Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

Enhancing BiStatix Bare Die Assembly Yield Using an Additional Ink Layer

IP.com Disclosure Number: IPCOM000008599D
Original Publication Date: 2002-Jun-25
Included in the Prior Art Database: 2002-Jun-25
Document File: 1 page(s) / 92K

Publishing Venue

Motorola

Related People

Jad S. Rasul: INVENTOR

Abstract

Attaching a bare die to the ink/paper based BiStatix substrate is a cost effective alternative to the current bumped die process. The elimination of both the conductive polymer bump as well as the die dielectric, as shown in Figure 1., yields a more cost effective alternative to the current design.

This text was extracted from a Microsoft Word document.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 78% of the total text.

Enhancing BiStatix Bare Die Assembly Yield Using

an Additional Ink Layer

Jad S. Rasul

      Attaching a bare die to the ink/paper based BiStatix substrate is a cost effective alternative to the current bumped die process.  The elimination of both the conductive polymer bump as well as the die dielectric, as shown in Figure 1., yields a more cost effective alternative to the current design.

Figure 1. A schematic representation of bare flip chip on paper assembly

      Assembling the bare die to the flexible, ink/paper substrate is very challenging.  The height of the nickel/gold die pad is only 5 microns and the height of the carbon ink layer is about 10 microns.  The assembly force required to attach the die to the ink substrate using a 15 um. ACF is the critical factor in insuring a high yield process.  Due to the small height of the die pad and the flexibility of the ink/paper substrate, the conductive ink layer comes in contact with the edge of the die during the assembly process leading to an electrical short as depicted in Figure 2.  This contact causes a low assembly yield due to the shorted die.

Figure 2. Shorted die

      We developed a solution that incorporates the use of an additional ink layer in the area where the die pads make direct contact with the current ink layer on the paper substrate.  This results in an increased ink height in that area with respect to the current ink surface area.  As the compression force is applied to attach the die to the substrate, only the thicker ink lay...