this post was submitted on 20 May 2024
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[–] [email protected] 74 points 7 months ago* (last edited 7 months ago) (3 children)

When you're done soldering, cover the soldering iron tip in solder, and store it covered in solder. This prevents it from oxidizing when you're not using it

[–] [email protected] 39 points 7 months ago

See? I'm not lazy, I'm careful!

[–] [email protected] 6 points 7 months ago

I solder for work and I cover my tip every time I put it down. Never ever needed to use tip tinner. Also never had to replace a tip either.

[–] [email protected] 4 points 7 months ago (1 children)

Oh, is this why my old soldering iron had the tip explode?

Good to know.

[–] [email protected] 3 points 7 months ago (1 children)

Wow, that's a thing that can happen!?

[–] [email protected] 4 points 7 months ago (2 children)

When I say explode, I mean the tip shot bits in a 1-2 inch radius after I put pressure on a thick copper wire. It nearly hit my non-dominant hand which was holding the circuit board on the floor tile I used to isolate my soldering shit from the ~~now singed~~ table

[–] [email protected] 3 points 7 months ago (1 children)

If you're trying to make me less terrified of soldering now, it's not working.

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[–] [email protected] 66 points 7 months ago (2 children)

One tip that isn't mentioned is DITCH THE CONICAL TIP, USE A CHISEL TIP.

Conical tips have terrible thermal contact, as they have both poor surface area in contact. Also the tip is further from the heating element, preventing it from heating faster.

Additionally that tiny point doesn't store any heat, it cools down significantly as soon as it touches anything. A broad chisel tip stores more heat and is far more appropriate for through hole joints like this.

[–] bitfucker 29 points 7 months ago (1 children)

Great, now I can blame my past shitty soldering job to the tips!

In all seriousness, thanks for the tips!

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[–] [email protected] 10 points 7 months ago (1 children)

conicals are good for the small smd parts though, when having a huge contact area and big thermal mass means completely desoldering the part and dragging it off the board when you pull away.

of course, those aren't the conicals on a $20 orange handle plug in iron...

[–] [email protected] 4 points 7 months ago

I use a j tip for fine SMD. You still have a fine point but you also have a broad elbow good for drag soldering and other larger components.

[–] [email protected] 36 points 7 months ago (3 children)

If you have problems, you should probably add flux (make sure to extract fumes if soldering with flux for a while). Some say there is never enough flux.

[–] [email protected] 34 points 7 months ago (1 children)

They don't want you to know, but you can extract all the fumes and flavors using only your nose!

Seriously though, flux fumes do have a somewhat nice smell to them.

[–] [email protected] 14 points 7 months ago

Depends on brand. And my head always hurts after inhaling them for more than a minute without a fume extractor. (I just use a PC fan and some old who-knows-what HEPA-like filter discarded from ventilation equipment. For quick jobs, I hold my breath and/or move out of the way.)

[–] [email protected] 12 points 7 months ago (6 children)

What does flux actually do?

[–] [email protected] 28 points 7 months ago* (last edited 7 months ago)

What it looks like: You shat all over the board.
What it smells like: Nasty chemicals but only when hot.
What it does: it helps distribute heat, and causes the solder to be less viscuous and stick to metals readily.
What it feels like to start using it: Wow, it's like I just gained one year of soldering experience!
What it feels like to remove it from the board after soldering: Aargh... I swear, one more board and I go buy an ultrasonic cleaner. (Some brands are easier but I usually need to employ a spudger, brush, then alcohol annd Q-tip)

Note that some solder comes with a core that contains flux or some similar substance of that effect.

[–] [email protected] 19 points 7 months ago (1 children)

Cleans and keeps the solder points clean. Prevents oxygen from reaching the solder joint

[–] [email protected] 11 points 7 months ago

This is the best answer. It removes oxides which allows the solder to flow and bond with the metal.

[–] [email protected] 5 points 7 months ago
  1. It removes the oxide layer from existing surfaces so the solder sticks and flows better
  2. It increases surface tension of the liquid solder so you get a nice round shape and no whiskers and less bridges
  3. It helps distribute the heat a bit. It works a little bit like thermal paste, especially when the contact area between the tip and the pad/component is very small.

Generally, flux is your friend and soldering without flux is terrible.

[–] [email protected] 4 points 7 months ago

It makes the tin non sticky. Heat up a blob of solder for a minute or so to evaporate the flux and then try working with it.

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[–] [email protected] 4 points 7 months ago (1 children)

Remember that all the flux you use will need to be cleaned off eventually. That can sometimes be a pain if there's a lot.

[–] [email protected] 2 points 7 months ago

I know, I mentioned it in that long comment

[–] [email protected] 32 points 7 months ago (9 children)

Step 2 has never been very clear to me and this diagram doesn't seem to explain it either.

  • Do you touch the tip of the solder to the iron, the pin, or the pad?

  • Do you push the tip of the solder down into the pad, draw it up along the pin, or pull it away as it melts?

  • Why does the solder sometimes flow onto the iron instead of staying on the pad?

[–] [email protected] 32 points 7 months ago* (last edited 7 months ago) (1 children)
  • touch the tip of the solder where the iron meets the pad or the pin

  • try to get as much contact with both the pad as the pin as you can

  • the pad could be dirty or not hot enough. Especially when the pad is connected to a ground or power plane layer in the PCB it may take longer than expected to reach a sufficient temperature. Usually adding some flux helps remove any dirt.

[–] [email protected] 7 points 7 months ago

Thank you kind internet stranger!

[–] [email protected] 8 points 7 months ago* (last edited 7 months ago)
  • Do you push the tip of the solder down into the pad, draw it up along the pin, or pull it away as it melts?

According to what I remembered, you don't move the solder at step 2, but when you are almost finished (step 3-4), you should pull it up along the pin.

[–] [email protected] 7 points 7 months ago

Both, which is why conical tips suck. They make poor contact with the pin and pad. With a chisel tip you make good contact with the pin and pad

You add some solder to the tip, then drag it across the pin and pad. Solder flows towards heat and if the joint is properly heated the solder should flow beautifully.

Sometimes the pad isn't heated (probably because the conical tip isn't heating it) and doesn't want to stick to the pad. It can also be due to oxidation on the joint surface. Add some flux to the surface and try again, allowing the iron to melt and activate the flux.

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[–] [email protected] 31 points 7 months ago (2 children)

This works great if everything is fresh and new, now post a guide about cleaning up/redoing 20 year old solder without burning a hole in the board 😅

That solder wick stuff makes me want to rage

[–] [email protected] 18 points 7 months ago* (last edited 7 months ago) (3 children)

Clean everything with a board cleaner/alcohol.

Use a heat gun for the stubborn things.

Solder wick is fine, but if it's a through hole on a ground plane your going to be there a really long time.

Use the least amount of heat you can get away with.

Sometimes adding fresh solder on top of the old solder helps the heat spread so you can use the wick more effectively.

Constantly use fresh wick, and if it's really stubborn dip your wick in extra flux.

Desoldering guns are awesome, but a little spendy.

[–] [email protected] 7 points 7 months ago

Massive Ground planes on a multi layer board were my breaking point.

I tried to clean the through holes where a micro USB port was secured and only could get it cleared by drilling out the solder.... (Only had a soldering iron and wick available)

[–] kogasa 4 points 7 months ago

Adding fresh solder can also help if it's leaded / flux cored and the existing solder isn't

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[–] [email protected] 10 points 7 months ago

Add generous amount of flux and fresh solder to it

[–] [email protected] 21 points 7 months ago* (last edited 7 months ago) (1 children)

Utilize Flux and alcohol. Clean with alcohol utilizing a wipe-clean-wipe method. After soldering with Flux, clean off residual Flux with alcohol. Leaving Flux can promote corrosion. My phone keeps autocorrecting Flux to capitalize it, and I don't care enough to fix it. 🤷‍♂️

Edit: Do not use clinical isopropyl alcohol solutions (~70% whatever). Those solutions need some water to work as a disinfectant. You want as little water as possible (>99% solution).

Believe it or not, isopropyl alcohol leaves residue behind. If you've ever wiped a shiny metal surface with it, you might see it looks a bit duller. Wiping after using alcohol is attempting to remove the residue to give the cleanest bonding surface possible.

[–] [email protected] 6 points 7 months ago (1 children)

Fun fact, the only way you are getting > 96.2% alcohol is with a molecular sieve and some other random wack shizzle.

Don't drink more than 96%. It's not natural. It's also poisonous.

[–] [email protected] 5 points 7 months ago (1 children)

I couldn't remember what the standard industrial solution was. All I could remember is that it's impossible to have 100% because water is introduced to the solution the moment it's exposed to air.

[–] [email protected] 3 points 7 months ago

It's not impossible, just difficult. Depending on how water free you actually need the result do be, you might be able to get away with just a dehumidifier. If that is not good enough, you can put your entire purification process in a box and flood it with an inrert gas like argon or nitrogen. Storing this is not that difficult, but you need to be sure you are in a moisture free environment whenever you open the container.

Another interesting difficulty is you cannot direct distil it to beyond around 90%, because at that concetration water and isopropyl has the same boiling point. So, you need to mix in another chemical like benzene to distill out the water, then you can distill out the addidive as a second step.

[–] [email protected] 8 points 7 months ago (4 children)

What are the ideal iron temps for your typical solder? I have an old Weller system and I feel like my results are way too inconsistent.

[–] [email protected] 11 points 7 months ago* (last edited 7 months ago) (1 children)

Check the documentation for your soldering station, if your soldering station doesn't have any documentation you can go with the melting point of the solder itself plus some overhead.

But as illustrated below, it can get a little complicated, if you're doing a lot of soldering with the same solder you'll experiment and figure out what's good for you

Ideally you want to use the lowest temperature you can get away with, using too much temperature can potentially shorten the lifespan of your soldering tips, and potentially damage the printed circuit board.

Get a testing board, any old board will do, and do some soldering and desoldering at different temperatures.

https://kb.hakkousa.com/KnowledgebaseArticle10297.aspx

lets look at the melting points of common solders:

  • Tin/Lead (Sn63/Pb37) - 183°C
  • SAC 305 (Sn/Ag3.0/Cu0.5) - 220°C
  • SN100 (Sn) - 232°C

Now let's add the 50°C we need for making a good soldering connection:

  • Tin/Lead: 183°C + 50°C = 233°C
  • SAC 305: 220°C + 50°C = 270°C
  • SN100: 232°C + 50°C = 282°C

We now need to consider the type of soldering station we are using......Soldering Station which has very good performance, we should add approximately 100°C as the heat reserve for quick thermal recovery.  The resulting temperature settings are:

  • Tin/Lead: 233°C + 100°C = 333°C
  • SAC 305: 270°C + 100°C = 370°C
  • SN100:  282°C + 100°C = 382°C
[–] [email protected] 6 points 7 months ago (1 children)

350°C has been my sweet spot with my hakko soldering station

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[–] [email protected] 4 points 7 months ago

Probably because it is a "dumb iron" with no thermal control. As soon as it touches anything it cools way down. Nowadays fortunately, cartridge tip irons are cheap if you're willing to buy from China. Cartridge tips have the heating element and temp probe built directly into the tip, heat up and adjust extremely fast to thermal loads.

[–] [email protected] 4 points 7 months ago (1 children)

As mentioned, you need the pad to be hot for the solder to wick onto it. There is missing info in step 1. Step 1 should say to have a slightly wet iron (solder on the iron). You used this molten solder as the heat transfer medium. Hold the iron so the wet solder on it is touching the pad and lead. This gives more surface area for the heat to travel from the iron to the pad. A dry iron touching a pad will have poor thermal connection, so the pad will take a long time to heat up.

[–] [email protected] 3 points 7 months ago* (last edited 7 months ago)

I think an apt comparison is touching hot stuff with a wet glove. With a dry glove, the heat has to conduct through the fabric before heating your hand. With a wet glove, the heat is conducting through the water and burning your hand. The solder, like the water in the wet glove, is a bridge for the iron to transfer heat efficiently to the pad.

I think a lot of hobby soldering guides really neglect the idea of heat transfer and thermal mass.

[–] [email protected] 3 points 7 months ago

Have you tried eutectic solder? (63/37 tin/lead)

[–] [email protected] 5 points 7 months ago (1 children)

They make an entire guide now just to insult me with their last word, hmpf!

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[–] [email protected] 4 points 7 months ago

Adafruit my beloved

[–] [email protected] 3 points 7 months ago (1 children)

Highly recommend taking an IPC Cert course if you are able!

[–] [email protected] 3 points 7 months ago

Do I just search my local community college for "IPC"? Or look somewhere else?

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