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  SMD components, or surface mount components, are electronic components to be mounted on printed circuit boards to function. How to identify SMD components from their appearances? This article will guide you to identify surface mount components fast and easily. P art 1: Identify SMD Resistors SMD resistors are basic surface mount components that limit the current passing through them. “R” stands for resistance, and the unit of resistance is Ohm (Ω). 1KΩ equals to 1000Ω, 1MΩ equals to 100000Ω. There are two methods to indicate the resistance value on the SMD resistors’ appearance. In Arabic numbers: the first two numbers indicate the absolute numbers of the resistance value, and the last number means the power of 10. For example, 103 means 10000Ω, 391 means 390Ω, 473 means 47000Ω. In a combination of Arabic numbers and R: the Arabic numbers before the R stand for the whole part of the resistance value, and those after the R stand for the fractional part of the resistance value. For exa

 First of all, of course, to get the real furnace temperature curve! It should be said that it is necessary to obtain the actual temperature curve of the PCB board in the reflow oven because the temperature setting of the reflow oven and the actual temperature on the board have a large gap (about 10 ~ 30 °C difference), just Similar to cooking food in a gas stove, the temperature of the stove is different from the real temperature of the ingredients. By measuring the actual temperature of the PCB board, the temperature setting of the furnace can be fed back, optimized, and corrected to achieve the purpose of meeting the required temperature curve. Of course, it is better to have PCBs full of components. The final effect of the light board may differ greatly from the actual PCBA, so it is not recommended to use the light board. I have seen several production principles of temperature measuring boards. Some factories will scrap 1pcs PCBA as a temperature measuring board, this effect is,

 As we all know, circuit boards are made up of layers of copper foil circuits, and the connections between different circuit layers rely on these "vias". This is because today's circuit board manufacturing uses drilling holes. Connecting between different circuit layers is like connecting channels in multi-layer underground waterways. Friends who have played the "Brother Mary" video game may be aware of the reason that water pipes are connected. The difference is that water pipes are connected Water can circulate (not to be drilled for Brother Mary), and the purpose of circuit board connection is to conduct electricity for electrical characteristics, so it is called a via hole, but if it is just a hole drilled by a drill or a laser, it is It does not conduct electricity, so a layer of conductive material (usually "copper") must be plated on the surface of the drilled hole, so that electrons can move between different copper foil layers, because the sur