A reflow oven is used to attach electrical components to a printed circuit board, PCB. This is achieved with the use of solder paste. The process is a delicate balance of heating the solder paste just enough to attach the component or components, but the initial heat cannot be so high that is damages the components or the circuit board. The ovens are now available in the desktop reflow oven model. The prices range from around four to six thousand dollars.
The name of this technology is surface mount technology, referred to as SMT. The ovens are often called P&Ps, for pick and place machines. The costly floor models take up floor space and are many time more expensive than the desktop versions. The needs of businesses vary. Some small companies may only need the desktop model, while larger manufacturers may need one or more of the floor models, but may want the desktop as an added piece of equipment.
The soldering process is highly sophisticated and must be managed with precision. Computerized electronic systems are in many of the products people use every day. Computers, calculators and cars are only a few. Robotic surface mount technology, SMT, is used in manufacturing many of these products.
There are four stages to the reflow process. First is the preheat zone, next the thermal soak, then the reflow zone and last the cooling zone. Each zone accomplishes a different purpose. The preheat stage must be sensitive to the maximum slope, the rate at which the heat increases. If heat increase too quickly or too slowly the components could be damaged or the flux will not evaporate sufficiently.
The thermal soak zone is brief, typically only one to two minutes. This stage activates the flux, which is the chemical cleaning agent in the solder paste. The activation of the flux causes oxide reduction on the various component pads and leads. Again, precision is needed to attain the exact temperature. At the end of this zone there should be thermal equilibrium before going into the next zone.
The next stage is the reflow zone. The highest temperature occurs during this stage. Precision still is necessary. As a guideline the rule is that the highest temperature must be 5 degrees C less than the degrees tolerated by the component with the lowest heat tolerance. At this time the solder paste liquefies as it reflows through the PCB and components to achieve metallurgical bonding.
During the fourth and last stage, the cooling zone, the entire assembly will cool and solder joints will become solid. In the previous stage the assembly was at its maximum heat. During this stage it will cool at the rate of about 4 degrees C per second. The PCB and the bonded components are now ready for the next stage of assembly in the manufacturing process.
Take the time to research the various manufacturers of soldering ovens before making a purchase. Check with professionals knowledgeable in this area to get some brand recommendations. People who have used the machines can give you the best advice, if this is your first purchase of a reflow oven.
The name of this technology is surface mount technology, referred to as SMT. The ovens are often called P&Ps, for pick and place machines. The costly floor models take up floor space and are many time more expensive than the desktop versions. The needs of businesses vary. Some small companies may only need the desktop model, while larger manufacturers may need one or more of the floor models, but may want the desktop as an added piece of equipment.
The soldering process is highly sophisticated and must be managed with precision. Computerized electronic systems are in many of the products people use every day. Computers, calculators and cars are only a few. Robotic surface mount technology, SMT, is used in manufacturing many of these products.
There are four stages to the reflow process. First is the preheat zone, next the thermal soak, then the reflow zone and last the cooling zone. Each zone accomplishes a different purpose. The preheat stage must be sensitive to the maximum slope, the rate at which the heat increases. If heat increase too quickly or too slowly the components could be damaged or the flux will not evaporate sufficiently.
The thermal soak zone is brief, typically only one to two minutes. This stage activates the flux, which is the chemical cleaning agent in the solder paste. The activation of the flux causes oxide reduction on the various component pads and leads. Again, precision is needed to attain the exact temperature. At the end of this zone there should be thermal equilibrium before going into the next zone.
The next stage is the reflow zone. The highest temperature occurs during this stage. Precision still is necessary. As a guideline the rule is that the highest temperature must be 5 degrees C less than the degrees tolerated by the component with the lowest heat tolerance. At this time the solder paste liquefies as it reflows through the PCB and components to achieve metallurgical bonding.
During the fourth and last stage, the cooling zone, the entire assembly will cool and solder joints will become solid. In the previous stage the assembly was at its maximum heat. During this stage it will cool at the rate of about 4 degrees C per second. The PCB and the bonded components are now ready for the next stage of assembly in the manufacturing process.
Take the time to research the various manufacturers of soldering ovens before making a purchase. Check with professionals knowledgeable in this area to get some brand recommendations. People who have used the machines can give you the best advice, if this is your first purchase of a reflow oven.
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