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Embedded Trace PoP Disclosure Number: IPCOM000250234D
Publication Date: 2017-Jun-15
Document File: 4 page(s) / 469K

Publishing Venue

The Prior Art Database

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Embedded Trace PoP


The interposers used in PoP (package on package), such as substrate Cu post interposer and

substrate Cu core solder ball interposer in respective Figure 1A and 1B are typically resulted

in higher thickness profile compared to the common PoP package.

This invention presented in Figure 1C is disclosing the single layer Cu post interposer

integrated with MIS (Molded Interconnect Substrate) as MIS Cu post interposer PoP package

structure, which has some substantial merits in terms of overall package profile, material cost,

process handling, manufacturability, and reliability compared with the PPG (Prepreg) core

substrate interposer.

Prior Arts

Figure 1A: Substrate Cu Post Interposer PoP

Figure 1B: Substrate Cu Core Solder Ball Interposer PoP

Invention Design

Figure 1C: MIS Cu Post Interposer PoP


The invention for MIS Cu post interposer PoP encompassed the fabrication of single layer Cu

post interposer and the assembly with MIS substrate. The process flow of single layer Cu post

interposer is illustrated in Figure 2A to 2F. A panel of FR-4 CCL (Frame Retardant -4 Cu

Clad Layer) carrier consists of interposer carrier with Cu seed layer is prepared as shown in

Embedded Trace PoP

Figure 2A. Alternatively, SPCC (a kind of cold rolled Carbon steel sheet) or metal panel can

be used as carrier.

Figure 2A: Interposer Carrier with Cu Seed Layer

Through the image transfer process presented in Figure 2B, the surface of Cu seed layer is

patterned with the first film layer of photoresist. The Cu plating process is carried out to form

a Cu layer as a base for Cu post on the open area of photoresist Layer 1 as given in Figure

2C, following by the image transfer to pattern the second film layer of photoresist on the Cu

plating layer over the first film layer of photoresist, and overlapping partially on peripheral

surface of Cu layer as shown in Figure 2D.

Figure 2B: Image Ttransfer for Photoresist Layer 1

Figure 2C: Cu Plating for Cu Layer

Figure 2D: Image Ttransfer for Photoresist Layer 2

The Cu post layer depicted in Figure 2E is formed accordingly after another cycle of Cu

plating process. The fabrication of single layer Cu post interposer is completed after the mask

stripping, in which both the first and second photoresist layers are removed from the surface

of interposer structure having the Cu layer and Cu post...