soldering PCBs with molten metal 

Every LumenPnP we make is danger puddle approved: opulo.io/products/lumenpnp

When I was a kid, my father had a company that manufactured boards. They used a wave soldering conveyer system. It was about 8 feet long, had a track that the populated board would run along, and it would enter a solder pool which had a small 'wave' along its width that would just skim the bottom of the board as it passed through. It was pretty fascinating. You really need one of these! It can completely solder a board in about 10 seconds. By the way, you also need to seriously consider your ventilation solution. What you are using currently is not sufficient. If you're going through that process hundreds of times, your entire room will be coated in burned flux and solder particles, as well as your lungs. You don't want to develop problems 20 years down the road. Future you will be thankful that you dealt with it properly now. Love what you're doing! Don't cut safety corners! Cheers!

It's not about the shape of the edges. All the areas you want soldered are in air pockets, preventing the solder from going up to the board. If you hold a cup upside down and push it into water, the water is not going into the cup. That's what's happening here. You got it working, because you're rolling it over the solder, so air can escape on one side. What you could do instead, is make holes or channels to the areas you want soldered, where the air can escape. Then you won't have to grind the corners and you won't have to roll the board over the solder.

I have the same dip soldering machine at the company I work at and also started out with the same issues... We discovered the temperature at the surface is lower than what the display says, probably losing heat from touching air and being irradiated as infrared, or just the temperature sensor is inaccurate. Eventually we set the solder bath to 420C (on the display) to get the process right to perfectly solder the though-hole components. Another way to solve your mounting hole issue is just use non-plated through holes and keep solder mask on the bottom side of the mounting holes which prevents wicking... the top side of the mounting hole can still be connected to your PCB Gnd which will still make contact with the screw head.

Hey mate, in manufacturing you gotta always make sure you preheat things or you’ll not only get the issues you saw here but also premature failures. You should also cool down slowly using the suggested profiles of the solder you use. This typically happens on a conveyor belt in wave soldering but you can do mostly the same in a controlled oven (for prototyping we used a heavily modified fan assisted toaster oven with an arduino to control the heat/pid and allowed us to customise curves

Back in the day we used to call this flow soldering. Strongly suggest you get yourself an extraction hood above this thing. The flux and vaporized lead is super super bad for you. Even if you wear a mask while you’re using the machine the stuff hangs around in the air.

Adafruit uses a selective solder machine. It pumps the molten solder up a fountain then moves the nozzle around to cover only the areas needed. An alternative is to move the part around over a fixed nozzle.

That thing. It scares me. Especially seeing your energy around it and lack of glasses.

As others have said - wave soldering. Or something i have seen from a friend: He used a conveyor-toaster for reflow-soldering (worked great, he later took it apart and made the conveyor dip the boards into a pool of molten solder)

Rule number 1 of soldering: more heat Rule number 2: less solder Rule number 3: flux is magic Looks like you realized how important rule number 1 is!

the advantage of adapting a 3d printer design to make a selective soldering robot is that you'd have another complementary product to sell

the way you tilt the board in the dip, reminds me of wave soldering, your ensuring that there is a clear edge for the surface tension to peel-off along, so not to much sticks

Your interview with Thomas Sanladerer brought me here via the magic of the RU-vid algorithm. Your charisma is absolutely off the charts. You speak well and convey your information extremely effectively and with scintillating style. Very happy to have viewed your stuff so far. Very impressive team as well. You guys just ooze professionalism. Curious Marc style of intelligence.

Related to the screw holes, why not place the screws up top and have the bottoms line up with the bottom of the board and do this soldering job and then use a heat gun to remove the access solder so you can remove the screws afterwords after the circuit board is completely cooled? Experimentation is so much fun! Nice video you guys!

Stephen: *shows a crazy contraption thing* "this is for another video" The 10th Doctor: "it's a machine that goes... Ding..." *Ding*

Preheat makes so much sense! It's pretty much make or break for every soldering joint Ive ever made!

At work we use a selective soldering machine with kinda like a fountain of liquid tin. A panel with the PCBs put in moves over it so that it only touches the areas where there are pins to be soldered. Advantage is that there is a smaller amount of tin to heat up (so less energy consumption on that end). We also add nitrogen to reduce oxidation (extracting the nitrogen out of the air unfortunately does require some additional energy). In our previous facility we had a conveyor belt going through a puddle of liquid metal, but the results weren't as good as the selective soldering machine. Also, occasionally parts or boards would fall off of the conveyor belt into the puddle... The smell was horrendous 😂

As the other commenter said its trapping air. Treat it like mold casting give a route out for the air with no contained shapes. Also add some stoppers to the bottom of your tongs or some arms to stop at a depth you are plunging it into the flux without it being hand steadiness dependent.

Wave soldering is much less hassle, maybe there are home grow way to do it with sound or a spinning wheel to get a standing wave in a danger puddle

Small suggestion here to improve the fume issue as the danger puddle is still just chugging out fumes like a smoker who just got off an intercontinental flight. Set up an enclosure in kind of a \_/ shape (wider at the front) around the solder pool with the filter fan on the back (may need a bigger fan) with the walls as tight in as possible. Either vent the air outside (shouldn't be hard to make a vent tube adapter for a window) or through a suitable filter, but having it enclosed on all sides but the front will allow the fan to pull all the fumes to the back. Probably wise to put the port for the vent tube on the box at the top, near the back. This also will help contain any splashing if anything goes wrong, as well as massively reduce the amount of flux and solder fumes in the building.

So happy to see where it started and where this project has come to! I would love some videos about the process of making this project into a company and all the challanges that come with it, i think you mentioned a little at the end of this video. Maybe something super rough, just talking head style, on a second channel as im sure a lot of people here come for the pcb work aspect of this channel

that method reminds me of wave soldering. with that method, you don't dip the pcb into the solder. you have small motor that creates waves in the solder. and only the maxima of the waves reach the board. works well on industrial scale.

What a legend. Taking away power from the big manufacturers and giving it to the people!

i just love your energy when it comes to solving very specific problems most people won't understand. this is just refereshing to watch :) keep it up

Nice work! In commercial wave soldering, A pump is used to make a little molten ridge which the boards are passed over. (This gives air pockets a chance to escape, which I think was one of the problems with the chamfered stencil. Cutting vent channels in the stencil and/or drilling vent holes in the board might solve that.) They do wave-soldering with surface-mount parts too, but the pick-and-place machine actually puts little glue dots under each part, to hold them to the PCB during soldering, since they pass through the solder wave upside-down.

in the industry they used a solder machine and they still have rework to do at the end of that process depending on the boards oh and they use a wave soldering technique so the solder cascades over a crest to touch the board also the boards are on a traveling track

I was think a low tech was to improve efficiency of the connector assembly process could be to make some sort of 3d printed sheath that had stacks of the connectors in the correct alignment to slip onto the pcb and then within the sheath thingy you'd need some mechanism to only let one layer of the connectors out. down side would be that if you changed something small on the pcb that affected alignment you have to change the design of the sheath thingy to account for that. think making a good release mechanism could also be finicky... also maybe a future lumenpnp could have a connector toolhead/ little gripper that could place larger through-hole parts/connectors

Happy that you figured it out, but come ON! SMT parts everywhere!

Very cool! Two suggestions… not that I’ve ever done this, but watching your process they came to mind. 1. Use a hot plate or a jig with blown hot air to bring the boards partway up to temperature. You want it lower heat than to melt the solder so no chance to burn stuff. 2. A jig where the board sits over a small contained sprayer chamber (like from a windex bottle or maybe electric pump or piezo) with your alcohol flux might work easier than the dip.

Super fun! You should add locking pins to the next round of boards so the through hole parts stay in place

I used to work at a place that built controller PC boards for cable boxes, and since this was before SMD came into the fore everything was through-hole. The actual soldering was handled by a belt-fed wave-soldering machine roughly the size of a refrigerator on its back. It had an adjustable width feeder that accepted an assembled PCB (or in this case a palletized PCB with three modules on it), passed it over a foam roller in a trough that applied flux, then over a heater to preheat the board and parts, and then through a "wave" - basically a roughly quarter-inch hump - of molten solder (thus the name) being pumped over an angled barrier to do the actual soldering. The end result was a near-perfect solder job every time. Populated but unsoldered boards went in one end and came out the other end ready to be bench-tested/QCed/pre-tuned (there was a trimpot that needed to be set to "dial out" parts tolerances in one of the critical timing circuits), and then packed for shipping.

The process is called wave soldering where the molten solder is pumped out of a fountain, making the solder appear as a wave. There's also a conveyor system to move the board over the puddle at the correct speed. This video is a good demo of the machine and the process: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-q4pUKfRHd8Q.html

A solder fountain machine would be perfect if a bit expensive and you could automate it with one of your pic and place motion systems

We use wondermask p to mask our boards. Also paper backed masking tape has worked as well. We use a full wave soldering machine though. I don't think dip soldering should really change much to make them incompatible but I don't have any experience with dip soldering boards.

When i used to work a solder flow machine and we used a product called seal peel .you put it on the bits you don't want soldered then it just peels off easy .

Really love you work, enthusiasm and energy! Keep up that great and inspiring work Stephen. And perhaps till Electronica in Munich 👌🏼

The spatulas look like a great $4 solution - but if you want to go for consistency in dipping the plane of your boards a specified amount in -Z, I'm thinking about modifying something like a "Drill press". The poor-man's drill press is this $50 dremel stand (do not recommend, crappy plastic). But perhaps something like this could be modified to install a board and then use the lever to dip it down a certain amount in Z to be consistent for dipping in both flux and solder pools.

I'm no specialist XD. my guess is that the thermal capacity of the metal is low (in general), so it will dissipate the heat it has really fast into anything that comes in contact with it. In other words, your assumption that the temperature has to be higher is not wrong! However, I believe making it a bit hotter (not a lot) and leave it less time in there will make the "pads" and "component' dissipate the heat of the liquid metal real fast (making it solid) and the other parts on the boards won't have time to solidify the liquid metal and the liquid will just leave back into the pod. Nice video and demonstration :)

It seems like you need vents so that the air doesn't get trapped under the board and prevent solder from filling in.

if you were to be able to make air channels in your pallet it might help with getting solder up into the cavities when upside down. (think of placing a glass upside down into water).

If I remember right from when I worked on the board line at NCR many years ago we used Kapton dots to cover the holes and they were applied by the PnP before SMT reflow. Then the boards were stuffed by hand (with only a very few TH parts it wasn't economical to have a TH PnP machine) and then through the wave solder machine. We also had a desktop "mini-wave" machine that was used to replace large items like PCI edge card connectors. You could use the wave to heat up and remove the entire connector in one shot. Then you'd clean the holes out and replace, flux and mini-wave again to re-solder it.

Hope your new PCB kits will be available soon)

Congratulations on getting to this step, net is research for " Wave Soldering " which you almost were doing by hand. You just need a bar to ' tap ' enough lead to create a wave to wick up above the mask at the right temperature.

You will get less dross if you cover the solder pot surface with some peanut oil. But conveyorized wave solder with preheat is the professional way to go.

Silicone plugs is also a solution to protect your mounting holes, given you have the volume to warrant fabricating a ton.

The grinding of the PCB has me worried. From what I've heard, powder generated from PCBs is really not good. For tasks like that, I hope you have a bubble set up with a HEPA filter. This keeps the dust out of the main environment. It's super easy to build, I made one for a project I was working on in my bedroom which involved cutting insulation a lot. All it was was a bubble made from heavy plastic sheeting, all sealed with super stick tape. I then attached a box with a fan built into it and attached a car cabin HEPA filter (cheaper than many special purpose ones) to the box so all air flow had to go through it. This created a negative pressure space in the bubble, so any leaks would mean outside air would blow in and particulates couldn't escape. Also, don't forget about your clothes. After you are done and take off your respirator, the particulates can be on your clothes. It would be a real benefit to have a mid chamber to change in. Obviously, in your setup it would be easier to use something like tyvek suits or something that goes over clothes. Still, don't forget about your hair. I had mine in my bedroom, so I just had pair of clothes dedicated for that type of work that I would change in an out of for the tasks at hand. This sort of stuff won't have a noticable effect on health usually for a long time, but it will. My bubble cost me around $100. It's cheap and easy, just takes time to set up. I highly recommend one if you are dealing with particulates. Also, for your project, you could probably easily get away with a bubble in a box. That sort of thing where you stay outside and just put your arms in through attached gloves.

Wondering about the method used in removing the board is also a key to the solder adhering correctly. A swooping/rolling method rather than straight dipping and then straight removing.

Next step, get a small wave-soldering machine. Makes it soooooo much easier.

I've never done anything like this before at all, but a suggestion might be to put a few unplated drill holes in the pcb that you're soldering for venting purposes.

Group B racing was incredible. The main reason it was so dangerous was the difficulty of convincing people in South American countries that waiting in the middle of the road for the cars go cars to go by wasn't a good idea. My favorite car was the Lancia Stratos. A friend of mine had one of the limited production models...

It's *almost* like you're manually imitating what a solder fountain does, by rocking it into the molten solder and out again.

Just curious why you didn't get a wave soldering system instead of the puddle? Way more easy to control, not much larger, and will give you the perfect solder joint every time.

One of my friend tried this and experienced 2 fatal mistakes: 1. Dunk the board but can't pull it up because he had no idea where's the board, oh wait there's $400 ARM SoC in it 🗿 2. Dunk and pull success! then the ARM SoC become loose and fall into the puddle 💀 Total loss is around $1100. Lesson to learn: PCB oven is a lot safer than tin puddle!

Really fun to watch!

Shortly after I started at my job, everyone (this was a very large company) received a "safety" mug for drinks. Per rumors, a tech spilled a drink into a solder pot. "Danger puddle" indeed!

Get yourself a small space heater with those infrared/ceramic elements and mount it flat (you may have to disable a tilt cutout switch) to stage the board over to preheat it before dipping, this can increase your workflow as you can have multiple boards preheating and then dip them in succession. If you're interested in "hacking" one together, checkout what people are doing for DIY vacuum forming, its a similar "heatbox" idea, just different implementation.

Temp is always critical. Just wondering why you are so reluctant to crank the temp. I’d try at least 340, maybe even 350

oh, and get an actual ir pre-heater for pcbs should help with consistent temp pre-dippping

I'm hoping that "this thing" is a machine for automating this. Because that would be so frickin awesome

I was thinking silicon studs for fans, to push into the holes on the pcb. Or some other silicone that fits the holes. then you could just push it down onto the 4 silicon things and dipp in solder.

One thing that I wonder, when looking at the design of the board, is why are there so many thru-hole components in the first place? You could have used SMD connectors in many places, and I'm still not sure why all the motor drivers are on little breakout PCBs instead of being integrated directly.

10:15 aka the " French fry machine"

If you like to remove the flux from the top, just a toothbrush and alcohol, then blow away the excess with heatgun.

I want to put my hand in the puddle of _forbidden gallium_

I would imagine that surface mount editions of all those connectors exist, and would therefore be less work than old tech danger puddles

Hello! I have no insights on the process, other than maybe ask adafruit some pointers? they do a lot of in house manufacturing and are pretty friendly, perhaps one of their engineers can tell you to look at reference PDF X that will help... I mostly came to say that you shouldn't worry about the videos schedule, as those kind of videos is insanely interesting, and comes only from doing what you do. I think many of us are really interested in this aspect of the manufacturing chain (i mean problem solving, engineering, etc), and if it takes less frequent/less regular videos, so be it! When i equip my fablab, i'll definitely search for funds for an Opulo!

hope the ideas i just ordered PCBs for are successful so i get a reason to build a lumen

I waaaaant to automate this. I want to build basically a hanging kinetic platform, the basic structure is a pillar mounted near the edge of the basin which has a rocker arm horizontally across the top, and further outboard this rocker arm is actuated by a servo, then inboard a linkage hangs down. 3 of these hold up a platform which receives this pallet or one like it. Push a button and the servos go through the routine of lowering the board near the solder to preheat, then doing that rolling dip maneuver (or whatever maneuver proves best). Afterwards it lifts the pallet back up so the operator can grab it. Advantage: probably almost none, would allow for more consistency, would be cool, definitely more complexity, somewhat of a distraction, will probably need some design tuning to deal with being next to this hot thing all the time. A real advantage would be seen if it could be built into an automated workflow where panels are palletized, dipped, and depalletized so the operator can focus on populating boards without switching tasks, but that's definitely downtown distractiontown

Stephen I LOVE the kitchen tongs!😂

If you don't wanna worry about flux an ultrasonic bath in branson ec cleaner will make it look brand new

commercial systems use a wave in the solder bath

You should get a fan for all the fumes.

While you are at electronica you can find a cheap wave soldering machine. Also in industry we use oil in molten solder.

im not suprised the paper didnt burn, im suprised the adhesive didnt stop working and fall off

Obvious one, but don't use plated through holes for mounting; just a hole through the fibreglass. Not only will that remove your solder problem, but in general you can't rely on a good electrical connection from the PTH to the chassis there over time unless you are very carefully controlling the surface chemistry to prevent oxidation. Also the act of tightening down the screw/bolt can delaminate the copper or introduce non-conducting hairline fractures.

Watches your vids a while ago "Cool the dude is making a pick and place machine" Now "Dude already got a company and is mass producing it...qhat the hell"

6:24 :D RU-vid recomended this video , Note :that is why SMT Owens has heterophile before flow soldering.

you need a solder pump and a slotted insert to form a solder wave.

Did you know that you can use pine resin as flux for soldering?

If you think this is that amazing, you should look into wave soldering. Also, use capton circles for your areas you don't want soldered instead of tape. The little circles are easier.

What if, for preheating, you had some sort of hotplate to place the boards on? I have a hotplate, The Charlatan, that just gets hot enough to seal cellophane and activate dry mounting tissue. I feel like that would be absolutely perfect for this, it would streamline production quite a bit more.

Next PnP machine to build... a PnP for through hole items!! LOL

That fume extractor is adorable...*plumes of smoke* lol. Please open a window you're doing good work for open source!

Use a double wave solder bath for through hole components

Perhaps air pockets are preventing the solder from reaching the solder points. Have you tried carving channels in your templates for air to escape when you dip it into the solder bath?

In other videos I have seen the tin is not stationary but flowing and the board just passes over the flowing tin.

Would a sponge in your flux tub help with applying the flux?

9:10 you can use a 3d printer or simular device it will be not fast but acceptable automatization, TIP create rotary hed for lifting different components.

I guess now that you have the danger puddle it wouldn't be worth it to get something else, but what you should have been using is a solder fountain.

Amazing work, I hope you get a good fume extractor for those fumes , its a leaded solder so enhaling those fumes is no bueno. Good luck man!

Just a thought here, what about taking one of your pick and place machines, changing the head to a soldering iron and adding a solder reel, and converting the machine to a solder machine that autofeeds the tin and visually checks each connection. Slower then the molten bath method but less Rework needed and if done right can use the same mounting system /trays for the pick and place

Please Don’t forget about preheat your PCB before dipping:)

Did you think about doing the mechanical holes not plated/npth? When you could avoid your just dip the whole board without the pallet. So instead of working with the pallet you avoid the problem completely. Also, if you get some pins not soldered I would be kinda skeptical if the solder properly flows through the plated holes or just creates a fillet at the bottom. As these mechanical connectors will be used by the end user there will be some stress at the pins and you obviously don't want them to fail.

I've heard of wave soldering, not dip. Also I like the diy Bluetooth ath-m50

Try Superior 99 Liquid Flux ... Probably be a good idea to pick up a stove hood for a fumic struction system

How about cutting a thin sponge the size of the plastic container for the flux, saturating the sponge with flux, and then you might not get flux on top of the board.

You might consider just using thinner PCBs for the pallet instead of all that work with the chamfering.

I’m going to be at Electronica!!🎉 I am going to make sure I come by and say Hi!

You guys would have seen it by now but have a look at core electronics selective soldering machine. There’s also lots of cheap used selective soldering and wave soldering machines in the USA even on eBay as they’re not super commonly used here anymore.

also wave soldering machines mist the pcb with flux, maybe you could mist it inside a tupperware so you don't inhale too much