To add some pointers that are only partly related to this-
  
My most recent homemade board, I used 90gsm tracing paper instead of a
plastic transparency. Although it doesn't look particularly transparent
when compared to the plastic, it's good enough. I found exposure time
needed to be about 20% longer than with transparency.

But the real magic is that the tracing paper holds its charge better, so
you get real solid blacks and much finer lines. That, coupled with the
fact that it's much much cheaper, and i'm not looking back. 

Jon

> -----Original Message-----
> From: piclist-bounces@mit.edu 
> [mailto:piclist-bounces@mit.edu] On Behalf Of Herbert Graf
> Sent: 22 March 2005 16:35
> To: Microcontroller discussion list - Public.
> Subject: Re: [EE] SMT on homemade pcbs
> 
> On Tue, 2005-03-22 at 22:27 +0800, Daniel Chia wrote:
> > Hi,
> > 	With so many nice chips only available in fine 
> pitch(0.5mm) QFP / 
> > LQFP / TQFP packaging, I was just wondering whether it is actually 
> > feasible to do such chips on a home made pcb or is it just wishful 
> > thinking on my part..
> 
> Certainly possible. Making the PCB will be the easy part, 
> it'll be soldering the part onto your PCB without a solder 
> mask that will be difficult.
> 
> I did it with a 22 pin connector with 0.5mm pitch, a 
> microscope is necessary IMHO. If I had to do it again I would 
> certainly send it out to a board house. TTYL
> 
> 
> -----------------------------
> Herbert's PIC Stuff:
> http://repatch.dyndns.org:8383/pic_stuff/
> 
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