The reflow soldering oven is used for attaching electric components to their contact pad, usually printed circuit boards (PCB) through a reflow process. A mixture of powdered solder and flux (usually sticky) is first used to loosely fix the electrical components on to the PCB which is then subjected to a controlled heat, melting the solder in the process resulting 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.
In a conventional reflow soldering oven, there are four phases or zone with a unique thermal profile for each. It all starts in the preheat zone where the time/temperature relationship (ramp-rate) is determined. This is the rate at which the temperature changes on the PCB and it is important so that the PCB does not crack or components do not get destroyed. The solvent in the paste starts to evaporate at this phase.
Thermal soak zone with temperature ranging from 60 to 120 is the next stage for the circuit board. The purpose is the removal of solder paste volatiles and flux activation (oxide reduction from leads and pads). Temperature control at this phase is also very essential. Too high temperature leads to damage to the PCB and the components while too low temperature leads for failure of full oxidation of flux.
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 phase for the PCB is the cooling zone where the board and its components cool and the soldier solidifies. The temperature control is also significant here to avoid thermal shock excess intermetallic formation. The primary goal here is to achieve a mechanically sound and fine grain structure.
In the modern ovens with the most up to date technology, there is usually no need for solder to flow more than once as these advances techniques guarantees that the granules in the paste can surpass the reflow temperature of the solder used. The trick is therefore to select an oven that can perform optimally at all the phases resulting into the best possible PCB with attached components.
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.
In a conventional reflow soldering oven, there are four phases or zone with a unique thermal profile for each. It all starts in the preheat zone where the time/temperature relationship (ramp-rate) is determined. This is the rate at which the temperature changes on the PCB and it is important so that the PCB does not crack or components do not get destroyed. The solvent in the paste starts to evaporate at this phase.
Thermal soak zone with temperature ranging from 60 to 120 is the next stage for the circuit board. The purpose is the removal of solder paste volatiles and flux activation (oxide reduction from leads and pads). Temperature control at this phase is also very essential. Too high temperature leads to damage to the PCB and the components while too low temperature leads for failure of full oxidation of flux.
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 phase for the PCB is the cooling zone where the board and its components cool and the soldier solidifies. The temperature control is also significant here to avoid thermal shock excess intermetallic formation. The primary goal here is to achieve a mechanically sound and fine grain structure.
In the modern ovens with the most up to date technology, there is usually no need for solder to flow more than once as these advances techniques guarantees that the granules in the paste can surpass the reflow temperature of the solder used. The trick is therefore to select an oven that can perform optimally at all the phases resulting into the best possible PCB with attached components.
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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