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Old October 6th 04, 03:55 PM
Tom Bruhns
 
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"Joe" wrote in message link.net...
"Tom Bruhns" wrote in message
...

....
Easy enough to use SMT components soldered to a piece of copper-clad
for a ground plane. Just put down the two caps and the shunt resistor
"tombstone" style, ...

Joe: "I don't even know what you mean by 'tombstone style',"

Tombstone style...just solder one end to the copper-clad board, and
the other end sticking up in the air. Looks like a micro-size
tombstone sticking up from the board.

....

Cheers,
Tom


Hi Tom,

Being so new at this, I don't even know what you mean by 'tombstone style',
and it sounds like an awful lot of work to be scoring pcboard with an Xacto
knife to create transmission line effects.


It's really not all that difficult. Just use a ruler to guide the
knife, use a sharp knife, and the strips you want to remove can
usually just be pulled up in one piece (each). Or do it as Ian
suggested, with sticky copper tape.

As Ian wrote, keep lead lengths extremely short, like "zero." He
suggested putting a piece of heavy copper wire through the board where
you want to connect to the ground plane. Another way is to simply
drill a hole through the board and drop an 0805-size surface mount
part into the hole, and solder both ends. A 1/16" hole would work,
but you'd do better to pick a size that just fits the part you want to
use. Not all 0805 parts are quite the same size, but the body lengths
are pretty accurate and work nicely in 1/16" thick board material.
Any of the methods mentioned by Ian and myself will work well, and all
are reasonably easy to implement with a bit of practice and patience.

Cheers,
Tom
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Old October 6th 04, 06:20 PM
Cecil Moore
 
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Tom Bruhns wrote:
Any of the methods mentioned by Ian and myself will work well, and all
are reasonably easy to implement with a bit of practice and patience.


One method of "etching" that worked for me was using a reamer
bit on a drill press to cut through the copper and barely into
the PCB material. This has the advantage of leaving a ground
plane in between the active traces. Also great for scouring
and sizing PCBs.
--
73, Cecil, W5DXP
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Old October 6th 04, 07:11 PM
Paul Burridge
 
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On Wed, 06 Oct 2004 12:20:57 -0500, Cecil Moore
wrote:

Tom Bruhns wrote:
Any of the methods mentioned by Ian and myself will work well, and all
are reasonably easy to implement with a bit of practice and patience.


One method of "etching" that worked for me was using a reamer
bit on a drill press to cut through the copper and barely into
the PCB material. This has the advantage of leaving a ground
plane in between the active traces. Also great for scouring
and sizing PCBs.


This is where those Dremmel tools come into their own!

--

"What is now proved was once only imagin'd." - William Blake, 1793.
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Old October 6th 04, 08:51 PM
Cecil Moore
 
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Paul Burridge wrote:
Cecil Moore wrote:
One method of "etching" that worked for me was using a reamer
bit on a drill press to cut through the copper and barely into
the PCB material. This has the advantage of leaving a ground
plane in between the active traces. Also great for scouring
and sizing PCBs.


This is where those Dremmel tools come into their own!


As a matter of fact, when I did this stuff at home, I used a
Dremmel tool.
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Old October 6th 04, 09:34 PM
Joe
 
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Thanks all for the suggestions, I have a dremel, and this might be a good
project for me to learn how to use smt stuff. I will need to get a small
lighted magnifier tho, cause my eyes ain't what they used to be, even with
my reading glasses.

Joe




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Old October 8th 04, 07:33 PM
Tam/WB2TT
 
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"Joe" wrote in message
ink.net...
Thanks all for the suggestions, I have a dremel, and this might be a good
project for me to learn how to use smt stuff. I will need to get a small
lighted magnifier tho, cause my eyes ain't what they used to be, even with
my reading glasses.

Joe

Joe,
If you are like me, you will want to use 805 or larger SM. 402 type drive me
batty, and if you ever drop one on the floor, it is gone forever.

Tam/WB2TT


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Old October 9th 04, 01:39 AM
Joe
 
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"Tam/WB2TT" wrote in message
...

"Joe" wrote in message
ink.net...
Thanks all for the suggestions, I have a dremel, and this might be a

good
project for me to learn how to use smt stuff. I will need to get a small
lighted magnifier tho, cause my eyes ain't what they used to be, even

with
my reading glasses.

Joe

Joe,
If you are like me, you will want to use 805 or larger SM. 402 type drive

me
batty, and if you ever drop one on the floor, it is gone forever.

Tam/WB2TT



Hi Tam,

Actually, the ones that looked easiest to use were the 1210 case size. I
ordered some from mouser yesterday. I hope they're big enough for me to see.

I was wondering about a post I read somewhere else a long time ago. Is there
such a thing as a paste (that comes in a tube) that can be applied to the
terminals of a surface mount device and then when it is stuck to the board,
the paste hardens into something like hardened solder? So it is mounted to
the board and soldered with this paste?

Joe
KB1KVI


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Old October 9th 04, 02:47 AM
Roy Lewallen
 
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Joe wrote:
. . .
I was wondering about a post I read somewhere else a long time ago. Is there
such a thing as a paste (that comes in a tube) that can be applied to the
terminals of a surface mount device and then when it is stuck to the board,
the paste hardens into something like hardened solder? So it is mounted to
the board and soldered with this paste?


One-part conductive epoxy fits that description. It's commonly used to
mount SMT parts on hybrid circuits. However, the ones I'm familiar with
require curing at an elevated temperature (e.g., 150C for an hour). I
believe there are also some UV curing conductive epoxies. Conductive
epoxy can be used for mounting parts on a PCB, too, but I don't think
it's commonly done because it's considerably more expensive than solder.
There might be two-part conductive epoxies that cure at room
temperature, but I've never used one and am not sure they exist. The
one-part epoxies I've used aren't conductive until they're cured -- the
tiny conductive (gold or silver) particles in the paste don't contact
each other until the curing process causes the epoxy to shrink and pull
them together.

Then there's solder paste, nearly universally used for mounting parts on
PCBs. This also fits your description and can by applied by hand with a
syringe, then melted by a number of means -- hot air, IR, soldering
iron. It's actually a slurry of flux and tiny spheres of solder. It's
not really sticky, but sort of gummy, so some other means (like
superglue) has to be used if the parts need to be kept in place when the
board is inverted or severely disturbed before the paste is melted.

Roy Lewallen, W7EL
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Old October 9th 04, 09:50 PM
Joe
 
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"Roy Lewallen" wrote in message
...
Joe wrote:
. . .
I was wondering about a post I read somewhere else a long time ago. Is

there
such a thing as a paste (that comes in a tube) that can be applied to

the
terminals of a surface mount device and then when it is stuck to the

board,
the paste hardens into something like hardened solder? So it is mounted

to
the board and soldered with this paste?


One-part conductive epoxy fits that description. It's commonly used to
mount SMT parts on hybrid circuits. However, the ones I'm familiar with
require curing at an elevated temperature (e.g., 150C for an hour). I
believe there are also some UV curing conductive epoxies. Conductive
epoxy can be used for mounting parts on a PCB, too, but I don't think
it's commonly done because it's considerably more expensive than solder.
There might be two-part conductive epoxies that cure at room
temperature, but I've never used one and am not sure they exist. The
one-part epoxies I've used aren't conductive until they're cured -- the
tiny conductive (gold or silver) particles in the paste don't contact
each other until the curing process causes the epoxy to shrink and pull
them together.

Then there's solder paste, nearly universally used for mounting parts on
PCBs. This also fits your description and can by applied by hand with a
syringe, then melted by a number of means -- hot air, IR, soldering
iron. It's actually a slurry of flux and tiny spheres of solder. It's
not really sticky, but sort of gummy, so some other means (like
superglue) has to be used if the parts need to be kept in place when the
board is inverted or severely disturbed before the paste is melted.

Roy Lewallen, W7EL



Thanks Roy,

It sounds like the solder paste is what I heard about. Sounds easier than
trying to solder such small parts with an iron. I will see if mouser carries
it and give it a try.

Joe
KB1KVI


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