Reflow profile designer
Design a reflow profile from editable zones and check it against the solder paste's window (SAC305 from Indium8.9HF's data sheet, Sn63Pb37 from Kester EP256's) and the J-STD-020E limits for your most sensitive package — ramp, soak, time above liquidus, peak and cooling — on a plot; overlay and compare oven thermocouple logs, and export JSON or CSV.
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How to use it
How to use it
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Pick the solder paste. Each comes with an example profile that sits inside its maker’s recommended window.
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Enter the thickest package body on the board and its volume (length × width × height, in mm³). That gives the package classification temperature Tc from J-STD-020E (Table 4-1 for SnPb, Table 4-2 for Pb-free). Tc is the hottest the part is qualified to survive, so your peak has to stay at or below it. Large, thick parts such as electrolytics, inductors and connectors are often the limit, not the chips.
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Edit the zones. Each zone runs in a straight line from the previous zone’s end temperature to its own, over the time you give, and shows its ramp rate. Use your oven’s setpoints, or the board temperature you are aiming for. Add and remove zones as needed.
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Read the checks:
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Paste window — the paste maker’s figures. ✓ is inside the recommended range, ! is outside it but still acceptable, ✗ is outside both.
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J-STD-020E limits — maximums only. The standard’s minimum times (preheat 60–120 s, 60–150 s above liquidus) describe the test that qualifies the component, not your board. What carries over to assembly is "do not exceed": average ramp-up from Tsmax to the peak ≤ 3 °C/s, ramp-down ≤ 6 °C/s, time above TL ≤ 150 s, time from 25 °C to the peak ≤ 8 min (6 min for SnPb), peak ≤ Tc, and at most 30 s (20 s for SnPb) within 5 °C of Tc.
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Oven logs — import a CSV from your controller or thermocouple logger. The first column whose name mentions time is the time, in seconds,
mm:ssorhh:mm:ss, or milliseconds if the header saysms. Every other numeric column is a thermocouple. Setpoint, duty and heater columns are skipped, and columns whose header marks them as °F are converted. Each log is shifted so it reaches 100 °C when the design does; change the shift if you want them lined up differently. The table gives each log’s peak, time above liquidus, soak and ramp, the RMS and worst difference from the design, and how many limits it breaks. Logs are kept for this visit only and never go into links. -
Export JSON saves the zones, the sampled curve, Tc, the metrics and the checks. Open JSON reads the file back. Export CSV writes time and temperature at 1 s steps for a controller that takes a profile table. °C or °F is remembered.
⛶ Full screen (or F) gives the plot the whole screen.
Where the numbers come from
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J-STD-020E (IPC/JEDEC, 2014), Table 5-2 "Classification reflow profiles": Pb-free Tsmin/Tsmax 150/200 °C, TL 217 °C, ramp-up ≤ 3 °C/s, ramp-down ≤ 6 °C/s, 25 °C to peak ≤ 8 min, 30 s within 5 °C of Tc. SnPb eutectic: 100/150 °C, TL 183 °C, the same rates, ≤ 6 min, 20 s. Tables 4-1 and 4-2 give Tc (235 or 220 °C for SnPb; 260, 250 or 245 °C for Pb-free) by package thickness (< 1.6, 1.6–2.5, > 2.5 mm) and volume (< 350, 350–2000, > 2000 mm³).
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SAC305 — Indium Corporation, Indium8.9HF Pb-free solder paste product data sheet, Form 98485 (A4) R19, "SAC305 parameters". Average ramp from ambient to peak 0.5–1 °C/s recommended (0.5–2.5 acceptable). Optional soak 30–90 s at 160–180 °C (30–120 s at 150–200 °C acceptable). Time above liquidus 45–60 s (30–100 s). Peak 230–260 °C (230–262 °C). Cooling 2–6 °C/s (0.5–6). SAC305 melts at 217–220 °C. The tool measures the soak between 150 and 200 °C, and the cooling rate from the peak down to 200 °C.
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Sn63Pb37 — Kester, Easy Profile 256 (EP256) solder paste data sheet, recommended reflow profile. Rising ramp under 1.8 °C/s, soaking zone 30–60 s typical (120 s max), reflow zone above 183 °C 45–75 s typical, peak 210–225 °C, time to peak 3.5–5.0 min typical (5.5 min max). The soak temperatures are read off the data sheet’s chart, so the tool counts the soak from 150 °C up to the liquidus and the ramp as the average from the start up to 150 °C.
All of these are guidelines. Your paste’s own data sheet comes first. Measure the board with a thermocouple, because the setpoints on a hot plate or toaster oven are not the board temperature.
Limits
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Two pastes. Other SAC alloys (SAC387, SAC0307) and low-temperature SnBi pastes have different windows. Their makers' data sheets are not built in.
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The design is piecewise linear. A real board lags the air and overshoots, so measure it and compare with the log.
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Tc covers moisture-sensitive packages under J-STD-020. Some parts (LEDs, crystals, connectors, electrolytic capacitors) have their own lower ratings in their data sheets.
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Time "within 5 °C of Tc" is measured against your Tc, not the peak.
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