Browse Prior Art Database

Method to Improve Die-Attach for Stacked Packages

IP.com Disclosure Number: IPCOM000031332D
Original Publication Date: 2004-Oct-25
Included in the Prior Art Database: 2004-Oct-25
Document File: 1 page(s) / 63K

Publishing Venue

Siemens

Related People

Juergen Carstens: CONTACT

Abstract

In the current assembly process of stacked FBGA (Fine Pitch Ball Grid Array) packages, there is a contamination of the re-distribution layer (RDL) of the bottom chip during the spacer die-attach step. Due to the capillary effect of the RDL topography, the die-attach glue flows between the RDL traces and prevent mold compound adhesion between the RDL traces as seen in figure 1. In order to avoid the bleed-out of the die attach glue, a special design of the RDL coverage is proposed (figure 2). The RDL coverage features a glue trap that confines the die-attach glue in the vicinity of the spacer.

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Method to Improve Die-Attach for Stacked Packages

Idea: Sebastian Mueller, DE-Dresden; Octavio Trovarelli, DE-Dresden

In the current assembly process of stacked FBGA (Fine Pitch Ball Grid Array) packages, there is a contamination of the re-distribution layer (RDL) of the bottom chip during the spacer die-attach step. Due to the capillary effect of the RDL topography, the die-attach glue flows between the RDL traces and prevent mold compound adhesion between the RDL traces as seen in figure 1.

In order to avoid the bleed-out of the die attach glue, a special design of the RDL coverage is proposed (figure 2). The RDL coverage features a glue trap that confines the die-attach glue in the vicinity of the spacer.

Thus, the mold compound adhesion and with it package reliability is increased.

Figure 1: Contamination of the Re-distribution Layer

  Glue bleed-out

  Glue bleed-out

  Glue bleed-out

    Bleed-out Contaminating RDL surface and side-walls

    Bleed-out Contaminating RDL surface and side-walls

    Bleed-out Contaminating RDL surface and side-walls

Bottom Chip

Bottom Chip

Bottom Chip

Figure 2: Proposed Design of the RDL Coverage

Top-side view Cross-section

Top-side view Cross-section

Top-side view Cross-section

Glue Trap

Glue Trap

Glue Trap

Spacer region "Glue Trap"

Chip

Spacer region "Glue Trap"

Chip

Spacer region "Glue Trap"

Chip

RDL-coverage

RDL-coverage

RDL-coverage

Substrate

Chip edge

Substrate

Chip edge

Substrate

Chip edge

RDL

RDL

RDL

Spacer region

Spacer region

Spacer re...