Utilizing Tabletop Reflow Oven To Connect Electric Components

By Coleen Torres

Reflow soldering is widely used to manufacture a wide range of electrical components. The tabletop reflow oven forms an integral part of the soldering process, and are also great for DIY component makers. The bench top design of it calls for minimal installation and simple operation for the home or commercial user.

Reflow soldering is commonly used to attach surface mounted components to a circuit board. Less commonly, reflowing can also be used to attach through-hole components to the circuit boards. Solder paste (solder mixed with flux) is used to temporarily attach electrical components to a contact pad. This newly assembled contact pad and attached electrical components are then subject to heating in order to melt the solder, creating a permanent joint. This second step is where the use of this machine comes in.

Reflow ovens must be used so that the areas other than the paste aren't burnt or heated to the point of damage. The four specific features of the oven successfully targets the paste. These consist of preheat, soak, reflow, and cooling stages.

The longest stage of the soldering machine is the first preheating feature. Between 1 to 3 degrees Celsius rises per second through the entire time. This gradual increase by a static number of degrees Celsius is often referred to as ramp-up rate. The ramp-up rate is an important feature the machine offer so that the intensity of heat on the component is safely progressive rather than abrupt.

The couple minutes after the preheat stage is the thermal soak zone. The oven exposes the combined component to a brief period where the paste is secured and the fluxes are stimulated. There's a restricted range of temperature that is released in order to prevent potential splatter or oxidization. This range not only applies to the maximum heat, but also the minimum limit since the fluxes still need a certain amount of heat to activate.

The third feature of the re-flow oven that offers peak temperatures is the reflow zone. Temperatures during this stage usually range between 20 to 40 degrees Celsius. Meanwhile, the specific temperature relies on the lowest heat tolerance of the component inside.

As a general rule, this temperature will be below 200 and 60 degrees Celsius, as this is the temperature at which damage may occur to the internal makeup of the components. The TAL is as important as selecting the correct temperature because only the correct time above reflow will allow the individual solder powders to combine and form the required bond. Incorrect TAL can result in either drying of the paste or create defective joints.

The cooling stage is the final step the re-flow oven performs. As the name suggests, this involves the gradual cooling of the board and newly attached components. This process is important in inhibiting the formation of excess intermetallic formations, as well as avoiding thermal shock. This is a short process because fast cooling rate creates the most mechanically sound structure. A commonly used cooling rate is around four degrees Celsius per second.

About the Author:

No comments:

Post a Comment