How to Calibrate Die Shear Testers
Die shear testing is used to determine the strength of adhesion of a semiconductor die to its substrate. For example, it can be used for die pads of a lead frame or cavity of a hermatic package. But how do you calibrate die shear testers? Follow the steps below to learn of a productive process in die shear testing calibration.
Step 1: Make sure your tester includes its basic components: a mechanism that will apply loads to die with an accuracy of plus or minus 5 percent of full scale or 50 grams, whichever is greater; a die contact tool that will allow for contact with full length of die edge to apply force from one end to another; provisions to make sure that tool is perpendicular to the die attach plane; provisions to make sure the die-holding fixture can be rotated so the die edge and contact tool will align to be parallel to each other; and a binocular microscope and lighting system. These items will ensure observation of the die and contact tool during testing.
Step 2: Be aware of the force applied to the die during the testing. It will have to be sufficent to shear die from its mounting or twice the lower spec limit for the strength of the die shear, whichever happens first.
Step 3: There are failures in die testing. These include meeting die shear strength requirements. Also, there will be a separation that will occur at less than 1.25 times the minimum die shear strength or less than 50 percent adhesion of the die attaching material. The final failure is a separation that happens at twice the minimum die shear strength and if there is less than 1 percent adhesion of the die attach material.
Step 4: Mode of separation should be classified as follows: shearing of die itself with remaining silicon, separation of die from die attach material and separation of die and die attach material from substrate.
Tips
- The purpose of die shear testing is generally to assess quality of the die-attach process, which includes integrity of materials and how capable processes are that are used in mounting die.
- After initial contact is made and force application has commenced, the position of the tool shouldn’t change and should not contact die attach material or the substrate.
Items Needed
- Die Tester with components
- Die
- Force to be applied