High drop performance interconnection: Polymer cored solder ball

Abstract

The reliability life of solder joints is a well-known key topic for the electronics industry. Board level temperature cycling test is most common test method and provide an approximate means of relating the results from these performance tests to the reliability solder attachments for the use environments and conditions of electronic assemblies. Recently, due to environmental debates, SnPb solder has replaced by lead free materials. The two most common compositions are Sn3.0Ag0.5Cu and Sn4.0Ag0.5Cu, respectively. Since small and thin package is the future tendency, the structure of shorter interconnection of chip scale package (CSP) with ball grid array (BGA) is customarily occupied for handheld products. In virtue of recognizing package quality for actual status, board level drop impact is a great concern to simulate mishandling during usage. As well known, the common Sn3∼ 4Ag0.5Cu of lead free solder is poor drop performance due to higher Young’s modulus by high volume of Ag3Sn. Lower silver content solder was introduced to replace Sn3 ∼ 4Ag0.5Cu solder to satisfy trend requirement. But, the drop performance is not still enough to satisfy the end user demand.