Fillet or not?
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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 _______________________________________________ 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 |
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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 _______________________________________________ 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 |
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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 _______________________________________________ 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 |
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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 > _______________________________________________ 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 |
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