DE10139839A1 - Coil body, for an inductive electrical component, is composed of a malleable thermoplastic material at low temperatures, and a heat-setting material to resist high temperatures, formed by multi-component injection molding - Google Patents

Abstract

The coil body (20) is composed of two different plastics materials. They can be in a combination of thermoplastic materials which can be shaped again at a low and at a high temperature, or a combination of a thermoplastic material and a heat-setting material (26). The contacts (24,25) are partially embedded at the wound coil zone within the heat-setting material, or the thermoplastic material (27) which can be reshaped at low temperatures. The heat-setting material is at least partially shrouded by the malleable thermoplastic at low temperatures at the contact bar. The coil body is produced by injection molding, structured for the injection of two different materials.

Description

The invention relates to a coil former with a winding space and a molded-on, containing contact elements Contact bar and a process for its manufacture as well an electrical component comprising a bobbin and a contains a coil attached to it.

Inductive electrical components such as coils, chokes or Transformers need a bobbin, on the one hand the windings of wound wire and on the other hand Contains contact elements, the connections on the one hand with the Connected winding ends and on the other hand with an external Circuit are connectable. This allows manufacturing defined inductors and a safe, also automatic Further processing.

At the actual winding space of the bobbin, which the Winding or picking up the windings is one or two Molded contact strips that contain the contact elements. The contact elements can be shaped so that the Component suitable for surface mounting or as Contact pins be designed so that the component for a plug-in assembly is suitable.

The bobbins are usually made of a plastic by injection molding using an injection molding tool manufactured. For reasons of processing security and out economic reasons one uses for the production of Standard bobbins have one injection mold and one Plastic. Another molding process would be too complex and the mechanical specifications of such Coil body generally subjected to large tolerances.

In order to handle the component, e.g. B. for transportation, during assembly and during the soldering process at around 500 ° C mechanical and thermal stresses to which the Contact elements can be exposed to be grown it is necessary that the contact elements are secure and stable in the Coil body or the contact strip are fixed. As Plastic embedding material for injection molding comes out this aspect a thermoset or a high quality and expensive High temperature thermoplastic is considered, the contact elements both mechanical and different Temperature stress securely fixed.

During the injection molding process, thermosets remain relative sharp-edged burrs and overmolding on the connections stand that are expensive in a post-processing process must be removed. Otherwise, these ridges can be there they are also very stable, the insulation of the winding wire the coil. You therefore provide one Risk of short circuit. This applies in particular to the Changing room and the wire guide area. The overspray on the connections also affect after their extensive Remove solderability by significantly worsening it is.

Another disadvantage with thermosets is that that cavities are not completely filled during injection molding become. This can be mechanical as well as electrical Cause problems.

In order to avoid these dangers due to unfilled cavities, deteriorated solderability and damage to the Prevent wire insulation with sharp-edged thermoset burrs, is usually used as an injection molding material Thermoplastics. Thermoplastics are for the changing room, i. H. the Winding tube and its outer flanges are very advantageous. Thermoplastics are, as the name suggests, in their plastic Properties dependent on temperature and can be higher Temperatures become soft again or in extreme cases melt. On the other hand, thermoplastics are used in the injection molding process not particularly thin, so there are fewer burrs, which are also not so hard and sharp that they are Can cause dangerous damage to wire insulation.

Thermoplastic materials are used to embed the contact elements However, thermosets are inferior because they pose the risk of Misalignment of the contact elements at higher temperatures mountains. Thermoplastics therefore come in training as deformable thermoplastic at high temperatures Material or in short as high temperature thermoplastics, then, however, for many applications, as a compromise material in question.

A crucial disadvantage of high-temperature thermoplastics compared to thermosets is the price:
High-temperature thermoplastics are considerably more expensive than thermosets. Another difference is the processing: while thermoplastics have to be cooled after injection molding to get their final shape, thermosets have to be heated up so that they can harden.

The invention is based on the object known bobbins and their manufacturing processes as well electrical components with bobbin improvements provided.

The invention solves this problem with the features of Claims 1, 8 and 15. Developments of the invention are marked in subclaims.

According to the invention, a bobbin is provided, the two different plastics in a combination of one at low temperatures and one at high temperatures reshapable thermoplastic materials or in a combination of a thermoplastic material and contains a thermosetting material. That’s it possible, both the requirements for the electrical, mechanical and thermal properties optimal on the different functional areas of the bobbin vote. Furthermore, it is possible to take a Manufacturing costs to produce optimized bobbin moreover compared to known bobbins as a whole has improved properties.

Under the name "at high temperatures again deformable thermoplastic material "is understood Thermoplastics that are above a temperature of approx. 300 ° C become deformable, and under a "at low Thermoplastic material that can be deformed again " Thermoplastics are understood to be used at temperatures above become deformable at approx. 200 ° C.

A thermoset material is in particular a hardenable material advantageous.

In a preferred embodiment, the contact elements are in the curable material or that at high temperatures again deformable thermoplastic material in the field of Contact bar of the coil former partially embedded, and that thermoplastic deformable at low temperatures Material is provided in the area of the changing room. This allows both the thermal-mechanical properties for the contact elements as well as the electrical-mechanical Properties optimized in the electrical part of the coil former become. The contact elements are embedded in thermosetting plastic even at high temperatures and mechanical loads, securely fixed. On the other hand, without post-processing the injection molding process also in the electrical area of the Component yields in device manufacturing Optimized due to the use of the thermoplastic material, so that no elaborate post-processing is required, and the risk of short circuits is reduced.

In a further embodiment it is provided that the hardenable material in the area of the contact strip at least is partially surrounded by the thermoplastic material. This is it is possible for those areas of the contact bar that are connected to the Winding wire can come into contact, a thermoplastic Use material and still the contact elements to embed predominantly in a thermoset. This significantly increases processing reliability.

It is advantageous if the winding wire receiving Areas of the contact strip and the changing room thermoplastic material are molded. This will ensures that the wire to be wound is not sharp edged thermosets come into contact, but with suitable thermoplastics, which the processing safety of Component increased.

It is also advantageous to provide a coil former where the hardenable material or at high temperatures again deformable thermoplastic material on the one hand and that is deformable at low temperatures thermoplastic material on the other hand Have connection area in which both materials compacted mesh. This happens when both materials at the same time or with only a slight time lag be injected. This results in a special one stable connection area and high strength of the Connection of both materials. This has the further advantage that at the junction a positive and positive Connection between the two materials arises and moreover a shrinkage compensation between the materials can be done. Overall, this leads to a significant improved mechanical stability of the bobbin.

In another advantageous embodiment, that the curable material or that at high temperatures again deformable thermoplastic material on the one hand and that is deformable at low temperatures thermoplastic material, on the other hand, a micro-toothed Have connection area. This arises when first in a pre-molded part is produced and then in a second stage the pre-molded part.

In a method for producing the invention Coil body is provided that first one Injection molding tool with a first and a second Injection point for injecting different Injection molding materials is provided that the Contact elements in the area of the first injection point be arranged that the injection of a curable Material or one at high temperatures again deformable thermoplastic material through the first Injection point is such that the contact elements only partially overmolded, and that injecting one at low temperature re-malleable thermoplastic Material through the second injection point.

This method has the advantage that for the production of a coil former provided a single injection molding tool is, but for the optimization of the mechanical and electrical properties of the bobbin two in this In terms of different materials are injected can.

A thermoset is preferred as the hardenable material injected. This allows the special mechanical and thermal properties of a thermoset optimal for the Coil body are used. These properties include in particular a high dielectric strength low abrasion behavior and high Temperature resistance, also against soldering temperatures.

Thermoplastics, on the other hand, have the Advantage of high impact strength.

The hardenable material or again at high temperatures deformable thermoplastic material on the one hand and that at low temperature re-deformable thermoplastic Material on the other hand can be made according to a given time sequence are injected offset to each other. This allows an optimized arrangement and distribution of the thermoplastic and hardenable material.

A mold is possible as an injection mold in which a almost simultaneous injection at different points he follows. This makes it possible to do the injection molding process optimize that in the connection area of the two Materials results in a material densified area that has mechanically and thermally optimized properties.

Alternatively, a tool known per se is possible, in which a preform is first produced in two stages, this then translationally or rotationally to another Part of the tool is moved and in a second stage Is finished molded. The order in which the Injection takes place in the latter case is a question of professional choice and also depends on whether in each If the pinning is pre-assembled with the contact elements or done retrospectively.

It is a design that works at low temperatures re-malleable thermoplastic material in the Injection mold to inject earlier than that thermosetting material or high-temperature thermoplastics. This ensures that in the transition area of the two Materials a compression of the thermoset material results, at the same time a cavity formation of the thermoset material clearly in this area is reduced.

It is another embodiment that is low Thermoplastic material deformable in temperatures inject the injection mold later than that thermosetting material or high-temperature thermoplastics. It can be achieved that fine cracks, which are in a thin sleeve surrounding the contact elements from the thermosetting material or the high temperature thermoplastic can result from one of the low temperature Thermoplastic outgoing bracket effect, due to its Internal tension, to be compensated. This can even be constructive be used to make a thin contact element sleeve manufacture.

Finally, the invention relates to an electrical component with a bobbin and a coil in which the Bobbin has the features of the invention and after the method according to the invention is produced.

The invention is based on Embodiments described in more detail. Show it:

Fig. 1 is a schematic three-dimensional view of a bobbin according to the invention,

Fig. 2 shows a cross section through a further embodiment of a bobbin according to the invention,

Fig. 3 is a schematic view of an injection molding tool for the simultaneous injection of the thermoset or the high-temperature thermoplastic and the low-temperature thermoplastic and

Fig. 4 shows a cross section through an overmolded contact element.

In the exemplary embodiment in FIG. 1, a surface-mountable inductive component is shown. Are provided according to FIG. 1, in the elements of the device with respect to the symmetry and to improve the clarity partly on only one side of the winding tube by reference signs, a perspective view of the device is illustrated. The inductive component is in particular a coil, a transformer or a choke and can also have subdivisions of the winding space.

The coil former 10 has a winding space which is not further divided in the exemplary embodiment. The winding space is defined by a winding tube 11 , which in the exemplary embodiment is approximately circular in cross section, but can also have a different cross-sectional shape, for example ellipsoidal. The winding space or the winding tube is laterally delimited by outer flanges 12 a, 12 b. Contact strips 13 a, 13 b are integrally formed on the outer flanges 12 a, 12 b. The contact strips each contain contact elements 14 , 15 , which are pin-shaped in the exemplary embodiment and which can be connected on the one hand via winding pins 14 a to 14 d to the ends of the windings and on the other hand via printed circuit board pins 15 a to 15 d with corresponding contact surfaces, for example on a printed circuit board. The other contact strip contains in the same way in the figure not shown winding and PCB pins.

It is understood that the contact strips can also have other forms of contact elements, as are known per se for electrical components. The geometry of the electrical contact elements of the coil former is largely independent of the configuration of the contact strips 13 .

The parts of the contact elements which protrude on the underside of the contact strips, the circuit board pins 15 , are shaped such that the connection contact areas of the contact elements are bent and flattened. The flattened undersides of the PCB pins are coplanar in one plane so that the component can be easily placed on a printed circuit board and soldered. In the exemplary embodiment, these regions run in a plane that runs parallel to the axis A of the winding tube.

To make it easier to contact the winding, the contact elements are guided within the contact strips in such a way that a second part of the respective contact element, the winding pin 14 , projects laterally from the coil body. These ends of the contact elements provided for the winding contact also run essentially in one plane parallel to the axis A of the winding tube. However, the component can also be designed with push-through contact elements or other geometries of the contact elements.

According to the invention, it is now provided that the coil body 10 contains two different plastics in a combination of a thermoplastic material which can be deformed at low temperatures and a thermoplastic material which can be deformed at high temperatures, or in a combination of a thermoplastic material and a thermosetting material. It is provided in the exemplary embodiment that the contact strip 13 is formed essentially from a thermosetting material than the thermosetting material, and the area of the winding space with the winding tube 11 and the outer flanges 12 is formed from a thermoplastic material, in particular a low-temperature thermoplastic. The low-temperature thermoplastic material may be an inexpensive normal thermoplastic, since, due to the invention, this will not be exposed to high temperatures and need not be a high-temperature thermoplastic such as PEEK (polyether ether ketone) or LCP (liquid crystal polymer), while the latter materials are intended for contact element encapsulation could be.

The coil former shown in FIG. 1 is produced in one operation, for example by means of the illustration in FIG. 3, in that a casting tool 30 is provided, which consists of a lower part 31 , an upper part 32 and optionally an insulation 33 arranged between these two molded part halves consists. Furthermore, a core 34 is provided for producing the winding tube. The injection mold has two injection points 35 and 36 . Through the injection point 35 is preferably thermosetting material such as phenolic and cresol resins, for. B. phenol formaldehyde, and through the injection point 36 thermoplastic material such as polybutylene terephthalate, polyethylene, PVC or polyamide. As a special feature, it is provided that the injection point 35 branches out and contains injection channels in each case for the contact strip regions provided. For the sake of simplicity, the figure does not show the contact elements 14 , 15 to be introduced into the contact strip regions 37 a or 37 b before injection molding, as shown in FIG. 1.

In the area of the lower part 31 of the injection molding tool, heating channels or heating elements 38 , not individually identified, are provided around the areas 37 a, 37 b for the contact strips to be produced. With coolants, not shown, for. B. cooling channels, on the other hand, the upper part 32 of the injection mold can be cooled. This takes into account the different processing properties of thermoplastics and thermosets. Temperature compensation between the heatable lower part 31 and the coolable upper part 32 is prevented or at least made more difficult by the insulating layer 33 .

It is provided that the thermosetting plastic is first injected into the injection molding tool through the injection 35 and is distributed over the area of the later contact strip to the areas for the later flanges. With the help of the effective heating of the lower part, the thermoset is heated and cross-linked. In the upper part, a thermoplastic is injected at different times from the injection of the thermoset by the injection 36 . The thermoset material in these areas has not yet solidified due to the cooler areas 32 and is now pressed into the areas of the coil and the transition areas of the later contact strips by the injected thermoplastic. The curing of the thermosetting plastic in the lower part 37 of the tool prevents the thermoplastic from pressing the thermosetting plastic back into the injection 35 .

In the areas 37 , the inflowing thermoset typically flows in with an undensified flow front, which is also severely torn up to the thermoplastic area boundary. Thermoplasts are largely incompressible per se, so that only a little fissured flow front of the thermoplastic has formed. When the thermoplastic bumps against the thermoset, the thermoplastic flow front will compress the thermoset, thereby compensating for uneven fillings and achieving a good compression of the thermoset material. Since the core of the thermoset part hardens last, thermoplastic material can penetrate into the interior of the thermoset contact strip.

The penetration of the thermoplastic melt into the thermosets takes place primarily through the high injection pressure. With the aid of this method, an inaccurate filling of the thermoset in the comparatively small volume of the region 37 is therefore largely compensated for as a further advantage. There are no burrs at the junction between the thermoset and the thermoplastic because the thermoset penetrates into the thermoplastic and there is no tool separation. In addition, there is the advantage that the thermoset is compressed by the thermoplastic, thus creating a denser thermoset area that is also mechanically more stable.

Furthermore, a clear formation of cavities is achieved in this way the thermosetting flow front prevented.

It goes without saying that the manufacture is also in itself known two-step process can be done, first in a first injection of a first part of the tool a preform and then after one translatory or rotary movement of a turntable or after removing a slide in a second stage of Finished molding is produced. The translational or rotary variant also has like the one previously described Process the advantage of low clock rates.

Referring to FIG. 2 is a sectional image display is provided showing a plug mountable coil body according to the invention in cross section. The special feature of the illustration chosen in FIG. 2 compared to FIG. 1 is that the contact elements 24 , 25 of the contact strips 23 a, 23 b have contact connections 25 projecting downward from the coil body 20 perpendicular to the axis A of the winding tube. The manufacturing method according to the invention has achieved that the essential part of the contact elements is embedded in a thermoset 26 . Due to the peculiarity of the shape, a wire guide slot 21 can also be seen in cross section in the thermoplastic region 27 , which leads to the winding pins 24 . This makes it possible to contact the reel to be wound directly via the wire guide slots to the winding pins.

FIG. 4 shows a contact element 40 which is surrounded by a thermosetting or a high-temperature thermoplastic sleeve 41 which is embedded in a low-temperature thermoplastic 42 . The expensive sleeve material 41 can be minimized in this way, since even if cracks occur in the sleeve, the low-temperature thermoplastic 42 exerts a clamping effect due to its elasticity, which stabilizes the sleeve. The transition area between the two materials forms secure micro-gearing. Conversely, the sleeve protects the low-temperature thermoplastic 42 thermally during a later soldering process, since the sleeve is poorly heat-conducting.

Claims (15)

1. coil body with a winding space and a molded thereon, contact elements containing contact strip, characterized in that the coil body ( 10 ; 20 ) two different plastics in a combination of a thermoplastic material which can be deformed at low temperatures and at high temperatures or in a combination contains a thermoplastic material and a thermosetting material. 2. coil former according to claim 1, characterized, that the curable material is a thermoset. 3. Coil body according to claim 1 or 2, characterized in that the hardenable material ( 26 ) or the thermoplastic material which can be deformed again at high temperatures partially embeds the contact elements ( 24 , 25 ) in the region of the contact strip of the coil body ( 20 ) and that the low-temperature deformable thermoplastic material ( 27 ) is provided in the area of the winding space. 4. coil former according to claim 1 to 3, characterized in that the curable material in the region of the contact strip ( 13 ) is at least partially surrounded by the thermoplastic material which can be deformed again at low temperatures. 5. Bobbin according to one of claims 1 to 4, characterized in that the winding wire receiving areas of the contact strip ( 13 ) and the winding space are formed from the thermoplastic material ( 27 ) which can be deformed again at low temperatures. 6. coil former according to one of claims 1 to 5, characterized, that the curable material or that at high temperatures again deformable thermoplastic material on the one hand and that is deformable at low temperatures thermoplastic material on the other hand Have connection area where the materials compacted mesh. 7. coil former according to one of claims 1 to 5, characterized, that the curable material or that at high temperatures again deformable thermoplastic material on the one hand and that is deformable at low temperatures thermoplastic material, on the other hand, a micro-toothed Have connection area. 8. A method for producing a coil former according to one of claims 1 to 7, characterized by the following steps: - Providing an injection molding tool ( 30 ) with a first and a second injection point ( 35 , 36 ) for injecting different injection molding materials, Arranging the contact elements in the area ( 37 a, 37 b) of the first injection point, Injecting a hardenable material or a thermoplastic material that can be deformed at high temperatures through the first injection point in such a way that the contact elements are only partially overmolded, and - Injecting a thermoplastic material ( 35 , 36 ) which is deformable at low temperatures through the second injection point. 9. The method according to claim 8, characterized, that the curable material or that at high temperatures again deformable thermoplastic material on the one hand and that is deformable at low temperatures thermoplastic material on the other hand according to a predetermined time sequence are injected to each other. 10. The method according to any one of claims 8 to 9, characterized, a thermoset is injected as a hardenable material. 11. The method according to any one of claims 8 to 10, characterized, that the deformable at low temperatures thermoplastic material is injected rather than that hardenable material or again at high temperatures deformable thermoplastic material or that the temporal Injection sequence is reversed. 12. The method according to any one of claims 8 to 11, characterized, that first in a part of the injection mold Preform is made and then after one translatory or rotary movement of the Pre-molded in another part of the injection mold a finished molding is produced. 13. The method according to any one of claims 8 to 12, characterized, that the two injections using one Isolating slide are carried out one after the other. 14. The method according to any one of claims 8 to 10, characterized, that the deformable at low temperatures thermoplastic material on the one hand and the curable material or that which can be deformed at high temperatures thermoplastic material on the other hand at the same time be injected. 15. Electrical component from a coil former and one a coil, marked with a Coil former according to one of the claims 1 to 14.