TW202329171A - Method for producing an inductive component, and inductive component - Google Patents

Abstract

The invention relates to a method for producing an inductive component having an electrically conductive coil and having a magnetic material which at least sectionally surrounds the coil, wherein the coil has a helical part and at least two connection points which are connected electrically to the helical part, wherein the following steps are provided: producing a preform from a compound containing particles of the magnetic material, wherein the compound contains in particular the magnetic material in powder form, for example ferrite powder, and a binder, wherein the preform has a cavity, the outer contour of which corresponds or is similar to an outer contour of the coil, sintering the compound forming the preform and consequently forming a mould composed of magnetic material, filling the cavity of the mould composed of the magnetic material with liquid metal, in particular copper, and cooling the metal and consequently forming the coil with the helical part and the connection points.

Description

Manufacturing method of inductance element and inductance element

The invention relates to a method for manufacturing an inductive element having an electrically conductive coil with a magnetic material at least partially surrounding the coil, wherein the coil has a helical portion and at least two coils electrically connected to the helical portion. connection point. The invention also relates to an inductive component produced by the method according to the invention.

In the case of miniaturization of the inductance element, when the current carrying capacity is high, the electric power loss is significant. A problem here may be the connection of the helical part to the connection point, which is usually realized in the form of a solder or solder point. Consequently, the connection of the coil to the connection point has a higher ohmic resistance, possibly even a different ohmic resistance over the entire cross-section of the solder joint or solder point. In the case of miniaturization of inductive components, for high ampacities, this can lead to power losses that are no longer tolerable.

A method of manufacturing an inductive element and an inductive element are intended to be improved by the present invention.

In this regard, according to the present invention, there are provided a method having the features of claim 1 and an inductance element having the features of claim 9 . Advantageous refinements of the invention are specified in the subclaims.

In a method for manufacturing an inductive element, the inductive element has an electrically conductive coil and has a magnetic material at least partially surrounding the coil, wherein the coil has a helical portion and at least two connections electrically connected to the helical portion point, wherein the following steps are provided: producing a preform from a compound containing particles of the magnetic material, wherein the compound in particular contains the magnetic material in powder form (for example ferrite powder) and a binder , wherein the preform has a cavity with an outer contour corresponding to or similar to an outer contour of the coil; sintering the compound forming the preform, and thus forming a mold of the magnetic material; with Liquid metal, in particular copper, fills the cavity of the mold formed of the magnetic material; and cools the metal, and thus forms the coil with the helical portion and the connection points.

Casting of the coil allows the helical portion and connection point to be formed in one piece. In this way, it is not necessary to produce a connection between the connection point and the screw part in a separate working step. Thus, it can be ensured that a connection between the connection point and the helical part does not differ in electrical properties from the connection point and the helical part. In particular it can be ensured that a connection between the connection point and the helical part has uniform electrical properties over the entire cross-section, and in particular a uniform ohmic resistance. Therefore, casting the coil with the helical parts and the connection points as a one-piece coil offers considerable advantages with regard to the electrical properties of the coil. Furthermore, in the case of a finished inductive element, the coil is cast in a mold formed by magnetic material surrounding the coil. After the liquid metal has cooled, the inductive element is thus in a substantially finished state. In particular, the hitherto known work-intensive method steps of embedding a helical part in a magnetic material in powder form and then pressing the magnetic material in powder form in order to form one of the magnetic materials with a conductive coil and with a surrounding coil Inductive components can be disposed of. Therefore, the method according to the invention not only enables the electrical properties of the inductive element to be significantly improved, but moreover, the method according to the invention also allows efficient manufacture of the inductive element.

In a refinement of the invention, it is provided to manufacture a one-piece mold of magnetic material by sintering the compound forming the preform.

For example, the compound contains magnetic material in powder form (for example, ferrite powder) and a plastic-based binder. The compound forms a preform, which is then sintered. During sintering, the binder is expelled and the magnetic material in powder form is sintered together to form a solid. This is achieved by forming so-called sinter necks, by which individual particles of magnetic material are bonded. After the magnetic material has been formed into a solid, the mold formed in this way can be filled with liquid metal to form a coil with helical portions and connection points. During sintering, a shape change procedure, in particular a shrinkage procedure, takes place so that the cavity of the preform usually only resembles that of the finished mold. In a refinement of the invention, the cavity of the mold is filled before the mold made of magnetic material has completely cooled.

In this way, the method according to the invention enables structural engineering in a very advantageous manner in terms of energy. The metal must be liquid in order to be able to fill the cavity in the mold. However, if the mold has not cooled completely after sintering, this facilitates the flow of metal into and through the mold.

In a refinement of the invention, provision is made to manufacture the preform from two mold halves and a mold core, wherein a cavity corresponding to or similar to the helical portion is formed between the mold core and the two mold halves.

For example, mold halves and mold cores are manufactured from ferrite powder mixed with a plastic binder and brought together to form a preform. During sintering of the preform, the two mold halves and the mold core are then joined to form a one-piece mould, since a sinter neck is also formed between the contact surfaces of the two mold halves and the mold core. In other words, the two mold halves and the mold core are sintered together in order to then form a one-piece mold which can be filled with liquid metal.

In one refinement of the invention, provision is made to bond the mold halves and mold cores prior to sintering.

In a refinement of the invention, a binder mixed with the particles of magnetic material is used as the adhesive.

In a refinement of the invention, the binder includes water glass.

Adhesion of the mold halves and core prior to sintering facilitates the handling of the preform and provides a reliable formation of a one-piece mold by sintering. Here, it has been found that water glass mixed with particles of magnetic material, for example with ferrite powder, is very suitable for producing one-piece molds from multiple mold components during sintering. Water glass refers to amorphous, water-soluble sodium silicate (Na ₂ SiO ₃ ), potassium silicate (K ₂ Si ₂ O ₅ ) or lithium silicate (Li ₂ SiO ₃ ).

In a refinement of the invention, provision is made to coat the cavity in the mold with a temperature-resistant and electrically insulating layer, in particular water glass, before filling the cavity with liquid metal.

Water glass can form an electrical insulation layer between the coil and the magnetic material. Water glass, whether molten or water-miscible, is liquid, and thus can be used for lining or wetting cavities. After the water glass has solidified or dried, the water glass remains as a layer on the inner surface of the mold when the mold is filled with liquid metal (eg copper). In this way, the electrical properties of the inductive element can be significantly improved, since then the layer of water glass forms an electrically insulating layer between the magnetic material (eg ferrite) and the coil (eg a copper coil).

The problem on which the invention is based is also solved by producing an inductive element according to a method according to the invention in which the coil is formed in one piece and the connection point is formed in one piece with the helical part.

This inductive element has very good electrical properties because the ohmic resistance at the junction between the junction and the helix is no different from the ohmic resistance of the junction or the helix. In particular, electrical power losses at the connection between the connection point and the helical part are avoided in this way.

In a refinement of the invention, the magnetic material surrounding the coil is integrally formed.

In this way, improved electrical properties are achieved because, due to the integral formation of the magnetic material surrounding the coil, there are no air gaps and losses are thus avoided. By sintering the mold halves and mold cores to form a one-piece component, the magnetic material surrounding the coil can be formed into one piece.

In a method according to the invention for producing an inductive element having an electrically conductive coil and having a magnetic material at least partially surrounding the coil, it is first provided that a preform is produced from a compound containing particles of the magnetic material. For example, the compound contains magnetic material in powder form (eg, ferrite powder) and a binder (eg, a plastic-based binder). Next, the preform 10 shown in FIG. 1 has a cavity (not visible in FIG. 1 ), the outer contour of which corresponds or is similar to that of the coil.

According to FIG. 1 , the preform 10 consists of a lower mold half 12 , an upper mold half 14 and a mold core 16 . The two mold halves 12, 14 and the mold core 16 will be described in detail below. As mentioned above, the mold halves 12, 14 and the mold core 16 are manufactured from a compound containing particles of magnetic material and a binder. Next, the two mold halves 12 , 14 are brought together and the mold core 16 is inserted in such a way that the preform 10 depicted in FIG. 1 is formed. Next, the mold halves 12, 14 and the mold core 16 are joined to each other by sintering, so that after sintering they form a one-piece mold. During sintering, so-called sinter necks are formed between the particles of magnetic material, in other words, the binder is expelled because high temperatures are used during sintering and the particles of magnetic material are combined to form a solid. In this case, shape change procedures, in particular shrinkage procedures, can take place. For this reason, the cavity in the preform 10 usually only resembles the outer contour of the finished coil. In contrast, the cavity in the sintered one-piece mold corresponds to the outer contour of the finished coil.

Thus, after sintering, there is a one-piece mold in which a cavity is formed, the outer contour of which corresponds to the outer contour of the coil, ie the connection points and the helix. Next, the cavity is filled with liquid metal, for example liquid copper. In this way, a one-piece coil is formed, and specifically, the connection point and the helical part of the coil are formed in one piece, so that no excess volume than the connection point and the helical part occurs at the connection between the connection point and the coil. Greater electrical power loss.

After the liquid metal has cooled, the inductive element is then largely completed, since the mold consists of magnetic material which, in the finished state of the inductive element, surrounds the coil.

To obtain energy advantages, the mold is also filled with liquid metal after sintering and before complete cooling. This facilitates the distribution of liquid metal in the cavity. Copper has a melting point in the range of approximately 1000°C to 1100°C. For example, the preform 10 is sintered at a temperature in the range of 800°C to 900°C. Filling of the one-piece mold can be achieved while the mold still has a temperature of between about 500°C and 600°C.

Figure 2 shows the lower mold half 12 and the mold core 16 with the upper mold half 14 removed. Between the mold core 16 and the lower mold half 12, three grooves 18 formed in the lower mold half 12 are now visible. The groove 18 is closed by the outer surface of the cylindrical core 16, so that the mold core 16 and the groove 18 thus form a section of a cavity, the outer profile of which corresponds to or is similar to the outer profile of the helical part. During filling with liquid metal, the section of the helical portion is thus formed in the groove 18 .

FIG. 3 shows the lower mold half 12 in a view from above. It can be seen that the lower mold half 12 has a basic shape of a cube with a recess 20 in the form of a semicircular cylinder. The groove 20 (see FIGS. 1 and 2 ) matches the cylindrical mold core 16 so that thus half of the mold core 16 (see FIG. 2 ) can be received in the groove 20 and, during the procedure, the mold core 16 The outer surface seals against the surface of the groove 20 . Grooves 18 are both formed in grooves 20 . The view in FIG. 3 further shows two holes 22 which extend from the top side of the lower mold half 12 down to the bottom side thereof. In the finished mould, the hole 22 forms a cavity with an outer contour corresponding to the outer contour of the coil attachment point. Liquid metal may be introduced through one or both of the holes 22 .

A protrusion 24 in the form of a hemisphere can be seen on the top side of the lower mold half 12 . This protrusion 24 engages into a suitable groove of the upper mold half 14 and thus ensures the correct orientation of the lower mold half 12 and the upper mold half 14 . A further protrusion is provided to ensure the correct orientation of the two mold halves 12 , 14 and the core 16 . However, since the mold core 16 also contributes to the correct orientation of the lower mold half 12 and the upper mold half 14, in the illustrated embodiment a single protrusion 24 is sufficient for both mold halves 12, 14 the correct orientation.

Figure 4 shows the finished mold 11 after sintering from the bottom side. For the sake of clarity, the dashed parting line between the two mold halves 12 , 14 and the mold core 16 is also shown in FIG. 4 . After sintering, however, the separation lines are generally no longer visible and the mold 11 forms a one-piece component at any rate after sintering.

Hole 22 is visible on the bottom side. In the finished mold 11 , holes 22 are used to introduce liquid metal, for example liquid copper, in order to form the coil in the mold 11 in this way.

Before filling the cavity of the mold 11 with liquid metal, the cavity of the mold 11 may be wetted or lined with liquid water glass. The water glass then solidifies on the surface of the cavity and after filling with liquid metal also forms an insulating layer between the metal of the coil and the magnetic material of the mold 11 . The surfaces of the two mold halves 12, 14 and the core 16 form the cavity and after the two mold halves 12, 14 and the mold core 16 are brought together and sintered the mold 11 is then formed, which can be coated with water glass before sintering. These surfaces of the two mold halves 12 , 14 and the core 16 are covered. This results in the mold halves 12, 14 and mold core 16 being bonded at the contact surfaces of the mold halves 12, 14 and mold core 16 prior to sintering. This facilitates the handling of the so-called green body before the preform 10 is sintered. The filling with water glass can also take place only after sintering, ie in the cavity of the finished mold 11 . As already discussed, after filling with liquid metal, the layer of water glass may then form at the surface of the cavity an electrically insulating layer between the metal and the magnetic material of which the mold 11 consists.

FIG. 5 shows the upper mold half 14 in a view obliquely from below. A recess 26 in the form of a hemisphere can be seen, formed in such a way as to match the hemispherical protrusion 24 on the lower mold half 12 (see FIG. 3 ). The protrusions 24 and grooves 26 provide for correct orientation of the mold halves 12, 14 relative to each other when the mold halves 12, 14 are placed one on top of the other. Rotation of the two mold halves 12 , 14 around the protrusion 24 or groove 26 is prevented by placing the mold core 16 .

The upper mold half 14 likewise has a recess 20 in the form of a half cylinder. In this groove, a total of three grooves 18 each having a semicircular cross-section can be seen, which extend over 180°. The grooves 18 then form together with the surface of the mold core 16 a cavity having an outer contour corresponding to or similar to that of the section of the helical part of the coil.

FIG. 6 shows an inductive element 30 according to the present invention. Element 30 has mold 11 formed from magnetic material 32 . Inside the magnetic material 32 , a coil (not visible in FIG. 6 ) is arranged in the cavity of the mold 11 . The coil 40 is electrically connected at the bottom side of the cube of magnetic material 32 by means of two electrical contact surfaces 34 . Within the context of the present invention, the contact surfaces 34 can be produced with liquid metal when filling the mold 11 (see FIG. 4 ); however, they can also be coated on the underside of the magnetic material 32 at a later stage.

FIG. 7 shows a cross-sectional view of the inductance element 30 in FIG. 6 . It can be seen that the magnetic material 32 is integrally formed. The helical portion 36 within the magnetic material 32 is also shown and is depicted multiple times in the cross-sectional view of FIG. 7 .

FIG. 8 shows a coil 40 of an inductive element 30 according to the invention, wherein the magnetic material 32 has been omitted, and wherein the coil 40 is formed by the helical portion 36 and the connection point 38 . As already discussed, the connection point 38 and the helical portion 36 are formed when the mold 11 is filled, and thus the coil 40 is in one piece. In a connection region between the connection point 38 and the helical portion 36 , the ohmic resistance per unit cross-sectional area is thus the same as in the other regions of the connection point 38 and the helical portion 36 .

The separation lines between the connection point 38 and the helical part 36 and in the course of the helical part 36 are only auxiliary lines in the diagram of FIG. 8 . As mentioned above, the coil 40 is manufactured as a one-piece component by casting.

As mentioned above, the contact 34 can be manufactured simultaneously when the mold 11 is filled, or it can be applied and connected to the connecting portion 38 at a later stage.

In the embodiment discussed, the mold core 16 (see FIG. 2) is in the form of a cylinder. This results in a semi-circular cross-sectional shape of the helical portion 36 . Within the context of the present invention, the cross-sectional shape of the helical portion 36 and the connection point 38 can be freely selected. For example, the surface of the mold core 16 may be provided with grooves having a semicircular cross-section, so as to also give the helical portion 36 a circular cross-section. The connection point 38 does not necessarily have to be cylindrical. For example, the cross-section of the connection point 38 may widen towards the contact surface 34 in order to allow an electrical connection between the contact 34 and the connection point 38 with the smallest possible losses.

Fig. 9 shows a further cross-sectional view of an inductive element 30 according to the invention. In the view of FIG. 9 , the magnetic material 32 is shown in transparent form. Thus, in the illustration in FIG. 9 , a cross-section of the spiral portion 36 , the connection point 38 and the contact piece 34 can be seen.

FIG. 10 shows a further cross-sectional view of the inductive element 30 . Compared to FIG. 9 , the cross section has been shifted towards the viewer and the magnetic material 32 is again shown in transparent form. Thus, the cross-sectional view in FIG. 10 shows the complete coil 40 embedded in the magnetic material 32 such that only the face side of the connection point 38 is still accessible from the bottom side of the cube-shaped magnetic material 32 . Contacts 34 are also arranged on the bottom side.

10: Preform 11:Mold 12: Lower mold half 14: Upper mold half 16: Mold core 18: Groove 20: Groove 22: hole 24:Protrusion 26: Groove 30: Inductive element 32: Magnetic material 34: Contact surface/contact piece 36: spiral part 38: Connection point 40: Coil

Further features and advantages of the present invention emerge from the claims and the following description of a preferred embodiment of the present invention. In the schema: Figure 1 shows a perspective view of a preform used in the method according to the invention, Figure 2 shows the preform of Figure 1 with one upper mold half removed, Fig. 3 shows the lower mold half of the preform in Fig. 1 in a perspective obliquely from above, FIG. 4 shows a perspective view of a mold formed by sintering from the preform in FIG. 1 from a view from below, Figure 5 shows the upper mold half of the preform in Figure 1 from a perspective angled from below, Fig. 6 shows a finished inductive element according to the present invention in a perspective obliquely from the front, Figure 7 shows a cross-sectional view of the inductive element in Figure 6, Fig. 8 shows a coil of one of the inductive elements in Fig. 6, wherein the surrounding magnetic material has been omitted, Figure 9 shows a cross-sectional view of the inductive element of Figure 6, with the magnetic material surrounding the coil shown in transparent form, and Figure 10 shows a further cross-sectional view of the inductive element of Figure 6, with the magnetic material surrounding the coil shown in transparent form.

10: Preform

12: Lower mold half

14: Upper mold half

16: Mold core

Claims (10)

A method for manufacturing an inductive element (30) having an electrically conductive coil (40) with a magnetic material (32) at least partially surrounding the coil (40), wherein the coil (40) has a helix part (36) and at least two connection points (38) electrically connected to the helical part (36), the method comprising the steps of: manufacturing a preform (10) from a compound containing particles of the magnetic material (32) ), wherein the compound specifically contains the magnetic material (32) in powder form, for example ferrite powder, and a binder, wherein the preform (10) has a cavity whose outer contour corresponds to at or similar to the outer contour of the coil (40); sintering the compound forming the preform (10) and thus forming a mold (11) of magnetic material (32); with liquid metal, specifically filling the cavity of the mold (11) made of the magnetic material (32) with copper; and cooling the metal, and thus forming the coil (40) with the helical portion (36) and the connection points. The method according to claim 1, wherein the mold (11) composed of magnetic material (32) is integrally manufactured by sintering the compound forming the preform (10). The method according to claim 1 or 2, wherein the cavity is filled before the complete cooling of the mold (11) made of the magnetic material (32). A method according to any one of the preceding claims, wherein the preform (10) is manufactured from two mold halves (12, 14) and a mold core (16), wherein the helical The cavity of part (36) is formed between the two mold halves (12, 14) and the mold core (16). The method according to claim 4, wherein, before the sintering, the mold halves (12, 14) and the mold core (16) are bonded. The method according to claim 5, wherein the binder comprises a binder mixed with particles of the magnetic material (32). The method according to claim 6, wherein the binder comprises water glass. The method of at least one of the preceding claims, wherein, prior to the filling of the cavity with liquid metal, the preform (10) or the preform (10) or the preform (10) is coated with a temperature-resistant and electrically insulating layer, in particular water glass The cavity in the mold (11). An inductive element (30) manufactured by a method according to at least one of the preceding claims, wherein the coil (40) is formed in one piece such that the connection points (38) are integrally formed with the helical part (36) . The inductance element according to claim 9, wherein the magnetic material (32) surrounding the coil (40) is integrally formed.