Post by thread:[EE]: Soldering

Arthur Brown wrote: > > Hi Lindsay, > One of the most important things is the Tip must be kept clean use a wet > sponge and if your tip is copper replace with an iron plated one, this will > last longer. use the tin of tip cleaner sparingly as it's very corrosive. > > Regards Art Oh, no! I can see this might start a big flame war but here goes. We stopped using "wet sponge" in the workshops here about 10 years back, it's just not the best method. Cooling the tip from 350 degrees down to 20 degrees over and over causes metal fatigue and porosity of the tip, and a porous tip (ie, rough, lots of tiny holes etc) is no good to solder with. I have had regular fights with my apprentices who have just finished soldering/hand tools (yr1 subject) over this. They get taught the "wet sponge" stuff by the teacher so it must be right! ;o) The system we use in the two workshops here is the "solder blob" method, basically it replaces the wet sponge with a big solder blob. When the tip gets dirty, you apply fresh solder, give the core flux a second to do it's job and then wipe it on the solder blob. All the crud gets wiped onto the blob, which grows in size. The tip gets clean and polished. This has a lot of advantages. Doesn't make steam, doesn't cause tempering damage to the tip from rapid cooling, no constant wetting of the sponge is needed, and the best benefit is that the tip is slowly polished by the rubbing against metal (solder blob), and after a few weeks like this the tips get really good, because they are non-porous and polished all the crud wipes straight off and wetting is excellent. We get 3 times the life from tips now compared to the old days. It's quicker, little/no re-heat time needed, as the tip doesn't cool much. There is also always some residue flux left in your big solder blob, so rubbing the tip on this blob causes great cleaning. I cringe when I have to use another iron that sees "wet sponge" usage. It really is a step backward. I also hate using new tips, knowing it will be a couple of weeks before it gets polished enough to give good performance like the old ones did. For the record, I like the Weller magnetic type irons, good steel jacket tips. We only have to replace them when they get arc damage from soldering charged caps (we've all done it!) as with the solder blob method they don't wear out. -Roman -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

On Mon, 16 Oct 2000 16:21:47 +1000, you wrote: >Arthur Brown wrote: >> >> Hi Lindsay, > >> One of the most important things is the Tip must be kept clean use a wet >> sponge and if your tip is copper replace with an iron plated one, this will >> last longer. use the tin of tip cleaner sparingly as it's very corrosive. >> >> Regards Art > > >Oh, no! I can see this might start a big flame war but here goes. >We stopped using "wet sponge" in the workshops here about 10 years >back, it's just not the best method. Cooling the tip from 350 degrees >down to 20 degrees over and over causes metal fatigue and porosity >of the tip, and a porous tip (ie, rough, lots of tiny holes etc) >is no good to solder with. ..which is why you don't use a _wet_ sponge but a _moist one_ to avoid cooling the bit too much. The only pain is that it dries out fairly quickly. -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

Hi all, When I said Wet sponge of cause I meant damp sponge and the iron is cleaned on the way back to the irons test, not on the way from the rest to joint being done. I did not to give a very detailed account of every action in the process of keeping the tip of the iron clean. But the original poster did say he had an iron was tip was so contaminated that the only way to clean it would be to take a file to it. The point I was making was it's very important to keep the irons tip clean. You could use loads of tip cleaner but that is not the best way as it is costly both money wise and in replacing tips. The job in hand is also contaminated by the strong cleaning compond used. In the past I have seen people use tip cleaner for every joint they make. The tip I have in my Weller 1301 is Only 8 years old, do you think it may win an award for long service. mind you it's now only used 2 days a week now as it's on my rework bench. but it's on for 48-46 hours. now saying that what's the odds it now fails at the next switch on.... I have done a lot of Ministry of Defence rework for a well known British company and you have to follow their rules. for example ESD, Work Shop practice, down to what is allowed in the shop and what's not. Soldering standards include things like if you replace a resistor you trim the lead to length before soldering, I have seen work rejected because someone cleared the pads inserted resistor soldered the resistor in circuit then cut off surplus lead length. so I think every job as to be done to the standards of the employer. Regards Art {Original Message removed}

Arthur Brown wrote: > Soldering standards include things like if you replace a resistor you trim > the lead to length before soldering, I have seen work rejected because > someone cleared the pads > inserted resistor soldered the resistor in circuit then cut off surplus lead > length. I always leave the leads intact while soldering because they provide an extra measure of heat transfer away from the component. -- Best regards Tony ICmicro's http://www.picnpoke.com spam_OUTsalesTakeThisOuTpicnpoke.com -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

On Mon, 16 Oct 2000 22:46:16 +0100, you wrote: >Hi Tony. > >The reasons for the work being rejected was that > >1. cutting the lead put the joint under stress.? <unlikely> If it's cut too close to the solder blob (i.e. cuts part of the joint) it could potentially put stress on the pad. >2. the end of lead was exposed something to do with oxidation. <again >unlikely> > >I know that sounds daft but this was military hardware and in this piece of >kit all the via's had to be filled with Solder, again for what reason?. Probably to reduce the risk of the via detatching from the pad under extreme stress/vibration conditions. -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! use .....listservKILLspam@spam@mitvma.mit.edu?bodyT%20PICList%20DIGEST

> Soldering standards include things like if you replace a resistor you trim > the lead to length before soldering, I have seen work rejected because > someone cleared the pads > inserted resistor soldered the resistor in circuit then cut off surplus lead > length. I'm curious. What is the advantage to trimming the lead before soldering? I would have thought the other way around to be more reliable. ***************************************************************** Olin Lathrop, embedded systems consultant in Devens Massachusetts (978) 772-3129, olinKILLspamcognivis.com, http://www.cognivis.com -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! use .....listservKILLspam.....mitvma.mit.edu?body=SET%20PICList%20DIGEST

> From: "ArthurBrown" <EraseMEartbspam_OUTTakeThisOuTCABLEINET.CO.UK> > I know that sounds daft but this was military hardware and in this piece > of kit all the via's had to be filled with Solder, again for what reason?. Maybe it was to restore some of the mechanical strength of the boards lost by the drilling? If so they're wasting their time. As anyone who's ever tried to tear a stamp from a sheet or a cheque from a stub can attest, the perforations are invariably the strongest part... . -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! use listservspam_OUTmitvma.mit.edu?body=SET%20PICList%20DIGEST

At 08:21 AM 10/17/00 -0400, you wrote: >I'm curious. What is the advantage to trimming the lead before soldering? >I would have thought the other way around to be more reliable. It avoids the possiblity of fracturing the solder joint or lifting a pad when cutting the joint. The latter can be a particularly common failure mode on single sided boards with heavy-leaded parts in sloppy holes (typical consumer electronics construction for easy assembly). Best regards, =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Spehro Pefhany --"it's the network..." "The Journey is the reward" @spam@speffKILLspaminterlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com Contributions invited->The AVR-gcc FAQ is at: http://www.bluecollarlinux.com =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! use KILLspamlistservKILLspammitvma.mit.edu?body=SET%20PICList%20DIGEST

Olin Lathrop wrote: > > > Soldering standards include things like if you replace a resistor you > trim > > the lead to length before soldering, I have seen work rejected because > > someone cleared the pads > > inserted resistor soldered the resistor in circuit then cut off surplus > lead > > length. > > I'm curious. What is the advantage to trimming the lead before soldering? > I would have thought the other way around to be more reliable. I can believe this! A lot of the problems with bad joints we get in TVs are because the exposed tip of the steel leg started to corrode, then this travelled down the outer surface around the leg and eventually dry jointed. Dissimilar metals and oxygen and stuff. When re-soldering these bad joints I scruff the top surface of the pin as well as the sides, so the solder then forms a full seal around it. I was very intrigued by the military soldering info, I think it would be very schmick to cut the leads just clear of the board, then solder them to completely cover the lead and protect it from the environment. Sounds like a bit more work, and may need something to hold the component while soldering so it doesn't fall out. If we didn't already encapsulate our product and use very cool running parts I would consider this. Classy move, especially where the parts run warm or are exposed to the air. Also filling the vias is a classy move, thinking about doing that one! -Roman -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! use RemoveMElistservTakeThisOuTmitvma.mit.edu?body=SET%20PICList%20DIGEST

> From: "Olin Lathrop" <spamBeGoneolin_piclistspamBeGoneCOGNIVIS.COM> > > Soldering standards include things like if you replace a resistor you > > trim the lead to length before soldering, I have seen work rejected > > because someone cleared the pads inserted resistor soldered the resistor > > in circuit then cut off surplus lead length. > I'm curious. What is the advantage to trimming the lead before soldering? > I would have thought the other way around to be more reliable. According to one mil-supplier I did some work for recently it's because of the shock-loading of the finished joint when the lead is cropped. Seems a little excessive to me, but then I suppose that at the prices the military pay, they could have their stuff made exclusively by left-handed unicyclists if they ask... . -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! use TakeThisOuTlistservEraseMEspam_OUTmitvma.mit.edu?body=SET%20PICList%20DIGEST

I got the part about precutting leads, but why fill the vias again? Bruce Cannon Style Management Systems http://siliconcrucible.com (510) 787-6870 1228 Ceres ST Crockett CA 94525 Remember: electronics is changing your world...for good! {Quote hidden}> I was very intrigued by the military soldering info, I think it > would be very schmick to cut the leads just clear of the board, > then solder them to completely cover the lead and protect it from > the environment. Sounds like a bit more work, and may need something > to hold the component while soldering so it doesn't fall out. > > If we didn't already encapsulate our product and use very cool running > parts I would consider this. Classy move, especially where the parts > run warm or are exposed to the air. Also filling the vias is a classy > move, thinking about doing that one! > -Roman > -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! use listservEraseME.....mitvma.mit.edu?body=SET%20PICList%20DIGEST

>I got the part about precutting leads, but why fill the vias again? Corrosion. Sometimes a via can get corroded in a point it inserts a significant resistance on the circuit, or even interrupt a circuit. When it happens, as you say, it's a "pain in the ass" to fix. I've seen lots of cases of things like this happening. And it's always hard to troubleshoot. you only find the fault when you have nothing else to see. --------------8<-------Corte aqui-------8<-------------- All the best!!! Alexandre Souza EraseMExandinhointerlink.com.br --------------8<-------Corte aqui-------8<-------------- -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! use RemoveMElistservEraseMEEraseMEmitvma.mit.edu?bodyT%20PICList%20DIGEST

At 10:59 AM 10/17/00 -0700, you wrote: >I got the part about precutting leads, but why fill the vias again? It's not all that uncommon for there to be a micro-crack at the interface between the plated hole barrel and the traces. Easy to see when you section the PCB and look at it through a microscope, difficult to inspect non-destructively. Putting solder in the hole makes the vias more reliable because it flows from top to bottom, not relying solely on the integrity of the plating. This used to be a very big problem with boards, it is much less these days, but if you are paying $10,000 per pound to loft something into space, putting it under the ocean or if someone's life might depend on it, it seems like cheap insurance. Best regards, =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Spehro Pefhany --"it's the network..." "The Journey is the reward" RemoveMEspeffspam_OUTKILLspaminterlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com Contributions invited->The AVR-gcc FAQ is at: http://www.bluecollarlinux.com =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! use RemoveMElistservTakeThisOuTspammitvma.mit.edu?body=SET%20PICList%20DIGEST

Bruce Cannon wrote: > > I got the part about precutting leads, but why fill the vias again? > > Bruce Cannon > Style Management Systems > http://siliconcrucible.com > (510) 787-6870 > 1228 Ceres ST Crockett CA 94525 I guess to stop possible corrosion in the hole, and because it electrically joins the top and bottom layers of the board without relying on the PTH mechanism that may fracture. ?? -Roman -- http://www.piclist.com hint: To leave the PICList EraseMEpiclist-unsubscribe-requestspamspamBeGonemitvma.mit.edu