Browse Prior Art Database

Revolutionary Leadframe Design for Flash Small Outlined Packages

IP.com Disclosure Number: IPCOM000020321D
Publication Date: 2003-Nov-12
Document File: 2 page(s) / 206K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method that uses two or four mini paddles (without windows or holes) connected by a reinforced tie bar to the leadframe mainframe. Benefits include reduced interfacial stresses and moisture absorption, while using less adhesive.

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 92% of the total text.

Revolutionary Leadframe Design for Flash Small Outlined Packages

Disclosed is a method that uses two or four mini paddles (without windows or holes) connected by a reinforced tie bar to the leadframe mainframe. Benefits include reduced interfacial stresses and moisture absorption, while using less adhesive.

Background

Currently, there is a very limited number of solutions to address low Moisture Sensitivity Level Classification (MSLC) problems. Often, reliability concerns (i.e. interfacial delamination) of large die sizes may make it difficult to meet the MSLC level 1 or 2 criteria, and therefore, they may result in a lower MSLC rating (see Figure 1).

.

General Description

In the disclosed method, tie bar expansion/contraction is unidirectional, unlike current designs that expand in various directions as a result of the angular tie bar components. Also, possible warping (due to thermo-mechanical loads) is minimized by the disclosed method’s straight configuration. The new tie bar is 67% wider than the current design, thereby further strengthening the die paddle support (see Figure 2).

The disclosed method’s mini-pad design uses a lighter die paddle, which applies less overall weight on the tie bars. This also reduces stress on the die, adhesive, and paddle layers (see
Figure 3).

Advantages

The following are advantages of the disclosed method:

§         Improved moisture reliability performance

§         Better package quality and yield improvement against die pad float and exposed pad...