Have you ever seen soldering this close? [video]

This is true for most surface mount packages, the surface tension of the solder will usually center the parts in their pads during reflow.

Surface tension for the win.

In the extreme misalignment example they also did not use flux so I guess they were purposefully showing what NOT soldered looks like. They did show how the solder flows in the "too much solder paste" example.

And if it doesn't work on all pads, you may need an X-ray to figure it out.

Yup, when we rework BGA boards it's sufficient to go off the silkscreen outline of the package, if the board has one.

Also the cool-down BGA effect they showed is a lead-free thing, you don't see that on leaded solder balls unless something is wrong.

As someone who doesn't solder or really do much with hardware at all, this answers a longtime question of mine. I always wondered how people got all their stuff aligned perfectly ;)

you have to have the right amount of solder on 100% of the pads for this to work correctly though

Strange Parts did a great video about, "A boy and his microscope..."[0]

We bought the same one 6(?!) years ago and still use it every day. It was ~$900 back then, looks like it's $230 now[1].

I had a really hard time spending that much back then, but it is easily the most valuable tool in our PCB engineering & assembly shop.

[0] https://www.strangeparts.com/a-boy-and-his-microscope-a-love...

[1] https://www.aliexpress.us/item/2251832694057535.html?gateway...

I believe that's a Keyence microscope, and yes, way outside the scope of a hobbyist! They have a range of microscopes for this kind of thing. Some are also able to perform accurate dimensional measurements (sort of like the old optical comparators machinists used to use but far better). They're typically used for incoming inspection in manufacturing processes.

I bought this microscope that has HDMI port for connecting monitor. Cost me little over 100€. Has no lag. Quality worse than what in video but better than some I see on youtube that also lags. This microscope is not perfect but capable to do smd soldering.

https://a.aliexpress.com/_EIRqaY9

I bought one of those pore cleaners when I had some pores and quickly realized it was a microscope camera basically, so removed the pore thingy tip and started using it as such (which seems to be the same as you from the description). It was so interesting to explore all sort of stuff! From checking a small cut I got in my head, moles and other parts of my skin, to electronics, different kinds of fabrics, woods, etc.

I am using 1500€ Amscope for soldering tasks. It does not have such amazing magnification. Such magnification is also not needed for daily work. But it replaced 10k Olympus device from a decade ago. Optical devices got radically cheaper in last 20 years. SMD rework is not possible without them.

Such amazing scope is built in into 70k professional SMD rework station I use sometimes for complex repairs. Replacing RAM and processor chips is easy, but slow. Honestly I don’t think, that the scope in video is extraordinary expensive. Definitively cheaper than my old Olympus gear.

How much does this thing cost? What ballpark are talking about?

Soldering by hand is a dying art...

I'm not sure. Back in the day we avoided SMD like the plague and it had a reputation of being unapproachable. THT parts were highly sought after and I would even say that a good deal of the success of AVR was because they offered THT versions of their µs long after most others had stopped. Some of us even engaged in the uphill battle of lead-free soldering only to be disillusioned.

We thought hand soldering will die with THT but it didn't.

I see a young generation that has mostly overcome these hurdles. With their young steady hands, sharp eyes, high-lead solder, small temperature controlled irons and other modern equipment they just go about. I envy them.

Id definitely disagree about hand soldering being a dying art! There are lots of other great techniques, but hand soldering is still vital to developing hardware. Any hardware company worth it's salt has at least a couple rework technicians that are absolute wizards with soldering.

Also stuff like reflow solder is/can still be done by hand! Its a common thing to do if you need to touch up or modify a PCB and dont want to reflow the whole thing/damage any components

I respectfully disagree, and say that hand soldering is not a dying art. If you’re working on boards on the regular you probably have a soldering iron and use it often.

> Soldering by hand is a dying art...

Let me tell you that I'm holding up the flag. Very poorly and with shaky hands, but I'm trying to hold it up... :-D

Link to decent soldering scopes? Looking for one since I need to solder/desolder ICs. Been using T15 or whatever tips, they are great because of how varied they are.

> Seems like today you can buy all these tiny resistors, capacitors, chips, etc and pretty much do your own boards at home, right?

The "starter kit" I would suggest is:

- temperature controlled soldering iron. This is worth the premium over "dumb" irons, especially for leadfree solder. People have different opinions about brands, but try Hakko or Weller. Start with a small chisel tip

- solder paste is a more advanced substance, and is perishable and should be kept in the fridge. Stick to a reel of thin solder to get started

- flux pen is surprisingly useful

- resistors are cheap enough that you can just buy all of them: https://www.aliexpress.com/item/4001321720241.html

- ICs you should stick to Digikey or other local supplier and NOT aliexpress

- PCBs: services like JLPCB will make these and ship them to you

- desk lamp. Possibly one with a magnifier.

- some people will get serious about fume extraction; personally I quite like the smell of flux and just leave a window open. Be careful with airflow in case you blow away smaller components

- solder braid: annoying, doesn't work well. Try a solder sucker

- advanced but extremely useful tool: solder tweezers

- hot air gun and/or oven: again a more advanced tool, but critical for certain parts. Avoid those parts.

For most SMT repairs, we use a pair of these hot air guns[0] and one or two Hakko Omnivises[1].

A 3/4" copper pipe elbow JB Welded on one of them turns it into a 90 degree bottom-board heater and other is waved by hand over the top of the board.

Nearby parts can be protected with a little Kapton tape or other heat resistant shielding.

[0] https://www.amazon.com/gp/product/B0752Z4165

[1] https://www.amazon.com/gp/product/B000B61IHW

- simple boards can be made by first transferring your PCB design to a copper-plated board using toner transfer or UV exposure, then etching the rest of the copper away using an etchant solution (if you're willing; takes some elbow grease and dangerous chemicals). Or you can get a cheap fab-house to manufacture and ship you something (like 7-14 days, a few tens of bucks per batch)

- simple boards you can probably solder with a cheapo (~50-100$) soldering system, or a solder-paste+hot air machine setup

- components you can get for very cheap from LCSC, aliexpress or at okay prices but good reliability from digikey, mouser etc.

You'll also need stuff like multimeter, ocsilloscope, logic analyzers, etc for debugging your boards but you'll know when you need them, and there are cheap-enough options available up to the point when you start doing advanced stuff and you know what you need.

Reflow oven

It's quite feasible to do reflow soldering by applying solder paste with a stencil and then using a cheap toaster oven. However, the lack of a precisely controlled temperature profile makes it less repeatable and reliable than the industrial process. I've done it successfully a few times but generally had to touch up one or two components with a hot air station or soldering iron.

Here's a SparkFun blog post: https://www.sparkfun.com/news/3319

Moar flux.

Really. Just add more flux than you think it could possibly need. The biggest failure mode I've seen with solder of all kinds is not enough flux.

This Amtech no-clean is really gooey[0], but pretty useful for rework.

This Kester water-soluble is incredible, but needs to be washed[1].

If you need to hand-clean PCBs, a small photography developing tub and a sonicare (or similar) toothbrush is a game changer.

[0] https://www.amazon.com/gp/product/B09Y7N6QHF

[1] https://www.amazon.com/gp/product/B00DEDB5CM

could it be that you are using lead-free solder? that's almost impossible to use without precise temperature control and it's the most common source of annoyance in recent years with hobby soldering

To counter the sibbling comment: I've assembled many dozens of boards on a hotplate with no complaints. Watching them reflow with a stereo microscope (AmScope SM4) over the hot plate is fun. I've never worried about temperature profiles; I've just started it from cold on the maximum setting and turned it off when all the solder has melted.

* The hot plate I used was the "Presto 07211 Liddle Griddle", which worked well. https://www.amazon.com/gp/aw/d/B00006IUWL

Using a hotplate is like driving with one eye closed. Sure you’ll get there, but your accuracy will suffer!

Though I’ve had many a SOICs magically realign on the hot plate — they were pretty forgiving — it’s not worth it to run without proper temperature profiling, even if it’s from a hacked toaster oven :)

I followed the link in the description and it brought me to the microscope product page. I clicked "price" and it had a page that told me to enter my business email for a quote lol.

I'm also shocked at how seeing hand-shake up close (via a microscope) tends to diminish the amplitude.

I'm old, and drink too much coffee most days, but I can hand-solder down to 0402 with my microscope.

Best money I ever spent was a cheap, stereo soldering microscope.

Yes! It's ridiculously difficult to hand-apply solder paste without a stencil.

We use a pointy dental tool for larger pads and acupuncture needles for the teeny-tiny's.

I'd love to learn about better ways though, anyone else got tips for applying solder paste before a repair gets reflowed?

"High quality" and "can buy on aliexpress" huh. I'd drop the latter requirement.

Kester rosin core is available everywhere including Amazon and is excellent quality. 60/40 works nicely, #44 too.

I love that channel. If you like that look up MyMateVince too and JoeyDoesTech. Super good.

Yeah - me too!

FWIW, We got a training class from a grumpy guru a couple years ago, and "cold joint" was his most despised phrase.

He insisted we call them "dry joints," because that's what they actually were.

Now, whenever I hear (or read, or say) the terrible phrase, I can't help but think of the old guy, "No! it's dry!"

They make it in a variety of particle sizes. For certain pitch devices (usually under 0.4mm) you need to switch to finer particle sizes (Type 5 typically is used for the small stuff).

See:

https://fctsolder.com/solder-paste-type-3-vs-type-4-vs-type-...

The finer the solder particles, the greater the ratio of surface oxide to actual solder. Oxidized solder consumes some of the flux's reducing effect.

There are a few reasons. Smaller ball size means more surface area. When the paste flows, the surface tension of the solder makes it cling to the part and pad, and moves the part to align with the pad. With more surface area, you can start to get solder that clings to itself, making solder balls outside of the pad, called balling. This wastes solder and makes conductive components that are effectively contamination, they now have to be cleaned off, you can't let them remain to roll around and potentially make a short. I had issues with smaller balls clinging to stencils; i think the price is also higher.

I think there is a rule of thumb for choosing solder ball size, and it was something along the line of 5-8 balls should fit in the width of the smallest solder aperture. This will give good performance according to the component size without too much balling or other flow issues.

They have used microscope to record it.