![]() An incompatible temperature profile will cause solder failures. So, our reflow profile does match the solder paste specification. The reflow process of the Pb-free material is suggested to follow or modify from the standard of J-STD-020D1, and every section in the reflow profile, including the preheat, soaking, reflow, and cooling sections, ought to be set up and monitored accordingly. Solder integrity is determined by the magnitude of the shear force the joint can withstand. The reflow profile affects the mechanical integrity of lead-free SJs. The cooling ramp rate, from Figure 2, is (250-90)☌/(5.7-3.8) min = 160☌/(114 sec) = 1. 40☌/sec, which is within the acceptable rate of the solder paste spec. Effects of Reflow Profile on the Integrity of Solder Joints in Surface Mount Chip Resistors. The resulting surface oxide can lead to a number of solder defects such as voiding, beading/balling, graping, and head-in-pillow. that challenges the solder paste’s flux to effectively perform its fluxing action. The peak temperature is 250☌, again within the specification recommended range as seen in Figure 1. Figure 2 - Ramp/soak/spike reflow profile. There is no “soak” in this profile, so we can ignore this part of the solder paste spec.įrom Figure 2, the time above liquidus is 4.4 – 3.1 minutes (78 Seconds), right within the recommended range of the solder paste spec. This result is just over the recommended spec, but within the acceptable spec as seen in Figure 1. Check the solder joint quality, PCB and component. Reflow the board and measure the real time thermal profile simultaneously. Typical RTS Profile Profile Length: 3-4. A virtual reflow profile is based upon soldering theory, the recommended solder profile from the solder paste manufacturer, size, thickness, cooper weight, layers of the board and size, and the density of the components. ![]() RSS profiles are appropriate when the assembly has a large thermal mass or large T. Ramp Profile: From Figure 2, the oven goes from room temperature to liquidus in 3.1 minutes (186 seconds) this gives a slope of (219 – 25)☌/(186 - 0 ) sec = 194/186 = 1.04 ☌/sec. RTS profiles are suitable for use in most applications for enhanced solder performance. Now, let’s take each reflow profile requirement individually: The solder paste reflow specification is shown in Figure 1 below.įurthermore, let’s assume that we have a reflow profile that we have used in the past, as seen in Figure 2. ![]() Assume we want to start using Indium Corporation’s Indium8.9HF Pb-Free Solder paste. Matching a reflow profile to a solder paste spec is a required skill for an SMT process engineer.
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