Looks better than my first ones!

I usually etch 30-60 sec.s past than the point where I don't see any more
unwanted copper.  When doing small pitch stuff I watch the etching progress
pretty closely.  Usually the dropout problems start with the resist not
being firmly attached to the copper to begin with.  You can get .5 oz copper
clad if you worry about undercutting on the thin traces.  I've been able to
get fairly reliable 100 pin tqfp's
(http://www.xilinx.com/bvdocs/packages/tq100.pdf) (the pitch limit of my
ability to hand solder) using the laminator + toner/magazine page transfer
process and watching the etch closely.  3.9 mil clearances / 10 mil traces
are doable with this method and with a bit of practice. 12 - 6 is
comfortable.  Small double-sided boards aren't that big of a deal either, if
you don't have a lot of vias to drill and line up.  I can get you pictures
if you think it might help.

One thing to watch out for is that the small pads don't like to be heated on
the .5 oz copper very much.  Reworking the board could result in pulled up
traces -chip quik or not.
-Dal
----- Original Message -----
From: "Alex Kilpatrick" <AlexK@HCITRAINING.COM>

I wanted to show off my first attempt at making a PCB.  I wanted to see
if I could make something as small as a SSOP package for a PIC16F628.
This package has a pitch of .65 mm, which is pretty small to me.

Here is a picture: http://home.austin.rr.com/kilpatrick/FirstPCB.JPG
(note that I didn't bother to etch the entire board.

The results were outstanding, much better than I expected.  The lines
are much sharper than they look in the picture.  The only problem I had
was one bit of copper left between a line and a pad.  I think that would
have come off if I had kept etching longer.

For those of you with experience with this kind of stuff -- do you need
to worry about etching too long (within reason)?  I am paranoid that if
I leave it in too long, I may start to lose some of my thin traces.

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics