Why are soldering tips made of copper - Page 1
Forum section: electronics / beginners

author: Jane
author_rank: Frequent Contributor
timestamp: October 17, 2015, 05:19:45 am
content: I know copper has very good conductivity, but very low resistance. It means it takes a longer time to heat properly.Is the conductivity more important then time needed to heat up the soldering tip?Or what are the most important reasons that CU ( alloy) is used for soldering tips?

author: TheAmmoniacal
author_rank: Unknown
timestamp: October 17, 2015, 05:40:08 am
content: Solder tips are not resistive elements in soldering tips, i.e. no electricity is flowing through the tip to make it hot. The tip is only thermally connected to a heating element (often placed inside it). Apart from that, I don't know why copper is used - or if better alternatives exist.

author: DimitriP
author_rank: Super Contributor
timestamp: October 17, 2015, 05:41:06 am
content: QuoteItmeansthe opposite, but the answer to your question is no.

author: DimitriP
author_rank: Super Contributor
timestamp: October 17, 2015, 05:46:28 am
content: Thermal properties of metals tablehttp://www.engineersedge.com/properties_of_metals.htm

author: nanofrog
author_rank: Super Contributor
timestamp: October 17, 2015, 05:59:33 am
content: Copper is a relatively inexpensive material that's an excellent conductor, is easy to form, and can be done quickly on simple tools, such as a lathes and belt sanders (reduces costs).

author: PointyOintment
author_rank: Frequent Contributor
timestamp: October 17, 2015, 06:14:14 am
content: Copper is used because it's an excellent conductor of heat. The fact that it's also an excellent conductor of electric current is irrelevant, because the heating element is generally a separate component, as others have said. The tip's job is to conduct the heat from the element to the joint.Generally, the copper is plated with some other metal such as iron, because an uncoated copper tip would rapidly dissolve in the solder.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: October 17, 2015, 07:14:30 am
content: Because copper is cheaper than silver....

author: tautech
author_rank: Super Contributor
timestamp: October 17, 2015, 07:31:03 am
content: Quote from: Jane on October 17, 2015, 05:19:45 amThermal recovery.

author: TimFox
author_rank: Super Contributor
timestamp: October 17, 2015, 02:40:03 pm
content: In soldering guns, as opposed to irons, a low-voltage secondary winding applies a very high current to a copper tip that then dissipates enough power to heat up.

author: brobbuilder
author_rank: Contributor
timestamp: October 18, 2015, 04:43:02 am
content: Copper wets out with lead/tin solder quite well, so you can get very good control over where the solder is flowing. IME it actually dissolves in the lead over time, hence why it's usually plated with something. Some people prefer plated tips, I personally like copper tips. Different strokes for different folks.

author: SteveLy
author_rank: Regular Contributor
timestamp: October 18, 2015, 05:21:10 am
content: Thermal and electrical conductivities of materials are strongly correlated for physical reasons: both have to do with how easy it is for electrons to become excited. To a first approximation, they are proportional at a given temperature. But lattice vibrations complicate things so this is not strictly so, but it's a good rule of thumb for most metals.http://www.electronics-cooling.com/2000/05/how-thermal-conductivity-relates-to-electrical-conductivity/

author: IanB
author_rank: Super Contributor
timestamp: October 18, 2015, 06:26:50 am
content: Quote from: Jane on October 17, 2015, 05:19:45 amCopper has good thermal conductivity, and thus low thermal resistance.Copper also has good electrical conductivity, and thus low electrical resistance.But can you explain why you believe either of these makes it take longer to heat properly?First of all, objects with higher thermal conductivity will tend to heat faster, since the heat can flow more quickly throughout the part. This is the opposite of your conclusion.Secondly, the time to heat an object depends on the thermal capacity of that object. Objects with more thermal capacity take more heat to bring them up to temperature, so they will tend to heat up more slowly. Thermal capacity is not directly related to thermal conductivity.It turns out that for metals the thermal capacity per unit volume doesn't change all that much between one metal and another. So for an object of fixed size like a soldering tip, the amount of heat required to bring it up to temperature will be similar whether it is made of copper, or say, iron.However, copper is preferred since the better thermal conductivity makes it better at transferring heat from the heating element to the solder joint.

author: crispy_tofu
author_rank: Super Contributor
timestamp: October 18, 2015, 06:32:32 am
content: A less explanatory (more concise!) answer by Google:Quote

author: SteveLy
author_rank: Regular Contributor
timestamp: October 18, 2015, 06:38:48 am
content: ^

author: Simon
author_rank: Unknown
timestamp: October 18, 2015, 12:07:10 pm
content: When you are using a soldering iron tip is acting as a buffer between the heater and your joint. The tip holds heat ready to go into your joint. When you make your joint you are sinking heat from the tip into the joint. When you do this but it gets colder and would not be able to make another joint. But the heater is there at the other end ready to feed more heating. So obviously you want your tip to be made of a material which will conduct heat quickly enough so that when heat is taken out the tip to make a joint it can be replenished quickly or you will have quite a stop start soldering experience.Of course the other side of this is that when supplying heat to your joint you want the heat flow into a joint quickly. If your tip was made of a metal that does not conduct or relinquish heat easily you would end up with many dry joints as the heat would not be provided quickly enough and insufficient quantity.And because of this you do need to size your tip to your joint sides. Small tips will not really do large joints for obvious reasons.

author: dom0
author_rank: Super Contributor
timestamp: October 18, 2015, 01:38:20 pm
content: Quote from: Simon on October 18, 2015, 12:07:10 pmThat depends on the soldering system. Low thermal mass systems only have a tiny amount of thermal energy in the tip.

author: Richard Crowley
author_rank: Super Contributor
timestamp: October 18, 2015, 01:55:29 pm
content: Quote from: Jane on October 17, 2015, 05:19:45 am"Very good conductivity" MEANS "very low resistance".Resistance and conductivity are the inverse of each other by definition.It is not clear that you have properly distinguished between ELECTRICAL resistance and THERMAL resistance.Those are two very different things. Copper happens to have both good electrical and good thermal conductivity (i.e. low resistance)QuoteHow long it takes to heat is mostly a factor of mass, heat input, and heat sink (going out).It has little to do with thermal resistance.QuoteThey are BOTH important. As with most things, trade-off decisions are made at every step in the design process.QuoteGood thermal conductivity and convenient mechanical properties at low cost.

author: G7PSK
author_rank: Super Contributor
timestamp: October 18, 2015, 03:26:41 pm
content: Good thermal conductivity is essential to a soldering iron. It dose not matter if the iron is of the low or high mass type it has to be able to dump the heat into the work without too much of an internal heat gradient, if you tried making the iron tip from stainless (ignoring the fact that solder wont stick to stainless very well) the heat gradient will be so high that the tip will get to cold to melt solder when applied to the work while at the other end the heating element will be more than hot enough.