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Method for high-speed ball-pull metrology for testing the strength of solder joints

IP.com Disclosure Number: IPCOM000008884D
Publication Date: 2002-Jul-19
Document File: 5 page(s) / 192K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for a high-speed ball-pull metrology that tests the strength of a solder-joint interconnect. Benefits include improved functionality and performance of solder-to-component strength testing, and improved product mechanical robustness, high-yield and high-quality production.

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Method for high-speed ball-pull metrology for testing the strength of solder joints

Disclosed is a method for a high-speed ball-pull metrology that tests the strength of a solder-joint interconnect.  Benefits include improved functionality and performance of solder-to-component strength testing, and improved product mechanical robustness, high-yield and high-quality production.

Background

              Ideally, solder connections to various components should be tested by achieving failure at the solder-to-component interface, and not in the bulk solder or component materials.  This goal is conventionally met by using testing techniques such as:

•             Peel Test

•             Low-Speed Ball-Pull Test

•             Low-Speed Ball-Shear Test

•             Bend (3-Point or 4-Point) Test

      Consider the effect of the rate of the pull strength on the failure mode of solder interconnections to a package substrate (as one example).  At lower rates, the solder deforms considerably and often breaks.  At higher rates, the solder is not only stiffer, but it also has a higher yield strength.  The interface between the solder and the package substrate is not a bulk material, so its strength is not rate dependent.  When a solder joint is pulled at a high rate, the failure mode can shift to the interface (if it is sufficiently weak) and consistent (rate-independent) pull strengths occur.

General description

              The disclosed method tests the bond strength and failure mode of solder interconnects.  Special fixtures pull the package away from the testing fixtures at high rates.  The materials being tested stiffen and prevent excessive deformation of the joint and surrounding material during the test.  Excessive deformation typically results in premature failure of the bulk solder or surrounding bulk material components.  This premature failure prevents most other techniques from obtaining the true bond strength at the joint-to-component interface.

The key elements of the method include:

•             A standard so...