![]() The bottom is 10-20C colder from my thermocouple investigations but does catch up if I let it sit for too long. The FTDI chip on top didn't fall off the board when I reflowed a second time with it hanging upside down. I did two steps, top side with less components first, then bottom side with more components. I'll produce some videos so you can see what I see. All temperatures refer to the center of the package, measured on the. Tolerance for time at peak profile temperature (tp) is defined as a supplier minimum and a user maximum. Users are advised to optimize their own board level. I have to hand solder the holder next time. Standard Reflow Profile fo r Standard and Lead-Free Packages The reflow here in provided is for reference only. Many yellow-orange residue and some seem more than just surface. I just did the same run again and similar result. Will have to turn the heat up & down a little at the hold temperatures as the oven cools, and then heats up again. I tried to find temperature with my thermocouple taped to a board but the center seems to be up to 25DegC hotter than indicator on the oven and there is considerable hysteresis. Turn off the heat, crack open the door a little, let the temperature cool down, once below 180C you can open the door full. Maybe my coin battery holder will not melt. Maybe I need longer pre-heat time and higher temperature? If it is not a result of sitting for too long in the oven after soldering phase, I will increase the "keep" temperature and let the oven cool boards sooner. The oven seems to be ramping at max rate all the time and then just sit at the set temp once it reaches it. The oven has only 3 temperatures and timers, and then a fourth temperature below which it turns on air cooling.
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