Embedding Methods for Fine-Pitch Components and Corresponding Component Carriers

Abstract

A method of manufacturing a component carrier includes: (i) embedding a poorly adhesive structure in a stack, wherein the stack comprises at least one electrically conductive layer structure and/or at least one electrically insulating layer structure; (ii) forming a cavity in the stack by removing a stack piece, wherein the stack piece is in part delimited by the poorly adhesive structure; and (iii) selectively exposing a bottom of the cavity by partially removing the poorly adhesive structure. A corresponding component carrier includes analogous features.

Claims

1. A method of manufacturing a component carrier, the method comprising: embedding a poorly adhesive structure in a stack, wherein the stack comprises at least one electrically conductive layer structure and/or at least one electrically insulating layer structure; forming a cavity in the stack by removing a stack piece, wherein the stack piece is in part delimited by the poorly adhesive structure; and selectively exposing a bottom of the cavity by partially removing the poorly adhesive structure.

2. The method of claim 1, further comprising: applying a finishing structure to the exposed part of the bottom of the cavity.

3. The method of claim 2, wherein the finishing structure is electrically conductive.

4. The method of claim 3, wherein the finishing structure is applied to an electrically conductive contact structure at the bottom of the cavity.

5. The method of claim 4, wherein the finishing structure has a smaller lateral extension than the electrically conductive contact structure.

6. The method of claim 4, wherein the material composition of the electrically conductive contact structure differs from the material composition of the finishing structure.

7. The method of claim 2, wherein a center-to-center distance between two separate elements of the finishing structure is smaller than 100 μm.

8. The method of claim 2, wherein the finishing structure comprises a plurality of sublayers.

9. The method of claim 2, wherein the finishing structure comprises at least one of nickel, gold, palladium, tin and an organic solderability preservative.

10. The method of claim 2, wherein the finishing structure is applied by at least one of a plating process, an electroless plating process, and an immersion process.

11. The method of claim 10, wherein the poorly adhesive structure is resistant against materials used in the plating process and/or in the immersion process.

12. The method of claim 2, further comprising: applying a solder structure to the finishing structure.

13. The method of claim 2, further comprising: mounting a component in the cavity using the finishing structure as an interface between the stack and the component.

14. The method of claim 13, wherein the component is a double-sided component.

15. The method of claim 1, wherein the poorly adhesive structure is partially removed by laser processing.

16. The method of claim 1, further comprising: removing the poorly adhesive structure before completing manufacture of the component carrier.

17. The method of claim 1, wherein a sidewall of the cavity is at least partially covered with a shielding structure.

18. The method of claim 1, further comprising: forming at least one trench in the selectively exposed bottom of the cavity; and filling the at least one trench with an electrically conductive material to form an electrically conductive contact structure.

19. A component carrier, comprising: a stack comprising at least one electrically conductive layer structure and/or at least one electrically insulating layer structure; a cavity formed in the stack; an electrically conductive contact structure at a bottom of the cavity; and a finishing structure on the electrically conductive contact structure; wherein the finishing structure has a smaller lateral extension than the electrically conductive contact structure.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0079] FIG. 1, FIG. 2, FIG. 3, and FIG. 4 show structures obtained during manufacture of a component carrier according to an exemplary embodiment of the invention.

[0080] FIG. 5 shows a component carrier with a bottom of a cavity partially exposed from a poorly adhesive structure according to an exemplary embodiment of the invention.

[0081] FIG. 6 shows a component carrier with a finishing structure applied to a contact structure partially exposed from a poorly adhesive structure according to an exemplary embodiment of the invention.

[0082] FIG. 7 shows a component carrier with a contact structure and a finishing structure at the bottom of a cavity according to an exemplary embodiment of the invention.

[0083] FIG. 8, FIG. 9, and FIG. 10 show structures obtained during mounting of a component in a cavity of a component carrier according to an exemplary embodiment of the invention.

DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENTS

[0084] The illustrations in the drawings are schematically presented. In different drawings, similar or identical elements are provided with the same reference signs. For the sake of clarity and comprehensibility, reference signs are sometimes omitted for those features, for which reference signs have already been provided in earlier figures.

[0085] Before, referring to the drawings, exemplary embodiments will be described in further detail, some basic considerations will be summarized based on which exemplary embodiments of the invention have been developed.

[0086] A basic idea of embodiments of the invention is to reduce pitch for embedding a component, in particular a double-sided component, in one or more build up layers of a component carrier. It is proposed to use 2.5D technology, e.g., to create a cavity, in which the component is embedded. A poorly adhesive structure such as a release layer in the cavity would have two functions: first, as a release layer and second, for applying a finishing structure, e.g., for the surface finishing of an underlying contact structure, e.g., of pads such as interconnection pads. The steps could be: create cavity and de-cap, partly remove, e.g., by laser drilling, the poorly adhesive structure on the pads, perform surface finishing on the pads, strip the poorly adhesive structure. Thus, the poorly adhesive structure is used as a mask for surface finishing. This process flow could limit the exposed area on the pad for surface finishing and thus allow fine pitch. By contrast, according to conventional methods, the pads may be plated with surface finish entirely thus adding around 14 μm in total to the pad diameter.

[0087] These and similar methods may be advantageous because the poorly adhesive structure may be used as a protective foil during plating. Also, the method may enable to obtain fine pitch lines, in particular where soldering is not possible. It may enable gold plating of an electrically conductive contact structure in order to mount components by thermal compression bonding. Finally, signals may be shielded due to the sidewalls of the cavity, in particular due to shielding structures on these sidewalls.

[0088] FIGS. 1 to 4 show structures obtained during manufacture of a component carrier 100 according to an exemplary embodiment of the invention. In FIG. 1, a stack 101 is shown with an insulating layer structure 103 partially covered on opposite sides by respective electrically conductive layer structures 102. The stack 101 may for example be a core. A poorly adhesive structure 110 covers parts of one of the electrically conductive layer structures 102 and of a corresponding main surface of the insulating layer structure 103, on which this electrically conductive layer structure 102 is arranged. The electrically conductive layer structure 102, in particular where it is covered by the poorly adhesive structure 110, includes pads and traces.

[0089] In FIG. 2, two further electrically insulating layer structures 103 forming part of the stack 101 are applied, e.g., laminated, on opposite sides of the structure shown in FIG. 1. One of the further electrically insulating structures 103 covers the poorly adhesive structure 110 such that the poorly adhesive structure 110 is fully embedded in the stack 101. In FIG. 3, two further electrically conductive layer structures 102 forming part of the stack 101 are applied, e.g., laminated, on opposite sides of the structure shown in FIG. 2. Vias 304 are formed between different electrically conductive layer structures 102. Still further electrically insulating layer structures 103 forming part of the stack 101 are applied in a step between FIGS. 3 and 4.

[0090] In FIG. 4, a cavity 420 is formed by removing a stack piece, wherein the stack piece is in part delimited by the poorly adhesive structure 110. The stack piece corresponds to the portion of the stack 101 previously located, where the cavity 420 is shown in FIG. 4. The cavity 420 is delimited from the stack 101 by a bottom 421 of the cavity 420 and adjacent sidewalls 423 of the cavity 420. The bottom 421 of the cavity 420 is formed by a main surface of an electrically insulating layer structure 103 and by an electrically conductive layer structure 102 arranged thereon. On the bottom 421 of the cavity 420, the poorly adhesive structure 110 is arranged. A part of the mentioned electrically conductive layer structure 102 at an outer portion of the bottom 421 of the cavity 420 is not covered by the poorly conductive adhesive structure 110. Thus, a gap is formed between sidewalls 423 and the poorly adhesive structure 110.

[0091] In FIG. 5, shielding structures 524 are shown covering sidewalls 423 of the cavity 420. Holes 511 have been formed in the poorly adhesive structure 110 exposing parts 522 of the bottom 421 of the cavity 420. In particular, pads 531 and traces 532 of an electrically conductive contact structure 530 have been partially exposed, wherein the contact structure 530 forms part of an electrically conductive layer structure 102 of the stack 101. Furthermore, a surface portion 522 of an electrically insulating layer structure 103 of the stack 101 has been exposed from the poorly adhesive structure 110 and a trench 512 has been formed in this surface portion 522.

[0092] In FIG. 6, a finishing structure 640 is formed on the exposed parts 522 of the bottom 421 of the cavity 420, in particular on the exposed pads 531 and traces 532 of the electrically conductive contact structure 530. Furthermore, the trench 512 has been filled with electrically conductive material to form part of the electrically conductive contact structure 530. On the electrically conductive contact structure 530 in the trench 512, a finishing structure 640 has also been applied.

[0093] In FIG. 7, the remaining poorly adhesive structure 110 has been removed, e.g., washed off. The resulting component carrier 100 comprises a stack 101 with several electrically conductive layer structure 102 and with several electrically insulating layer structure 103. A cavity 420 is formed in the stack 101. At a bottom 421 of the cavity 420, an electrically conductive contact structure 530 is arranged. A finishing structure 640 partly covers the electrically conductive contact structure 530. For each pad 531 of the electrically conductive contact structure 530, a lateral extension e.sub.f of the finishing structure 640 is smaller than a lateral extension e.sub.c of the pad 531. In other words, the contact structure protrudes by length p.sub.fc beneath the finishing structure 640, where p.sub.fc may be the minimum protrusion length. As has been repeatedly pointed out in this document, this smaller extension of the finishing structure 640 may allow for a smaller pitch, characterized by the center-to-center distance d between adjacent elements of the finishing structure 640 and/or adjacent elements of the contact structure 530 such as pads 531. For a pitch of 30 μm, e.sub.f may be 10 μm, e.sub.c may be 20 μm and/or p.sub.fc may be 5 μm. For a pitch smaller than 30 μm, e.sub.f may be smaller than 10 μm, e.sub.c may be smaller than 20 μm and/or p.sub.fc may be smaller than 5 μm.

[0094] FIGS. 8 to 10 show structures obtained during mounting of a component 850 in a cavity 420 of a component carrier 100 according to an exemplary embodiment of the invention. In FIG. 8, a double-sided component 850, in particular its electrical contacts, is attached to the finishing structure 640. With the finishing structure 640 serving as an interface, the component 850 is electrically connected to the electrically conductive contact structure 530 and thus to electrical circuitry of the stack 101. The component 850 may be attached and electrically connected by means of a solder structure 851. It may be attached and electrically connected by thermal compression bonding, e.g., if the finishing structure 640 comprises gold. In FIG. 9, an underfill 952 is provided in the cavity 420 for the component 850. In FIG. 10, further electrically insulating layer structures 103 and further electrically conductive layer structure 102 are applied, e.g., laminated, to both sides of the structure shown in FIG. 9. In particular, a further electrically insulating structure 103 is applied, e.g., laminated, over the cavity 420 fully covering the double-sided component 850. Vias 304 are formed in this further electrically insulating layer structure 103 electrically contacting the double-sided component 850 on a side opposite to the side contacted by the electrically conductive contact structure 530. A package results with a fully embedded double-sided fine-pitch component 850.

[0095] It should be noted that the term “comprising” does not exclude other elements or steps and the use of articles “a” or “an” does not exclude a plurality. Also, elements described in association with different embodiments may be combined.

[0096] Implementation of the invention is not limited to the preferred embodiments shown in the figures and described above. Instead, a multiplicity of variants is possible which use the solutions shown and the principle according to the invention even in the case of fundamentally different embodiments.

LIST OF REFERENCE SIGNS

[0097] 100 component carrier [0098] 101 stack [0099] 102 electrically conductive layer structure [0100] 103 electrically insulating layer structure [0101] 110 poorly adhesive structure [0102] 304 via [0103] 420 cavity [0104] 421 bottom [0105] 423 sidewall [0106] 511 hole in poorly adhesive structure [0107] 512 trench [0108] 522 exposed part of bottom [0109] 524 shielding structure [0110] 530 electrically conductive contact structure [0111] 531 pad [0112] 532 trace [0113] 640 finishing structure [0114] 850 component [0115] 851 solder structure [0116] 952 underfill [0117] e.sub.f lateral extension of finishing structure [0118] e.sub.c lateral extension of contact structure [0119] p.sub.fc protrusion of contact structure beneath finishing structure [0120] d center-to-center distance