Tip temperature isn't the setting — thermal mass and why your joints won't flow

The number on your soldering station is the temperature of the heating element, not the joint. What matters is how fast heat can move from the tip into the pad, and how fast the board pulls it away.

Ground planes are heat sinks

Large copper areas — ground pours, power rails, connector pins — conduct heat away quickly. A fine conical tip simply can't deliver enough energy, so people turn the dial up and hold longer, which cooks the surrounding board.

The fix

• Use the largest tip that fits — a chisel or bevel tip transfers far more heat.
• Tin the tip and add a small bridge of fresh solder for thermal contact.
• Preheat the board from below on heavy ground joints so the iron isn't fighting the whole plane.
• Aim for a joint that flows in 2–4 seconds. Longer means the wrong tip, not a low temperature.