Watts to Degrees?

[AudioJunkie]

Wondering how one equates Watts to Degrees (F or C). A manual for a tonearm a friend wants rewired says not to use an iron bigger than 10W. But I have a Hakko variable temp iron. Did some searching and couldn't find any way of converting wattage directly to degrees, and I can't think celarly today to figure out how to relate them.

Any easy formulas or anything?

Daniel
(*not* JZ) :green:

 

[rodabod]

Well, a 12W Antex iron runs at around 370 degrees C.

I would therefore maybe suggest around 350 degrees. The amount of time in contact is obviously important.

 

[rlaury]

AFAIK there is no actual correlation of watts to degrees.
The wattage of a soldering iron basically relates to the
"capacity" of the iron. Just use a good temperature controlled iron
with a very small tip and you should be fine.


RonL

 

[rodabod]

That is very true.

Greater wattage permits ahigher amount of heat to be transferred and maintains tip temperature.

However, the lower wattage Antex soldering irons are cooler than the higher powered ones.

 

[Svart]

the problem is that the Wattage is relative to not only the area of heat but also the amount of mass in the object heated. there would be no direct equation for figuring out the heat transfer to the part being soldered due to everything from the heatsinking effect of the object being heated to the ability of the soldering iron to maintain it's temperature.

In short, a 10w iron may still be 600degF but what you are trying to solder might be able to sink 5 of those Watts, so for a short period of time your total wattage transfer mightl be 5 and then gradually rise as the part heatsoaks and likely burns up. However if you use an iron that monitors the temp and compensates by supplying more power to the tip, you might burn it up immediately. also, there is the relationship of the size of the tip to the amount of heat transfered....

I don't know what parts you are soldering, but you might get away with heatsinking the parts to be soldered so that their average temperatures do not rise quickly.

using a cold, wet rag is actually the best for this as water demands a great deal of applied "heat" to raise it's average temperature, but you might not want to do that due to the moisture..

your best bet is to prepare the parts well and move quickly while soldering !

 

[PRR]

> how one equates Watts to Degrees

Heatsinks have a number "Degrees/Watt". A small sink might be 50C/W, a big one 0.5C/W.

Your phono pin is a "heatsink" of unknown Degrees/Watt and also some heat "capacity" that slows the rate of rise of temperature.

But if you have the luxury of a thermo-controlled iron, that's pointless. The thermo-iron will run 100 Watts until it hits the set temperature, then turn-down or cycle to stay AT that temperature.

Use the same Degrees you use for most small joints. Basically a few degrees above solder-melt. Enough above solder temp so the working end of the joint comes up to temp before the far end melts the housing or wire and you can get soldered and get off before harm is done.

 

[Svart]

using low temperatures with on traces/planes/parts with large metal areas will only cause you to leave the iron on the joint for much longer as the metal soaks until the melting temperature of the solder is reached. IF there are any plastic bits or heat sensitive parts on that same plane, then they will surely have a lower maximum temp than the solder's melting temp and will surely have reached that point much sooner than the solder did...

I speak from experience!

Use a hot tip that regulates it's heat well and can apply a great amount of power quickly so that you don't heat up the pcb or any other surrounding parts. prepare the areas well, use good solder and move quickly and you will have no problems, since most problems are usually related to dirty solderpads or cheap/incorrect solder.