Technical Library | 2023-01-17 17:27:13.0
Reflow profile has significant impact on solder joint performance because it influences wetting and microstructure of the solder joint. The degree of wetting, the microstructure (in particular the intermetallic layer), and the inherent strength of the solder all factor into the reliability of the solder joint. This paper presents experimental results on the effect of reflow profile on both 63%Sn 37%Pb (SnPb) and 96.5%Sn 3.0%Ag 0.5%Cu (SAC 305) solder joint shear force. Specifically, the effect of the reflow peak temperature and time above solder liquidus temperature are studied. Nine reflow profiles for SAC 305 and nine reflow profiles for SnPb have been developed with three levels of peak temperature (230 o C, 240 o C, and 250 o C for SAC 305; and 195 o C, 205 o C, and 215 o C for SnPb) and three levels of time above solder liquidus temperature (30 sec., 60 sec., and 90 sec.). The shear force data of four different sizes of chip resistors (1206, 0805, 0603, and 0402) are compared across the different profiles. The shear force of the resistors is measured at time 0 (right after assembly). The fracture surfaces have been studied using a scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS)
Technical Library | 2019-05-23 10:30:22.0
Increasing I/O numbers, device complexity, and product miniaturization requires high precision bonding tools, and sophisticated equipment. Careful consideration should be given to wedge geometry while selecting the tool for a fine pitch wire bonding application. Wire bonding is a process that creates an electrical connection between a die and a substrate or lead typically using gold or aluminum wire. Wedge bonding is a specific type of wire bonding that uses a wedge shaped tool to create the welds. The design of the wedge tool has changed very little over the past decade. The wire is fed at an angle through the back of the wedge. This angle is typically 30 to 60 degrees and is application dependent. Some applications require a higher feed angle due to package clearance issues. Some deep access applications require a 90 degree feed angle. In this configuration, the wire is fed through a hole in the shank of the wedge tool. Wire feed is shown in Figure 1.
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