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Method Of Removing Copper Burr At Saw Singulation

IP.com Disclosure Number: IPCOM000234563D
Publication Date: 2014-Jan-17
Document File: 3 page(s) / 242K

Publishing Venue

The IP.com Prior Art Database

Abstract

Segregating an integrated circuit from a metal lead frame using established known manufacturing processes like punching or sawing is common in the semiconductor industry. For lead frames where there is little or no space available for punching or a lead frame with finer spacing between integrated circuits, sawing is used to separate the units. As with punching, sawing often leaves behind copper burr as the tool shear through the bulk of the metals from the lead frame. The copper burr can create problems such as electrical shorting of two or more terminals of the same unit or hindering the unit from soldering to the board. Though process optimization or proper blade selection can help to minimize the amount or size of the burr, this alone will not eliminate the burr completely especially in situations where the leads have half-etched or dimple features that tend to trap the copper particles during the sawing process. Some semiconductor companies have resorted to using a wet chemical process to remove the copper burr. Such processes not only introduce added process steps and lengthen the assembly cycle time, but also increase the overall assembly packaging cost.

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TITLE

Method Of Removing Copper Burr At Saw Singulation

ABSTRACT

Segregating an integrated circuit from a metal lead frame using established known manufacturing processes like punching or sawing is common in the semiconductor industry. For lead frames where there is little or no space available for punching or a lead frame with finer spacing between integrated circuits, sawing is used to separate the units.  As with punching, sawing often leaves behind copper burr as the tool shear through the bulk of the metals from the lead frame. The copper burr can create problems such as electrical shorting of two or more terminals of the same unit or hindering the unit from soldering to the board.  Though process optimization or proper blade selection can help to minimize the amount or size of the burr, this alone will not eliminate the burr completely especially in situations where the leads have half-etched or dimple features that tend to trap the copper particles during the sawing process. Some semiconductor companies have resorted to using a wet chemical process to remove the copper burr. Such processes not only introduce added process steps and lengthen the assembly cycle time, but also increase the overall assembly packaging cost.

CONTENT

Copper burr removal by means of chemical process or brushing by hand or with a standalone machine is not new. This method of burr removal is commonly seen in the industry.

The idea of integrating a brushing mechanism on the dicing machine is uncommon. In this idea, a brush is attached to a metal plate right beside the mounting wheel of the saw blade. Figure 1 provides a full illustration how the brush looks and location where it is mounted.

Figure 1 Brush mechanism and mount location inside the saw machine

The brush is ...