[Elecraft] Cutting component leads in tight places.
Hi Here is a tip that some of you might want to try when building kits and trying to cut off a component lead in close quarters. Like when putting components on the bottom of the board and soldering on the top. I learned it as a farm boy back in the 30's when we couldn't afford a pair of pliers for cutting wire. After you solder the component lead, take a pair of long nose pliers, catch the end of the lead and bend it back and forth five or six times and it will break off at the top of the solder joint. Just be sure to keep tension on the lead while bending it. I didn't learn it building radios, it was fences! Am building my second K2 and just remembered breaking wire that way. 73 Scott N5SM ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
Re: [Elecraft] Cutting component leads in tight places.
On Sunday 30 March 2008 1:50:29 pm Scott McDowell wrote: Here is a tip that some of you might want to try when building kits and trying to cut off a component lead in close quarters. Like when putting components on the bottom of the board and soldering on the top. I learned it as a farm boy back in the 30's when we couldn't afford a pair of pliers for cutting wire. After you solder the component lead, take a pair of long nose pliers, catch the end of the lead and bend it back and forth five or six times and it will break off at the top of the solder joint. Just be sure to keep tension on the lead while bending it. I didn't learn it building radios, it was fences! Am building my second K2 and just remembered breaking wire that way. That's a great way to fracture the solder joint and cause future problems with intermittent connections. Never flex the component lead to break it off. Get a proper reduced space close cutting tool. There are a variety of these made for just such a purpose. They do not stress the solder joint when cutting off the excess component lead length. Some will capture the cut off component lead to avoid having it fly off somewhere to cause a failure later if you don't find it. Rick Kunath, k9ao ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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] Cutting component leads
The following is from a NASA-certified solderer ... me. (:-)) Contrary to the belief/practice of many, component leads protruding through a solder pad should NEVER be cut off flush with the board. They should be cut off at a length that is several diameters of the wire ... at least ... above the board. Yes, there are instances of machine-finished boards where the entire lead side of the board is ground or sanded off, but this is a process usually found in the mass-produced consumer product industry. Wiggling a lead to break(!) it off isn't the way to do it. The component's leads should be pre-cut to the desired length before insertion into the holes for soldering. FWIW ... 73! Ken Kopp - K0PP [EMAIL PROTECTED] or [EMAIL PROTECTED] ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
RE: [Elecraft] Cutting component leads
-Original Message- From: Ken Kopp The following is from a NASA-certified solderer ... me. (:-)) Contrary to the belief/practice of many, component leads protruding through a solder pad should NEVER be cut off flush with the board. They should be cut off at a length that is several diameters of the wire ... at least ... above the board. Above the board or above the top of the solder joint? Why leave wire protruding? - Keith KD1E - ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
Re: [Elecraft] Cutting component leads
At 09:30 AM 10/23/2006, Ken Kopp wrote... The following is from a NASA-certified solderer ... me. (:-)) Contrary to the belief/practice of many, component leads protruding through a solder pad should NEVER be cut off flush with the board. They should be cut off at a length that is several diameters of the wire ... at least ... above the board. Time for a refresher class. According to the current standard, NASA-STD-8739.3 w/Change 2, December 1997, Section 8.5(.3) ( http://www.hq.nasa.gov/office/codeq/sldrbch2.pdf ): Straight-Through Lead Terminations. Part leads terminated straight through the PWB shall extend a minimum of 0.5mm (0.020 inch) and a maximum of 2.29mm (0.090 inch) .020 is one lead diameter for a 1/8W resistor, and can be less than one diameter for larger parts. ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
Re: [Elecraft] Cutting component leads
The NASA wonks are correct in their citation of construction practices. However, as hams we like to know why as well as thou shalt not: In this case the bad thing being avoided is called cold-working. The solder used to solder parts is an alloy of two of more metals, which arrange themselves in a lattice of greatest strength immediately before solidification of the joint. Any deformation of that joint after solidification (including that caused by thermal expansion and contraction) is called cold-working, and embrittles the joint to some degree, setting it up for future failure in a way which is nearly undetectable by our feeble eyes. This is why you shouldn't use toenail clippers, etc. to get at the last nub of an exposed lead -- by doing so you are cold-working the joint. Clip it instead at the top of the meniscus formed by the solder on the lead. FWIW, SMD parts are designed to thermally expand at roughly the same rate as PCB material in order to minimize this phenomenon, or else they are constructed so as to relieve thermal stress. Darwin, Keith wrote: Above the board or above the top of the solder joint? Why leave wire protruding? - Keith KD1E - -- Marshall Jose, WA3VPZ ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
