3/18/2024 0 Comments Solder reflow profile![]() So, our reflow profile does match the solder paste specification. It is possible to make virtual profiles automatically for both reflow and wave soldering. A virtual profile gathers all the typical data that is measured by instrumented profiles. 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. The virtual profiling process eliminates the need to physically attach thermocouples to the same production board each time. The voids are usually formed when the solder paste transforms from a solid to liquid state when heat energy is applied to the solder. When used in materials such as solder paste, they are vital for the assembly of components on printed circuit boards (PCBs) through processes such as reflow soldering. Once the flux is activated, the chemical reaction removes the surface oxides from both the component leads and PCB pads to promote soldering once the solder becomes molten. The pre-reflow section is where the flux is activated. The peak temperature is 250☌, again within the specification recommended range as seen in Figure 1. Various factors may result in the formation of voids during the reflow soldering process, for example, the type of solder paste, the aperture of the stencil, and the reflow profile. Solder alloys play a pivotal role in surface mount technology (SMT). The ramp rate should be 0.5 2.0☌/second and depends greatly on the belt speed4. 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. To achieve this there are usually 4 stages which are Preheat, Thermal Soak, Reflow and Cooling. Reflow Soldering is the soldering of components to the PCB. After soldering the boards are inspected in detail. This result is just over the recommended spec, but within the acceptable spec as seen in Figure 1. Reflow profiles or processes that are not well optimised can lead to poor or non-wetting, damaged components or cold soldering. 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. 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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