Browse Prior Art Database

Method for noncircular pads to improve substrate routing

IP.com Disclosure Number: IPCOM000012202D
Publication Date: 2003-Apr-16
Document File: 3 page(s) / 193K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for noncircular pads to improve substrate routing. Benefits include improved performance and improved support for future technologies.

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 54% of the total text.

Method for noncircular pads to improve substrate routing

Disclosed is a method for noncircular pads to improve substrate routing. Benefits include improved performance and improved support for future technologies.

Background

      Conventional controlled collapse chip collect (C4) bump and ball pads are uniform circular bumps for flip-chip C4 or solder ball attachment.

              The conventional flip-chip memory molded matrix array package substrate is designed with a very tight C4 bump pitch (218.5 µm) that does not enable a trace to be routed through adjacent bump pads (see Figure 1).

              To enable trace routing, several conventional approaches can be used. The trace pitch can be tightened, which requires significant advancements and cost in manufacturing technology. Alternatively, the silicon design can be changed to enable more space, which is difficult to implement because the substrate must be changed to fit the silicon.

      The use of noncircular copper pads has been used conventionally on via pads in substrate designs but not on C4 bump pads or ball pads.

General description

      The disclosed method is the use of noncircular pads to improve substrate routing. The method addresses design routing issues with flip chip and wire-bond packages. The disclosed method uses noncircular copper pads to increase the distance between two pads, enabling more trace routing between pads. The method can be accomplished using soldermask-defined pads so solder joints are not affected by the nonuniformity.

 

      The key elements of the method include:

•     Nonuniform, noncircular C4 bump pads or ball pads on a substrate application

•  ®..