Method for producing a coil and electronic device

Abstract

The invention relates to a method for producing a coil integrated in a substrate or applied to a substrate, wherein the coil has first winding portions, which each have first ends and second ends, and wherein the coil has second winding portions and third winding portions, wherein each two of the first ends are electrically interconnected by the second winding portions and two corresponding second ends of the first winding portions are electrically interconnected by the third winding portions, such that coil windings of the coil are formed hereby, wherein at least the first winding portions are applied by means of a 3D printing method, wherein this is aerosol jet or inkjet printing, for example.

Claims

1. An electronic device comprising at least one coil integrated in a substrate or applied to a substrate, the at least one coil including first winding portions, which each have first ends and second ends, the at least one coil having second winding portions, third winding portions, and a coil core, wherein each two of the first ends are electrically interconnected by the second winding portions and two corresponding second ends of the first winding portions are electrically interconnected by the third winding portions to form the at least one coil, the electronic device produced in accordance with a method comprising: printing, using a three-dimensional printing technique, the first winding portions and the second winding portions; and printing, using the three-dimensional printing technique, the third winding portions on the coil core to form the at least one coil having an axis that runs parallel to a surface of the substrate; and wherein the three-dimensional printing technique comprises at least one of aerosol jet printing and inkjet printing.

2. The electronic device of claim 1, wherein said device comprises at least one of a sensor and an actuator.

3. The electronic device of claim 2, wherein the sensor comprises at least one of a pressure sensor, force sensor, acceleration sensor, and a magnetic field sensor.

4. An electronic device comprising: an electronic printed circuit board including at least one coil integrated in or applied to the printed circuit board, the at least one coil including: a coil core; first winding portions, which each have first and second ends; second winding portions; and third winding portions; wherein each two of the first ends of the first winding portions are electrically interconnected by the second winding portions and wherein two corresponding second ends of the first winding portions are electrically interconnected by the third winding portions, with the result that coil windings of the at least one coil are formed hereby, the coil having an axis that runs parallel to a surface of a substrate; wherein the first winding portions and the second winding portions are applied by means of a three dimensional (3D) printing method; wherein the third winding portions are applied by means of the 3D printing method on the coil core; and wherein the 3D printing method includes at least one of aerosol jet printing and inkjet printing.

5. The electronic device of claim 4, wherein said device comprises at least one of a sensor and an actuator.

6. The electronic device of claim 5, wherein the sensor comprises at least one of a pressure sensor, force sensor, acceleration sensor, and a magnetic field sensor.

7. The electronic device of claim 1, wherein the at least one coil encloses a magnetic core, said method further comprising: forming said magnetic core from a paste comprising ferromagnetic particles, wherein said forming further comprises curing said paste.

8. The electronic device of claim 7, wherein said curing further comprises applying ultrasound to said paste during said curing.

9. The electronic device of claim 4, wherein the at least one coil is configured to enclose a magnetic core, said magnetic core formed by curing a paste comprising ferromagnetic particles.

10. The electronic device of claim 9, wherein said magnetic core is formed by applying ultrasound to said paste during said curing of said paste.

Description

(1) Embodiments of the invention will be explained in greater detail hereinafter with reference to the drawings, in which:

(2) FIG. 1 shows a schematic cross section of an electronic printed circuit board according to the invention with an integrated coil,

(3) FIG. 2 shows a perspective view of the printed circuit board according to FIG. 1,

(4) FIG. 3 shows a schematic cross section of an embodiment of a printed circuit board according to the invention with an applied coil,

(5) FIG. 4 shows a perspective view of the printed circuit board according to FIG. 3,

(6) FIG. 5 shows a cavity with applied and first and second winding portions,

(7) FIG. 6 shows an enlarged partial illustration of FIG. 5, which shows a portion of the base area and of a flank of the cavity,

(8) FIGS. 7-13 show an embodiment of a method for producing an electronic printed circuit board with an integrated toroidal or annular coil,

(9) FIG. 14 shows a plan view of an embodiment of a printed circuit board according to the invention with an integrated annular coil, and

(10) FIG. 15 shows a plan view of an embodiment of a printed circuit board according to the invention with an integrated oval coil.

(11) Corresponding or identical elements in the following exemplary embodiments are denoted in each case by the same reference signs.

(12) FIG. 1 shows a substrate 100, which may be a printed circuit board material, for example with glass-fiber reinforcement. For integration of a coil 140 (see FIG. 2) into the substrate 100, a cavity 106 is first produced in the substrate 100, whereby a surface 102 of the substrate 100 is opened.

(13) For example, the cavity 106 is produced in the substrate 100 by a machining process by milling the cavity 106 into the substrate 100. A base area 110 of the cavity 106, which for example runs parallel to the surface 102, is thus produced. Furthermore, lateral flanks 112 and 114 of the cavity 116, which each enclose an angle with the surface 102, are further produced as a result. The angle may be a right angle (as shown in FIG. 1) or an acute angle, in particular an angle of less than 50, for example 45.

(14) In the next step, the first winding portions 136 are applied to the flanks 112 and 114, and the second winding portions 138 are applied to the base area 110 of the cavity 106.

(15) This can be implemented in such a way that the first winding portions 136 and the second winding portions 138 are applied in a single process step by a 3D printing method, in particular by aerosol jet or inkjet printing. This can occur in the form of a conductive polymer.

(16) The cavity 106 is then filled with a core material so as to form the coil core, for example is filled with a paste 116, which contains ferromagnetic particles. Once the paste 116 has cured, third winding portions 139 are applied to the upper face 148 of the coil core formed by the cured paste, for example by means of a structuring technique or a two-dimensional printing method.

(17) The first winding portions 136 each have a lower first end 141 and an upper second end 147. Each two of the first ends 141 of two of the first winding portions 136 are electrically connected by one of the second winding portions 138, whereas two corresponding second ends 147 of two different first winding portions 136 are electrically contacted by the third winding portions 139, thus resulting in an approximately helical coil winding to form the coil 140.

(18) The paste 116 can likewise be introduced into the cavity 106 by means of printing. A selection of the angle of 45 is particularly advantageous when the paste 116 is introduced by means of screen printing, since the formation of air pockets in the paste 116 is then prevented in a particularly efficient manner. The paste 116 may further be acted on during the curing process with ultrasound or other vibrations in order to prevent slug formation as the paste 116 cures. Alternatively, the coil core can be formed by a solid instead of by the paste 116, said solid being introduced into the cavity 106.

(19) FIG. 2 shows a perspective view of the resultant printed circuit board 100 with the integrated coil 140.

(20) FIG. 3 shows an alternative embodiment, in which the coil 140 is applied to the substrate 100. To this end, the second winding portions 138 are first applied to the substrate 100. The core material, for example in the form of the paste 116 or as a solid, is then applied to the second winding portions 138, wherein the core material covers the second winding portions 138, at least in part, for example as far as edge regions of the second winding portions 138, as shown in FIG. 3.

(21) Once the coil core has been formed, that is to say for example once the paste 116 has cured, the first winding portions 136 are then applied to the flanks 112 and 114 of the resultant coil core, and the third winding portions 139 are applied to the upper face 148. The resultant printed circuit board 110 with the applied coil 100 is shown in FIG. 4 in a perspective view.

(22) FIG. 5 shows an embodiment of the invention in which an oval annular coil is to be integrated into the substrate 100. To this end, an oval cavity 106 is milled into the substrate 100, wherein the substrate 100 is glass-fiber-reinforced. FIG. 5 shows an intermediate product with the integration of the coil 140 into the substrate 100, after which the first and second winding portions 136 and 138 respectively have been imprinted by means of a 3D printing method.

(23) FIG. 6 shows a partial view of FIG. 5 enlarged by five times, wherein the rough surface of the cavity 106 and the resultant irregular structure of the first and second winding portions 136 and 138 respectively can be seen.

(24) The rough surface of the cavity 106 is caused by glass fibers of the substrate 100, which are severed as the cavity 106 is milled. The resultant irregular structuring of the winding portions 136 and 138 leads to a reduction of the effective cross-sectional area thereof, and therefore to an increase in the ohmic resistance, which ultimately leads to a reduction of the coil quality of the coil 140 to be produced.

(25) To remedy this problem, which may occur in the case of a substrate 100 having a glass fiber content, the following approach in accordance with the embodiment according to FIGS. 7 to 13 can be adopted:

(26) The substrate 100 is first provided and is glass-fiber-reinforced, as illustrated in FIG. 7. The cavity 106 is then milled into the substrate 100, wherein glass fibers are severed during the milling process, thus leading to a high surface roughness of the resultant cavity 106 (FIG. 8).

(27) The cavity 106 is then filled with a material 149. This material 149 may be a resin for example. This is illustrated in FIG. 9.

(28) The material 149 is then removed from the cavity 106 apart from a layer 151, for example likewise by means of milling. The layer 151 of the material 149 remaining on the surface of the cavity 106 may have a thickness from 10 m to 20 m, for example (see FIG. 10).

(29) In the subsequent method steps illustrated in FIGS. 11, 12 and 13, the actual coil 140 is then produced by first applying the first and second winding portions to the flanks 112 and 114 of the cavity 106 coated by the layer 151 and to the base area 110 coated by the layer 151 (FIG. 11). The core material for forming the coil core is then introduced into the cavity 106, for example by dispensing the paste 116 into the cavity 106 in order to fill the cavity 106 with the paste 116 (FIG. 12).

(30) The third winding portions 139 are then applied to the coil core thus formed.

(31) FIG. 14 shows a plan view of the surface 102 of the substrate 100 with the third winding portions 139 running in this plane, said third winding portions each electrically interconnecting two second ends 147 of the second winding portions 136, wherein the coil 140 is formed here as an annular coil.

(32) The first and last winding portions 139 of the coil 140 are connected here via conductive tracks 142 and 144 to contact faces 143 and 145 respectively.

(33) The diameter of the coil 140 may be less than 5 mm, for example 3.5 mm.

(34) FIG. 15 shows a corresponding coil 140 in an oval embodiment corresponding to the embodiment according to FIGS. 5 to 13.

LIST OF REFERENCE SIGNS

(35) 100 substrate 102 surface 106 cavity 110 base area 112 flank 114 flank 116 paste 136 first winding portion 138 second winding portion 139 third winding portion 140 coil 141 first end 142 conductive track 143 contact face 144 conductive track 145 contact face 147 second end 148 upper side 149 material 151 layer