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Stress reduction by applying rounded edges to the die at bare die and encapsulated packages

IP.com Disclosure Number: IPCOM000130565D
Published in the IP.com Journal: Volume 5 Issue 11A (2005-11-25)
Included in the Prior Art Database: 2005-Nov-25
Document File: 2 page(s) / 65K

Publishing Venue

Siemens

Related People

Juergen Carstens: CONTACT

Abstract

Up to now, the standard dicing und grinding processes on bare die IC-packages (IC, Integrated Circuit) and molded IC-packages did not offer any possibility to avoid pre-damage during the assembly process. There are several reasons for the mechanical deterioration such as micro cracks in the area of the edges of the dies as well as shell outbreaks that often occur during further processes. An improvement for this problem is given by the following solution. To improve the assembly and BI&T (burn in and test) yield as well as the reliability performance, the idea is to apply rounded edges on chips which will increase the mechanical stability and breakage safety during the further assembly steps. By applying rounded edges to the die, the mechanical stress in the critical area is reduced significantly, since the mechanical stress will be spread into a wide area of the die. This is achieved by a curve radius in the range of 2-8 micrometer and practically applied e.g. by using the plasma etching technique or the dry polishing process. A procedure which includes these techniques in a practical way is called DBG (dicing before grinding). The range of the radius has a great impact on the expected mechanical improvement. Two schematic embodiments are shown in Figure 1 (bare die package) and in Figure 2 (encapsulated package).

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Stress reduction by applying rounded edges to the die at bare die and encapsulated packages

Idea: Martin Reiss, DE-Dresden; Stephan Blaszczak, DE-Dresden; Bernd Scheibe, DE-Dresden;

Sylvia Winter, DE-Dresden; Stefan Liehr, DE-Dresden; Waldemar Moeller, DE-Dresden; Steffen Mimietz, DE-Dresden

Up to now, the standard dicing und grinding processes on bare die IC-packages (IC, Integrated Circuit) and molded IC-packages did not offer any possibility to avoid pre-damage during the assembly process. There are several reasons for the mechanical deterioration such as micro cracks in the area of the edges of the dies as well as shell outbreaks that often occur during further processes.

An improvement for this problem is given by the following solution. To improve the assembly and BI&T (burn in and test) yield as well as the reliability performance, the idea is to apply rounded edges on chips which will increase the mechanical stability and breakage safety during the further assembly steps. By applying rounded edges to the die, the mechanical stress in the critical area is reduced significantly, since the mechanical stress will be spread into a wide area of the die. This is achieved by a curve radius in the range of 2-8 micrometer and practically applied e.g. by using the plasma etching technique or the dry polishing process. A procedure which includes these techniques in a practical way is called DBG (dicing before grinding). The range of the radius has a great impact on the expected mechanical improvement. Two schematic embodiments are shown in Figure 1 (bare die package) and in Figure 2 (encapsulated package).

This solution offers several benefits. First of all, pre-damaging of the...