JTAG configuration error in CycloneIII

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some people said me that they are not very sensitives

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Thin packages are generally sensitive against delamination (cracking of the package due to evaporation of absorbed water during solder process), particularly if you don't keep the handling rules. It's e.g. necessary to perform a baking procedure when assembling the part after the floor lifetime of one week has expired. I think there's also a risk of overheating the device with small hot air tools. In my opinion, the best method to solder the exposed pad (together will all other pins) is a hot plate, a reflow oven, or a professional hot air tool with sufficient large nozzle. I agree, that with a suitable treatment, the parts aren't very sensitive.