If you are concerned about thermal dissipation, use solid copper instead. It has better thermal conductivity than aluminum and you can solder to boot. But beware you are going to have to use high powered soldering iron to get it hot enough to solder onto it. you wanted a big heat sink. So soldering is going to be very hard. If you want to safely dissipate 300W, just as an example, you are going to need something with over 300W for your soldering iron.
If you really want to solder onto aluminum there are aluminum specific solder. These are alloys of aluminum and lead and require much higher temperature than regular solder. Don't think regular soldering iron gets hot enough to melt the aluminum solder. I've used it but with a acetylene torch. Regular propane torch is just hot enough. MAPP gas torch without oxygen is doable. The temperature will definitely exceed temperature profile of power device mounting.
I do know of another engineer who said his tech used a TIG welder to weld a heat sink to a power device. Power device is not something you use every day. 1000AMP with breakdown of 1000V kind of things.
--- In Homebrew_PCBs@yahoogroups.com, "Nuno T." <nuno-t@...> wrote:
>
> Hi,
>
> Have no idea if what you ask is possible. Have you considered using a common
> FR4 copper PCB with common Al/Cu heat sinks bolted/screwed on the sides of
> the led with some thermal paste? Much cheaper...
>
> Usually, high power LED's came assembled in a heat dissipating base ready
> for heat sinks
>
> Nuno T.
>
> > -----Original Message-----
> > From: Homebrew_PCBs@yahoogroups.com
> > [mailto:Homebrew_PCBs@yahoogroups.com] On Behalf Of Rogerio F Cunha
> > Sent: domingo, 7 de Outubro de 2012 14:44
> > To: Homebrew_PCBs@yahoogroups.com
> > Subject: [Homebrew_PCBs] Aluminium base pcb
> >
> > Hi list,
> >
> > Hello List,
> > Anyone has a idea how to produce a aluminium pcb over a
> > virgin aluminum board?
> > I'm looking a way to home brew a pcb to solder some power
> > leds that are very sensitivy to thermal dissipation.
> > By what I've seen, the companies applying some kind of metal
> > deposit over a virgin aluminium board, to permit soldering.
> > Thanks.
> > Roger.
> >
> >
> > [Non-text portions of this message have been removed]
> >
> >
> >
> > ------------------------------------
> >
> > Be sure to visit the group home and check for new Links,
> > Files, and Photos:
> > http://groups.yahoo.com/group/Homebrew_PCBsYahoo! Groups Links
> >
> >
> >
>