Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F17/00—Fixed inductances of the signal type 
  • H01F17/0006—Printed inductances
  • H01F17/0033—Printed inductances with the coil helically wound around a magnetic core
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F17/00—Fixed inductances of the signal type 
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F30/00—Fixed transformers not covered by group H01F19/00
  • H01F30/06—Fixed transformers not covered by group H01F19/00 characterised by the structure
  • H01F30/16—Toroidal transformers
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F27/00—Details of transformers or inductances, in general
  • H01F27/28—Coils; Windings; Conductive connections
  • H01F27/2804—Printed windings
  • H01F2027/2814—Printed windings with only part of the coil or of the winding in the printed circuit board, e.g. the remaining coil or winding sections can be made of wires or sheets

Definitions

• the invention relates to an inductive component, in particular a miniaturized inductive component in a flat design.
• inductive components are produced by wrapping magnetic cores with metallic wires, in particular enamelled copper wires.
• split magnetic cores are used, the windings m generally being applied to a coil former and the coil former being plugged onto a part of the magnetic core. Then the magnetic core is put together and the magnetic core thus provided with windings is inserted into a housing.
• undivided magnetic cores so-called ring cores. These undivided magnetic cores are wound directly.
• closed core shapes e.g. Toroidal cores, the winding wire is pulled through the magnetic core inner hole.
• the windings are applied to the magnetic core in layers with or without a coil former.
• Toroidal winding machines on the one hand and winding by hand on the other hand prevent the wire thickness from being reduced and the use of very small magnetic cores.
• These procedural specifications typically only use enamelled copper wires in the diameter range between 0.05 and 0.15 mm, although in many cases significantly smaller diameter ranges would suffice from the electrical dimensioning.
• the closed magnetic core shape usually forces a residual hole, which leads to a reduced utilization of the construction volume.
• an inductive component which consists of a magnetic core, a substrate on the upper surface of which the magnetic core is applied, and at least one winding around the magnetic core, the windings of the windings consisting of conductor tracks which are on or in or under are attached to the substrate, and consists of bonded wires guided over the magnetic core between opposite ends of adjacent conductor strips.
• a miniaturized construction can be represented, in particular for closed magnetic cores, with which miniaturized inductive components can be produced in an inexpensive manner.
• the substrate also serves to fix the magnetic core and also offers the possibility of carrying the contacts necessary for connecting the inductive component.
• a circuit board in particular a so-called chip-on-board substrate, expediently serves as the substrate.
• chip-on-flex or chip-on-glass substrates can also be used. These substrates have proven to be very cheap, since with the multi-layer technology very complicated winding arrangements with a large number of turns can be achieved. In particular, with such substrates, an extremely dense covering of the available inner core hole with bonded wires is possible without leaving a residual hole.
• semiconductor substrates in particular those made of silicon, or substrates made of ceramic, in particular made of A1 2 0 3 or A1N, as substrates.
• semiconductor substrates in particular those made of silicon, or substrates made of ceramic, in particular made of A1 2 0 3 or A1N, as substrates.
• This has the advantage that the metallization methods available from semiconductor technology can be used.
• assembly compatibility with active semiconductor components can be achieved, so that inductive components produced with ceramic substrates can be introduced into power semiconductor modules or inductive components produced on silicon substrates, e.g. B. can be introduced into integrated circuits using chip-on-chip technology.
• the conductor tracks are arranged inside the substrate and the ends of the conductor trains are exposed on the upper surface of the substrate.
• the conductor tracks are arranged on the lower surface of the substrate and the ends of the conductor tracks are again exposed on the upper surface of the substrate.
• metallic pads are provided as the ends of the conductor tracks.
• the windings consist exclusively of bonding wires.
• bond wires are provided instead of the conductor tracks, which are attached very flatly above the substrate. Therefore, two bond connections are made on each metal pad.
• This embodiment has the advantage that the manufacturing process is facilitated by the known and reliable bonding process and at the same time a very inexpensive substrate can be used on which no conductor tracks have to be structured. This brings with it a cost advantage.
• the substrate has a depression in its upper surface, into which the magnetic core is introduced. This enables a particularly flat design for the inductive components. Furthermore, the recess facilitates the adjustment and fixation of the magnetic core during the manufacturing process.
• the magnetic core can be glued to the upper surface, but it is also conceivable to solder the magnetic core to the upper surface of the substrate.
• the "pad” that is, the terminals on the substrate for the electrical connections, are preferably deposited from up ⁇ aluminum or metallic multi-layer systems and serve as a circuit Connections for bonding. When bonding wires of gold or aluminum wires are used. It is however also conceivable to use other materials to use.
• wire thicknesses of approx. 30 ⁇ m can be used.
• the end of the wire is melted into a ball.
• the end of this is squeezed onto the metal pad, preferably an aluminum pad, at a temperature of approximately 200 ° C. from a hard metal cannula.
• the adhesive strength of this thermocompression bond is at least 50 mN.
• the materials to be joined are pressed together while supplying heat. Interatomic forces and diffusion at the interface mean that welding takes place without the occurrence of a liquid phase.
• the wires are bonded using ultrasound.
• ultrasonic bonding is a friction welding process without the supply of heat from outside.
• the wire is passed through a guide hole of a wedge-shaped contact tool, lowered onto the connection surface and deformed by pressure.
• the connection partners are then moved parallel to one another with a low amplitude.
• Surface layers tear, e.g. the oxide layer of an aluminum pad. Roughness is reduced, so that the surfaces are brought closer to the metallic connection.
• Both ultrasound bonding and thermocompression bonding are methods known from semiconductor technology. Common to both processes is that they have been standard processes in the field of semiconductor technology for over 20 years are tried and tested and have a high degree of automation.
• the typical contact area on printed circuit boards is approx. 150 x 150 ⁇ m, which, including the distance to the neighboring pad, means a contact area density of approx. 9 connections per m " . This value increases with the minimum possible pad size of approx. 60 x 60 ⁇ m about 40 connections per mm 2.
• the height of the bond connection above the circuit board level is a minimum of 120 to 150 ⁇ m.
• Closed magnetic cores are preferably used for the magnetic cores, since the highest permeabilities are achieved here.
• toroidal tape cores are preferably provided.
• disc cores e.g. created by punching from a sheet, more suitable.
• Soft magnetic alloys in particular amorphous or nanocrystalline alloys, are to be considered as particularly suitable magnetic materials. The advantage of soft magnetic alloys over ferrite magnetic cores lies in the significantly higher permeabilities, in the saturation induction that is two to three times higher, and in the magnetostriction that is negligible depending on the alloy.
• Magnetic cores based on sputtered or otherwise deposited are also available for extremely flat designs
• Layers of soft magnetic alloys possible.
• the alternating stacking of layers of soft magnetic material and an electrical insulator enables a laminated structure with correspondingly good high-frequency behavior to be achieved.
• Figure 1 is a schematic representation of a perspective view of a ⁇ An inductive component in accordance with the vorlie ⁇ constricting invention
• FIG 2 is a plan view of an alternative embodiment of the present OF INVENTION ⁇ dung a section along the line II of Figure 1, Figure 3 in a schematic representation,
• FIG. 4 shows a section along the line II-II from FIG. 3,
• FIG. 5 shows a schematic representation of a top view of a further embodiment according to the present invention
• FIG. 6 shows a section along the line III-III from FIG. 5
• FIG. 7 shows a schematic illustration of a cross section through a simple embodiment of the present invention
• FIG. 8 shows a schematic illustration of a cross section through a further embodiment of the present invention
• FIG. 9 shows a perspective view of a possible construction of the inductive component of the present invention in a schematic illustration
• FIG. 10 9 shows a section along the line IX-IX from FIG. 9
• FIG. 11 shows a perspective view of a further structure of the inductive component according to the present invention
• FIG. 12 shows a section along the line XI-XI from FIG. 11, FIG. 13 in a schematic representation 3 shows a cross section through a further embodiment of the present invention
• FIG. 14 shows a plan view of the component from FIG. 13,
• FIG. 15 shows a schematic illustration of a cross section through a further embodiment of the present invention,
• FIG. 16 shows a perspective illustration in a schematic illustration
• 17 shows an exemplary layout on the upper surface of the substrate a tape core with a ring Doppelübertragers ⁇ and concentric structure of two windings
• FIG. 18 shows the layout corresponding to FIG. 15 on the lower surface of the substrate
• Figure 19 is a schematic representation of a perspective
• FIG. Figure 2 shows a section along the line I-I of the same structure.
• the inductive component according to the present invention consists of a substrate 1 with an upper surface 2 and a lower surface 3.
• a depression 4 is made in the upper surface 2 of the substrate 1.
• the magnetic core 5 shown here is an annular band core made of an amorphous soft magnetic alloy.
• Conductor tracks 6 are arranged on the lower surface 3 of the substrate 1.
• the ends 7 of these conductor tracks 6 are exposed on the upper surface 2 of the substrate 1, since the conductor tracks 6 are contacted through from the lower surface 3 to the upper surface 2 of the substrate 1 via substrate conductor tracks 6 '.
• the ends 7 of the conductor tracks on the upper surface 2 of the substrate 1 have the shape of small metal surfaces, so-called pads 8.
• Wires 9 ' are bonded to the pads 8' of the respective winding ends 1 ', which lead to connection conductors 10, which in turn are connected to contact connections 11.
• the windings of the winding of the inductive component consist of the conductor tracks 6 applied to the lower surface 3 of the substrate 1, the substrate conductor tracks 6 ′ guided through the substrate 1 and the ones on the upper surface 2 of the substrate 1 the pads 8 bonded wires 9.
• FIGS. 3 and 4 show a further embodiment of the present invention, in which the substrate 1 has middle planes E1, E2 and E3, which are each provided with conductor tracks 6.
• the substrate 1 shown here is a chip-on-board circuit board, which consists of epoxy glass.
• the available area of the core inner hole 12 is optimally used for the arrangement of ends 7 of the conductor tracks 6.
• the ends 7 of the conductor tracks 6 shown here again have the shape of pads 8 made of aluminum.
• the substrate has the three levels E1, E2 and E3 and three windings, each with 24 turns, are shown.
• the magnetic core 5 shown is square and consists of a large number of magnetic foil disks stacked one above the other made of a nanocrystalline alloy.
• FIGS. 5 and 6 show an embodiment of the present invention, in which a substrate 1 consisting of ceramic Has substrate conductor tracks 6 ', which ensures the change of the line routing from the upper surface to the lower surface of the substrate and vice versa and has the mechanical function of a magnetic core carrier.
• the magnetic core 5 is located here on radial connecting webs 13 between a central portion 14 and an outer part 15 of the substrate 1.
• the ra ⁇ Diale leadership of the conductor part 6 is achieved on both sides of the magnetic core 5 by bonded wires.
• a plastic cover cap 16 is used here. In addition to the protective function, the cover cap 16 also ensures a flat surface for mounting, as is customary in SMD components with the aid of vacuum pipettes using the customary “pick-and-place” technology.
• FIG. 7 shows an embodiment of the present invention in which a structure is implemented on a planar substrate.
• the construction of the inductive component is realized exclusively with bonding wires.
• the substrate 1 has 2 pads 8 on the upper surface. The pads are arranged so that they are arranged concentrically around a center point on the upper surface 2 in a ring band core. Each two opposing pads 8 are connected to a lower bond wire 9 'and an upper bond wire 9.
• the lower bonding wire 9 ' is to be bonded to the substrate with a sheet that is as flat as possible, then an insulated magnetic core is placed on the lower bonding wires 9.
• all of the upper bonding wires 9 are bonded over the core with the highest possible floor.
• FIG. 8 shows an exemplary embodiment in which the connections are likewise made exclusively by means of bonding wires.
• the substrate 1 has a depression which is adapted to the size and shape of the magnetic core.
• the depression 4 is ring-shaped.
• the lower bonding wires 9 are bonded to two opposing pads 8 using a sheet that is normal during bonding. Subsequently, with a tool adapted to the shape of the depression, all of the lower bonding wires 9 are printed downwards such that all of the lower bonding wires 9 m lie in the groove and are adapted to the edge of the depression 4.
• the tool required for this has the shape of a stamp, which is precisely adapted to the edges of the recess.
• the insulated magnetic core 5 is in turn placed on the lower bonding wires 9 located in the recess 4.
• the upper bonding wires 9 are then bonded to the pads 8 above the magnetic core 5.
• the advantage of this arrangement is, in turn, that no through-contacts have to be provided in the substrate.
• An inexpensive substrate can therefore be used for the production of the inductive component. Furthermore, a flat structure is guaranteed, since the magnetic core m of the recess lies in the substrate. This protects the core at the same time. It is also held or fixed by the upper and lower bond wires.
• FIG. 9 shows a further possibility of realizing the inductive component according to the invention in a perspective view.
• Figure 10 shows a section along the line IX-IX of the same structure.
• the substrate 1 has an annular depression 4 on its upper surface 2.
• a magnetic core 5 (not shown) is introduced into this recess 4.
• the substrate 1 has a surface structured with conductor tracks 6 in the recess 4.
• the conductor tracks 6 have a radial course within the recess 4.
• the conductor tracks run both on the bottom of the depression 4 (radially) and on the walls of the depression (perpendicularly from the bottom to the upper surface 2).
• the conductor tracks 6 each have pads 8 at their ends. These pads 8 are each located on the upper surface 2 of the substrate 1.
• FIG. 10 shows a cross-section of this embodiment example with “internal” conductor tracks according to FIG. 9. It can be seen in the figure that the bottom and the walls of the recess 4 have conductor tracks 6 which run radially from the inside to the outside. At the ends of the conductor tracks 6 there are pads 8 on the upper surface 2. After inserting the insulated magnetic core 5 m into the recess 4, two opposing pads 8 are each connected by means of a bonding wire 9, which should have a bend that is as flat as possible. tive component.
• FIG. 11 shows a further embodiment of the invention in a perspective view.
• the inductive component now has “external” conductor tracks.
• FIG. 12 shows one
• the substrate 1 has two concentric depressions 4 and 4 on.
• the recess 4 ' is arranged in the center of the induct ⁇ tive device and going through the whole substrate 1 therethrough.
• the depression 4 has an annular border and is arranged concentrically with the depression 4.
• the recess 4 is only partially introduced into the substrate 1.
• the inductive component has 4 conductor tracks 6 on the outside and on the lower surface and the wall of the inner recess. These are arranged radially on the lower surface 3. At the ends of the conductor tracks 6 there are pads 8 on the upper surface 2 of the substrate 1.
• the annular magnetic core 5 (not shown in the picture) is introduced into the depression 4. Two opposing pads 8 can then be connected to one another by means of a bonding wire 9.
• the advantage of this arrangement is that the substrate does not require any vias.
• the use of uninsulated magnetic cores is also possible.
• Figure 12 shows the embodiment of the invention in section along the line XI-XI. From the drawing it is clear that the substrate has a continuous recess 4 in the center. Along the edge of the recess 4, conductor tracks 6 run vertically from the upper surface 2 to the lower surface 3 of the substrate 1. The conductor tracks 6 continue in the radial direction to the outer edge and on this edge in the vertical direction to the upper surface 2. On the upper surface 2 6 pads 8 are attached to the respective ends of the conductor tracks. After the introduction of the magnetic core 5 m into the depression 4, two opposing pads 8 are connected with a bonding wire 9. Care should be taken to ensure that the bonding wire 9 is guided flatly. This arrangement is characterized by “external” conductor tracks.
• FIG. 14 shows a plan view of the component shown in FIG. 13.
• the substrate 1 again has two depressions 4 and 4.
• the depression 4 ′ is arranged in the center of the substrate 1 and passes through the substrate 1.
• the recess 4 is arranged concentrically to the recess 4 and has a ringför ⁇ -shaped border on.
• the recess 4 is again only partially introduced into the substrate 1.
• the conductor tracks 6 are applied radially on the one hand to the bottom of the depression 4.
• the conductor tracks 6 run vertically on the wall of the recess 4 from the bottom to the upper surface 2, radially along the lower surface 3 and again perpendicularly along the outer border of the substrate 1 to the upper surface 2 hm.
• the conductor tracks 6 each have pads 8, which are arranged on the upper surface 2.
• Two opposite pads 8 of the inner conductor tracks and two opposite pads 8 of the outer conductor tracks are connected to each other. In this way, an exactly concentric arrangement of windings is possible. In this way, very good coupling conditions, ie very low leakage conductivities, can be achieved. It must again be ensured that the bonding wires 9, which connect two opposing inner pads 8 to one another, are bonded as flatly as possible above the magnetic core 5. This also enables a flat connection of two pads 8, which connect external conductor tracks 8 to one another.
• FIG. 14 shows a top view of the component according to FIG. 13 with a special arrangement of the pads 8.
• the concentric arrangement of the depressions 4 and 4 can be seen in FIG.
• the inner or outer ends, ie the pads 8, are arranged on the upper surface 2 of the middle part 14 and of the outer part 15.
• the illustration shows that the pads 8 of the outer conductor tracks are arranged offset with respect to the pads 8 ′′. This has the advantage that the bonding wires 9, the two opposite ones co co ro t- P> P 1
• the advantage of this arrangement is that no through-contacts are necessary in the substrate 1.
• the structuring of the substrate is simple since it only has to be produced in one plane.
• the substrate 1 can therefore be manufactured inexpensively.
• the rest of the wiring can be produced using the known bonding method.
• FIG. 16 shows a further embodiment of the invention with a rod-shaped magnetic core 5.
• a rectangular recess 4 is made in the substrate 1 in the upper surface 2.
• Each two opposing pads 8 are z. B. interconnected by vias in the substrate 1.
• the production of the lower lines is conceivable by any of the options described above. So could the lower lines z. B. be produced by internal conductor tracks in the recess 4.
• Two opposing pads 8 on the upper upper side 2 of the substrate 1 are connected to one another by means of bonding wires 9.
• An arrangement shown in Figure 16 could, for. B. can be used advantageously to build small or flat chokes and find its use in filter applications.
• the magnetic core 5 shown in the figure is designed as a laminated rod core.
• Bond wires can be combined and is not limited to the variants shown.
• FIG. 17 and FIG. 18 show an example of a layout on the upper or lower surface of the substrate of a double transformer with two toroidal cores and a concentric structure of two windings in each case.
• Figure 17 is the layout shown on the upper surface of the substrate.
• Two adjacent R banded cores 5 and the pads 8 lying on the central parts 14 and on the outer parts 15 can be seen.
• the middle part 14 of the layout it can be seen that two concentric windings are provided around the belt 5.
• the pads 8 of the one winding are arranged closer to the center, while the pads 8 of the second winding are closer to the belt core 5.
• the pads located on the outer part 15 correspond to the arrangement of the pads in the central portion 14. Further seen ⁇ a plurality of terminal conductors 10, which are connected to contact Rauen.
• the double transmitter has a total of 12 contact connections 11, which means that each coil has a center tap on the primary or second side.
• FIG. 18 shows the layout corresponding to FIG. 17 on the lower surface of the substrate 1.
• the arrangement of the conductor tracks 6 can be seen, at the ends of which there are pads 8.
• the connection of the pads 8 on the upper and lower surfaces of the substrate can e.g. B. by vias through the substrate.
• a double transducer realized according to the layout of FIGS. 17 and 18 achieves dimensions of approximately 15.6 x 8.5 x 3.5 mm after the bonded pads have been cast on the upper upper side with an epoxy material.
• the outward-reaching contact connections are, for. B. realized via an SMD header.
• the resistance of the four windings of the double transformer is approx. 0.4 ohm each.
• the inductive component according to the present invention is located on a chip-on-board substrate which is provided with non-encapsulated active components 16, 17 and 18.
• the assembly of the inductive component according to the invention is possible here without any problems, since the active components 16, 17 and 18 are likewise applied to the chip-on-board substrate by means of bonding processes.
• the common covering made of a plastic as well as the shared use of the connecting parts makes no difference to the outside compared to normal ICs.
• this procedure is particularly advantageous for realizing low-power DC / DC converters, since the circuit board can be populated fully automatically in one operation with active components and inductive components in accordance with the present invention.
• the bonded wires 9 usually do not have an insulation coating, care must be taken to ensure that the wires are guided in a defined manner during bonding, in particular in the case of crossovers. For the final execution, it may be necessary to subsequently encapsulate the area of the bond connections. In the simplest case, this can be done by covering with a hardening agent
• Plastic mass take place. Subsequent insulation and mechanical stabilization is also possible by coating the surfaces provided with bonding wires with a thin plastic layer.
• All of the drawing shown in the drawing can be produced using the bonding techniques known from semiconductor technology. Bonding technology has been a standard process for producing miniaturized electrical connections for over 20 years and is generally very reliable regardless of the process type, the wire material and the wire diameter.
• the metal pads shown are approx. 150 x 150 ⁇ m, which, including the distance to the neighboring pad, means a contact area density of approx. 9 connections per mm. With the minimum possible pad size, this value increases from approx. 60 x 60 ⁇ m to approx. 40 connections per mm 2 .
• the height of the bond connections shown is approximately 120 to 150 ⁇ m.
• a connection carrier is required, to which the wire ends are attached and soldered.
• the circuit board with the core holder and integrated connection carrier is required. Any further assembly and soldering are omitted.
• Closed magnetic cores are preferably used for the magnetic cores, since the highest permiabilitates are achieved here.
• belt cores are preferably provided.
• the z. B. generated by punching from a sheet are more suitable.
• Soft magnetic alloys, in particular amorphous or nanocrystalline alloys, are to be considered as particularly suitable magnetic materials.
• an amorphous alloy Fe a M b S ⁇ B y R z , where M em or several elements from the group Co, Ni. R denotes e or more elements from the group C, V, Nb, Mn, Ti, Cr, Mo or W.
• the sum of a and b is preferably 73 ⁇ a + b ⁇ 85 at%.
• the two alloys mentioned above After heat treatment, the two alloys mentioned above have an amorphous structure.
• nanocrystalline alloys are described below which, after heat treatment, have a finely crystalline structure with grain diameters of less than 100 Nm, these grains being surrounded by an amorphous phase which occupies less than 50% of the material volume.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Coils Or Transformers For Communication (AREA)

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• 1997
  • 1997-06-02 DE DE19723068A patent/DE19723068C1/de not_active Expired - Fee Related
• 1998
  • 1998-06-02 KR KR19997011280A patent/KR20010013287A/ko not_active Application Discontinuation
  • 1998-06-02 WO PCT/DE1998/001487 patent/WO1998056016A1/de not_active Application Discontinuation
  • 1998-06-02 JP JP50128499A patent/JP2002501678A/ja active Pending
  • 1998-06-02 EP EP98934837A patent/EP0986821A1/de not_active Withdrawn

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