A bond tester is a scientific instrument used to measure the mechanical strength of bonds, evaluate bond strength distributions or determine compliance with specified bond strength requirements of the applicable acquisition document. Typically a load is applied to a bond by a hook or shear tool, whereafter a force measurement is taken and the failure mode of the tested sample is recorded. More often than not bond tests are destructive and samples are scrapped after testing. In aerospace and medical applications, non destructive testing is common, whereby the bond is loaded up to a point to reveal nonacceptable bonds while avoiding damage to acceptable bonds.
Electrical and thermal bonds are such an integral part of electronic and semiconductor construction that they may often be taken for granted. Modern electronic assembly methods employ a myriad of bonding processes, each one a vital step in the manufacture of the final product. A typical consumer product such as a laptop computer may contain hundreds of thousands of bonds yet if one fails it will probably result in a system breakdown. A precise knowledge of bond strength quality measurement during product design and subsequent manufacture is directly related to product success, customer satisfaction and profitability.
The most common test types performed on a bond tester are the wire pull test, which generally puts an upward force on a gold/aluminum/silver/copper wire, and the die shear test, which generally comprises loading a die from the side. When equipped with tweezers, bond testers may also perform cold bump pull tests. During such a test, a solder ball down to 50 µm in diameter is reform it to the shape something like a mushroom and then pulled off the surface. Modern bond testers can perform a wide variety of tests with high precision, because automation eliminates human influence on the measurement.
Standards
MIL-STD-883, JEDEC and other standards are commonly followed in the industry.