Saturday, May 31, 2014

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.

This machine is used to permanently solder two flat components together. The process uses a powdered solder mixture that is placed at critical locations on the board and circuits to be soldered. The prepared board is then heated to the point of melting the solder to permanently affix the two components together. There are four stages in conventional processing typically called zones.

The beginning zone is called a preheat period. As the name implies it serves to find the proper temperature needed to complete the task. The ramp up rate is important because if the temperature is too hot or too cold it will create problems with the finished product. When the heat rises too fast or too high it can cause solder to crack or spatter and too low or slow can create problems with the melting process of solder leaving it dull or brittle.

The second step is called a thermal soak. In this zone the board sits for up to two minutes in the heat and works to activate flux components that starts the oxide reduction and removes the excess paste from the actual circuit ends and pads. As with all steps in this process the temperature must be exact. Too high and there will be spattering or balling of any solder being used. Before moving to the next level the boards receive a complete thermal assessment.

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.

Having a window to watch the entire process is one of the ways the manufacturer helps the operator. Most of the machines are computerized and can be pre-programmed to do the work without human assistance but being able to see what is happening is important especially on a new run. Many have USB connections so the operators can view them on their computers.

The importance of these ovens is seen every day in nearly every household in the country. People use electronics virtually everywhere they go whether it is to the office or school or driving down the road using a service to find your way. These ovens help provide the convenience of electronics that have become a way of life for many.

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