inductive electronic component for transmission by flat contacts - Google Patents

Description

The present invention relates to an inductive electronic component for the flat transfer, comprising a pulley consisting of two cheeks secured to a mandrel on which is wound an electrical winding whose ends are respectively connected to an electrode, a mechanical protection means such as 'a resin coating the winding substantially up to the height of the cheeks.

The electronic components for the flat transfer are commonly designated under the name "chip". These known components, both inductive and capacitive, have a generally parallelepiped shape having two planar electrodes arranged on two lateral faces of the parallelepiped allowing the flat transfer of said component. In this flat transfer technique, these components, for example placed in chargers, generally supply automatic insertion machines and are positioned on the printed circuit for which they are intended using a point of glue. When the printed circuit is completely lined with the various active and passive elements which must be connected to it, these are then connected to the printed tracks of the circuit by the technique known as “wave soldering” to “dipping” or any other connection system well known to those skilled in the art.

Inductive components of the chip type are known, for example from patent DE-A-3,042,433 and from patent FR-A-2,509,529. Patent DE-A-3,042,433 describes an inductive electronic component for flat transfer comprising a pulley consisting of two cheeks secured to a mandrel on which an electrical winding is wound. The ends of the winding are welded to one face of the cheeks covered with a metallization forming an electrode. On the other hand by referring to the description and the drawings appended to patent FR-A-2 509 529 it will be readily understood that the solution proposed in this patent is particularly complicated. Indeed, it uses a pulley on which the inductive winding is wound, said pulley having lateral cheeks whose end faces have a hollow shape in which comes a metallization on which comes a leg , the assembly being coated in a resin then said curved tab.

Contrary to what is stated in said patent, the Applicant thinks that the problems of eddy current loss, as well as the value of the quality coefficient Q of the inductances thus formed can be improved thanks to a much simpler structure, using electrodes obtained by metallization.

The electronic component according to the invention is characterized in that each cheek and its conductive layer have an open groove extending parallel to the mandrel and at least until the extension of the latter at the cheeks, each end of the winding being respectively fixed in each groove, by means of a weld, ensuring electrical contact between the electrodes and the ends of the winding. Preferably, this welding will be carried out by an electrically conductive solder, said solder at least partially filling each of the grooves.

According to a preferred embodiment, the bottom of the groove will be located in the extension of the mandrel. Preferably, it will include at least one flat face which will be extended by a flat part in each groove.

The component thus formed, which does not have the disadvantages of chips of the same type of the prior art, namely losses by eddy current a very low quality coefficient Q, has the essential advantages of the simplicity of manufacture leading to reduced production costs.

In particular, it will be noted in the characteristic structure of the invention, two particularly important points, these possibly being able to be used alone insofar as the improvement brought by the other point is not considered essential in the application envisaged. The first point is the presence of a groove in each of the cheeks of the pulley, groove crossing these from their internal face to their external face, and extending at least to the level of the mandrel of the pulley ( but preferably stopping at this level). In this way, the problem of fixing and / or welding the ends of the windings of this inductance is considerably simplified. In addition, we will choose the depth of this groove (in other words the height of the cheek) large enough so that the wire can be introduced into it and fixed using a solder, for example of the tin-lead type, without this it does not overflow outside said groove. In this way, the coating of the component with an epoxy-type resin, for example, can be limited to the external dimension of the cheeks. In this way, the component thus formed has external dimensions, equal to the dimensions of the pulley used. With this structure, no additional thickness is added to the pulley to produce the component. A second important point of the invention, which, combined with the previous one provides the same advantages of small external dimensions, is the use of metallization electrodes deposited on the external face of the cheeks of the pulley. In this way, the width of the component is only very slightly increased while retaining the height and the thickness of the pulley. This structure also has the great advantage of the complete indifference of the component as to its soldering face on the printed circuit. Indeed, in the case of a pulley of parallelepiped external shape, when for example the electrodes are formed on two opposite lateral faces (external face of the cheeks), the component can be welded by being positioned on the circuit on the any of the other four faces of the parallelepiped, as will be readily understood later.

In general, the pulley may be made of plastic, ceramic or preferably made of ferrite or agglomerated iron powder in order to increase the magnetic properties of the component. Whatever the material used, this pulley can be either molded or obtained from a rectified parallelepiped bar. The external shape of the pulley can be either cylindrical (as described for example in the French patent cited above) or parallelepipedic with a central mandrel constituting a section section smaller than that of the side cheeks integral with the mandrel.

The electrodes deposited on the external faces of the cheeks of the pulley will preferably be produced by dipping in a silver, silver-palladium bath, or deposited by screen printing, by chemical, electrolytic deposition or by vacuum metallization, etc., in a manner known per se. In the case of screen-printed deposition, the inks chosen must be appropriate, in particular in the case of deposition before firing of ceramics or ferrites

The grooves made in each cheek will be either directly by molding, or by rectification, in the latter case before or after depositing the electrodes. In the case where the pulleys and the grooves are produced by molding, the deposition by dipping or by screen printing of the electrodes makes it possible of course to directly obtain the appropriate grooves in the corresponding part of the electrodes.

The winding wire will be placed at each end of the latter in said grooves, and welded in said groove electrically, by pressure, by ultrasound (or by the technique known as "Ball bonding" used in microelectronics), etc. or also using tin or tin-lead solder, so as to mechanically join the wire and the pulley on the one hand, and to ensure an electrical connection between the end of the winding and the electrodes on the other go.

The final coating of the component will generally be carried out using suitable molds so as not to soil the ends of the electrodes of the component, or by wrapping of adhesive films or plastic wires or using a sleeve. heat-shrinkable plastic, etc.

• - la figure 1, une vue en perspective de la poulie du composant selon l'invention;
• - la figure 2, une vue de dessous du composant terminé;
• - la figure 3, une vue d'extrémité du même composant;
• - la figure 4, une vue en coupe dudit composant dans un plan parallèle aux gorges.

The invention will be better understood with the aid of the following exemplary embodiments, given without limitation, together with the figures which represent:

• - Figure 1, a perspective view of the pulley of the component according to the invention;
• - Figure 2, a bottom view of the finished component;
• - Figure 3, an end view of the same component;
• - Figure 4, a sectional view of said component in a plane parallel to the grooves.

In Figure 1, there is shown the pulley according to the invention coated with its end electrodes. This shaped pulley is composed of a mandrel 1 itself parallelepipedic carrying at each of its ends parallelepipedic cheeks 2 and 3. The outer faces of said cheeks 2 and 3 are covered respectively with metal layers of electrodes 4 and 5. A lateral face of each cheek 2 and 3 has a groove 6 and 7 arranged on the same side relative to the mandrel 1. Each groove 6 and 7 extends to the face 8 of the mandrel 1 which it extends by a flat part respectively 10 and 9.

In Figure 2, there is shown a side view of the component according to the invention obtained from the pulley of Figure 1, wound and then coated with resin. In this figure and in the following figures, the same elements have the same references. The winding of the wire 12 is wound around the mandrel 1 and ends at its ends 13 and 14 placed respectively in the grooves 6 and 7. The pulley is filled between its lateral cheeks at the mandrel with a resin 11 of epoxy type coating the winding 12 and arriving at said cheeks.

The end view of the component of FIG. 3 allows a better understanding of the fixing of each winding end in the corresponding groove. The end 13 is made mechanically integral with the pulley by introduction into the groove 6 and fixing using a tin-lead type solder 15. This tin-lead solder 15 also electrically connected the end 13 and the electrode 4. During filling with epoxy resin 11, the part of the groove which may not be filled with solder is completed with resin 11.

Figure 4 which is a sectional view parallel to the median plane of the grooves 6 and 7 shows the finished component.

Claims (4)

1. Inductive electronic component for flat mounting, of the type comprising a bobbin formed of two flanges (2, 3) fast with a mandril (1) whereon an electric coil is wound the ends (13, 14) of which are respectively connected to an electrode, a protection means (11) surrounding the winding substantially up to the flanges (2, 3), and the flanges (2, 3) being covered with an electrode forming a conductive layer substantially exclusively on their outer faces, characterized in that each flange (2, 3) and its conductive layer comprise an open groove (6, 7) extending parallel to the mandril (1) and at least up to the extension of the latter at the level of the flanges (2, 3), each end (13,14) of the coil being respectively fixed in each groove (6, 7) by means of a soldering ensuring the electric contact between the electrodes (4, 5) and the ends (13,14) of the coil.

2. Electronic component according to claim 1, characterized in that the soldering ensuring the electric contact is formed by means of an electrically conductive brasing (15) which at least partially fills each of the grooves (6, 7).

3. Electronic component according to any of claims 1 and 2, characterized in that the bottom of the groove (6, 7) lies in the extension of the mandril (1).

4. Electronic component according to claim 3, characterized in that the mandril (1) comprises at least one plane face (8) which is extended by a plane portion (9, 10) in each groove (6, 7).

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