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Old 03-27-2014, 08:05 PM   #21 (permalink)
hth
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I can vouch for using lead solder, even at my work place we don't use lead-free in any of our processes. Not only that, it melts at a lower temperature so the risk of the pcb burning is less likely.

And as I am reading this i'm a little shocked that even MCB hobbiest (maybe?) soldering skills maybe better than some workplaces. But then again the type of soldering that I saw on the rotor was also very surprising to say the least
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Old 03-27-2014, 09:26 PM   #22 (permalink)
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If using a cheapo soldering iron... quickly sand the tip of it when it's hot (don't burn your fingers... just rub the tip on a flat surface with the sand paper on it the surface). Then quickly as possible solder. If you don't do this, it will take too much time to heat up the solder and contact point on the board, and you risk burning the contacts right off the board (honestly). It is much better to use a more expensive solder iron that is very hot so contact time is minimized and heat is localized as much as possible.

Basically, try not to burn the board by keeping contact with it limited. Pads - can - be tricky, if in doubt, ask an electronics or tv repair shop to do it for you.
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Old 03-27-2014, 11:16 PM   #23 (permalink)
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Quote:
Originally Posted by Grendel View Post
Rosin Flux - is a type of organic [flux] chemical used to clean metal surfaces by etching the the oxides off the metal. There are many types of Fluxes and Rosin is but one of them. Most people refer to some solder as Rosin Core solder. This is a type of solder that has Flux already inside it and it is very common.
Rosin and flux are not the same thing, although they serve the same purpose. I can't remember which one is which off the top of my head but IIRC Flux is acidic and Rosin is Basic. Both are corrosive and thus corrode the oxidation away (to reiterate what you mentioned). In simpler terms, it's like putting a penny in vinegar, and much like that analogy (which is kinda perfect since it's copper and acid as well) if you don't properly remove the remaining flux or rosin you will have problems.

I've never had a latent failure yet, and even if you aren't cleaning with isopropyl and using additional flux/rosin it is still better practice than most manufacturers use anyways. As I mentioned it's a board for a paintball gun, that is the type of practice used for something like avionics. In hobbyist terms I just don't feel that extra time, effort, money and hazards are justified. Again you are 100% correct, it is a better more reliable method.

I'm curious about your background, you seem to have a very in depth knowledge. And thank you for the insight into the two different alloys, I knew different alloys existed but never really knew the difference between them. So if I understand this correctly, by alloying you keep things liquid longer and then they go solid faster (thus minimizing what you referred to as the plastic state)? Although I've only ever used 60/40 and 63/37.

As far as lead solder vs unleaded solder there are certain legislative circumstances requiring the use of unleaded solder. This is not one of those circumstances and leaded solder is much easier to use and much more forgiving. Unleaded solder doesn't have the same toxic fumes that leaded solder does and is overall a better product. Unleaded solder however still has the unsolved problem of whiskering.

Sanding the tip of the iron is bad, it actually decreases the performance of the tip (unless you are going to polish it). You want to properly tin your tip before and after the job to avoid oxidation of the tip. If your tip is in such bad shape that you need to sand it, it's time to get a new tip.

Soldering is a fine balancing act. The true masters use almost no solder and almost no heat when soldering, only what is required. If you are melting your pads off (which I am guilty of doing once or twice) you are dumping WAY to much heat into that pad.

@hth I may be a hobbyist but I did pick up many tricks during my schooling from professionals. I'm no expert, but I certainly know enough to be dangerous. WRT your point about the Rotor, the likelihood that a true technician performed the soldering is quite low, those guys rightfully cost a lot of money. If the board was hand soldered it was likely done in a factory in China by people who have about as much knowledge and experience as any random person you pick off the street.

More on topic, I got busy today and didn't have time to shoot a video. I'll try again tomorrow.
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Old 03-28-2014, 07:20 AM   #24 (permalink)
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Quote:
Originally Posted by Keys_JR View Post
Rosin and flux .....

I've never had a latent failure yet, .......

I'm curious about your background, ......

As far as lead solder vs unleaded solder there are certain legislative circumstances requiring the use of unleaded solder. This is not one of those circumstances and leaded solder is much easier to use and much more forgiving. Unleaded solder doesn't have the same toxic fumes that leaded solder does and is overall a better product. Unleaded solder however still has the unsolved problem of whiskering.

Sanding the tip of the iron is bad, it actually decreases the performance of the tip (unless you are going to polish it). You want to properly tin your tip before and after the job to avoid oxidation of the tip. If your tip is in such bad shape that you need to sand it, it's time to get a new tip.
Rosin, Flux, Rosin/Flux.....etc is a subject that there have been books written about and many material science papers written and published. Rosin and Flux get used interchangeably all the time but actually are not necessarily the same thing, it is a terrible habit in the electronic field and causes much confusion in discussions. The only real important thing to remember is you use Solder/Fluxes that specifically say they are for electronics on the label.

Poor soldering practices is one of the top failures when you pareto consumer electronics and typically the failures are latent failures [A malfunction that occurs following a period of normal operation]. Not saying you solder poorly nor will have latent failures but a little care goes a long way to preventing annoying failures on the field. I tend to do things "over engineered" I think is is hard wired into my psyche can be a problem but......

As for my background I'm a long time Electronic Technician [Navy Trained] who went on to become an electronics engineer and work in a failure analysis lab [currently] working on electronic equipment root cause failure analysis. I also taught for both the military and in the electronics industry Hand Soldering. I actually took the Pace Course I linked in an earlier post [Damn that was a long time ago >.<] I've been in the industry for a rapidly approaching 30 years.

Yup, in general sanding a solder tip is not a good practice unless you are trying to recover a bad tip [temporarily] and yes you should tin your solder tip immediately after heating it up, periodically while working and right before you turn the iron off. Tinning a tip is putting a light coat of solder on the tip to protect it and promote heat transfer through better conduction.

As to Lead vs. Lead Free, for functionality Lead solder is magnitudes better then Lead Free solder in all aspects [electrically, physically, corrosion...etc.] and is way easier to work with. Soldering with Lead Free solder SUCKS. The only reason Lead Free is being pushed is to eliminate lead from consumer products [though Lead Free has its own health risks that are just as bad as lead [politics a bigger driver then actual risk but we won't go there ]. As to legislative restrictions on lead solder there really are none in the US currently though there is a move in that direction. Manufacturing is moving to Lead Free to meet import requirement for other countries not for US restrictions [primarily the EU, you can not ship to the EU unless you are certified Lead Free (there are some exceptions too)]. There is nothing in the states that prevents end users from using lead solder in repairs. If we do not have to maintain integrity of Lead Fee in the lab we always go back to using lead based solders for making the work easier [good reasonable ventilation is important and not just for the Pb but also the flux fumes that are irritants.

As Keys_JR stated you do not have to be anal about it but it will save you a lot of future hassle if you take basic precautions.
  1. Always remove old [dead] solder
  2. Always clean the areas/parts to be soldered with Alcohol >90% is best can be denatured or isopropyl
  3. lightly pre-tin all surfaces to be soldered [add light coat of solder] before soldering the joint
  4. Add heat to the parts to be soldered and add solder to that that is being soldered not to the heat source.
  5. Clean surfaces when done [some fluxes in the solder can cause corrosion if left on]

The really weird thing is I own nor have I ever owned an electronic paintgun and the most "advanced" hopper I have used is an old Veiw Loader Shredder [I still have it too though not used it in years]. I guess paintball is one place I try to escape from my job fully Long Live Hopper Ball on Mechanical
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Last edited by Grendel; 03-28-2014 at 07:36 AM.
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Old 03-28-2014, 02:58 PM   #25 (permalink)
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Quote:
Originally Posted by Grendel View Post
Electronic Technician [Navy Trained]
Knew it! You military trained techs are always talking about high reliability! I was taught by a couple of guys like you. I was certain you were an electronic tech and had a distinct feeling there was some military work in there too.

I'm a recent Comp Eng grad, but I picked up some soldering skills working on extra-curriculars. I've always enjoyed soldering, although as you will see in the videos I have the steady hands of a surgeon (NOT!).

Two things that I forgot to mention in the videos were the cleaning with Alcohol, which you would do after removing the old solder. And cleaning the connection after you have made it (again with Alcohol) I normally do the cleaning after soldering with rubbing Alcohol but don't normally clean after removal of old material.

I split the video in two because I didn't have the right size wick on hand so it took me a while to actually get all the solder out of the hole.

Part 1
Part 2
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