Reflow profiles or processes that are not well optimised can lead to poor or non-wetting, damaged components or cold soldering.Īfter soldering the boards are inspected in detail. For all soldering methods, the optimal reflow profile for a circuit board assembly is dependent on several factors other than just the Coilcraft component. The processed board is cooling down in the last zones of the reflow oven, the solder alloy solidifies and makes the solder joints. The component that has the lowest maximum temperature allowance will define the maximum temperature. Technical Notes: The final reflow temperature profile will depend on the type of solder paste and flux chemistry used in the SMT process. Figure 1: SMT Reflow Profile Examples Note: If using paste or solder balls with a low solidus temperature, such as SACQ, Innolot, or other Bi-doped alloys, consider whether profile adjustment/optimization is neces-sary. This maximum temperature must remain under the maximum allowed temperature of the components. the 240☌ to 250☌ range are commonly used for SAC305 surface mount solder pastes. In the third section the solder paste is melted and the process reaches its maximum temperature. The Temperature gradient is important because too quick changes of temperature can cause damage to components.ĭuring the thermal soak the flux is activated to reduce oxidation of pads and leads of components and improve wetting. The aim of the preheating stage is to accumulate heat smoothly in the board and the components. Reflow solder profiles usually have four stages, preheat, thermal soak, reflow and cooling. The solder profile is influenced by the number of layers in the PCB, the copper distribution on the board, the number and size of components. Solder profiles need to be optimised for each individual assembly job. Multiple segments help to get an optimised heat transfer and minimum temperature differences between different points on the PCBA. These are long convection ovens with many heating zones that together create a soldering cycle.Įach heating zone of the oven has a regulated temperature set to the solder profiles for the assembly process. Solder Process Heat Profile Recommendations - The following is the maximum recommended soldering profile for time and temperature taken at or near the connector. The solder paste melts during this process and cools down again to create a good solder joint. During the Pick & Place operation, components are glued to the board by the solder paste.Ī reliable connection is made during the reflow soldering process.
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