A Buyer's Checklist for a High-Precision Push-Pull Testing Machine.

Given the extremely small forces being measured, regular and proper calibration of a push-pull testing machine is absolutely essential for data integrity. Calibration is the process of comparing the machine's measurements to a known, traceable standard to ensure its accuracy. This should be performed on a regular schedule, typically annually, by a qualified technician. The process involves using a set of certified micro-weights to verify the accuracy of the load cell across its entire operating range. The positioning accuracy of the X, Y, and Z stages may also be verified using precision instruments. Without this regular verification, there is no guarantee that the force readings from the push-pull testing machine are correct, which can invalidate test results and compromise quality control. WBE offers accredited calibration services to ensure our clients' machines continuously operate at their peak specified accuracy.

When evaluating a push-pull testing machine specifically for wire bond pull testing, several key specifications are critical. Force accuracy, typically expressed as a percentage of the reading, is paramount; look for high accuracy even at the low end of the sensor's range. The Z-axis resolution and accuracy determine how precisely the machine can control the position of the pull hook, which is vital for repeatability. The range of pull hooks available is also important, as you will need different sizes and shapes to accommodate various wire diameters and loop heights. The magnification and lighting of the optical system are crucial for allowing the operator to precisely position the hook on fine wires. Finally, the machine's ability to record not just the peak force but also the JEDEC-standard failure mode is essential for effective process diagnostics when using a push-pull testing machine.

The data from a push-pull testing machine provides much more than just a peak force number; proper interpretation is key to process improvement. The numerical force value tells you the strength, but the failure mode tells you why it failed. For example, in a wire bond pull test, a "wire break" in the middle indicates a good, strong bond, while a "ball lift" (the entire bond lifts off the pad) points to a problem with the bonding surface or parameters. The software on a WBE machine helps operators log these JEDEC-standard failure modes. Analyzing the distribution of these modes, along with statistical data like the mean force and standard deviation (Cpk), gives engineers a complete picture of their process health. A high average strength with a low standard deviation and a desirable failure mode distribution is the hallmark of a stable, high-quality manufacturing process, all revealed by the data from a push-pull testing machine.

Selecting the right push-pull testing machine requires a careful evaluation of your specific applications. First, identify the types of tests you need (e.g., wire pull, die shear, ball shear). This will determine the required test modules or heads. Second, determine the force ranges needed for each test. A machine used for fine gold wire will need a very sensitive low-force sensor, while a machine for large die shear will need a high-force capability. Look for a system with interchangeable load cell cartridges for maximum flexibility. Third, consider the level of automation and the required throughput. Manual or motorized stages may be sufficient for a lab, while a fully automated system might be needed for high-volume production. Finally, evaluate the software capabilities, ensuring it can perform the necessary analysis and generate reports that meet your quality standards. Consulting with an expert at WBE can help you navigate these options to configure the perfect push-pull testing machine.