Can Aluminum Be Soldered To Copper? (Important Facts)

• Post By: Brandon M. Fox  • Updated: 04/22/22
• Soldering

Joining materials that are not similar can be a tricky job. Joining aluminum and copper can be used for electronic devices or metal sculpting. That raises the question – Can aluminum be soldered to Copper?

We’ll find the answer to that question in this guide. You’ll know what metals are best for soldering aluminum wire or copper wire and how you can solder aluminum and copper.

We’ll also share some tips to help you solder aluminum and copper and discuss whether you need to use flux for soldering copper. Without further ado, let’s get started!

What kind of solder will stick to aluminum?

The range of solders and solder fluxes you can use is minimized when working with aluminum. You cannot use all types of solder for aluminum. The flux must contain Zinc Floride to work with aluminum.

As for the soldiers, they need to have a high tin content. A tin-lead solders works well with aluminum. It works well with super alloy and aluminum alloy.

A tin-lead solder like Indalloy 121 or most SAC alloys works well with aluminum foil. The higher the Tin-Aluminum intermetallic will be, the stronger the solder joint.

Can you solder copper?

You can solder copper as it has a high melting point. Lead soldiers work best with copper. However, you can also use aluminum or Zinc Floride solders for soldering copper.

Like any other metal, the soldering process is quite simple. Make sure that the copper pipe or tube and the solder are clean. It’s very easy to solder copper since it doesn’t melt quickly.

Can you solder aluminum?

You can solder aluminum. But it’s a little trickier than the other metals. Aluminum alloys have a coating of aluminum oxide in them, which reacts to the environment. That makes it challenging to work with aluminum.

You need a soldering iron capable of working with aluminum. The soldering process must go quickly so that the aluminum oxide layer is not formed. If the aluminum is highly oxidized, it can require acetone or sanding to clean it.

How do you solder aluminum to copper wire?

It’s accessible to solder aluminum with a copper wire. Copper wire has a much higher melting point than aluminum. So, you can raise the temperature of the soldering iron such that it can quickly melt the aluminum solder without damaging the copper wire.

Aluminum needs to be cleaned first with an abrasive material to remove any oxidation. After that’s done, aluminum is as easy to solder as any other metal.

Tips for soldering aluminum to copper

Follow these tips to get the best results when trying to solder aluminum and Copper together.

Remove oxidation

Both the elements must be clean before you attempt to solder them. You must remove the oxidation of metals to eliminate all the dust particles present in the element.

It uses an abrasive metal to braze the metals. If the cleaning isn’t thorough, the solder joint wouldn’t be strong, and it can break.

Preheat the metals

Aluminum has a much lower melting point than Copper. Apply more heat to the Copper part as it retains more heat and a little heat to the Aluminum part as it melts quickly. Doing so will get both the metals to working temperature soon.

You can use a propane torch to heat the metals first before going in with your soldering iron. That’ll give you the best result.

Apply flux

Flux helps in the oxidation process and acts as a cleaning agent. It also flows as a liquid and makes it easy to solder the metals. Apply a little flux on the metals when your soldering iron is hot and ready.

Pay attention that the flux doesn’t turn black when you’re working. Turning black is a sign that you’ve applied excess heat.

Cool off after soldering

Give appropriate time to cool off the soldered joint and check the pressure after it’s fantastic. If you did a good job, the solder joint would be substantial.

Do you need flux to solder aluminum?

You need flux to solder aluminum. But you need the right kind of flux. There are special aluminum soldering fluxes available in the market designed to solder aluminum wiring.

The flux that works on stainless wouldn’t necessarily work on the aluminum plate. An aluminum solder flux is generally available in liquid, gel, or solders paste form.

However, it’s essential to minimize the use of flux when you’re soldering aluminum to electronics. The flux can also become corrosive flux and form a weak solder joint. The mechanical properties of alloy are different than most other metals.

Can you solder copper without flux?

It’s possible to solder copper without soldering flux. But flux is always helpful as it cleans the solders and increases the liquidity of the solder. The absence of flux will make it hard to solder any metal to Copper.

But because copper has such a high melting point, you can set a high temperature in your soldering iron when working with copper. You’ll always have a better experience with flux as you will have more control when you use it.

You’ll also be able to work faster with flux. However, it’s not necessary to use flux when soldering copper. You can get by without it just fine.

Final words

Welding and brazing used to be a solution when working with aluminum. But that’s not the case anymore. Soldering has made it easier than ever to work with any dissimilar metal.

Make sure the filler metal is clean when working with any metal surface. Whether you’re working with silver solder, precious metals, cast iron, or even stainless steel, this is true.

We hope the tips we shared will help you work with aluminum and copper from now on.

Brandon M. Fox

I have completed Diploma at Welding. I have spent 10+ years in Welding. Now love to write about welding and welding products and share my own experiences. Find me: Twitter | Facebook

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