Even new PCB's need some pre-dressing before populating and soldering.
A light buffing of the copper traces with one of those "scrubby pads" to shine up the surface and remove oxidation, then a wipe with alcohol or a non residue cleaner like CRC electronic cleaner.
If your PCBs need a scrubby pad, they aren't new PCBs or you need to find a new fabricator.
Oxidation starts to take place on copper immediately when it's exposed to air.
You may not see it, but it's there.
And of course visible oxidation which you are referring to needs to be removed.
Some boards use a micro-coating to retard oxidation, and that also should be removed.
No one in serious electronics manufacturing does this, and Sunstone, for example, vacuum packs all Immersion Silver PCBs before they ship.
The copper isn't exposed to air because boards come finished with OSP, ENIG, Immersion Silver, etc. or HASL for cheap boards. Using anything on an ENIG board on pads will destroy them.
This might all apply to 20 year old boards and methods, but ask Apple, NASA, or the automotive industry if they use a magic eraser on their boards before they go into the paste printer and pick and place machine.
Kester, other American brands of leaded solder, were, and still are the staple that techs used without issues for decades.
And as far as that BS stuff about "lead-free" - it's nothing but yet another politically correct bunch of hype.
Yep.... Been a repair tech for 40 years now, and most of that time used leaded solders.
Before I retired I was a tech in a calibration lab, we had to use lead free solder ( I hate the stuff), lead free solder even the good ones, we found reduced the life of the iron tips. Maybe part of this was having to run the iron at higher temps.
In my home lab I use Stannol 62/38/2 melts at 179°C and at 0.5mm is ok (not ideal) for SMD
You can no longer weld as before, SMD complicated everything, if you heat up the points to join, goodbye component, or raise the thinner printed circuit. Only a "touch" causes cold welds.
A technician friend invested in an immersion welding station, to provide the service to third parties.
A technician friend invested in an immersion welding station, to provide the service to third parties.
Attachments
The trick is to solder quickly if your soldering iron runs hot.
I have two irons, a weller 25 watt iron that runs really hot and is good for soldering heat sink's and heavy connectors.
I also have an Antex 30 watt iron that doesnt run so hot that I use for SMD and thin tracks. I have just soldered a 28 pin SSOP SMD IC today and applied a lot of heat but it still worked fine. I just don't keep the iron on one spot for a long time.
Both of my soldering stations are 70W but this only means that the iron will hold its temperature better. for regular components I run the Iron at 250°C, if I'm soldering on a ground plane I turn the Iron up to 480°C. Also use the largest tip that will fit in the area.
I was taught (as an apprentice) to run my iron hot and be quick. Run the iron at a temp that you can solder a joint in less than 2 seconds. This technique leads to far less heat soak into the component and less chance of lifting a PCB pad.
I was taught (as an apprentice) to run my iron hot and be quick. Run the iron at a temp that you can solder a joint in less than 2 seconds. This technique leads to far less heat soak into the component and less chance of lifting a PCB pad.
I was taught basically the same thing in soldering school when I first went to work for GTE Labs in the early 1980s. I typically solder at 700°F/371°C and can do it very quickly. I do a lot of SMD this way as well as through hole and point to point. No problems to date, I sometimes see stuff I built 30+ years ago and 99% of the time the solder joints are just fine. (The only time I have ever seen a problem is when I used exotic solders.)
I generally get several years out of a given tip, but I wipe regularly on a wet sponge and re-tin frequently. Turn off iron as soon as done. The Weller stuff is pretty durable. I solder a lot.
OK. I have been soldering for about fifty years. In that time, I went through two Weller "controlled temp" irons (model W60) until I bought a couple of Weller and JBC digital stations. During the past fifty years I mostly used leaded 60/40 or rather similar leaded with 2% silver, or 4% silver. I still have several 1lb. Rolls of the 2% and 4% silver solder, once you try it, you never want to go back to anything else. Sadly, the Kester 4% silver hasn't been made since around 1990 (as far as I know).
I use pretty much used the 2% or 4% for the last twenty years, even when the prices doubled, tripled, and tripled again. Occasionally (when in the mood) I will pull off a hank of 50 feet or 100 feet of the 2% or 4% and put it up on eBay, while I still love both, I have enough to last me another 30 years, so I have plenty to spare. You should be able to find this by searching on eBay, knowing that I'm Stevenel57 (if anyone is interested).
Steven
Yes, the good thing is most (all?) of the Metcal irons will go into power saving mode after a few minutes and also don't heat the tip when it's in the stand/holder.
I run my tip at 380c, and if I need to solder a bundle of wires or something, I break out the 60W crappy iron with the giant tip.
Also, while I don't use lead-free solder, I understand why the ROHS initiative exists. Far too many people just throw away devices that have heavy metals in them rather than recycling them. Those who say it's just for "political correctness" remind me of the people who said the same when leaded gasoline was banned. Other than being harder to work with, and the possibility of tin whiskers shorting out HV parts in a tube build, I see no reason why at least industry shouldn't use lead-free solder.
Also, while I don't use lead-free solder, I understand why the ROHS initiative exists. Far too many people just throw away devices that have heavy metals in them rather than recycling them. Those who say it's just for "political correctness" remind me of the people who said the same when leaded gasoline was banned. Other than being harder to work with, and the possibility of tin whiskers shorting out HV parts in a tube build, I see no reason why at least industry shouldn't use lead-free solder.
I am not too concerned with the length of time one has soldered.
I've used several tons of lead free, working out the process the techs needed to be successful, by first developing the techniques..
Honestly, the flux is the most important. Also, lower tip temp with higher tip mass is also key.
Jn
There is a huge difference, the lead in petrol was an organic compound readily absorbed into the body and proved to be present in people living near busy roads.
Lead in solder is far harder to get into you unless incinerated. I am not aware of high lead levels being found even in production workers soldering all day.
I live in country where lead is found in the rock, so ground water has low levels of lead anyway.
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