The metal tray that slides in underneath the rack helps to distribute the intense heat generated by the lower heating element.Actually, there a few things I like about this oven: Maybe that stuff helps, but it’s not essential. It is nothing fancy-no convection, no infrared, no digital display. In this article we will cover preliminary information and techniques, and the next article will present a detailed procedure for compelling a toaster oven to obey the temperature profile of your choice. But you won’t get anywhere until you have a hot container in which to melt your solder paste, so first we need to focus on pressing an ordinary toaster oven into service as a reflow appliance extraordinaire. There are a few steps-along with plenty of tips and techniques-involved in the entire DIY PCB reflow process. But again, DIY reflow is achievable with little more than a cheap toaster oven, a tube of solder paste, and a system for measuring and recording temperatures. ![]() It’s not easy, especially with tiny or small-pitch components, and it’s not an automated, defect-free, assembly-line sort of operation-your brain is needed to help the toaster oven control its temperature, and your hands may be needed to remedy a few solder bridges or “tombstoned” capacitors. Also, let’s say you decide to splurge on the initial assembly job-what happens when you need to replace that 100-pin microcontroller? Even if you have a hot-air soldering station to help you with this kind of rework, before long you will probably be wishing for a tube of solder paste and a reflow oven.įortunately, low-cost, simple, DIY reflow is perfectly achievable. Professional assembly is rarely a feasible option: it is surprisingly expensive, especially for small quantities, and coordinating with the assembly house can be awkward if you are trying to use whatever stray components you have lying around your lab/office/garage/bedroom. Hand soldering is becoming increasingly burdensome-sometimes impossible-owing to the proliferation of miniscule components, leadless packages, and ball-grid arrays. This temperature feedback will enable you, the assembly technician, to accurately control the oven’s heating profile via simple, real-time adjustments.Īs you may know, surface-mount assembly can be a serious impediment for students, hobbyists, entrepreneurs, or anyone else who wants to design and test high-performance circuit boards without paying for professional assembly. In short, the system displays the current temperature and a graph representing the temperature history, as follows: That article tells you how to build and use the system, and it provides links for downloading the microcontroller code and the Scilab script. In a previous article ( Make an EFM8-Based System for Monitoring and Analyzing Thermocouple Measurements), we developed an EFM8-and-Scilab-based system for collecting, recording, and displaying thermocouple temperature measurements. Cooling zone: This is the last zone to gradually cool the PCBA and solidify the solder joints.With the help of a DIY thermocouple measurement system, you can use a cheap toaster oven to accurately reproduce a reflow-soldering temperature profile. ![]() The maximum allowable peak temperature limit is determined by the type of electronic component on the PCB assembly with the lowest tolerance for high temperatures (the component most susceptible to thermal damage). ![]() It is part of the reflow process where the maximum temperature is reached. Reflow zone: This zone is also called “ time above reflow” or “ time above liquidus”.Thermal soak zone: This is the high temperature zone where the temperature is high enough to melt solder paste so that the component leads get soldered to the pads on the circuit board.The temperature of the board and all the SMD components is gradually and uniformly raised to prevent any crack to the SMT PCB due to thermal shock. Preheat zone: This is the first chamber or zone of any reflow oven.Different Zones of Reflow Oven and Reflow Soldering Process ![]() Now the electronics industry has made tremendous progress in redesigning heating elements to eliminate earlier problems.
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