Effect of pad size on shear strength and microstructure of LED solder joints

The pad size was changed while keeping other parameters unchanged to make LED J-Solder Joints. Next, the Intermetallic Compounds (IMC) of Solder Joints with different pad sizes and the morphology of the J-Solder joint were studied. The shear force and Shear Strength of the J Joints were assessed using a shear tester to examine the effect of pad size composition on the Shear Strength of the LED J-solder joints. It was observed that the anti-shear Strength rose with decreasing pad size, indicating that the shear data or anti-shear Strength of the J-shaped Solder Joints of LEDs with smaller pad sizes were more concentrated and uniform. Due to the high concentration of copper in the large-size pad Solder Joints during reflow Soldering, the liquid brazing material in the tin element reacts quickly with them, causing a wide range of brittle lead-rich phases to precipitate, This leads to a brittle fracture, which is the primary cause of the low Shear Strength.