Tungsten Disulfide Used in Reflow Furnace

Tungsten disulfide can be used at high temperature, so it has high application in the lubrication of reflow furnace. Reflow soldering process is very strict in temperature control, which requires the lubricating material must have performance of high temperature resistance.

Reflow furnace is a kind of equipment to weld surface mount devices (SMDs) and printed circuit board (PCB) together with solder paste alloy.The equipment has high production efficiency, few soldering defects and stable performance, together with the high application in surface mount technology (SMT).

Pre-heat zone, soak zone, reflow zone and cooling zone are four main zones of SMT Reflow Profile. They are as following:

1. Pre-heat Zone

The first step of reflow soldering is preheating, which is to make the solder paste active, avoiding the bad welding caused by high temperature heating during tin immersion. PCB is heated evenly to the target temperature and the heating rate is controlled during the process.

2. Soak Zone

The main purpose of this stage is to keep the temperature of PCB and SMDs stable and keep SMDs temperature consistent. The sizes of SMDs are different. Large devices need much heat and the temperature rises slowly, while the temperature of small devices rises fast. So, there is enough time for the temperature of large devices to catch up with that of small ones.

3. Reflow Zone

In this stage, the temperature of the heater rises to the maximum, and the temperature of the SMDs rises to the maximum rapidly as well. The peak temperature of soldering varies with the solder paste used. It is generally between 210°C and 230 ° C. The reflow time should be short to prevent adverse effects on SMDs and PCB.

4.Cooling Zone

The temperature is cooled below the freezing point of solder paste, so as to make the solder joint solidify. The faster the cooling rate, the better the soldering effect. And the cooling rate is generally about 4 °C / s. The target temperature is 75°C.

The temperature is strictly controlled during the reflow soldering process. Therefore, the lubricating material used in reflow soldering must also be suitable for complex temperature environment. Tungsten disulfide has good high temperature resistance and oxidation resistance. It can maintain excellent lubrication effect at 650 °C and -273°C. So it is considered an ideal lubricating material for reflow soldering.

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