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Protruded Cu Post CMIS Interposer for Fine Pitch

IP.com Disclosure Number: IPCOM000248053D
Publication Date: 2016-Oct-21
Document File: 4 page(s) / 286K

Publishing Venue

The IP.com Prior Art Database

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Page 01 of 4

Protruded Cu Post CMIS Interposer for Fine Pitch

Background

Cavity Molded Interconnect substrate (CMIS) is contributing a viable solution for a thinner PoP integrated package structure to use thicker IC chip, such that the attached IC chip on the substrate is positioned within the cavity opening created in the underlying interposer. The use of cavity within interposer would narrow the distance or gap in between the contact pads of interposer with the contact pads of substrate, thus smaller conductive bumps can be used to electrically couple the interposer and substrate in PoP structure. This indicates higher density of I/O count and flexibility of design.

The CMIS is having the cavity feature formed by mold chase on the mold compound that integrated with Cu frame structure as shown in Figure 1A. This invention is driven by comparatively lower in cost than laminate substrate interposer. The MIS structure itself is inherently benefited from the fine pitch capability and I/O layout flexibility by Cu patterning design as well, thus, is contributing on ease to assemble with various packages in the PoP integration.

Figure 1A: CMIS (Prior art) as interposer

For enhancement on the existing CMIS to achieve finer ball pitch density or I/O layout flexibility, this new invention discloses the protruded Cu post feature on CMIS. The protruded Cu post appeared as padless, it is extended conductive pillar for micro solder ball interconnection with the substrate pad under it, which is shown in Figure 2A. The conceptualized process flow for fabrication of CMIS with protruded Cu post is further illustrated in the next section, especially the molding process which required the FAM (film assisted molding) system for CMIS fabrication in general.

Figure 2A: CMIS with protruded Cu post (new invention) as interposer


Page 02 of 4

Protruded Cu Post CMIS Interposer for Fine Pitch

Description

Figure 3A represents a bare etchable carrier or Cu base panel is prepared. It is subjected to Cu plating process to pattern and deposit a layer of Cu as traces and pads depicted in Figure 3B. Corresponding to the required conductive interconnection with substrate ball pads, the Cu post layer formation as observed in Figure 3C is performed by Cu plating as well, which will be ready for molding after completion as given in Figure 3D.

The FAM technology system is employed for molding process, whereby thermal film layer is overlaid on the bottom mold chase with middle projection design as shown in Figure 3D-1. However, the projection design location on bottom...