Uses Of A Reflow Soldering Oven

By Marci Glover


Everything you purchase today that is electronic uses circuit boards to keep them running. How these circuit boards are made demands use of complicated specialty equipment designed specifically for making the components for tablets, smart phones and virtually every other electronic devise available. One of the machines needed to create these mobile connections and ensure they work is the reflow soldering oven.

By placing a powdered solder mixture on the circuit board manufacturers can bond two materials. The boards are heated in ovens until the solder becomes liquid and will, when cooled, permanently bind the circuits to the board. To complete the process the boards and circuits must travel through four stages of heat and cooling. These stages are called zones by the manufacturers.

The preheating step is first on the list. This process determines a ramp up rate for the amount of heat that can be applied to the boards in question. When heat is applied too fast it can cause thermal shock to the components or boards. Thermal shock can cause cracking of components or boards and solder paste spattering. Conversely, heating too slow causes the flux in the paste to be incomplete.

The next step in the process is called the thermal soak zone. This is a process that is sixty to one hundred twenty seconds long and serves to remove excess paste from circuit leads and activate the oxide reduction process. Temperature is very important at this stage also to prevent the solder from being damaged or damaging other parts being processed. Thermal assessment of the entire board is done at this point prior to sending it to the next phase of production.

Next is the reflow zone. This is one of the most sensitive zones in the process. It is when the highest temperatures will be used on the board. Every piece has a temperature where the most fragile component is damaged by heat. If this temperature is surpassed thermal damage will occur making the piece non-functional. Operators must closely monitor the process to ensure this does not happen.

The final step is the cooling zone. This is a slow process that gradually cools the board and causes the liquid solder to become solid. When done properly it can help to prevent excess thermal shock to the boards and their components. Many companies pay little attention to the cool down rate because it is less critical than the ramp up rate but a cooling rate of four degrees Celsius per second is recommended.

Most equipment used in this process allows the operator to see what is happening inside the closed unit. Some are equipped with viewing windows and others can be attached to a screen using a USB connection. This viewing allows the operator to adjust the temperatures while monitoring the progress of each board.

These ovens make it possible for you to enjoy the technical electrical gadgets that make life easier. As the technology advances they will become more streamlined and advanced to keep pace.




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