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Method for a pull-rod for testing tensile and shear strength without specimen preload

IP.com Disclosure Number: IPCOM000012344D
Publication Date: 2003-Apr-30
Document File: 8 page(s) / 316K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for a pull-rod for testing tensile and shear strength without specimen preload. Benefits include improved performance and improved reliability.

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Method for a pull-rod for testing tensile and shear strength without specimen preload

Disclosed is a method for a pull-rod for testing tensile and shear strength without specimen preload. Benefits include improved performance and improved reliability.

Background

              Measuring the true tensile, compressive, and shear strengths of packaging materials (polymer, solder TIM materials, and underfill materials) is required for the improvement of package reliability and performance. Conventional methods cannot ensure correct specimen alignment. Conventional fixturing requires the application of a significant preload force on the specimen and the moving of the specimen during the setup operation. The preloading results in slight misalignments between the specimen and the two pneumatic clamps that hold the specimen.

              The sample is first clamped at one end (see Figure 1). Making sure the specimen is aligned correctly is extremely difficult during this step. When the second actuator is engaged, it loads the specimen (see Figures 2-6). The pneumatic actuator applies air pressure, which provides clamping force for holding specimen. Specimen preload has been measured in excess of 90 N (more than 20 lbf), which has been shown to damage the material before the testing begins. For the accurate testing of low-strength materials, testing must start with a zero preload to ensure damage is not induced prior to testing.

              Conventionally, no successful solution for ensuring specimen alignment and eliminating specimen preload exists. Fixturing is not designed to ensure proper specimen alignment or to eliminate preload on the specimen. The preload condition induces cracks or fractures in the TIM material. If the preload damage goes undetected, erroneous data is collected.

General description

              The disclosed method is a pull-rod for testing tensile and shear strength without specimen preload. The method enables the testing and measuring of the tensile, compressive, and shear strength of packaging materials, such as polymers, underfills, polymer-solder hybrids and lead-free solders.

              The key elements of the method include:

•             Pull-rod design utilizing pinned attachments

•             Solder specimen fixture design

Advantages

              The disclosed method provides advantages, including:

•             Improved performance due to ensu...