EEVblog Electronics Community Forum
Electronics => Projects, Designs, and Technical Stuff => Topic started by: cheater on August 17, 2021, 04:40:04 pm
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Hi all,
I am modifying a cooler and I was wondering if anyone had experience soldering copper to aluminum using pure indium or indium-silver solder In97Ag3. Additionally, I'm looking for a source of indium in Europe.
I have been able to deposit a good bond of solder to the heatsink in question using normal Sn60Pb39Cu1 (the Cu is for not dissolving solder tip plating) using AmTech NC-599-v2-TF flux.
However, 60/40 will only have a thermal conductivity of 50 W/mK as opposed to 73 W/mK of the Indium-Silver solder or 83 W/mK of pure indium, plus indium and the indium solder melt at 156C and 143C respectively as opposed to 183-190C for normal 60/40. This is important because the heatsink itself has its fins soldered to the base using a solder which I think is at around 200-220C melting point.
However, I am not aware of the properties of indium when soldering, and I am curious if anyone has any experience, or can suggest any good fluxes.
I want to solder copper sheet metal (roughly 40x20x1.5mm) to a part copper, part aluminum heatsink base (the border between those two happens where I have to put down the sheet metal).
I am hoping for a sturdy bond that will withstand some pressure and which will transfer heat well.
BTW, I know this will require a lot of power from the soldering iron, I have six very powerful soldering irons available, and if need be I can use them all at once.
Regarding buying pure(ish) indium, I've looked around and prices even for bars are anywhere between 2x and 10x market value, which is pretty crazy. Can someone suggest a place I could get indium in Europe at anywhere close to 180 Eur/Kg (in quantity of say 50-250g)?
I will need about 3000-5000 mm^3 of indium for my project, and at these prices, I might as well not start my project at all...