In the assembly industries, the process of attaching electronic components on to a printed circuit board (PCB) is usually done by soldering them onto the board. Reflow soldering oven is one of the most modern devices used for to achieve this attachment. The process starts with a sticky mixture of flux and powdered solder that helps to attach the components on to their correct positions on to the board. A process of controlled heating and cooling then follows to achieve permanent joints.
One or more ceramic infrared heaters can be used for heating the oven. The heat is then directed through the radiation process to the assembly compartments although infrared ovens use fans to direct heat to the assembly. The target is usually to expose PCB to the optimum heat conditions enough to melt the solder into the correct positions without damaging the PCB or devices on it.
The process starts with loose attachments of the components to the desired positions on the PCB using sticky solder powder and flux mixture. This is then directed to first of the four phases through which the process undergoes. The first of this is the preheat zone which involves determination of temperature/time relationship (ramp rate). This significance of this comes in other stages as the maximum temperature and time exposure should be maintained to avoid destroying the PCB and the components on it.
The second phase is the thermal soak zone where the solder paste volatiles are removed. It also involves flux activation(removal of oxide from leads and pads) and the temperatures can range anywhere between 60 to 120 depending on the tolerance levels of mounting board and the components on it.
The reflow zone is the third place where the temperatures reaches maximum peak, usually above the liquidus point. The soldering paste is molten under efficiently controlled conditions reducing the surface tension of flux at the point of metal juncture. The result of this process is the permanent fixing of electrical components on to the circuit board. The ramp rate and temperature control is highly significant at this phase. The sudden change of temperatures from the soak zone to above liquidus can easily destroy the devices through temperature shock and thus calls for very efficient control mechanisms.
Cooling takes place in the last phase also known as the cooling zone from where the molten solder solidifies into the precise target points permanently fixing the electronic components on to the PCB. The temperature control is still significant as such problems like thermal shock or the excessive metallic formation must be avoided I order to obtain a mechanically sound devices attached with fine grained structured solder.
The modern high tech ovens allows for only one reflow at the third phase as the granules in the paste are made to surpass the temperatures at this phase. For optimality and lower consumption therefore, it is advisable to shop for an efficient oven that put in place the most recent technological advancement.
The changing customer needs, competition, market condition and the general technology all calls for adopting measures that optimizes operating efficiency in terms of yield and profitability. It is such measures that can ensure the survival of a firm into the future. For assembly firms in particular, an efficient and modern reflow soldering oven is more than necessary as it increases the production rate and minimizes on power consumption.
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