DE4029666A1 - Partly casing electrical component - by standing lower part of component, e.g. coil, vertically in trough, encapsulating in cast resin and cooling resin to set - Google Patents

Abstract

At least the base part of a casing is produced on electrical components, coils, toroidal core windings, transformers, capacitors etc.; in the process the lower part only of the component is inserted into a bath with open top and a set volume of a low viscosity resin is poured into the bath; when the resin has cooled the component with the part cast on to it is withdrawn upwards out of the bath. ADVANTAGE - The process enables various types of electrical component, and particularly those which are more difficult to manipulate, to be securely attached to PCBs whilst at the same time ensuring that most of the surface of the component remains uncoated for heat dissipation. In an example, an annular core winding (10) with base is produced by placing the basic coil so that it stands vertically in the bath of suitable shape. Suitable connecting pins (15a, 15b) with appropriate ends to join the winding (10) are preferably positioned beforehand e.g. having top loops (16) for taking wires (17) pressed together with the wire. The base (19) of the coil is thus cast in position, which is preferably heated already. The resin penetrates all interstices in the coil, especially if under moderate pressure, e.g. from a gear pump. (6pp Dwg.No.1/5)

Description

State of the art

The invention is based on a method according to the Genus of claim 1, a device according to the Genus of claim 7 and an electrical Component according to the preamble of claim 12 and is specifically aimed at such electrical components elements, even when using highly integrated Circuits as separate parts, for example Printed circuit boards, circuit boards and. Like. applied need to be, either because of such electrical construction elements in the form of a chip cannot be produced, such as transformers, chokes, toroidal chokes and. the like or because of the expected heat loss  larger dimensions required for such components Lich to ensure the necessary heat dissipation Afford.

The following will focus on the realization of the Invention based on a toroidal choke, although it is understood that the invention also applies to other suitable electrical components in which the same problems arise can and therefore on the application form in a ring core choke is not limited.

Toroidal chokes are often used in such electri circuits where phase gating is required controls or general control processes reali be fixed or interference must be carried out sen.

So it is known so far, toroidal chokes to be attached to printed circuit boards or circuit boards, that their very thin connecting wires through Drilled holes in the printed circuit board and on the other on the other side or directly on the Ver. On the component side with contacts running there be tied up while looking at the body of the toroidal corpses sel attached to the printed circuit board in that one put a drop of hot glue on it and the throttle then press it into the hot glue. Such a pri mitive type of attachment is always problematic, ins especially because such a throttle is more violent Also solve impacts and general short can lead to conclusions; another known possibility  ability to attach electrical components, again, for example, chokes on one PCB surface consists in that the Throttle in a separately molded plastic base uses, for example, in some way to on snapping brings, laboriously connecting wires the throttle through corresponding holes in the base must be performed and then the throttle with this base in a suitable manner on the print plate te attached, for example gluing the base or otherwise attached.

Another possibility that offers itself here the attachment of chokes on a printed circuit board would be that the throttle itself completely molded with a suitable plastic housing, whereby then also suitable connecting wires can bring, possibly also in the form of starch Ren cones, which are then secured in the plastic casing are chert. The um speaks against this solution stated that precisely with the general tendency of the Ver heat dissipation even with such chokes tion takes on a very special meaning, which at a complete overmolding is so bad that very few suitable uses would result.

The invention is therefore based on the object to create that make it possible, especially difficult electrical components to be handled such as the ring shaped toroidal chokes, transformers, suppression chokes, Special inductors and Like. on circuit boards  fasten securely and immovably, at the same time It is ensured that a larger part of the components surface remains free for heat dissipation.

Advantages of the invention

The invention solves this problem with the mark the features of claim 1, claim 7 and of claim 12 and has the decisive advantage that it is without the usual injection molding ken succeeds, such an electrical component, spe specifically an inductor, choke or toroidal choke to be provided with a base-like partial housing, wel ches from a suitable, after cooling and curing ten fully stable plastic, which is with the Dros sel is inextricably linked and in turn one Wall-free mounting option for the throttle the printed circuit board offers.

It is also advantageous that the throttle connection wire itself either in the one that forms the base Baked plastic and through it down are passed through, which is a possibility of Ge of such a choked throttle, if you put these thin connecting wires into the wants to further process this form or the base art Fabric picks up stable pins and stores them se, with which the actual choke connecting wires internally inside the base plastic in a suitable Way connected. Pierce the connector pins then the base plastic material down and bil  which are at the same time the means for anchoring and fastening the throttle on a circuit board. This can for example by pushing through in ge suitable openings arranged in the distance Circuit board and back soldering done.

It is also advantageous that the throttle now over a larger cross-sectional area than previously possible by means of a flat underside coming from the base is formed, flat and flush on the circuit board can sit on, anyway, and this is a wide one advantage of such a base, no more space is required is considered to be the cross section of the throttle itself speaks, in other words even with very small coils the additional base does not interfere with the assembly, since it does not exceed the dimensions of the choke, but only manageable and a variety of manipulations.

Regarding the manufacturing process itself advantageous that in deviation from the usual spray casting processes in which with closed molds and very high pressures and almost pasty art is worked materials in the invention an upwardly open trough-shaped form is used into which the choke or any other suitable electrical component is used from above so that in the area of the upper trough boundary - and the The shape of the trough can be specified as desired - approximately the external dimensions of the component used, So the throttle can be reached here, so that the Dros selform itself a kind of conclusion of the mold trough  forms above. Then a given volu amount of very thin plastic practically pressure brought freely into the mold cavity, whereby to the other parameters like ambient temperature, Cooling rate, possible heating of the Mold trough u. The like. Care is taken that after filling in the mold cavity with the liquid plastic this in completely cures in no time and the finished socketed throttle can be removed.

This pressure-free molding process is an advantage further that in this case there are no problems with the There is a sprue because after the introduction of a volume-determined Plastic quantity in the mold cavity by a reversie rende control of the feed device (pump) liquid ger plastic from the feed opening - the expression Injection opening is avoided in this case - how which can be sucked off, so that a sprue is even does not form through this suckback effect. That remains advantageous that when promoting the very thin A gear pump into the mold cavity with which the volume can be set amount of the plastic material to be fed up to Fractions of a gram, for example if desired to be determined to the nearest 1/100 g.

With an electrical component produced in this way ment ensures that the extreme thin rivers liquid of the plastic inserted into the mold cavity a particularly effective link between art fabric and the component, for example the wick lungs of the toroidal coil is possible because of this art  material flows into every tiny space and the entire base wrapped around the outside Toroidal core coil claws into a one-piece component, even if the toroid is only half full their torus diameter (i.e. not the coil diameter knife) sits in the base shape. A release or off break the toroidal shape of the toroidal coil out of the shaped base is absolutely excluded.

By the measure listed in the subclaims These are advantageous further training and improvements possible according to the invention.

drawing

Embodiments of the invention are in the drawing tion and are described in the following section spelling explained in more detail. Show it:

Fig. 1 in a greatly enlarged representation of a ring core coil according to the invention as before ferred possibility of partial housing molding to an electrical component in a view from the front and

Fig. 2 shows the same toroidal core with base in Be tenansicht;

Fig. 3 shows the toroidal coil of Figure 1 on a natural scale.

Fig. 4 shows a possible embodiment of a simple molding device for attaching sockets to electrical components in plan view and

FIG. 5 shows the molding device of FIG. 4 in section along the line VV of FIG. 4.

Description of the embodiments

The basic idea of the present invention is to more problematic to handle and for example electrical to be attached to circuit boards or printed circuit boards Components such as coils, transformers, toroidal coils, larger capacitors u. Like a base or half Mold the plastic base while avoiding common problems injection molding techniques, due to the need to to have to use an open mold, because not the entire component is to be encapsulated, not for Can come and at the same time to ensure that thereby a fixation, integration and bracket of the electrical connecting wires.

A "socketed" electrical component in accordance with the present invention, especially a toroidal core coil 10 , is produced in such a way that the wound coil blank is inserted, for example, standing upright into the mold cavity 11 of a suitable molding device 12 , it being understood that the cavity shape of the mold cavity of the external mold of the electrical component to be socketed is adapted approximately. The mold trough thus has such a depth, width and longitudinal extent as one would like to subsequently find a base on the lower part of the electrical component, in this case the toroidal core coil, whereby it can be assumed that the plastic during the molding process then approximately matches the mold trough occupied with the throttle blank fill flush to the top. The trough should be at least slightly conical upwards, if only to make it easier to remove the socketed component.

Furthermore, the mold trough should be such that the component used in the upper edge area the trough is largely flush, so that in addition to a certain final effect the mold trough mainly for the imported Plastic tends to recede in relatively thin layers to get on top of other materials so that precisely in these upper end areas the temperature of the plastic quickly drops and the sealing temperature is reached so that the Form trough is completed by the rapidly cooling plastic in connection with the used coil bobbin while in the lower Plastic may still flow into the area.

The basic function in the molding of the base is such that after inserting the coil blank and by threading its connecting wires through holes in the bottom of the mold hole 13 a, 13 b - to deal with a particularly simple exemplary embodiment here - via special inflow openings 14 , the For example, can be arranged centrally to the side of each mold trough 11 a, 11 b, 11 c, 11 d, relatively low-viscosity to very low-viscosity plastic with low to lowest pressure is introduced.

The pressure of the plastic to be fed is just so high that the thin plastic can flow through the inlet openings 14 , which can also taper conically from the outside in the direction of the mold cavity, into the mold cavity and fill it to the edge. Here, for example, pressures in the range of about 1/10 bar or even less come into consideration, the supply of the plastic being based on the fact that a predetermined volume quantity is supplied, that is to say not like in the case of other injection processes with a closed mold at a specific predetermined one Printing is canceled.

The feed has proven to be particularly advantageous here the plastic with a gear pump, with which it succeeds, down to orders of magnitude of 1/100 g to promote exactly. The gear pump is preferred by an appropriately controlled stepper motor driven.

The plastic then rises in the open top Trough shape of the mold cavity, as above briefly mentioned, always higher, encloses the lower parts of the used electrical component, here the ring core coil, penetrates extremely due to its initially liquid state in all winding cavities the coil and claws into it and rises continue until it reaches the upper edge of the trough also begins to solidify immediately after cooling - at the same time this is done by a corresponding intelligent control of the gear pump  funding stopped the stepping motor.

A further embodiment of the invention is in this Then to see context in that, given if after a short wait to make a transition into a certain thick liquid of the main part of the To reach plastic in the mold cavity by a short reversal of the gear pump delivery liquid plastic in the area of the feed channel is sucked back up to the insertion opening, so that with such a "base formation" also no sprue can form on the molded material - in particular the sprue formation is with conventional spray casting a problem that with sophisticated Temperature and cooling processes must be met. Since the guarantee by the present invention the molding process does not form a sprue, remains the supply channel also as a result of sucking back from a plastic plug that may have already fallen below the sealing temperature could, freely, so that the next spraying in can be carried out in the same way without any problems, without an increase in pressure being required, such as which is otherwise the case with injection processes remove the sprue plug from the spray channel.

As a result of the fact that there is no sprue, the removal from the mold, that is to say only the removal of the socketed toroidal coil from the mold trough 11, is problem-free, since it only has to be pulled off upwards. It should also be pointed out that the lower passage openings 13 a, 13 b for the connecting wires of the toroidal core coil can be quite larger in diameter than the connecting wires themselves; nevertheless, plastic flows only insignificantly or not at all into these openings, since it cools down immediately at this point and seals against further penetration.

An advantageous embodiment of the invention is also that it is possible, even before the Socke development of the electrical component whose connection wires with correspondingly strong trained to provide connecting bars, pins or pins, as at 15 a, 15 b in FIGS . 1 and 2 are shown. Such connection pins of suitable length and thickness and flexural strength can best be designed in the upper region, i.e. where they are connected to the connecting wires of the electrical component, in the manner of wire end ferrules, ie they can have funnel-shaped insertion openings 16 in a corresponding lead wire 17 is inserted; then you can mechanically press this hollow eyelet at the upper end of the connector pin, so that there is good electrical contact and a firm connection between the two parts. The connecting pins 15 a, 15 b can then be guided through the bottom openings 13 a, 13 b of the mold trough 11 a, 11 b, 11 c, 11 d when the electrical component is used, and they are then firmly enclosed by the plastic base when it is molded on and after hardening of the base form safe rigid connection contacts, with which it is then easy to fix the entire construction element on a suitable circuit board. This results in an advantageous lower smooth bottom surface 18 of the toroidal core coil, with the outer dimensions evidently practically not exceeding the cross-sectional dimension of the original unsocketed toroidal core coil.

From the representations of FIGS. 1 and 2 it can be clearly seen that the plastic base 19, the toroidal core coil only in its lower area, but at this point absolutely secures and secures and the majority of the toroidal core coil or, more generally, another component upwards can be released so that there is an almost unaffected heat dissipation.

Finally, it is pointed out that the claims che and in particular the main claim wording try the invention without extensive knowledge of State of the art and therefore without limitation Are prejudice. Therefore, it is reserved, everyone in the description, the claims and the drawing shown features both individually as also in any combination with each other as fiction essential to look at and down in the claims as well as the main claim in its feature set stop reducing.

Claims (15)

1. Method for molding at least part of the housing (base) to electrical components, coils, toroidal core coils, transformers, capacitors and. Like., characterized in that
the electrical component ( 10 ) is only used with its lower part in an upwardly open, the molded housing part (base 19 ) corresponding mold ( 11 a, 11 b, 11 c, 11 d) and that
a predetermined volume of a thin plastic gene introduced into the mold cavity and the electrical component with molded-on part housing is withdrawn from the mold cavity after cooling of the plastic. 2. The method according to claim 1, characterized in that the part of the electrical component ( 10 ) receiving the mold trough ( 11 a, 11 b, 11 c, 11 d) with a particularly thin plastic is applied almost without pressure. 3. The method according to claim 1 or 2, characterized  records that the plastic for base formation on the electrical component laterally in about half Height of the mold cavity by means of an insertion opening a gear driven by a stepper motor pump is fed volume-controlled and that after reaching the specified volume Plastic by reversing the gear pump Plastic is sucked back in the feed area to avoid sprue formation. 4. The method according to any one of claims 1-3, characterized in that when the electrical component ( 10 ) is inserted into the upwardly open trough shape, the connecting wires are threaded through separate openings in the bottom of the trough. 5. The method according to one or more of claims 1 to 3, characterized in that before the insertion of the electrical component in the Formmul de its connecting wires connected to stable connection pins and the connection pins through bottom openings ( 13 a, 13 b) of the mold trough are guided to firmly anchor the connection pins in the base of the electrical component. 6. The method according to claim 5, characterized in that the connection pins are in the manner of wire end sleeves in the connection area with the connecting wires Chen the electrical component funnel up open in the shape and after insertion of each connection wire are squeezed.   7. Device for molding at least part of housings (bases) on electrical components, coils, toroidal coils, transformers, capacitors and. Like., where liquid plastic is supplied, characterized marked by an open at the top, which is to be provided with a partial housing or base electrical component (toroidal coil 10 ) with its lower part accommodating molding trough ( 11 a, 11 b, 11 c, 11 d ) into which liquid plastic is fed via a feed opening ( 14 ). 8. The device according to claim 7, characterized in net that for volume controlled feeding of liquid plastic into the mold cavity of a gear pump is provided. 9. The device according to claim 8, characterized in net that the gear pump from a stepper motor is controlled. 10. The device according to claim 9, characterized in that the stepper motor is reversible for introduction a return of plastic through the tooth wheel pump after reaching a predetermined, in the amount of plastic to be fed. 11. The device according to any one of claims 7-10, characterized in that the mold trough in its bottom passage openings ( 13 a, 13 b) for the electrical connections of the component. 12. According to the method according to any one of claims 1-6 manufactured electrical component, in particular coil, toroidal coil, transformer, capacitor u. Like., characterized in that a plastic base ( 19 ) is formed on the component directed to a mounting plate, circuit board or printed circuit board, in which the electrical connecting wires ( 17 ) of the component ( 10 ) are embedded. 13. Electrical component according to claim 12, characterized in that the connecting wires ( 17 ) with stable connecting pins ( 15 a, 15 b) are connected, which are firmly embedded with their upper ends in the plastic mass of the base ( 19 ). 14. Electrical component according to claim 12 or 13, characterized in that the stable connection pins ferrule-like, the connecting wires of the component receiving and squeezed together Have hollow eyelets that are inserted into the plastic base are bedded. 15. Electrical component according to one of claims 12-14, characterized in that the base ( 19 ) forms a lower smooth contact surface through which the electrical connection pins penetrate and the majority of the component remains free of the plastic covering of the base.