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Underfill Sheet with Embedded Conductive Cu-Au Balls for Substrate and Die Joint

IP.com Disclosure Number: IPCOM000020168D
Publication Date: 2003-Oct-29
Document File: 3 page(s) / 282K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for embedding Cu-Au balls along the bump pitch inside an underfill sheet between the die and substrate join, connecting the die and substrate with a bumpless structure. Benefits include improving process yield, and reducing material and process costs.

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Underfill Sheet with Embedded Conductive Cu-Au Balls for Substrate and Die Joint

Disclosed is a method for embedding Cu-Au balls along the bump pitch inside an underfill sheet between the die and substrate join, connecting the die and substrate with a bumpless structure. Benefits include improving process yield, and reducing material and process costs.

Background

Currently, solder bump volume is controlled at production. There are long throughput times for die and substrate productions, as well as for the assembly process, due to the bump formation and C4 joint processes. These processes can increase material and assembly costs.

General Description

The disclosed method embeds Cu-Au balls along the bump pitch inside the underfill sheet, between the die and substrate join, connecting the die and substrate with a bumpless structure.

Figure 1 shows the conductive metal balls with Au plating. Figure 2 shows the embedded balls along C4 and die pads inside the underfill sheet. Figures 3 and 4 show the thermal and ultrasonic treatment.

Advantages

The following are advantages of the disclosed method:

§         For the die/substrate bumpless structure:

  • Eliminates bump related issues
  • Improves process yield
  • Simplifies the die/substrate process
  • Reduces material costs

§         For the underfill sheet with conductive metal balls structure:

  • Improves die/substrate and assembly production throughput time
  • Improves joint strength by eliminating one connecting point
  • Reduces assembly process costs

Fig. 1

Fig....