Since the bonding parts are subjected to various stress tests in actual use, we perform different tests in the laboratory to ensure the bonding quality. A common practice is to test RFID tags made with production equipment. The positioning of the chip can be detected by the vision system, and the performance of the tag can be tested by the card reading system.
In addition to the rapid test methods that come with these production equipment, there are more detailed follow-up test methods for testing the quality of the bond.
Shear force of the chip: The tool of the shear tester is used to push the chip away from the substrate. In the shear test, the ideal adhesion between the adhesive, the chip and the substrate should not be less than 25 N/mm2.
Degree of cure of the adhesive: DSC analysis (differential scanning calorimetry) can be used to detect if the adhesive is fully cured within the selected parameters. This test method can reflect abnormal conditions due to too short curing time or low temperature.
Photomicrographs: Micrographs of the chip and substrate show the extent to which the chip and its bumps are pressed into the antenna. Insufficient pressure can lead to poor chip contact, and too much pressure can cause damage to the chip or substrate.
Determining the reading distance: In this test, the power of the card reader is kept constant, and the tag to be tested is kept away from the card reader until the card reading error is prompted. Or, continue to increase the reader's transmit power until the tag begins to send data; in this case, the distance between the tag and the reader is set in advance.