If there are other defects such as false welding, cold welding, etc., it can also be extended appropriately.Ĥ. Under normal circumstances, the time range exceeding 200☌ is 30 seconds, but it depends on the specific situation. The ideal temperature profile is that the “tip area” that exceeds the melting point of the solder covers the smallest volume and is symmetrical. For 63Sn/37Pb solder paste with a melting point of 183☌, the peak temperature is generally 210-230☌, and the reflow time should not be too long to prevent adverse effects on the PCB. Generally, it is recommended to add 20-40☌ to the melting point of the solder paste. The soldering peak temperature varies with all solder pastes in the reflow section. The reflow zone (The high-temperature zone): In this zone, the heater temperature is set to the highest so that the component’s temperature rises to the peak temperature quickly. After many experiments, we set the time range of this zone to 60-100 seconds.ģ. It should be noted that all components on the PCB should have the same temperature at the end of this section otherwise, entering the reflow section will cause various bad soldering phenomena due to the uneven temperature of each part, so the time in this section should be controlled. At the end of the heat preservation zone, the oxides on the pads, solder paste balls, and component pins should be removed, and the temperature of the entire printed board will reach equilibrium. Give enough time in this area to make the temperature of the more significant component catch up with the minor component and ensure that the active ingredient of the flux in the solder paste is fully functional. The primary purpose of this temperature zone is to make the temperature of each component on the PCB tend to be uniform and minimize the temperature difference. The insulation zone (The Constant Zone): refers to the area where the temperature rises from 120☌ to 160☌. Usually, the temperature rise rate is set to 1-3 degrees per second.Ģ. To prevent thermal shock from damaging the components, it is generally specified that the maximum heating rate is 4☌/sec. Due to the faster heating rate in this zone, the temperature difference between the components in the latter part of the temperature zone is relatively significant. If the temperature rises too fast, thermal shock will occur, and the PCB and components are easily damaged if the temperature rises too slowly, the flux activity will affect the welding quality.
The Preheating Zone: The function of this zone is to heat the PCB at room temperature as soon as possible to reach the second set goal, but the heating rate should be controlled within an appropriate range. Therefore, good optimization of the reflow temperature curve can achieve better SMT placement quality.ġ. These defects can be avoided by improving the reflow profile. SMT defects caused by improper reflow soldering curve include component burst/crack, component warpage, bridging, virtual soldering, PCB delamination or blistering, etc. The curve of the solder joint temperature between the printed circuit board and the surface mount component overtime must meet specific control requirements. The process control of reflow soldering is manifested as the control of the reflow curve in the process. Therefore, reflow soldering process control is the key to SMT quality control.
Solder reflow temperatures full#
If there is no reasonable and feasible reflow soldering process control, the full process control will become meaningless. The quality control of the reflow soldering process determines the quality of the terminals produced by SMT because defects caused by the design of surface mount components and printed circuit boards, solder paste printing, and component placement will eventually be concentrated in the reflow soldering process. The most critical process in SMT technology is the reflow soldering process. SMT technology meets the needs of the modern electronics industry and occupies a leading position in the production of the modern electronics industry.
It can achieve a higher assembly density of electronic components per unit area of printed circuit boards. SMT technology has the advantages of high production efficiency and good electrical interconnection performance. SMT is the mainstream of secondary packaging in microelectronics technology, gradually replacing the early through-hole assembly in PCB assembly.
Solder reflow temperatures series#
SMT (Surface Mount Technology) is a series of comprehensive engineering technologies involving microelectronics, precision machinery and instruments, automatic control, welding, and material inspection. Testing & Inspection Methods for PCB and PCBA.6 Tips for Looking for a PCB Prototype Manufacturer.