SMT - Was Re: Wayne on KNBx

[Jim Campbell-7]

Like it or not, we are seeing another transition in kit building.  Just
as some of us witnessed
the transition from tubes to transistors, we are now seeing the
beginning of the transition from
parts with leads to SMT.  I would guess that in ten years or so it will
be increasingly difficult
to find parts with leads.  Perhaps those of us that are uncomfortable
with SMT should start
stocking up on discrete parts and parts with leads.

I successfully made the transition from tubes to transistors and am
beginning to embrace the
transition to SMT.  I just received one of Steve Weber's ATSIII kits. It
is the most dense
SMT kit I have attempted so far, but I am convinced that I can do it.  
Steve did  teach me
something new about SMT.  He said to hold down the small parts with a
toothpick with some
beeswax on it.  I could have used that info when assembling the AA-908.  
I was holding a
really small part with tweezers when "twang" it went off to somewhere.  
I never did find it
and had to wait for the arrival of its replacement.

Jim, W4BQP
Happy owner of K2 #2268 and a bunch of other Elecraft do-dads.
_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[Stephen W. Kercel]

Jim:

I used to design electronic instrumentation at Oak Ridge National
Laboratory, usually built under my direct supervision by the very competent
technicians in my research group. However, when we came to installing SMT,
we always farmed it out to an expert SMT constructor (a young woman with
extremely steady hands and sharp eyes who did the SMT work for the whole
Division). Admittedly, we did that for cost effectiveness of construction,
and arguably, the cost of the time of an amateur constructor need not be
taken into account. Perhaps it is possible for the typical amateur
constructor to learn how to build SMT gear.

However, as Wayne pointed out in a post some months back, there is another
issue with SMT. It is extremely costly for the kit manufacturer to support
amateur constructors of SMT when the constructed kit fails to work
correctly. If SMT kits are to become popular among amateur builders and
profitable to the vendors, then some cost effective means of technical
support needs to be devised.

73,

Steve
AA4AK


At 03:19 PM 7/19/2005 -0400, you wrote:

>Like it or not, we are seeing another transition in kit building.  Just as
>some of us witnessed
>the transition from tubes to transistors, we are now seeing the beginning
>of the transition from
>parts with leads to SMT.  I would guess that in ten years or so it will be
>increasingly difficult
>to find parts with leads.  Perhaps those of us that are uncomfortable with
>SMT should start
>stocking up on discrete parts and parts with leads.
>
>I successfully made the transition from tubes to transistors and am
>beginning to embrace the
>transition to SMT.  I just received one of Steve Weber's ATSIII kits. It
>is the most dense
>SMT kit I have attempted so far, but I am convinced that I can do it.
>Steve did  teach me
>something new about SMT.  He said to hold down the small parts with a
>toothpick with some
>beeswax on it.  I could have used that info when assembling the AA-908.
>I was holding a
>really small part with tweezers when "twang" it went off to somewhere.
>I never did find it
>and had to wait for the arrival of its replacement.
>
>Jim, W4BQP
>Happy owner of K2 #2268 and a bunch of other Elecraft do-dads.
>_______________________________________________
>Elecraft mailing list
>Post to: [hidden email]
>You must be a subscriber to post to the list.
>Subscriber Info (Addr. Change, sub, unsub etc.):
>http://mailman.qth.net/mailman/listinfo/elecraft
>
>Help: http://mailman.qth.net/subscribers.htm
>Elecraft web page: http://www.elecraft.com

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[Craig Rairdin]

> Like it or not, we are seeing another transition in kit building. Just
> as some of us witnessed the transition from tubes to transistors, we
> are now seeing the beginning of the transition from parts with leads
> to SMT.  I would guess that in ten years or so it will be
> increasingly difficult to find parts with leads.

There's a fundamental difference between the two watershed moments you
describe. The shift from tubes to transistors brought new capabilities.
These were primarily the result of the need for less power and the dramatic
change in size. Being able to do the same thing in a smaller package that
required less power and dissipated less heat brought about lots of
innovation.

The shift from leaded parts to surface-mount parts is different. It is a
change of form to accommodate automated assembly. There is some change in
size but overall it's the same stuff in a different-looking package. There
are things the old parts can do that the new ones can't. For example I have
resistors in my airplane soldered inline with fuses. It would be impossible
to replace this with a leadless part and impractical to design a circuit
board to hold a resistor and a fuse for the sole purpose of using a
surface-mount part.

One could argue that the shift from tubes to transistors is no different.
Transistors weren't plug-n-play compatible with the tubes they replaced, so
it was probably imagined that tubes would be around for a while. The problem
is that there was no application (other than repairing existing units) where
tubes had an advantage. In the case of leaded vs. leadless parts, there are
clear examples of the benefit of keeping around the old human-handlable
parts.

Surface-mount is the antithesis of kit building by its very nature. The
devices were built for the very purpose of being installed onto circuit
boards by machines, not people. Kit building is driven precisely by the
desire to create something by hand, without the use of machines.

This is (one of the reasons) why I don't get excited when I see kits like
the Sienna (www.getboost.com/dz). It's all preassembled.

Surface-mount technology has been in practical use for a very long time and
hasn't yet supplanted leaded parts. I can imagine there could come a time
when it won't be financially practical to manufacture every variety of IC in
both SMT and DIP formats, I'm having a harder time imagining leadless
resistors and capacitors replacing their leaded counterparts.

Write back in ten years and we'll see how it turned out. :-)

Craig
NZ0R
K1 #1966
K2 #4941

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[N8LP]

Even though I have used SMT parts in my personal projects Craig, I agree
with most of what you have said, and avoid them in projects aimed at kit
builders. I will take exception, however, with your last statement. We
are well past the point where every variety of IC is available in both
SMT and DIP format. Almost all new parts are available only in SMT, or
even dies, especially in the communications market. This is because the
designs are driven mainly by the wireless/cellular market where size is
paramount.

It should be noted also that performance generally suffers with leaded
parts in RF circuits. Parasitic strays in bypass caps, chokes, resistors
and other simple parts are far lower in SMT parts. This may not matter
much in HF gear, although even in HF gear it is often important to have
unconditional stability into the UHF range.

73,
Larry N8LP
www.telepostinc.com
 

Craig Rairdin wrote:

>Surface-mount technology has been in practical use for a very long time and
>hasn't yet supplanted leaded parts. I can imagine there could come a time
>when it won't be financially practical to manufacture every variety of IC in
>both SMT and DIP formats, I'm having a harder time imagining leadless
>resistors and capacitors replacing their leaded counterparts.
>
>Write back in ten years and we'll see how it turned out. :-)
>
>Craig
>NZ0R
>K1 #1966
>K2 #4941
>
>
>  
>

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com