Lead Frame and Wire Bond Pull Test

IPC TM-650 | ASTM F459-13

The Challenge

Lead frames used in various electronic packages, such as capacitors, resistors, and integrated circuits (IC), are used to provide electrical interconnection between the die and the substrate. Some components may have one or two leads, while other packages such as IC chips can have hundreds. These lead frames are bonded using solder paste materials. As part of reliability testing, it is critical to test the bond strength of the lead at the solder joint, allowing you to better understand where failure occurs. Tensile testing can reveal the benefits of using various materials, such as gold, copper, etc., when developing new lead frames and final assemblies. Some of the most common challenges in tensile testing of lead frames include accurate gripping, alignment of the package or components, gripping of printed circuit boards (PCBs), and determining the failure location with real-time data.

Our Solution

Instron® micro pneumatic grips are designed to hold the lead frames in an accurate position for the pull test. Other grips, such as wire pull hooks, are also available to align and hold the lead frame accurately. XY stages are designed to accurately mount and position any rigid or flexible printed circuit boards. These stages allow you to adjust the X and Y axis using a micrometer, as well as the angular position, theta, to enable easier gripping of micro components with a fine pitch assembly. The XY stages are available in a manual version, or you can fully automate the lead pull test with the motorized version, ensuring high accuracy and repeatability. The TestCam module for Bluehill® Universal is designed to shoot high-frame rate videos while tests are being conducted. The camera can be synced with the software to observe images and videos at various test points in real-time. Bluehill Universal software is designed for the user to add calculations and to plot various response curves, such as force vs. displacement and stress vs. strain, that are relevant to the application. In the lead tensile test, the software can be used to plot the force vs. displacement curve in order to identify the maximum load needed to break the lead frame from the solder joint.