How to set solder paste reflux temperature curve

How to set the solder paste reflow temperature curve

in the printed circuit board (PCB) assembly using surface mount components, an optimized reflow temperature curve is one of the most important factors to obtain high-quality solder joints. The temperature curve is a function of temperature versus time applied to the circuit assembly. When drawing on the Cartesian plane, the reflow process represents the experimental steps at any given time: the temperature at a specific point on the PCB forms a curve

several parameters affect the shape of the curve, the most critical of which are the conveyor belt speed and the temperature setting of each zone. The belt speed determines the duration of the board exposed to the temperature set in each zone. Increasing the duration allows more time to make the circuit assembly close to the temperature set in that zone. The total processing time depends on the total duration of each zone. The temperature setting of each zone affects the temperature rise speed of PCB, and high temperature produces a large temperature difference between PCB and zone temperature. Increasing the set temperature of the zone allows the board to reach the given temperature faster. Therefore, a graph must be made to determine pc6 Oxygen index tester: temperature curve of combustion performance B of polymer under specified experimental conditions. Next is the outline of this step, which is used to generate and optimize graphics

before starting the curve making step, the following equipment and auxiliary tools are required: temperature curve instrument, thermocouple, tool for attaching thermocouple to PCB and solder paste parameter table. The temperature curve accessory kit is available from most major electronic tool suppliers, which makes it convenient to make curves because it contains all the required accessories (except the curve instrument itself)

many reflow soldering machines now include an on-board thermometer, and even some common faults 7: small, inexpensive table top furnaces. Thermometers are generally divided into two categories: real-time thermometers, which transmit temperature/time data and make graphics in real time; Another kind of thermometer samples and stores data, and then uploads it to the computer

thermocouples must be long enough to withstand typical furnace temperatures. The 2016 International Plastics and Rubber Exhibition in Dusseldorf, Germany (k exhibition) will be grandly opened on October 19, 2016. Generally, thermocouples with small diameter have small thermal mass, fast response and accurate results

there are several ways to attach thermocouples to PCBs. The better way is to use high-temperature soldering tin, such as silver/tin alloy, with the smallest solder joints

another acceptable method is fast, easy and accurate enough for most applications. A small amount of thermal compound (also known as thermal conductive paste or thermal grease) spots cover the thermocouple, and then stick it with high-temperature tape (such as Kapton)

another way to attach thermocouples is to use high-temperature adhesives, such as cyanoacrylate adhesives. This method is usually not as reliable as other methods. The attachment position should also be selected. It is usually best to attach the thermocouple tip between the PCB pad and the corresponding component pin or metal end. (end)