I understand, Matthias,
looks as you have very few bondpads indeed on each board and few chips. And small lots of  boards, you say. Then, if I were you, I would not go for anything more complicated than just manually burnishing of the bond pads before bonding. Seems to be simple and cheap a way, at least according to your brief description.
Regards/Ingemar

PS. Pumkins: following the english gentleman (M.F) who recommended a 2-3months maturing process before wine setting, so my babes (10kilos each)are at sleep waiting for the 1-year wine process. From Nova Scotia recipe (Steve), I will also make kind of marmelade. Now, the anti-pumkin people will get furious, he-he. By the way, in Aussilek's homeland, they had the worlds most enormous pumpkin this year: 360 kilograms! Sorry for this non-technical part of message. Waiting for the traditional outcry.....


On  6 Oct 99 at 15:02, Ingemar Hernefjord (EMW) wrote:

> Hi Matthias,
> don't use anything "wet" or "chemical" or "plastic" on the bond
> pads! There will be a powerful reaction from jk or Mike F or
> worse..from Aussilek!
[...]
>. May I ask what kind of wire bonding you
> aim at?

"classical" Al (thin) wire bonding on rigid material, mostly FR4,
wedge wedge, wire thickness depends on the specific application.

The problem is not the process itself. The problem is the number of
boards. (I make in-house only SMD prototyping) One or two prototypes
get wire bonded manually first, then glob top or s.th. else, then
solder paste by dispenser, then SMT assembly - mostly manually. In
mass production at specialized assembly houses, it is no problem
either to have a suitable cleaning process before bonding or a
fine-tuned SMD process which doesn't have any impact on the bond
pads.

The problem are lots which are too small for a fine-tuned mass
production but too big for the full-manual assembly I mentioned
first - let's say about 10 or 20 very populated boards with one or
two dies, or, even worse, one pressure sensor die which cannot be
glob-topped and (Murphy's law) be sure anybody will touch and bend
the bond wires during SMT placement :-(
[...]
>
> Cu
>
> Ingemar Hernefjord
> Ericsson Microwave Systems
>

Regards

Matthias Mansfeld

P.S.: I would be very interested in a short summary (needs not to be
on TechNet...) what did you with your pumpkins? Maybe I have
the same problem soon.
-----------------------------------------------
Matthias Mansfeld Elektronik
* Printed Circuit Board Design and Assembly
Am Langhoelzl 11, D-85540 Haar, GERMANY
Phone: +49-89-4620 0937, Fax: +49-89-4620 0938
E-Mail: [log in to unmask]
Internet: http://www.mansfeld-elektronik.de

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