#Reflow soldering machine free#

At this specific temperature range, the molten alloy demonstrates properties of adhesion. The goal of the reflow process is for the solder paste to reach the eutectic temperature at which the particular solder alloy undergoes a phase change to a liquid or molten state. The reflow soldering of through-hole components using solder paste in a convection oven process is called intrusive soldering. While this may be said of lead-tin solder pastes used previously, lead-free solder alloys such as SAC present a challenge in terms of the limits of oven temperature profile adjustment and requirements of specialized through-hole components that must be hand soldered with solder wire or cannot reasonably withstand the high temperatures directed at circuit boards as they travel on the conveyor of the reflow oven. When used on boards containing a mix of SMT and plated through-hole (PTH) components, through-hole reflow, when achievable by specifically modified paste stencils, may allow for the wave soldering step to be eliminated from the assembly process, potentially reducing assembly costs. Wave soldering however, has been the common method of soldering multi-leaded through-hole components onto a circuit board designed for surface-mount components. Reflow ovens meant specifically for the soldering of surface mount components may also be used for through-hole components by filling the holes with solder paste and inserting the component leads through the paste. Each segment of the oven has a regulated temperature, according to the specific thermal requirements of each assembly. Reflow soldering with long industrial convection ovens is the preferred method of soldering surface mount technology components or SMT to a printed circuit board or PCB. Heating may be accomplished by passing the assembly through a reflow oven, under an infrared lamp, or (unconventionally) by soldering individual joints with a desoldering hot air pencil. The solder paste reflows in a molten state, creating permanent solder joints. Reflow soldering is a process in which a solder paste (a sticky mixture of powdered solder and flux) is used to temporarily attach one or thousands of tiny electrical components to their contact pads, after which the entire assembly is subjected to controlled heat. The heat sensitive parts in the machine must be modified, or measures must be taken to prevent heat transfer to these parts.Example of reflow soldering thermal profile.

The design of the furnace must be changed to meet such requirements. for lead-free solder or non eutectic solder (used for BGA, double-sided plates, etc.), higher furnace temperature is required, These new processes usually require the temperature in the reflux zone to reach 3500c-4000c. Many furnaces used now are designed to have a high operating temperature of not more than 3000 C. The industry has applied the process as soon as possible, and the time has been saved. However, the industry must probably go through this painful learning period to solve the problems encountered. Nitrogen protection can partially eliminate oxidation and damage to PCB due to temperature increase. At present, many substitutes developed generally have a melting point temperature of about 40C higher than that of tin lead alloy, which means that reflow soldering must be carried out at a higher temperature. Reliable and economical lead-free solders are being developed. Although the lead used in the electronic industry is very small, less than 1% of the total consumption, it is also prohibited and will be phased out in the next few years. This is mainly caused by the characteristics of the solder alloy and the different fluxes.įor the sake of environmental protection, lead will be strictly restricted in the 21st century.

In terms of process, the welding process has the greatest impact. The change in material, especially in solder, is the largest. With the development of environmental protection, people pay more and more attention to lead-free technology. Early reflow solders were all made of lead containing materials.

#Reflow soldering machine free#

Lead free reflow soldering is also called lead-free reflow furnace.