Thanks. For my actual boards (this one is a practice board thing) I use a toothbrush and isopropanol alcohol to clean the flux off which should take care of the balls too, but I also inspect the boards with the microscope for said balls. Here is an example of a finished and cleaned board (showing the output filters of a USB DAC sound card): imgur.com/0COBwae

So the excess solder paste gets absorbed into the soldering on legs & pads. I noticed before the IC was put in place, looking at the pre-printed markings, a notch was in the end of the white outline. Does that correspond to the dot on the one end of the IC (for orientation)? Thanks

@@j.lietka9406 Yes, there's a dot and a notch to indicate the orientation, and should correspond with the IC. (some have a dot, some a notch, or both, to determine where's Pin 1).

@@hussssshie that's right! Thanks 🤓

@@j.lietka9406 As long as there is enough flux to remove the oxides, the solder will want to pool and flow only onto metal. So once it reaches molten temperatures it immediately shifts into as few "drops" as possible flowing onto the metal, pooling on the pad and wicking up the component leg. My other video on removing bridges shows this clearly.

It was the primary reason for the video. I watched Jullian Illet spend hours trying to lay paste on each pad individually, there is no need, as long as you don't use too much, as that causes the bridged pins as you seen.

The beauty of Flux!

What kind of paste?

the past used is a famose brand in the name of: mechanic easy used and use and enjoy it.

@@sarockpashotan thanks!! Good to know!!!

With what have you soldered before 🤔

​@@spacenodus7959solder wire

Dude.

The other side of the story though is that hitting a cold board with high temp air can cause unequal expansion and stress the PCB. You can split the operation into pre-warm and solder or just use slightly cooler air and work closer and closer as the general board area warms up and stops sucking the heat away.

What temperature would you reccomend as rule of thumb to start with?

In fact you should follow the heat curve, that heat curve takes like 6 minutes from preheat, heat spike and cooling. thats what a professional oven does.

@@harviecz check the specs of the solder paste and the chip

@@israelsalas4617 No, not really. Most ICs don't really care. If a curve has to be followed to prevent damage, it will be specifically stated in the datasheet. Also, even if the chip is not really sensitive but it's a large BGA package, you just cant blow it with 500°C continuously. But a good rule of thumb is to preheat the surrounding area to 130-150° for 20-30 seconds (at that temperature, the flux will be unaffected), ramping it up to around 450-470°. Solder takes heat more quickly than the chip will do. Being quick ensures it will not be damaged. Just don't do that from room temperature. The distance of the nozzle to the part also dramatically changes the heat you're putting into it. At 5cm at 400°, the IC will see around 230°. Not even close to the 400° coming out of the gun.

No. You want the chip to get hot. If you try and keep it cool it may suffer uneven expansion and crack the internal die. They are rated for 180+*C for up to a minute. Check the datasheets for heat profiles.

I think it would be trickier to do. When you do this at a larger scale, like a full board, you can buy a "solder mask stencil" with it that allows you to just paste over the mask and only the right areas get the paste. So it's much more economical that way.

Not an expert, however I believe it's not recommended. 18650s have pretty low temperature tolerances. Heating the end up hot enough to flow solder onto, even with an iron, let along hot air, would put the core of the cell well outside it's temperature limits. Doing so with a fully charged cell could have catastrophic results. To summarise. Not recommended, seek professional advice.

Make sure and warm the surrounding board up gently. Otherwise it will just suck the heat away. Solder paste is just balls of solder suspended in flux, but the flux is really important.

Thank you Paul! I finally got solder paste in the mail from Amazon so I am going to try this out very soon! I got some 247-LOWTEMP-15 paste that says Expiry 4/8/21 so it seems to be pretty fresh. It apparently has a MP of 137 Celsius. Maybe I'll try 130C to warm up the board and then crank it up to 250C and see what happens.

Left an older Weller 35 watt iron ON for 3 months (snowbird winter holiday). Was still on upon arriving home!

You can get them to work without bridges. Actually the bridge in this case was caused by just a little bit too much solder in that location to actually break into two blobs on two pins and stayed as one blob bridging the two pins. If you use a little less paste than I did, or even just apply it with a brush you won't get bridges. You can actually buy the stencil with your PCBs from the likes of PCBWay, it's like an extra $10. Apply the paste using a scraper or credit card and air solder it. You won't get bridges either.

Were you referring to the process they call "staking"? I wonder why that is, because where i work, we basically never use it. Only for re-routing wires

Reduce the air flow ....hold the part down by applying some pressure to it.

@@Gw0wvl I tried holding with tweezers. The solder paste did not melt fast enough

First you can align properly and keep solder dots on the 4 corners with pressing SMD chip towards the PCB

Idk but shouldn't be too much more of a challenge doing some SMD. As long as you are willing to pay for the proper equipment. Stereo microscope, tweezers that are high quality an hot air station.

solder paste (not flux)

Flux

No, that's thermal paste. This is solder suspended in flux.

Don't set the heat gun to 183, try 300 or 350*C Hell try 400!

Oh, you said you set the gun to 625? Surely that must be Fahrenheit?

Cheap 858D clone. MECHANIC XG-Z40 Liquid Solder Soldering Paste. Can't remember the temp, probably 300. Andonstar ADSM201 HDMI 1080 Digital Microscope

@@1over137 hey i bought mechanic xg z40 paste but its very very solid and very hard to get out of tube... definitely not liquid... how is yours? how do you get it out of the tube (i use a plunger but its still very hard) ? thanks in advance and thanks again :)

@@HalfLife2Beta First off, keep it in the fridge, but leave it out overnight before use. I always forgot so I would warm it for a few hours in water at 30*C. I used a wide needle, applied pressure, quite a bit, then waited. You only need a very slow "ooze". Be careful though it continues to flow for a few seconds after you release the pressure and it can occasionally start going run away and flowing much faster. The amounts you need are tiny, mostly it's just contact the pad and pull away is enough to get a single "drop" on the pad.

@@1over137 after putting the needle out, the solder paste is impossible to get it out (even with incredible pressure) but if I remove the needle the paste goes without effort. I think I need to buy a soldering dispensing gun...

@@HalfLife2Beta Bigger needle.

Flux 'wets' the solder, allowing surface tension to break the bridge. Sometimes it works with just 'add some flux and heat a bit', sometimes it requires a soldering iron tip (and flux in this case would make it much easier for the solder to move to the tip).

@@fhunter1test Yep. Flux once hot enough becomes a very nasty powerful anti-oxidant. It cleans the oxide layer off the solder which allows the solder to flow, retains it's surface tension like a "blob" or "drop" so you can pull it around. As long as everything is clean (well fluxed) it should always flow onto metal and will try and flow into larger and larger blobs, exacltly what you want. Dirty tips, dried up solder cores or no flux at all makes a mess as the solder sticks to everything, spreads out in spatters and just makes a mess.

Temp was 300 or 350*C. The air out of the gun probably halves every inch you get from the nozzle. You can point it at your hand from 5 inches away and not get burnt. So to do the warming profile, you have to start far away, covering the whole board and slowly, progressively move tighter and tighter into the areas to be soldered. Getting the tip closer and closer so you are trying to evenly warm things, getting progressively hotter and more focused until it all starts to flow. Then you have to keep it hot until it all flows properly. Ideally (not in this video), you want the whole chip, all legs, molten at the same time, so the chips will recenter itself on the pads due to the solder surface tension. At the same time you don't want to spent too long at it. Most ICs can hand 180-200*C for up to 5 minutes, higher temps for less time. What breaks ICs when air soldering is heating them up too fast, causes uneven expansion and can crack the dies.

Also worth noting. Prewarming, or starting slowly, also helps drive out water. If you suspect any of your components may have traces of water, the prewarming or alcohol washing helps drive it off before it becomes a problem. Trapped water under soldering heat can cause small steam explosions which can break components.

Solder flux

Yep, Flux is critical to this technique and is very often the defacto "get out of trouble" when soldering anything.

Cheap 858D clone. MECHANIC XG-Z40 Liquid Solder Soldering Paste. Can't remember the temp, probably 300. Andonstar ADSM201 HDMI 1080 Digital Microscope

ebay, amazon

about 330c

It is no-clean flux. However, all that means is the flux residue is not corrosive or conductive. It's still ugly and every bit of dirt sticks to it. A bath with Isopropanol alcohol and a toothbrush helps. I even use an electric toothbrush... carefully and delicately. Then rinse with lots of water and air dry quickly with a hair dryer or your hot airgun if you have to. Be warned... Isopropanol alcohol vapours, while evaporating, WILL, get you high. Not recommended, so do it in an open space.

Mechanic solder paste (lead based) off ebay + a bag of needles for the syringe also off ebay. Flux is in a comment below somewhere, off RS components.

Mechanic. AliExpress.

I think you will be fine. Just be aware that other components around the m.2 socket may also melt and reflow. For the socket it's self alignment will be 100% key. If you have just enough solder and you can get it to flow at the same time across all pins it should self align. Even slightly too much solder and it could bridge. You'll need a scope to see it. I would direct you towards some of Louis Rossmans' repair videos for a more qualified source on finer details of SMD rework.

@@1over137 yes, I was planning to use some kapton tape as shields and will check with a meter.

@@themadatheist1976 Checking the pins with a meter will require the pinout of the socket. For example many of the pins will be "ground", so with a meter they will appear shorted, but that's normal.

I think it was 350*C and 4.... about 40% airflow. Plenty, but not enough to knock stuff out of place.

Distance between ic and airflow gun ?

@@anfaautomation3838 Varies. Starts around 2 inches, comes in progressively closer to 5-10mm for the final flow. Air is set quite low, you can place you hand 15=20cm away from the nozel and not get burnt.

I think once the flux starts smoking and the solder starts flowing it is critical that you keep it flowing until it has ALL flowed, if you stop or move the nozzel away too far or too soon, it can reharden/set and you won't have flux to help fix it when you remelt it.

Contray to a lot of comments, if you set the temp high and hit the chip hard and fast you can crack the interior. You have to build it up slowly when doing this or you will cause damage. The air starts off quite far away blowing in the general area to warm the chip and the board first, before closing in to flow. The temp was 300 or 330 I can't remember. Most of the time was wasted with the experiment to see if I could get the bridge to flow out with just hot air. You can't. I would not recommend attmepting to do this and just use the iron to reflow the bridge.

I was learning how to use paste. Can't learn how to use paste without using paste!

@@manyau47 Maybe you know what is her name?

I assume it's a digital microscope. But u asked what is a camera rather than asking what camera he used.

The PCB may be "wicking" the heat away too fast. If I try and solder on the metal microscope base the same happens and the metal base wicks away the heat too fast. If it's just an awkward component or two I'd just fix em up with the iron. Other than that, make sure and preheat the board for a few minutes first. The whole circuit board should be too hot to touch before you start.

@@1over137 hi, this is very helpful, thank you! I didn't know I had to preheat the boardI just start cold. Unfortunately it's 5 tiny tiny parts in a really awkward location and I don't have the skills for doing it with iron. I'll try again today, I hope it works.

@@RootiferasRetroGameplay When designing a PCB there are things to pay note to. Copper transfers heat really well. So tracks do. When you have a large area of copper like a ground plane, the mass of copper can make it hard to flow as it wicks the heat away. Most PCB tools have a feature called "Thermal reliefs" which place a sparse area around the pad with 2 or 3 smaller tracks connecting it to the plain. This is to help soldering on ground plains. If you deliberately put "thermal vias" to transfer heat away from ICs in normal use, these will need special care when soldering as they have a high copper mass.

@@1over137 this is all new to me, I didn't know that. Thank you! I'm trying to repair an old VGA card, it has 6 broken smd resistors. my test solder pcb is significantly smaller than the vga card and it's just a "solder practice" pcb, I think it doesn't have any thermal relief or anything so the solder just melts. I'll give it another try today. Thanks for your help!

Andon star usb

It's better if you post videos + reference to your blog post as well. The plus: you can monetize both. I am searching for resoldering old motherboard with corroded pin right now tough...

incredible idea. go ahead boss

Are you blind? This was a really poor demonstration of using paste and hot air.

Yeah. I was experimenting. I think this was my second attempt at air soldering an IC. I wanted to see if I could pull the bridge out with just heat. Seems it not practical, the iron is much faster.

Solder when molten (and clean) likes to stick to other metals only. So it bunches up in blobs on the metal.

"Some other metals." Not all. Some are really hard to solder.

The [green] "varnish" or "lacquer" on the board is referred to as [a] "solder mask" (also "solder stop", "solder resist", etc.) ...it is a special polymer which is specifically designed to eschew solder (¿solderphobic?) ...When the solder gets hot enough to liquify, it "sticks to" [forms an alloy with] the pcb track and the chip leg - but CANNOT bond to the special "solder resistant" polymer ...Because we are now dealing with a liquid, the physics of "surface tension" kicks in, and the solder 'pools' to the points where it is (now) "stuck" to the metal parts :) ...That said, there is still very much a skill to getting it right.

Mechanic. AliExpress

@@1over137 thanks, how about the cleaning liquid? Does the solder paste need refrigeration?

@@douglasflores1462 flux is CW (Circuit Works) No Clean flux pen. CW8100

@@douglasflores1462 Yes on refridgeration. At room temp it's shelf life is about 1 month. In a fridge at 5*C it should keep for a year. You have to warm it up before you use it or it's really hard to work with. A cup of water with 30*C water for an hour should work.

No paste. Solder paste only works in well calibrated reflow machines. What he is showing will leave you with a huge mess. Just use thin solder and plenty of flux and you will be OK.

Off i go to re-watch the whole Matrix Trilogy thanks to this comment 😂

CircuitWorks CW8100 No clean flex pen

You'll like this :) kzfaq.info/get/bejne/laempNV3zKzNiZs.html

yes someone is

Amazon won't sell it in Europe, nor will any of the big electronics suppliers. It is leaded solder. You might find it on ebay though. MECHANIC Liquid Solder Soldering Paste www.ebay.co.uk/itm/162677306065

Also search for some applicator needles for it.

No sucker. The tools are, Hot Air Gun, Tweezers, and flux marker pen.