CIRCUIT SUPPORT FOR AN ELECTRONIC CIRCUIT, AND METHOD FOR MANUFACTURING A CIRCUIT SUPPORT OF SAID TYPE

Abstract

A circuit support for an electronic circuit may include at least one conductor track, a first insulation material with which the at least one conductor track is encapsulated by injection molding so as to form an insulating matrix and so as to leave open at least one first region for the connection of at least one electronic component of the electronic circuit, and a heat sink. The conductor track is encapsulated by injection molding with the first insulation material in such a way that the insulating matrix furthermore leaves open at least one second region which is arranged between the conductor track and the heat sink. The circuit support may further include a large number of spacers which are designed and arranged in order to set a height of the second region. The circuit support may further include a second insulation material with which the second region is filled.

Claims

1. A circuit support for an electronic circuit, comprising: at least one conductor track; a first insulation material with which the at least one conductor track is encapsulated by injection molding so as to form an insulating matrix and so as to leave open at least one first region for the connection of at least one electronic component of the electronic circuit; and a heat sink; wherein the at least one conductor track is encapsulated by injection molding with the first insulation material in such a way that the insulating matrix furthermore leaves open at least one second region which is arranged between the conductor track and the heat sink, wherein the circuit support further comprises a large number of spacers which are designed and arranged in order to set a height of the second region between the conductor track and the heat sink, wherein the circuit support further comprises a second insulation material with which the second region is filled.

2. The circuit support as claimed in claim 1, wherein the at least one conductor track is in the form of a lead frame.

3. The circuit support as claimed in either of claims 1 and 2 claim 1, wherein the first insulation material has a higher viscosity in the end state than the second insulation material in the end state, wherein the first insulation material has a viscosity of at least 10.sup.18 Pa.Math.s, in the end state, wherein the second insulation material has a viscosity of at most 10.sup.16 Pa.Math.s, in the end state.

4. The circuit support as claimed in claim 1, wherein the first insulation material is different from the second insulation material, or the first insulation material is identical to the second insulation material.

5. The circuit support as claimed in claim 3, wherein the spacers are in the form of particles which are distributed in the second insulation material.

6. The circuit support as claimed in claim 1, wherein the height of the second region is from 20 m to 200 m.

7. The circuit support as claimed in claim 1, wherein the conductor track has passage openings, wherein projections on that side of the conductor track which faces the heat sink, which projections are produced during overmolding of said passage openings with the material of the insulating matrix, constitute the spacers.

8. The circuit support as claimed in claim 1, wherein the circuit support further comprises fastening aids, in particular for the circuit support, which aids are formed from the first insulation material and/or from the material of the at least one conductor track.

9. The circuit support as claimed in claim 1, wherein the heat sink is electrically conductive.

10. The circuit support as claimed in claim 1, wherein the material thickness of the insulating matrix is between 0.2 mm and 0.4 mm.

11. A method for manufacturing a circuit support for an electronic circuit, the method comprising: producing at least one conductor track from a starting material by removing unnecessary material; encapsulating the at least one conductor track by injection molding using a first insulation material so as to form an insulating matrix, wherein the encapsulation by injection molding is performed in such a way that at least one first region of the at least one conductor track is left open for the connection of at least one electronic component of the electronic circuit; and providing a heat sink; wherein the encapsulating is performed in such a way that the insulating matrix furthermore leaves open at least one second region which is arranged between the conductor track and the heat sink; wherein the method further comprises: filling the second region with a second insulation material using spacers for setting a height of the second region between the conductor track and the heat sink.

12. The method as claimed in claim 11, wherein in producing the at least one conductor track, the conductor track is produced with the removal of material or without the removal of material.

13. A light source comprising a circuit support, the circuit support comprising: at least one conductor track; a first insulation material with which the at least one conductor track is encapsulated by injection molding so as to form an insulating matrix and so as to leave open at least one first region for the connection of at least one electronic component of the electronic circuit and a heat sink; wherein the at least one conductor track is encapsulated by injection molding with the first insulation material in such a way that the insulating matrix furthermore leaves open at least one second region which is arranged between the conductor track and the heat sink, wherein the circuit support further comprises a large number of spacers which are designed and arranged in order to set a height of the second region between the conductor track and the heat sink, wherein the circuit support further comprises a second insulation material with which the second region is filled.

14. The circuit support as claimed in claim 3, wherein the first insulation material has a viscosity of at least 10.sup.22 Pa.Math.s, in the end state, wherein the second insulation material has a viscosity of at most 10.sup.14 Pa.Math.s, in the end state.

15. The circuit support as claimed in claim 8, wherein the circuit support further comprises mounting and alignment aids.

16. The circuit support as claimed in claim 8, wherein the fastening aids are formed from latching lugs, centering openings, snap-action hooks, spacers, register marks, reinforcing ribs, measurement sensors and/or measuring points.

17. The circuit support as claimed in claim 10, wherein the material thickness of the insulating matrix on the at least one conductor track is between 0.2 mm and 0.4 mm.

18. The method as claimed in claim 12, wherein the conductor track is produced by a jet of water or a laser, or by punching.

19. The light source according to claim 13, wherein the light source is used for a vehicle headlamp.

Description

[0039] Embodiments of the present invention will now be explained in greater detail in the text which follows with reference to the appended drawings, in which:

[0040] FIG. 1 is a schematic illustration of a cross section through a circuit support concept known from the prior art using a printed circuit board;

[0041] FIG. 2 is a schematic illustration of a cross section through a circuit support concept known from the prior art using a lead frame;

[0042] FIG. 3 is a schematic illustration of a cross section through a first embodiment of a circuit support according to the invention; and

[0043] FIG. 4 is a schematic illustration of a cross section through a second embodiment of a circuit support according to the invention.

[0044] FIG. 3 is a schematic illustration of a first embodiment of a circuit support according to the invention. Said circuit support has a conductor track 22 which is in the form of a lead frame in particular. Passage openings and/or gaps 30 are provided in the conductor track 22, said passage openings and/or gaps, when the conductor track is encapsulated by injection molding with a first insulation material 17 so as to form an insulating matrix 16, likewise being encapsulated by injection molding and in the process also forming a projection 28, in particular, on that side of the conductor track 22 which is intended to be coupled to a heat sink 18. This projection 28 can also extend beneath the conductor track 22 in order to ensure a better friction and/or force fit. During encapsulation by injection molding with the first insulation material 17, the region 15, which is provided for mounting the electronic components 14, and the region 34 on the bottom face 32 of the conductor track 22 are accordingly left open. This is performed by corresponding design of the injection molding mold.

[0045] A large number of projections 28 of this kind, which act as spacers, are produced by providing corresponding passage openings and/or gaps 30 along the conductor track 22, that is to say in the direction perpendicular to the plane of the drawing.

[0046] If a heat sink 18 is now placed onto the large number of projections 28, a region 34 which has a height h1 of between 20 m and 200 m is produced. In contrast, the height h2 of the matrix material 17 is between 0.2 mm and 0.4 mm. The region 34 is then filled with a second insulation material 24 which can constitute, in particular, a thermally conductive paste or a thermally conductive adhesive.

[0047] As an alternative, the second insulation material 24 can be introduced between the projections 28, in particular by being sprayed on and then withdrawn, before the heat sink is fitted. (The projections which have already cured define the remaining height of the insulation layer composed of the second insulation material 24, wherein the heat sink 18 is then fitted.)

[0048] The first insulation material 17, from which the matrix 16 is formed, preferably has a viscosity of at least 10.sup.18 Pa.Math.s, in particular of at least 10.sup.22 Pa.Math.s, in the end state, which constitutes the cured state here, in order to provide the circuit support with the necessary stability. The second insulation material 24 preferably has a viscosity of at most 10.sup.16 Pa.Math.s, in particular of at most 10.sup.14 Pa.Math.s, in the end state, that is to say after the circuit support is complete.

[0049] Only a portion of the respective electrical contact of the electrical components 14 to the conductor track is shown in the illustration of FIG. 3. The exit point has not been shown on account of the mirror-image symmetry.

[0050] In the embodiment illustrated in FIG. 4, particles 36 are provided in the second insulation material 24 instead of the projections 28 which are formed by encapsulation of the passage openings and/or gaps 30 by injection molding, the diameter of said particles defining the height h1 of the insulation layer which is formed from the second insulation material 24. Particles 36 of this kind are formed, in particular, from hexagonal boron nitride-coated silver spheres.

[0051] In preferred embodiments, the second insulation material 24 cures a lot more slowly than the first insulation material 17.