Browse Prior Art Database

Enhanced Reliability of Flip Chip Packages with Organic Substrates by Using Crack Propagation Barriers

IP.com Disclosure Number: IPCOM000006691D
Original Publication Date: 2002-Jan-23
Included in the Prior Art Database: 2002-Jan-23
Document File: 1 page(s) / 54K

Publishing Venue

Motorola

Related People

Bill Stone: AUTHOR

Abstract

Enhanced Reliability of Flip Chip Packages with Organic Substrates by Using Crack Propagation Barriers

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 100% of the total text.

Enhanced Reliability of Flip Chip Packages with Organic Substrates by

Using Crack Propagation Barriers

Bill Stone

Flip chip package reliability performance in thermal cycling is often gated by trace cracking in the organic substrate. This failure mode is typically caused by cracks that initiate in the underfill epoxy and then propagate into the substrate and through trace circuitry.

Trace cracking can be reduced or eliminated by adding a metal crack barrier to impede the crack propagation prior to it reaching the trace circuitry.  The crack barrier can be designed into the substrate and fabricated by the substrate manufacturer.  The barrier can be in the form of copper fill on the top metal routing layer, flaring the trace widths, or can be a dummy or functional plane above the routing layer.

The cross sectional view in Figure 1 illustrates a flip chip package on an organic substrate, with a crack initiating in the underfill epoxy, propagating into the substrate and through the trace circuitry.  Figure 2 illustrates the use of the barrier to impede the crack propagation and preserve the integrity of the circuitry.

Crack

Barrier

Figure 2 2

Crack

Figure 1

Flip Chip Die

Substrate Cross-Section

Trace Circuitry