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Electronics => Manufacturing & Assembly => Topic started by: ocset on October 11, 2018, 04:53:53 am

Title: Heatsink is solderable?
Post by: ocset on October 11, 2018, 04:53:53 am

Do you think it will be possible to easily solder the solder tab on the SK 469 35 STS heatsink?.....

https://www.fischerelektronik.de/web_fischer/en_GB/heatsinks/A04/Extruded%20heatsinks%20for%20PCB%20mounting/VA/SK46935STS/ (https://www.fischerelektronik.de/web_fischer/en_GB/heatsinks/A04/Extruded%20heatsinks%20for%20PCB%20mounting/VA/SK46935STS/)$productCard/parameters/index.xhtml

...surely the soldering iron's heat will just get absorbed up into the heatsink itself?

Title: Re: Heatsink is solderable?
Post by: Berni on October 11, 2018, 06:05:08 am

Heat is not a problem, you can get 300W soldering irons that will heat up the little thing in an instant.

The problem is that it is aluminium. Not only that, it is anodized aluminium. The anodizing is basically alumina glass and its really tough.

The only thing you can do is grind the coating off and then TIG weld the aluminum heatsink to another aluminum object.

Title: Re: Heatsink is solderable?
Post by: ivaylo on October 11, 2018, 06:37:05 am

This works - https://www.ebay.com/itm/Flux-for-low-temperature-soldering-of-aluminum-Made-in-Russia/253517448373?hash=item3b06d144b5:g:xPoAAOSwoFZatru2 (https://www.ebay.com/itm/Flux-for-low-temperature-soldering-of-aluminum-Made-in-Russia/253517448373?hash=item3b06d144b5:g:xPoAAOSwoFZatru2)
It’s aggressive though, don’t use with expensive soldering gun tips. Remove the anodized layer of course...

Title: Re: Heatsink is solderable?
Post by: Berni on October 11, 2018, 06:45:18 am

Oh wait i just realized. Did you mean the little PCB mounting pin on the bottom? Those are not a problem because they are tin plated and designed to be soldered, but yes you will probably want a 100W soldering iron to get it hot enough in a reasonable time since heat will want to flow to the heatsink (But such a small rod has limited heat transfer capacity so its not that difficult). If you have trouble with a little under powered soldering iron you could still use a tiny flame to heat the heatsink body to 100°C before soldering.

Title: Re: Heatsink is solderable?
Post by: 2N3055 on October 11, 2018, 06:54:16 am

Those get easily soldered with my 80W Weller.

Title: Re: Heatsink is solderable?
Post by: Nusa on October 11, 2018, 11:32:34 am

It's even a hollow pin in the picture. You should have no trouble soldering it with any decent iron.