A Reflow Soldering Oven: How Does It Work?
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.
The heat in the majority of these ovens is produced from ceramic infrared heaters, and then directed to assembly chambers through radiation process. The infrared ones uses fans to force heat into the assembly chambers where the PCB and the components are exposed to optimal temperatures for melting of the solder for permanent fixing of the components on to the PCB.
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.
Maximum temperatures are reached at the reflow zone (the third stage). At this stage, the surface tension of the flux gets reduced at the metal juncture resulting to metallurgical bonding-all the solder powder combines. In considering the maximum tolerable temperature, the components with the lowest thermal damage is very significant as the maximum operating temperature is set slightly below this level. It is at this phase that full control of the temperatures and exposure time must be done for obvious reasons of avoiding device destruction.
The last stage is the cooling zone where the circuit board and its component are cooled. This process too is done under efficient temperature control as sudden temperature changes may result to thermal shock. It is also important to avoid excessive metallic formation at this stage as the desired finished circuit board should have components attached with fined grained structured solder making it mechanically sound.
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.
The heat in the majority of these ovens is produced from ceramic infrared heaters, and then directed to assembly chambers through radiation process. The infrared ones uses fans to force heat into the assembly chambers where the PCB and the components are exposed to optimal temperatures for melting of the solder for permanent fixing of the components on to the PCB.
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.
Maximum temperatures are reached at the reflow zone (the third stage). At this stage, the surface tension of the flux gets reduced at the metal juncture resulting to metallurgical bonding-all the solder powder combines. In considering the maximum tolerable temperature, the components with the lowest thermal damage is very significant as the maximum operating temperature is set slightly below this level. It is at this phase that full control of the temperatures and exposure time must be done for obvious reasons of avoiding device destruction.
The last stage is the cooling zone where the circuit board and its component are cooled. This process too is done under efficient temperature control as sudden temperature changes may result to thermal shock. It is also important to avoid excessive metallic formation at this stage as the desired finished circuit board should have components attached with fined grained structured solder making it mechanically sound.
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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