I looked into surface mount and I was taken aback about the $1000's
of dollars to get all the equipment needed.
The resisters in particular are so small they look like fly specks.
You need a binocular micro scope just to see them let alone handle
them. I decided to stick to through hole whenever possible. Some
times the PC board company charges a lot more for over 350 holes. I
decided to experiment with 1/10 watt resisters surface mounted.
The other problem is there are no markings on surface mount resisters
which makes it hard to trouble shoot mistakes in values.
I built a rig on a standard Pana Vise to hold the resister in place
with a small alligator clip while I soldered it.
This is what it looks like.
Paul Lamar
Paul, 1206 and most 0805 SMT resistors have markings. You don't need to
use the smallest.
David
Thanks for the help David. I guess you have to request 0805 1/4 W.
Digi Key sent me a bunch of 0402's.
0805 is 1.2 mm long and 2 mm wide. Giant size fly speck :)
.047 long and .078 wide.
I can replace the alligator clip with a sharp point.
I'll have to redo the PC board. Who do you use for PC boards?
Paul Lamar
Hi All-
You really don't need to spend that much to do surface mount. If you
start with 1206 size resistors, a pair of tweezers, strong reading
glasses and a GOOD soldering iron is all you need. You can pick up good
irons on ebay spend about $50. Also for handwork use solder with lead
in it, and try to get a fine gauge solder, one roll will last you a
lifetime, and is probably less lead than you lost while fishing as a kid.
5% resistors are marked so that is not an issue. Some vendors mark 1%
resistors, but not all do. Caps are not marked but not all through hole
ones are either.
Yes when you start out they look small, but you will soon find that you
can do 0805 parts. Once you have been doing it a while 0603s are what
most people who hand build things use. 0402 are possible, but they do
need a microscope.
If you do a lot of work, yes you will want to get a stereo microscope,
the one I use is adjustable and it is normally set to 7X. I have seen
10x-20x stereo scopes on ebay for less than $200. And if you want to
remove components, either a second iron, or a hot air rework station is
a wonderful luxury about $75.
Actually after a while you will find it is faster to do resistors and
caps with surface mount rather than bending leads and inserting them
into boards, rebending to hold in place and then cutting off excess.
Yes daunting at first, so do a practice board, I have been doing it a
while but with the right tools you can do even fine pitch QFP parts.
The secret with those is to use flux.
I don't know if this email goes to the group, or not.
brucee
It does.
Paul Lamar
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