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zdw | 77 comments

femto|next|

A nice video, though it missed one of the most interesting aspects of BGA packages: their ability to self-centre during soldering. If the misalignment is less extreme than in the video, surface tension will pull the BGA package into alignment. Here is an example

https://www.youtube.com/watch?v=dz7ltWBDm7U

Notice how in the second part of the video, once the solder has melted, the body of the BGA moves so it is correctly centred over the PCB pads. This is happening by itself, without an external influence pushing the chip into position.


kayfox|parent|next|

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

xondono|root|parent|next|

This. In my experience QFN-like packages self center better than comparable BGAs, it’s just that BGAs in general are big so they are easy to line up.

Small BGAs can be hell to hand solder.


aidenn0|root|parent|next|

I find SOICs to be by far the most forgiving; off by anything less than half the pitch and it tends to jump into place.

saagarjha|parent|prev|next|

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 ;)

beaglesss|parent|prev|next|

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

tirant|root|parent|next|

In BGA soldering, the concept of partial alignment doesn’t really happen. Here’s why: In a 2D plane (which is the PCB), only two points are needed to define alignment. If two solder balls are aligned with their pads, surface tension in the reflow process ensures the entire BGA package aligns with the rest of the pads automatically.

Surface tension acts on all the solder balls, pulling the package into place along both the X and Y axes. So once the first few balls are in place, the whole thing “snaps” into alignment. Misaligning only some pads while others are perfectly aligned isn’t possible unless something’s seriously wrong, like a warped board or damaged package.

It’s an all-or-nothing situation—either everything aligns, or nothing does.


yetihehe|root|parent|next|

> Misaligning only some pads while others are perfectly aligned isn’t possible

It's possible when your pcb-making process is on the odge of what designer wanted. Some pads on some boards may be not perfectly aligned in such cases. Or the board was heated not enough or in too short time and not all balls melted properly. Or it cracked under stresses because designer put too much vias in one place near the chip.

> It’s an all-or-nothing situation—either everything aligns, or nothing does.

In theory, practice and theory agrees. In practice, it sometimes does not.


loup-vaillant|root|parent|next|

I believe you forgot to quote "unless something’s seriously wrong". Your counter examples seem to describe exactly that: something going seriously wrong.

nyanpasu64|root|parent|prev|next|

I've heard of head-in-pillow defects where the solder may touch but fails to wet the pad on the chip or board. BGA probably makes it almost impossible to nudge a leg to check for mechanically solid connections. I don't know if bad joints from the factory are a problem in practice, or they usually only crack in use.

oefnak|root|parent|prev|next|

No wonder computers are binary.

the__alchemist|root|parent|prev|next|

Live by the balls; die by the balls.

Most of my soldering errors are from incorrect amount of solder, so, BGA tends to work better than other footprints.


brianpan|parent|prev|next|

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.


dyno12345|parent|prev|next|

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

avar|root|parent|next|

Do you? I'd imagine you can have too little on some of the pads, such that the melted material doesn't make contact.

As long as others pads have enough they'd pull the BGA into place, and at that point those pads would make contact and complete the solder.


ruph123|prev|next|

That microscope is amazing. Commenters debate whether it costs 30k or more around 100k so it is further out of reach for most hobbyist.

A few years ago I had quite a lot of fun with one of those cheap $30 wireless USB microscopes with up to 1000x magnification that connects to some app. My family and I always came up with new ideas about what we should look at next. Incredible fun. Unfortunately it broke down rather quickly. But it opened up the world much more than traditional backlight microscopes I am used to. They are basically “just” specialized cameras with bright flash lights.

I wonder if prices have come down a bit and if there are good options out there for such a portable microscope that doesn’t break so quickly. Better quality and magnification in the $200 range?


jve|parent|next|

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


lnsru|parent|prev|next|

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.


liendolucas|prev|next|

Just curious as I'm not into electronics but what is the name of the device where you put the PCB to be heated up? Is it expensive? What are the basic tools to perform full soldering of all components in a PCB? Seems like today you can buy all these tiny resistors, capacitors, chips, etc and pretty much do your own boards at home, right? Any suggestions on all these basic tools to have a relatively decent but not expensive lab setup?

nirava|parent|next|

- 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.


guthriej|parent|prev|next|

Reflow oven

foldr|parent|prev|next|

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


jpasmore|prev|next|

This is, by far, the best video on soldering I have ever seen. Soldering by hand is a dying art...My dad had a car radio repair shop - when radios were repairable (Delco: https://en.wikipedia.org/wiki/Delco_Electronics) - taught me how...like riding a bicycle, you never forget...

weinzierl|parent|next|

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.


dotancohen|root|parent|next|

High lead solder? Are you sure about that?

For what it's worth, I took the time to learn leadless soldering specifically so that I could teach my kids. I like to introduce them to safe hobbies (that why they all went skydiving before their 10th birthday, too).


nolist_policy|root|parent|prev|next|

I actually prefer lead-free solder because its more aggressive flux and higher soldering temperature.

This allows burning away and tinning enameled wire with the soldering tip.

Though there are only two lead-free solders that qualify. I use the Felder Ultra-Clear EL Sn100Ni+. The other one is the Amasan BF32-3.


jve|root|parent|next|

I suspect tip oxidation is an issue with leadfree? Or isnt it?

At what temperatures you solder mentioned leadfree?


pkolaczk|root|parent|prev|next|

Maybe it’s just me but I find SMT easier and faster to prototype with than THT. Apply paste, place all components on the board with tweezers, reflow, done. With THT I have to bend / cut the legs of most components, and solder each point individually.

As for “high lead solder” - you won’t buy it in Europe. We had to learn using lead free for rework and you know what - it’s not much different, assuming you have high quality equipment.


mistaken|root|parent|next|

As for “high lead solder” - you won’t buy it in Europe. We had to learn using lead free for rework and you know what - it’s not much different, assuming you have high quality equipment.

That's bollocks. You can buy leaded solder in Europe just fine. You only need to worry about lead-free if you want to sell a commercial product.


foldr|root|parent|prev|next|

>Some of us even engaged in the uphill battle of lead-free soldering only to be disillusioned.

I've never had any trouble using lead-free solder for through-hole or SMT (and I don't have any expensive or sophisticated equipment).


thebigman433|parent|prev|next|

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


dthakur|parent|prev|next|

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.

Taniwha|root|parent|next|

Yeah I agree, I solder parts like those in the video by hand (even occasionally BGAs with hot air)

elihu|root|parent|prev|next|

Yeah, hand-soldering as the means of mass production of consumer electronics devices has (mostly) died out, but the people who actually build and test things, or the people who fix consumer electronics devices, still usually do a lot of soldering.

It's also a necessary skill in a lot of technical hobbies. Modular synthesis by means of DIY modules, the whole mechanical keyboard thing, electric guitar maintenance...


martin_a|parent|prev|next|

> 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


iamflimflam1|root|parent|next|

That’s something that is so obvious under a microscope. My hands are pretty shaky, under a microscope it looks like there’s an earthquake going on.

mjmdavis|prev|next|

The microscope is from Keyence. An entry level model I believe. I have access to one with 3 lenses on an automated turret. They’re excellent for inspection and make for a ton of fun when you have anything small and interesting to look at.

They don’t have an API which is a big miss from my perspective. Every inspection requires a human operator to drive the thing.


Ecco|prev|next|

Actually I have, and you can too! All you need is a stereo microscope - even a cheap, sub-$100 will do :)

Now that being said, I would have never been able to record such a high quality video! The depth of field in particular is really amazing :)


stonethrowaway|parent|next|

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.

jdietrich|root|parent|next|

Practically all hobbyists and phone repairers use the same style of generic stereo zoom microscope, loosely based on the Meiji EMZ-5. AmScope will sell you one starting at around $400, or you can buy direct from China if you want to save a few bucks. Less expensive models with fixed magnification are available, but I can't recommend them.

https://amscope.com/collections/stereo-microscopes-zoom-powe...

https://eakinsmicscopestore.aliexpress.com/store/3200040/pag...

With 10x eyepieces and a 0.5x auxiliary objective, these scopes provide a very useful range of 3.5x-22.5x magnification and a comfortable working distance. At the minimum 3.5x magnification, the standard widefield 10x eyepieces give a field of view of about 50mm.

They are available in various bundles with a wide variety of stands and accessories; the essential accessories are a ring light and a 0.5x Barlow lens. I would recommend the biggest, heaviest boom stand you can reasonably fit on your desk, because any instability in the stand will be greatly magnified in your vision.

The key to using these microscopes successfully is to adjust the parfocal, which will allow you to adjust the zoom without having to refocus.

https://www.youtube.com/watch?v=R00KyVGRMpc

The preferred industrial option is the Vision Engineering Mantis, which uses very clever projection technology to provide a stereoscopic image without eyepieces. The ergonomics are dramatically better than a conventional stereo microscope, but you'll be lucky to find a used model on eBay for less than $1000. A big investment for a hobbyist, but worth every penny if you've got back or neck problems.

https://www.visioneng.com/products/eyepiece-less-stereo-micr...


stonethrowaway|root|parent|next|

Solid post.

armadsen|root|parent|prev|next|

I’ve owned this one for about 10 years and have never felt limited by it: https://a.co/d/c3z7JMf

gmiller123456|root|parent|next|

I've had that same one for a long time, and am pretty happy with it. But I would recommend shopping around and watching some reviews. Things may have changed.

One thing to consider is the light. I was never happy with the light on this scope, and instead use a different flexible desk lamp. Most of the ones mounted to the scope have pretty short stems, and can't be positioned to shine from the front, or very low to the side.


SAI_Peregrinus|root|parent|next|

I've got the SM-4 7-45x, with LED ring light, 0.7x Barlow, rubber eye cups, and double-arm boom stand. Basically this[1] with some extra accessories. Works excellently, the newer design allows mounting the ring light easily (there's a grove it sits in).

[1] https://amscope.com/products/c-sm-4ntp-64s?variant=414205946...


xondono|root|parent|prev|next|

The goto for most people is getting an AmScope on your budget range.

There are other options, but they tend to be less budget friendly, more targeted to professionals than DIYers.


_benj|prev|next|

That is really cool! I haven't tried hot plates because I didn't really have faith that solder would actually pull the component down and align it. I think this video might have improved that faith :-)

oasisaimlessly|parent|next|

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


adamrmcd|parent|prev|next|

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 :)


TechSquidTV|prev|next|

Watching how forgiving solder can be, and me still being bad at it is blowing my mind right now.

aulin|parent|next|

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

progbits|root|parent|next|

I respectfully disagree. I'm a mediocre hobbyist at best, I have cheap gear and use exclusively lead free solder/solderpaste without problems. The trick is to just use a lot of flux. I have a flux pen for hand soldering, and solderpaste usually has enough flux in it.

RulerOf|root|parent|prev|next|

I had that problem for an embarrassing number of years because I didn't know what flux was.

Today, I won't even plug in the iron if I can't find my flux first.


najork|prev|next|

It's super cool how they generated the 3D model on the fly, I'd love to spend some time playing with the microscope they used in the video.

komali2|parent|next|

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.

najork|root|parent|prev|next|

You know it’s expensive when they won’t even tell you the price.

Reddit says around $70k: https://www.reddit.com/r/microscopy/comments/nqo4qy/keyence_...


fabfabfab|root|parent|next|

We had them at a fab. About $85k + accessories at the time (~ 7 years ago).

metal_am|root|parent|next|

Nicest light microscope I've ever used.

gaze|root|parent|prev|next|

Whatever you do, DO NOT enter your email and absolutely do not give them your phone number. Keyence famously will not leave you alone. They’re very aggressive.

dlevine|prev|next|

I have watched way too much Steztix Fix on YouTube - it’s kind of addicting to watch people fix things). On that channel,he manages to fix all sorts of things with commodity tools, including a cheap microscope, hot air rework station, and soldering iron. He isn’t doing any BGA soldering, but there are YouTubers who reball BGAs (that looks frustrating).

tymscar|parent|next|

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

iamflimflam1|root|parent|next|

Can also recommend stezstixfix - lots of humour and he’s not massively technical so it’s in to hear his thought process as he puzzles out the problem.

horacemorace|prev|next|

Sure! Us olds routinely use microscopes. New things sure are small and you can’t solder it if you can’t see it.

ashconnor|prev|next|

Applying paste when you have a stencil is easy but I recently tried fixing the FPC connector on a Nintendo Switch and hand-applying solder paste is messier than hand soldering.

mecHacker|prev|next|

I'm wondering how common is damage to soldering connections in extreme temperatures and/or vibrations? Fascinating video btw!

spiritplumber|prev|next|

I have to do 0402 by hand to fix some old stuff this week. it's going.... let's just say that it's going

londons_explore|prev|next|

Anyone here know why solder paste isn't made of finer particles?

What are the tradeoffs on particle size?


Kirby64|parent|next|

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-...


CarVac|parent|prev|next|

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.

alhirzel|prev|next|

Really cool camera and very nice set of soldering "demos", including without flux.

the_arun|parent|next|

They have used microscope to record it.

pitaj|prev|next|

I was hooking to see an example of a cold soldier joint. (Applying soldier directly from the iron without heating the pin)

zaps|prev|next|

I sure haven’t

AdieuToLogic|prev|next|

Yes.