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Method for blocking copper migration for MMAPs

IP.com Disclosure Number: IPCOM000100666D
Publication Date: 2005-Mar-16
Document File: 3 page(s) / 28K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for blocking copper migration for matrix molded array packages (MMAPs). Benefits include improved functionality and improved performance.

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Method for blocking copper migration for MMAPs

Disclosed is a method for blocking copper migration for matrix molded array packages (MMAPs). Benefits include improved functionality and improved performance.

Background

      Copper migration occurs along the edge of MMAPs. Because plating bars are exposed to the outside at the sawed surface of the package after dicing, copper migration occurs easily at the package surface (see Figure 1).

      Diced package edges can be contaminated with a slight amount of copper from the sawing process. As a result, leakage occurs along the edge of the package when a bias is applied in high-temperature high-humidity conditions.

      Conventionally, the problem is solved by widening the space between plating bars.

General description

      The disclosed method is the blocking of copper migration that occurs along the edge of a diced MMAP.

              The key elements of the method include:

•             Copper etching process after package saw dicing to remove a small amount of copper from the plating bars that are exposed at the sawed surface of the package

•             Slight recess created by copper wet etching where the plating bars are originally exposed

•             Nickel barrier selectively plated on the recess to terminate the plating bar at the edge of the package

Advantages

              The disclosed method provides advantages, including:

•             Improved functionality due to terminating the edge of plating bars exposed to outside of package around the diced package edge

•             Improved functionality due to decreasing the surface area required for trace routing by shortening the plating bars pitch at the edge of package

•             Improved performance due to providing high resistivity against copper migration, which occurs along the edge of pa...