Homebrew PCBs

----- Original Message ----- 
From: "jerrytr2.com" <jerry@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Friday, February 20, 2009 8:27 PM
Subject: [Homebrew_PCBs] Surface Mount


> Hello,
>
>   Since encountering this group a month or so ago, I have refined my
> toner transfer process to the point that I am able to reliably do 15-
> mil traces.  Maybe smaller.  Hope so.
>
>   I'm doing a home project and have settled on PIC24F
> microcontrollers.  The latest version needs USB, and all the PICs
> that support USB are surface mount.  So I have been dragged kicking
> and screaming into the 21st century.
>
>   I bought an Aoyue 968 hot-air SMD rework station and some fine
> tweezers and have been  having a good time scrounging parts off some
> defunct computer boards - just to get used to the tool.  I'm going to
> need a microscope - half of these parts just look like bits of dirt!
>
>   One part I scrounged is the same package as the 24FJ256GB106
> processor I'm planning to use - a 64-pin TQFP.  Good LORD those pins
> are small.  Can Toner Transfer make boards this tight? According to
> the spec sheet, the pin pitch is .5mm, or about 20 thousandths of an
> inch.  So the traces need to be 10 thousandths of an inch, and will
> only have 10 thousandths of separation.  Ouch.

Some people can do that sort thing with TT, but it can be difficult. I can 
do fine pitch devices and 8/8 mil tracks with photo-etch without any 
problems.

Leon