Printed Circuit Board and Method of Manufacturing a Printed Circuit Board with at Least One Optoelectronic Component Integrated into the Printed Circuit Board

Abstract

In an embodiment a method for manufacturing a printed circuit board with at least one optoelectronic component integrated into the printed circuit board includes arranging the at least one optoelectronic component on a first metal layer, pressing a first electrically insulating layer onto the at least one optoelectronic component and creating at least one recess in the first metal layer and/or the first electrically insulating layer thereby at least partially exposing the at least one optoelectronic component, wherein the first electrically insulating layer comprises a fiber reinforced plastic or a glass fiber fabric.

Claims

1-18. (canceled)

19. A method for manufacturing a printed circuit board with at least one optoelectronic component integrated into the printed circuit board, the method comprising: arranging the at least one optoelectronic component on a first metal layer; pressing a first electrically insulating layer onto the at least one optoelectronic component; and creating at least one recess in the first metal layer and/or the first electrically insulating layer thereby at least partially exposing the at least one optoelectronic component, wherein the first electrically insulating layer comprises a fiber reinforced plastic or a glass fiber fabric.

20. The method according to claim 19, wherein creating the at least one recess comprises at least partially exposing a surface of the at least one optoelectronic component so that light generated by the at least one optoelectronic component is emittable through the exposed surface.

21. The method according to claim 19, further comprising pressing a second metal layer onto the at least one optoelectronic component together with the first electrically insulating layer.

22. The method according to claim 19, wherein the at least one optoelectronic component comprises a first main surface and a second main surface opposite the first main surface, wherein the at least one optoelectronic component is arranged with its first main surface on the first metal layer, and wherein the second main surface is configured to emit light.

23. The method according to claim 22, wherein creating the at least one recess comprises at least partially exposing the second main surface of the at least one optoelectronic component, and removing material of the first electrically insulating layer located laterally of the second main surface.

24. The method according to claim 19, wherein the first electrically insulating layer comprises a light absorbing material.

25. The method according to claim 19, wherein the first electrically insulating layer comprises a light reflecting material.

26. The method according to claim 25, further comprising arranging a further layer comprising light-absorbing material on the first electrically insulating layer.

27. The method according to claim 19, further comprising arranging a first structured metallization layer on the at least one optoelectronic component, the first metal layer and/or the first electrically insulating layer.

28. The method according to claim 27, further comprising: arranging a second electrically insulating layer on the first structured metallization layer; and arranging a second structured metallization layer on the second electrically insulating layer, wherein vias in the second electrically insulating layer electrically couple the first structured metallization layer with the second structured metallization layer.

29. A printed circuit board comprising: a first electrically insulating layer; at least one optoelectronic component integrated into the first electrically insulating layer; a first structured metallization layer extending over the first electrically insulating layer and the at least one optoelectronic component; and at least one recess in the first electrically insulating layer at least partially exposing the at least one optoelectronic component, wherein the first electrically insulating layer comprises a fiber reinforced plastic or a glass fiber fabric.

30. The printed circuit board according to claim 29, wherein the at least one recess at least partially exposes a surface of the at least one optoelectronic component so that light generated by the at least one optoelectronic is emittable through the exposed surface.

31. The printed circuit board according to claim 30, wherein the at least one recess is larger than the surface of the at least one optoelectronic component.

32. The printed circuit board according to claim 29, wherein the first electrically insulating layer comprises a light absorbing material.

33. The printed circuit board according to claim 29, wherein the first electrically insulating layer comprises a light reflective material.

34. The printed circuit board according to claim 33, further comprising a further layer comprising light-absorbing material arranged on the first electrically insulating layer.

35. The printed circuit board according to claim 29, further comprising: a second electrically insulating layer arranged on the first structured metallization layer; and a second structured metallization layer arranged on the second electrically insulating layer, wherein vias in the second electrically insulating layer electrically couple the first structured metallization layer with the second structured metallization layer.

36. A display comprising: one or more printed circuit boards according to claim 29.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In the following, embodiments of the invention are explained in detail with reference to the attached drawings.

[0042] FIG. 1A to 1E show illustrations of an embodiment of a method of manufacturing a printed circuit board with several LED semiconductor chips integrated into the printed circuit board;

[0043] FIG. 2A to 2D show illustrations of an embodiment of a method of manufacturing a printed circuit board with several LED semiconductor chips integrated into the printed circuit board and a first electrically insulating layer with light absorbing material;

[0044] FIG. 3A to 3D show illustrations of an embodiment of a method of manufacturing a printed circuit board with several LED semiconductor chips integrated into the printed circuit board and a first electrically insulating layer with light-reflecting material as well as a further layer with light-absorbing material arranged on the first electrically insulating layer;

[0045] FIGS. 4A to 4E show illustrations of an embodiment of a method of manufacturing a printed circuit board with several LED semiconductor chips integrated into the printed circuit board and an additional rewiring layer; and

[0046] FIGS. 5A and 5B show illustrations of an embodiment of a circuit board with a pixel matrix.

[0047] In the following detailed description, reference is made to the attached drawings, which form part of this description and in which, for illustration purposes, specific examples of embodiments are shown in which the invention can be exercised. Since components of embodiments can be positioned in a number of different orientations, the terminology of directions is for illustration purposes only and is in no way restrictive. It is understood that other embodiments can be used and structural or logical changes can be made without deviating from the scope of protection. It is understood that the features of the different embodiments described herein may be combined with each other, unless specifically stated otherwise. The following detailed description should therefore not be understood in a restrictive way. In the figures, identical or similar elements are marked with identical reference signs, where appropriate.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0048] FIGS. 1A to 1E schematically show an embodiment of a method of manufacturing a printed circuit board with at least one optoelectronic component integrated into the printed circuit board. FIG. 1E schematically shows an embodiment of a printed circuit board manufactured by the method.

[0049] In FIG. 1A, a first metal layer is provided in form of a copper foil 10.

[0050] FIG. 1B shows that several optoelectronic components are placed on copper foil 10. In the present embodiment, three LED semiconductor chips 11, 12 and 13 are fixed on copper foil 10 using an electrically non-conductive adhesive 15.

[0051] Each of the LED semiconductor chips 11, 12 and 13 has a first main surface 21, a second main surface 22 opposite to the first main surface 21, and four side surfaces 23 connecting the first and second main surfaces 21, 22. The LED semiconductor chips 11, 12 and 13 are flip-chip semiconductor chips whose electrical contact elements 24 are arranged exclusively on the first main surface 21. After mounting, the first main surface 21 faces the copper foil 10. The electrically non-conductive adhesive 15 is arranged between the electrical contact elements 24 of the LED semiconductor chips 11, 12 and 13 and the copper foil 10.

[0052] In the present embodiment, the LED semiconductor chip 11 is configured to emit green light. The LED semiconductor chips 12 and 13 are configured to emit red and blue light, respectively. The LED semiconductor chips 11, 12 and 13 can be surface emitters, which emit light only on the second main surface 22, but can also be volume emitters, which emit light on the second main surface 22 and additionally on the side surfaces 23. In the present embodiment, the LED semiconductor chips 11, 12 and 13 are sapphire flip chips.

[0053] LED semiconductor chips 11, 12 and 13 are bonded with a first electrically insulating layer 26, which is made of a suitable polymer, and a second metal layer in the form of a copper foil 27, as shown in FIG. 1C. The first electrically insulating layer 26 and the copper foil 27 arranged thereon are pressed onto the LED semiconductor chips 11, 12 and 13 by applying pressure and heat. After this step, the second main surfaces 22 and the side surfaces 23 of the LED semiconductor chips 11, 12, and 13 are covered by the first electrically insulating layer 26.

[0054] In FIG. 1D, several recesses 30 are created with a laser in the copper foils 10 and 27 and the first electrically insulating layer 26. This exposes the first and second main surfaces 21 and 22 of the LED semiconductor chips 11, 12 and 13. Furthermore, the copper foil 27 is removed in the area between the LED semiconductor chips 11, 12 and 13. In the present embodiment, the first electrically insulating layer 26 laterally from the LED semiconductor chips 11, 12 and 13 is not removed.

[0055] Furthermore, the laser is used to create through holes 31 laterally adjacent to the LED semiconductor chips 11, 12 and 13, which extend completely through the copper foil 10, the first electrically insulating layer 26 and the copper foil 27.

[0056] Finally, as FIG. 1E shows, a first structured metallization layer 32 is deposited on the electrical contact elements 24 of the LED semiconductor chips 11, 12 and 13, the copper foils 10 and 27, and in the through-holes 31. The first structured metallization layer 32 is produced by electroplating and can consist of one or more metal layers, in particular copper layers. Vias are created by depositing metal in the through holes 31.

[0057] FIG. 1E shows a cross section of the printed circuit board 100 manufactured with the aforementioned method. The second main surfaces 22 of the LED semiconductor chips 11, 12, and 13 are exposed, such that an Emission of the generated light against air is achieved.

[0058] Through the first structured metallization layer 32, external contact elements can be formed on the bottom and top side of the circuit board 100, through which the LED semiconductor chips 11, 12 and 13 can be electrically controlled from outside.

[0059] The manufacturing process makes it possible to manufacture a large-area printed circuit board 100 or several printed circuit boards 100 simultaneously. If necessary, the PCBs 100 can be separated after production, for example by sawing.

[0060] FIGS. 2A to 2D schematically show another embodiment of a method of manufacturing a printed circuit board. FIG. 2C shows a cross-section of the PCB 200 manufactured by this method.

[0061] The method shown in FIGS. 2A to 2D is a further development of the method shown in FIGS. 1A to 1E and therefore partially similar to the method shown in FIGS. 1A to 1E.

[0062] FIG. 2A shows LED semiconductor chips 11, 12 and 13 pressed with the first electrically insulating layer 26 and copper foil 27. Unlike FIG. 1C, the first electrically insulating layer 26 in FIG. 2A contains black or light-absorbing material or a filler. This material can consist of soot particles, for example.

[0063] FIG. 2B shows that several recesses 30 are created with a laser in the copper foil 10 and the first electrically insulating layer 26. The copper foil 27 is removed. As in FIG. 1D, the first and second main surfaces 21 and 22 of the LED semiconductor chips 11, 12 and 13 are exposed. In addition, the material of the first electrically insulating layer 26 is removed not only directly above the LED semiconductor chips 11, 12 and 13, but also laterally next to the LED semiconductor chips 11, 12 and 13 to avoid shadowing effects. Consequently, the base surfaces of the recesses 30 above the LED semiconductor chips 11, 12, and 13 are larger than the second main surfaces 22 of the LED semiconductor chips 11, 12, and 13.

[0064] In FIG. 2C, the first structured metallization layer 32 is deposited in the same way as in the embodiment in FIG. 1A to 1E.

[0065] FIG. 2D shows an enlarged section of the finished circuit board 200, which is intended to illustrate a dimension to determine the dimensions of the recesses 30 above the LED semiconductor chips 11, 12 and 13. In FIG. 2D, the height of the recess 30 is denoted by h and the width of the area laterally adjacent to the side face 23 of the LED semiconductor chip 11, where the material of the first electrically insulating layer 26 was removed to form the recess 30, is denoted by z. Furthermore, FIG. 2D shows a light beam 33, which indicates the propagation of light emitted at the outermost edge of the second main surface 22 of the LED semiconductor chip 11 and which is emitted into the environment just above the upper edge of the recess 30.

[0066] The light beam 33 forms an angle with the second main surface 22 of the LED semiconductor chip 11 and the base surface of the recess 30. The following relationship also applies:

[00001]$\begin{array}{cc}\tan =\frac{h}{z}& \left(1\right)\end{array}$

[0067] If a critical value for the angle is given, equation (1) can be used to determine values for the height h and width z. If the height h is also given, the width z can be determined directly.

[0068] For example, a viewing angle of 150 is usually required for video wall applications. Accordingly, the critical value for the angle is 15. With this value and equation (1) values for the height h and width z can be determined.

[0069] FIG. 3A to 3D schematically show another embodiment of a method of manufacturing a printed circuit board. FIG. 3D shows a cross-section of the PCB 300 manufactured by this method.

[0070] The method shown in FIGS. 3A to 3D is a further development of the method shown in FIGS. 1A to 1E. In the following, only the differences to the method shown in FIGS. 1A to 1E are described.

[0071] FIG. 3A shows the LED semiconductor chips 11, 12 and 13 pressed together with the first electrically insulating layer 26 and the copper foil 27. Unlike FIG. 1C, the first electrically insulating layer 26 in FIG. 2A contains white or light reflective material or a filler. This material can consist of titanium dioxide, for example, and serves to reflect the light that actually leaves the side surfaces 23 of the LED semiconductor chips 11, 12 and 13.

[0072] As shown in FIG. 3B, in order to achieve a high contrast, a further layer 35 is laminated onto copper foil 27, which contains black or light-absorbing material, e.g. soot particles.

[0073] In the laser processing shown in FIG. 3C, the further layer 35 is also structured to create the recesses 30 above the LED semiconductor chips 11, 12 and 13.

[0074] In FIG. 3D, the first metallization layer 32 is deposited and structured as described above.

[0075] FIGS. 4A to 4E schematically show another embodiment of a method of manufacturing a printed circuit board, which is a further development of the method shown in FIGS. 2A to 2D. FIG. 4E shows a cross-section of the PCB 400 manufactured by the method.

[0076] FIG. 4A shows the LED semiconductor chips 11, 12 and 13 pressed together with the first electrically insulating layer 26 and the copper foil 27, wherein the first electrically insulating layer 26 contains black or light-absorbing material or a filler, e.g. soot particles.

[0077] In FIG. 4B, recesses 30 are created using a laser beam to expose the first main surfaces 21 of the LED semiconductor chips 11, 12 and 13.

[0078] In FIG. 4C, the first metallization layer 32 is electroplated and structured on the first main surfaces 21 of the LED semiconductor chips 11, 12 and 13 and the copper foil 10.

[0079] In FIG. 4D, a second electrically insulating layer 36 and further copper foil 37 are laminated to the first metallization layer 32. Like the first electrically insulating layer 26, the second electrically insulating layer 36 can contain black or light absorbing material or a filler.

[0080] FIG. 4E shows that a laser beam is used to create recesses 30 in the first electrically insulating layer 26 as well as through holes in the second electrically insulating layer 36. Furthermore, a second metallization layer 38, for example of copper, is arranged on the second electrically insulating layer 36 and structured. The second metallization layer 38 extends into the through-holes in the second electrically insulating layer 36, creating vias 39 which electrically couple the first and second structured metallization layers 32 and 38.

[0081] By means of the second electrically insulating layer 36, the second structured metallization layer 38 and optionally other such layers, a fan-out area can be created, which makes it possible to arrange external contact elements 40 of the circuit board 400 outside the outlines of the LED semiconductor chips 11, 12 and 13. The distances between adjacent external contact elements 40 can be at least 250 m to be suitable for standard soldering processes.

[0082] FIGS. 5A and 5B show a PCB 500 in cross section and in a top view, respectively. The printed circuit board 500 can be used in a display.

[0083] The PCB 500 comprises a pixel matrix with a plurality of pixels 50. Each of the pixels comprises three sub-pixels, wherein each of the subpixels is formed by LED semiconductor chips 11, 12 and 13, which emit light in the colors red, green and blue.

[0084] Printed Circuit Board 500 can be manufactured using the method shown in FIG. 2A to 2D.

[0085] Although the invention has been illustrated and described in detail by means of the preferred embodiment examples, the present invention is not restricted by the disclosed examples and other variations may be derived by the skilled person without exceeding the scope of protection of the invention.