Soldering Aluminium to copper and PCB

Hi,
I have designed a PCB which I have to enclose in a complete Aluminium Cavity Enclosure. I have to rest the PCB inside Aluminium cavity and then fix it by soldering the PCB edges and some part of copper connector (mounted on PCB) to the Aluminium. As per my knowledge, we cannot solder copper to aluminium by our normal soldering process. And also I cannot use other very high temperature solder for soldering (because PCB will get damaged). Also Aluminium brazing is not an option.
So my question :- How to do this effectively without PCB getting damaged ? Is there any special flux or solder wire available for this ? Or any other possible option some one can suggest ?

Regards,
CR

There are special solder pastes but they may be expensive. Most manufacturers use riveted or welded copper rims on aluminum enclosures that allow soldering, or, have them nickel-plated so they can hold solder.

The easiest way is to forget aluminum and use thin tinned iron sheet like tin cans for food.

http://www.elektronikbasteln.pl7.de/...aluminium.html
http://www.youtube.com/watch?v=FmjdXKyDEWY

To anchor wire to non-solderable surfaces:

There is the conductive pen which applies a silvery liquid. It conducts electricity when dry.

Also conductive epoxy.

Thanks everyone..

One more question..

Will the copper be soldered to tin plated aluminium..??

You can plate alumimun housing to be solderable. Typically one nickel plates first, and then applies a thin layer of tin or gold on top of the nickel. Theoretically you can solder to the nickel, but it tends to oxidize right away and is hard to solder to.

You CAN epoxy the unit into the housing. There are silver loaded epoxies, either in paste form or in sheet form that are available, but they are fairly expensive.

Silver paint can work for an hour or so in the lab for a quick test. But it will fall off over time so it is not a permanent solution.

You may be able to simply attach the PCB board, if the board is flexible, to the housing with screws. Two screws on either side of each microwave launch to the board will probably work up to perhaps 5 GHz. Just use a washer under the screw thread so the board does not cold form around the screw head and loose its tension over time.

You could solder the PCB onto a brass or copper carrier sheet, maybe 0.1" thick, and then screw the carrier into the housing.

Can you tap some holes in the aluminum, and screw the PCB in ?
I have worked with many aluminum housings and that was how
it was done.

Cheers

You should know if you connect aluminium with copper you will make some kind of battery and potential difference.

Copper can be joined with aluminium but process depends what you want (I mean on TIG special rods for this purposes).

Combining different metals request careful decicions.

Thanks.

I have that option of mounting the PCB in Al box. But for better grounding purpose, I also want to solder PCB to body. I have already given tin plated Al box for fabrication. Hope it will work.

If it is already tin plated...it is probably the way to go!