Reflow Ovens

The soldering process involves the connection of two metal parts by means of solder (an alloy containing an active flux).

Soldering provides a mechanical connection of the terminals of the components to the contact pad, and also provides electrical contact.

The process of obtaining high-quality soldered joints involves the following steps:

1. Getting clean and shiny metal surfaces from the parts to be joined (removal of dirt and oxides) using a special flux;
2. Heating the solder above the melting point for a specific soldering time;
3. Activation of the flux by heating;
4. Uniform spreading of the molten solder on the surfaces of the parts to be joined;
5. Diffusion of atoms from the solid metal phase of the joined parts into the molten solder.

The soldering quality of the SMD component leads to the contact pads is characterized by a wetting angle

Active substances - fluxes that are part of solder pastes, are activated on the surface of the parts to be brazed when heated in the preheating zone of the furnace and improve the solder wetting due to the surface tension force.

With insufficient surface tension force, the wetting angle increases, which leads to non-penetration and as a result - poor-quality solder joint. Therefore, only a properly selected thermoprofile in a convection reflow oven for a specific flux can guarantee the correct activation of the flux and complete wetting and, as a result, the quality of the solder joint.

It is necessary to most accurately maintain this profile in the furnace according to the recommendations of the manufacturer of the solder paste, as well as depending on the size and heat capacity of the printed circuit board and the components on it.

Usually the temperature profile is selected by the technologist for each serial product.


The main stages of soldering in convection reflow ovens:

1.Preheating: prevents thermal shock of SMD components and boards. Preheating speed 2-4 ºС / sec
2. Stabilization stage activates flux
It is characterized by a slow rise in temperature. The flux is fully active when the temperature reaches 150 ºС
3. Reflow. The temperature above the melting point of the paste alloy is 30-40 ºС. This is necessary for reliable formation of the solder joint.
The profile peak is 205-225 ºС (on the board). Time above the melting point is 30-90 seconds
4. Cooling. Optimum cooling rate 3-4 ºС / sec to a temperature below 130 ºС
Privacy Policy
We never sell personal data and we carry out all processing operations in strict compliance with the EU General Data Protection Regulation (GDPR). Cookies are stored on your individual device and you have full control over their use. You may deactivate or restrict the transmission of cookies by changing the settings of your web browser. Cookies data that are already stored may be deleted (only if you are a registered user or provide us with the full cookie identificator) at any time by appealing to our support team — If you visit SMTtech site with cookies deactivated, you may possibly not be able to use all of the functions of our site to the full extent. You will not be able to opt-out of any cookies or other technologies that are “strictly necessary” for the functioning of our website and services. You can exercise any of the rights mentioned in this Privacy Policy in your Account and/or by contact with SMTtech team Where you have provided consent, you may withdraw it at any time, without affecting the lawfulness of the processing that was carried out prior to withdrawing it. Whenever you withdraw consent, you acknowledge and accept that this may have a negative influence on the quality of the SMTtech Site and/or Services. You further agree that SMTtech shall not be held liable with respect to any loss and/or damage to your Personal Data if you choose to withdraw consent. Where Personal Data is processed for the above purposes on the basis of SMTtech legitimate interests, under the GDPR, you may object to such processing at any time. To do so please contact: You may opt-out from having SMTtech collect your information when visiting an SMTtech Enabled Site at any time by contact with or SMTtech support team: