Phil: Plating on aluminum is not an easy task. The typical process is:
1. Alkaline clean
2. Acid desmut
3. Zincate 1
4. Nitric acid dip
5. Zincate 2
Then overplate with a copper strike electroplate or electroless nickel.
Since the die is "singulated" I don't think you can go the copper electroplate
route, which leaves the electroless nickel(not the easiest process to control).
The solder coating would follow. I believe there is no way you can solder dip
directly to the zincate and assure a good bond.
This application requires a lot of chemistry and control. I would not recommend
it unless you have a good background in plating and process control. Good Luck!
                                                regards
                                                        Michael Barmuta
                                                        Staff Engineer
                                                        Fluke Corp.
                                                        Everett Wa.
                                                        425-356-6076

On Mon, 29 Mar 1999 08:33:44 -0800 Phil Hersey wrote:

> From: Phil Hersey <[log in to unmask]>
> Date: Mon, 29 Mar 1999 08:33:44 -0800
> Subject: [TN] zincate dip for solder bumping?
> To: [log in to unmask]
>
> Does anyone know anything about "zincate" dip for sensitizing aluminum for
> electroplating?  Atotech has such a bath and evidently it makes aluminum
> plateable.  If so, I can envision a process to solder bump even already
> singulated die by zincating the bond pads and then solder dipping.
>
> Resp.
> Phil Hersey, Carson City Nevada USA
>
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