![]() The temperature of 180 is kept constant (Soak zone) before it is increased again to reach its spike value.Īs Observed for Lead-free solder, the temperature keeps rising gradually to reach its maximum (spike) value. These profiles were called ramp to dwell ramp to peak. More specifically, how quickly we pass from solid to liquid state of the solder. The first factor that will influence how simultaneous the reflow is, will be profile temperatures at the point of reflow. Years ago, when IR ovens were the norm and solder pastes were relatively unsophisticated, initial reflow profiles were developed (Figure 1). uniformity of the reflow head temperature to approximately 5 C giving a total T of about 10 C. Ramp Soak Spikes are primarily used for Leaded Solder and Ramp-to Spike profiles are suggested for Lead-Free solder.Īs mentioned in the table above, for Leaded solder the preheat stage usually starts at 150 and is increased to 180. Successful reflow soldering is a key to productivity and profitability, yet many assemblers may be using a nonoptimized reflow profile. Ramp soak spike profile indicates the temperature that is subjected to a given PCB is allowed to rest in the Soak zone (constant temperature value) before the temperature is increased again to hit the spike (maximum value).įor the Ramp to Spike Time-Temperature profile, the temperature is increased gradually without to reach its maximum value (Spike). So it is important to evaluate the reflow profile of the solder being used. Reflow Zone: The reflow zone allows the temperature to rise again (by 3 every 1 second) till it reaches the spike value so that the applied solder begins to melt and start wetting with the copper surface which helps in creating better solder joints.Ĭooling Zone: The cooling zone is the profile where no additional heat is applied to the PCB and air is supplied to supplement the cooling process such that the temperature is decreased at a rate of 4 at every 2 seconds so that the freshly created solder joint is solidified.ĭifferent types of solder have different reflow profiles. In case these lead-free solders, minor changes in temperatures do not cause any problems in soldering. For lead-free solder, the typical reflow temperature from 240 to 250☌ with 40 to 80 seconds over 220☌. Soak Zone: In the Soak zone, the temperature achieved through preheat zone is maintained so that the FLUX applied on the board is activated and constant temperatures can be maintained for all components present on the board. The solder reflow temperature depends on the solder mixture. Hence to prevent this, the PCB is subjected to preheating where the temperature is increased by 3 every 1 second. It cannot be subjected to high heat suddenly as there is the risk of thermal shock which can cause the components on the board to explode, melt or become nonfunctional. Preheat Zone: Initially the PCB is at room temperature. The reflow profiles are divided into four zones: Reflow profiling is used to optimize the soldering process by minimizing the drastic change in temperatures which might cause cold solder joints, charred boards, tombstoning and uneven wetting. ![]() In the reflow soldering process, the board with solder should be heated in a way to ensure that the solder melts and solidifies at particular temperatures over specific periods of time to ensure proper solder joints are formed. High peak temperature can cause the damage of the component, damage of the assembly or detach of the pervious soldered components.Reflow profiling is the process of evaluating the effect of heat on the solder being used on a printed circuit board. Adjust oven to (): Pre-heat zones: as normal settings (+/- 160☌) Reflow peak zones: as normal setting (+/- 280☌) Conveyor speed full speed. Mount all components on top side of the board. Apply solder paste on top side of printed board. Since larger components normally reach lower maximum temperatures during reflow than smaller ones, because of the different heat capacities, keeping them below their ratings may not be difficult, as long as 250 ☌ is used as the maximum temperature for the joints of smaller components. Determining the hottest and coldest spots on a PCBA top side. This means that 250 ☌ may not be usable as the maximum joint temperature for some components a lower temperature may be required. Although Intel BGAs are generally rated at 260 ☌, other components, especially large ones, may be rated at 250 ☌ or 245 ☌. Components are typically rated as per J-STD-020C (or later), based on their package thickness and volume. Higher T g material is not necessarily more resistant to this damage, and must be tested for compatibility. If maximum solder joint temperatures exceed 250 ☌, PCB damage such as delamination and warpage may result when standard FR4 (T g =130 ☌) material is used. 250 ☌ is recommended as the maximum temperature for all solder joints on the board, except for components with temperature ratings lower than 250 ☌.
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