Browse Prior Art Database

Innovative Concaved Substrate C4 Bump

IP.com Disclosure Number: IPCOM000034124D
Publication Date: 2005-Jan-17
Document File: 3 page(s) / 21K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method that introduces a concave shape to the substrate solder C4 bump. Benefits include reducing solder bridging and the die gap height as well as introducing mechanical hold of die. Possibility of eliminating or reduces UF usage.

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 53% of the total text.

Innovative Concaved Substrate C4 Bump

Disclosed is a method that introduces a concave shape to the substrate solder C4 bump. Benefits include reducing solder bridging and the die gap height as well as introducing mechanical hold of die. Possibility of eliminating or reduces UF usage.

Background

The current process is prone to bump bridging, die misalignment, and die float. These issues are anticipated to be eliminated or reduced by introducing a concave structure on the C4 bump for substrate that allow partly insertion of the die bump into the substrate concaved bump (see Figure 1).

General Description

The disclosed method reduces the flow of bump solder material to adjacent bumps, which is highly suspected to causes solder bridging (see Figure 2). As the pitch of the bump decreases, the tendency of bump solder flowing to adjacent bumps is increased because like materials have a tendency to move toward each other. However, with a slightly concaved structure, the die bump that is sitting in the concaved area provides higher tendency of substrate solder bump to flow upward to die bump instead of adjacent bump during reflow. The concaved structure also reduces the substrate solder bump volume. In addition, the gap between substrate solder bump is enclosed by thicker solder resist; hence preventing further flow of substrate solder bump to adjacent bump. With a concaves structure, it allows for die bumps to be fully inserted into the concaved substrate bump structure (the die sits flat on the substrate). This potentially eliminates the need of underfill (U...