Fillet or not?

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Fillet or not?

Able2fly
 
There are those who advocate no fillet when soldering plated thru  holes.  Is
an obvious fillet in that instance a sign of too much  solder?
 
K3UJ
 
=======================================

Never  trim precut to length leads such as ICs and relays, and resistor
packs, or  crystals.

These have just enough extension thru the normal fillet of  solder to not be
a problem


 
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Re: Fillet or not?

Stuart Rohre
Absolutely do not leave out the fillet.  If you have a lead that sticks out
of a hole, you should have a fillet around it.  That is a requirement of the
NASA soldering course of years ago, but has not changed as far as I see in
modern assemblies.

The flush plated thru hole is OK for solder bond to a lead, but you lose the
ability to clip on a test lead there.  Also, if ever you have to remove the
component, the extension of the lead out the plated thru hole gives you
something to grab; to wiggle the lead and break the solder bonds while the
solder is wet.  Continued movement of the lead keeps it from reattaching as
the solder cools, and facilitates removing the old component.

I think having a test point is as important as any of the other reasons for
not cutting leads flush.  Besides, the board has leaded components that will
stick thru and should not be cut, (are not designed to be cut) as I
mentioned in the earlier post. Those automatically determining that some
leads protrude thru the bottom of the board.

Now anyone is free to do what they want, but if I got a unit in my shop
years ago to repair that had been assembled with leads cut flush, I would
have to charge more for the aggravation of working on it, or refuse to
service it.

In building electronics, you should always design, lay out, and assemble to
facilitate future repairs.  Unfortunately, much of today's consumer
electronics is built to "throw away", but I doubt most hams would want to do
that with their kit when it has a simple failure that soldering in a new
component would fix.

I have followed the above in both design, modification, and selection of
professional science equipment for 45 years, and found that years after
something was obtained, attention to reparability saved the day when we had
to fix it.

-Stuart
K5KVH



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RE: Fillet or not?

Ron D'Eau Claire-2
In reply to this post by Able2fly
There are those who advocate no fillet when soldering plated thru  holes.
Is
an obvious fillet in that instance a sign of too much  solder?
 
K3UJ
 
=======================================

With Elecraft's plated-through holes, it's at least a sign of "more than
enough" solder. When soldering boards without plated-through holes, it's
virtually impossible to have good solder flow without something of a fillet
because the solder only has the copper around the opening of the hole to
bond with.

On Elecraft boards, if the lead is soldered *in* the hole, there's no need
at all for any fillet to rise above the hole.

If you're having trouble making fillets when you solder, use a
smaller-diameter solder. For Elecraft boards, I never use anything bigger
than .031 and I prefer .025" diameter.

It's not a big deal on most solder pads, but there are places where it can
cause real grief. A common one in the K2 is when soldering crystals. Excess
solder will form a fillet under the crystal where you can't see it. More
than one builder has agonized over a non-functioning rig until one of those
hidden fillets was found under a crystal shorting out the signal path. It
was a tough one to troubleshoot and was found only by removing the crystal,
cleaning off the excess solder, and re-installing it.

Other kits, like the KX1 and the T1, have some very close spacing in places
that require virtually no "bump" on the soldered side of some boards for the
unit to fit together and avoid shorts.

Ron AC7AC



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Re: Fillet or not?

Bob -  W5BIG
In reply to this post by Able2fly
I always feel more comfortable with a fillet.

Without a fillet it's much more difficult to inspect the lead to be sure you
have solder completely surrounding the lead.  It's possible to have the hole
partially filled with solder so it looks ok from one angle but the lead is
not securely connected. This may be hard to see. A fillet is easier to
inspect. If the height of the lead sticking out of the board is critical,
it's no extra trouble to trim the fillet along with the lead.

73/ Bob - W5BIG


----- Original Message -----
From: <[hidden email]>
To: <[hidden email]>; <[hidden email]>
Sent: Wednesday, March 30, 2005 2:21 PM
Subject: [Elecraft] Fillet or not?


>
> There are those who advocate no fillet when soldering plated thru  holes.
Is
> an obvious fillet in that instance a sign of too much  solder?
>
> K3UJ
>


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