A Beginners Guide to Soldering Surface Mount Components - Page 1
Forum section: electronics / beginners

author: Michael Lloyd
author_rank: Contributor
timestamp: March 13, 2017, 02:28:05 am
content: I'm a beginner and this is my guideWhen I was in my 40's I decided that SMD's were the spawn of satan and they would never catch onNow approaching 59... that's a long way from 60 just so you know... I have decided to start using surface mount devices. It makes perfect sense really. Now that 15+ years have gone by, I can't see worth a damn and my hands shake more than they used to (but not much). I normally work on things with tubes in them but I have an OtherMill Pro and dabble in making my own boards every now and then. I use the mill to make a prototype and then order from Osh Park if I want commercial boards (like for friends or gifts). When it comes to ordering boards, size mattersThis isn't the first project but it's a good for illustrating my list of things that a beginner should know about soldering surface mount devices. It's a double sided board with a bunch of 2.2k ohm resistors on both sides. There's also a diode and cap for rf detection. Apparently they screwed up the board somehow and the surface mount cap location is not usable.In no certain order these are the things that I know about soldering SMD's.Opinions(1) if someone tells you that you don't need a microscope to solder SMD's, poke their eyes out with a sharp stick and take their microscope (not really but that's bullshit)(2) use the correct soldering iron and tip. A 1/4" chisel tip might work fine on that old 1948 Zenith AM radio but it's not going to cut it for SMD work(3) make no mistake, SMD's ARE the spawn of satan. Especially if they are smaller than 0805(4) it's best if you know at least one or two expletives.(5) Do Not Yell Expletives at the Board While Looking Thru The Microscope. Your components will flit off into whatever dimension those little bastards come from(6) Concerning item 5. Add Sneezing, Coughing, or in some cases, Breathing to the list of things that shouldn't be doneLaws of PhysicsLaw 1: If your project requires x components, buy at least two more than x. SMD's can occupy other dimensions, so if you drop one, it's gone, forever.Law 2: If you place a component on the board you will need to either turn it or flip it or bothLaw 3: If you drop a component and it stays in this dimension (lands on the bench) it will be upside down. Especially if it's a resistor or capacitor. They are top heavyLaw 4: When you solder a resistor or capacitor to a board, make sure you either solder them all such that the numbers are the opposite of the silkscreen or solder just one the wrong way around. This will drive some people batty and it can be a source of amusementLaw 5: Make up some bullshit like Law 4 to try to cover up the fact that you soldered 1/2 the resistors on your board opposite of the silkscreenLaw 6: If a kit manufacturer supplies 2 extra components you will, at a minimum, lose 2 componentsLaw 7: The first component that you pick up with tweezers will make a click sound and disappear never to be seen again. Proof they come from another dimensionLaw 8: Resting the barrel of the soldering iron on your finger to stabilize it will result in some level of chaos and pain. Don't do thatLaw 9: Once you get into a rhythm don't take a break. If you stop in the middle of a project you will come back with the coordination of a spastic ape and fling components off into the other dimension (where satan stores them), tombstone parts, and generally turn your nearly complete board into an ugly mess.Law 10: If tweezers were the size of a small rocket we could use them to launch spacecraft on intergalactic missions. They apparently contain some form of warp driveFeel free to add any helpful advice that you see fit. Laws can be added at will. They are like speed limits, nobody follows them.Endeavor to persevere

author: tautech
author_rank: Super Contributor
timestamp: March 13, 2017, 02:45:51 am
content: Lovely and spot on.Nothing worthy to add........yet.

author: JoeN
author_rank: Frequent Contributor
timestamp: March 13, 2017, 06:51:32 am
content: You forgot a big one.11. More flux.If you have enough flux, you can use that 1/4" chisel tip. For parts with lots of really fine leads like QFN-48's and more, it actually becomes the principal tip to use. Flux the legs and pads and you can just drag solder across the legs. To clear any bridges, clean the tip, flux a little more, and use the tip's solder affinity to just pull the extra solder away - no braid needed most of the time. Soldering discrete parts like what you have shown is actually pretty easy, a first step, show us some QFP, or at least SOIC/SOP packages now.I find my 3x desk lamp/magnifier is good most of the time. It affords a very nice field of vision.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: March 13, 2017, 07:46:59 am
content: Hah... wait until you advance to the Hot Air Station and Solder Paste level. You'll discover entire new ways to lose multiple components at once with too much airflow, to melt all kinds of stuff you haven't melted yet like the more distant parts of your vise, new levels of pain when you lose control of the air nozzle and it falls into your lap... sheer terror when the dog makes off with the solder paste dispenser, complaints from S/HWMBO about the jars of solder paste and flux in the refrigerator....

author: Avacee
author_rank: Unknown
timestamp: March 13, 2017, 08:44:32 am
content: Law 6 has a mathematical error. The number of components lost will be Delivered - Required + 1Law 11: The chance of a component disappearing off to another dimension is directly proportional to a) its cost b) replacement delivery time c) a multiplication of a * b

author: OutbackBob
author_rank: Contributor
timestamp: March 13, 2017, 10:46:01 am
content: As a newbee looking to get in to surface mount as well, I have been looking into USB microscopes... Are the el'cheapos suitable? Any recommendations?Don't quite have the budget for Dave's Targano

author: Michael Lloyd
author_rank: Contributor
timestamp: March 13, 2017, 12:30:59 pm
content: Quote from: JoeN on March 13, 2017, 06:51:32 amI've used the "more" flux method when I built a clock kit a few months ago. I used my magnifying hood and a small chisel tip for that. I tacked a corner and then "strip soldered" (that's what I called it. I think it has a different name? Drag soldering?) the other side and then came back and did the same on the tacked sideQuote from: alsetalokin4017 on March 13, 2017, 07:46:59 amI have one of those. I think it was made for cleaning circuit boardsQuote from: Avacee on March 13, 2017, 08:44:32 am100% correctQuote from: OutbackBob on March 13, 2017, 10:46:01 amI had a really cheap AmScope but the field of view was poor. I happened across a YouTube guy (Louis Rossman) that repairs Apple boards (none for me thanks) and decided to go with his not as cheap AmScope with light. So far I like it.

author: klunkerbus
author_rank: Unknown
timestamp: March 13, 2017, 01:11:19 pm
content: Quote from: Michael Lloyd on March 13, 2017, 02:28:05 amEnjoyed the post.The resistors are actually 2200 ohms based on the 222 markings. 22 on each side puts 44 in parallel, which gives you the 50 ohms desired for a dummy load.On the cap, yeah, the board is generally set up so that you can use either SMT parts or through-hole parts. The through hole pads for C1 are on the rectified voltage and ground, which makes sense. But the SMT pads for the capacitor are between RF IN and the rectified voltage, which is likely a layout error.

author: Michael Lloyd
author_rank: Contributor
timestamp: March 13, 2017, 01:25:43 pm
content: Quote from: klunkerbus on March 13, 2017, 01:11:19 pmYes... admittedly I prefer colored stripes and profane mnemonics to determine resistor values but you are correct.All in all, it's a nice little board and I needed the practice, which is why I selected the SMD kit to begin with.

author: jolshefsky
author_rank: Regular Contributor
timestamp: March 13, 2017, 01:35:56 pm
content: I bought a pair ofGalilean 2.5x Loupes from LW Scientificthat clip on to my glasses. I like to call them "super bifocals" since with a 380mm working distance, I can comfortably work on boards at a natural distance. They were fairly expensive, but I just can't afford anything cheaper, as the saying goes. (That is, I paid the price I did to have no eyestrain using them for the rest of my life which is far cheaper than suffering with junky optics.)

author: Michael Lloyd
author_rank: Contributor
timestamp: March 13, 2017, 01:47:06 pm
content: Quote from: jolshefsky on March 13, 2017, 01:35:56 pmExpensive... yes... but 380mm working distance! And the convenience of having them right there

author: JoeN
author_rank: Frequent Contributor
timestamp: March 13, 2017, 06:40:24 pm
content: Quote from: jolshefsky on March 13, 2017, 01:35:56 pmWhat are the main advantages of using this over say a quality desk lamp and magnifier of the same magnification? These look interesting and I have never considered them, but my desktop magnifier has not let me down so far.

author: Housedad
author_rank: Frequent Contributor
timestamp: March 13, 2017, 09:17:23 pm
content: Michael, I just ordered a Amscope SM-4T 7X -45X scope, a .5x barlow off ebay, and a 114 led ring light. It will arrive Friday. I'm the same age and have the same aging eyes problem at 58 years old as you. I just hope when it gets in that it is comfortable to work with. Any Issues with your eyes using your scope?THEN I will try to solder SMD parts! I bought a bunch of practice boards off of Ebay and will cross my fingers.

author: jolshefsky
author_rank: Regular Contributor
timestamp: March 13, 2017, 11:18:51 pm
content: Quote from: JoeN on March 13, 2017, 06:40:24 pmIf your desktop magnifier works, then by all means stick with it. I have a cheap-ish one with a glass lens about 4" = 100mm in diameter. I had a hard time positioning it at the right spot between my hands and my work as it's basically a swing-arm lamp. It is barely big enough for both my eyes to see through, so I'd be looking through the edges of the lens where the optical distortion was worst, and also I'd have to adjust it, my head, and my work often making it a two-handed job just to look, the third hand for soldering. With the loupes, I can either look through or around with a tilt of my head just like bifocals. They are stereo and perfectly focused at my work distance with a large focal range of about ±50mm and a wide 100mm field of view. I find all this leads to less head strain and less eye strain making it much more comfortable to do SMD work or any close, small work.

author: Michael Lloyd
author_rank: Contributor
timestamp: March 14, 2017, 12:06:15 am
content: Quote from: Housedad on March 13, 2017, 09:17:23 pmI don't have any problems with mine and I didn't have any problems with the smaller one that I had other than it didn't have a ring light and it was fixed magnification (which hasn't been an issue btw). Mine had one eyepiece that could be adjusted and one that couldn't. Like binoculars. So you focus with the non-adjustable eyepiece and then adjust the other eyepiece until they match.

author: Cupcakus
author_rank: Contributor
timestamp: March 14, 2017, 06:18:38 am
content: Great post! I also use a desktop magnifying lamp and it's fine for 0603 and up, I don't usually have any issues. I do have much younger eyes though, ask me again in a few years.Except SOD23 diodes, those things are the devil. Somewhere in the void under my bench there are dozens of those never to be found again.

author: Southerner
author_rank: Regular Contributor
timestamp: August 17, 2017, 06:20:12 am
content: I, too, am a beginner but have tried a lot of different methods.SMD soldering is a subject that I have read about with interestfor years. I have never feared doing anything with smt parts andneither should you. I am old but my eyes are not too bad yet. I do wearprogressive focals though.I do not fear doing the job.There are some things not really touched on in the discussion.I find that a handheld magnifying glass is helpful in checkingparts and traces but difficult to use for soldering. I have many many magnifiers.I have searched and bought many from Amazon but buyer beware. I look for10x and 20x but so far have never received a 20x or even a real 10xwhen I order one. They seem to actually be 10 diopter which I understand is 3Xand that matches what I see. I do have a 4x UltraOptix (brand) and a slightly smaller5X of that brand, both with LED lights. They are great for inspection or identifying parts. Also be aware that onemight say 5x/10x and you will find a small circle somewhere in the big magnifier that is 10x where the main lens is 5x or 3x.I don't usually find the 10x little circle to be very helpful to me. Others might disagree.I also have one of the LED bench magnifiers (3X) and they are good for inspection but again does not have themagnification I need for soldering serious smt parts.I also bought a set of Harbor Freight jewelers loop set.The 10X loope is about the only one I use out of there.20X is too much magnification (for me) and the5X is usually not enough.I have bought the Harbor Freight and ebay over the head magnifiers andsome work and others are a poor excuse of a tool so being able totry them before you buy is often helpful.It was suggested to me and others that a binocular microscope would be a great tool. I have several!I bought a Nikon SMZ-1 and have 2 of those. I bought a Nikon SMZ-675. Mine are 10x and work great but donot have the focal length like I would like as I want the lens well away from the work. I had given upon achieving that until someone else on one of the Amateur Radio forums suggested a specific AmScope. I can'tfind the model number but it is great! It allows the bottom of the lens to be 6" or more above the work. The oneproblem I have with all of my microscopes, whether wearing my glasses or notis being able to spread the lenses far enough apart to getone view so have to close one eye but it works.I originally tried a cheap usb microscope but it did not provide sufficient resolution and was quickly abandoned.On the PCB or QRP-L list someone suggested getting a "docking camera" which you see inclassrooms for projecting an image from the computer orfrom a paper on the bed onto an overhead projector. Those work but take up a lot ofroom and a good microscope would get used a lot more. I do have onebut used it once and moved on.I have an Ottlite (brand) desk magnifier as well as the Ottlite hobby stand(has a light, a work platform, and a magnifier on a floor mount or desk mount stand)often found in craft and fabric storesas many quilters use them. They work and are good but the microscope workedbetter for me. Your mileage will vary.You will see many methods for soldering smt parts. I am currently trying to get areflow oven builtto try. Is it worth it for a hobbyist to acquire or build one? Probably not.The electric skillet method would do the samething and both would require use of solder paste. To apply paste a templateis good but I have not found any cheap oneslike I would have expected to find for hobbyists. It is amazing to watchwhat happens when you hit the right temperature andthe solder paste flows. Parts will often auto position (to some degree)if they were place on pads but not quite straight.You will see a lot of Chinese rework stations that often consist of aregular soldering iron plus a hot air gun for soldering or unsoldering.They have become quite cheap and most work well for hobbyists.Just be sure to use the right size air nozzle and be sure not tohave the air volume/pressure set too high or parts to be soldered will be in orbit around theroom never to be found again.Tweezers have often been mentioned for placing parts to solder. I use a crossed type and havenever had a part go sailing across the room but I see a lot of others mention that the tweezer isnothing more than a catapult in disguise. They have worked well for me but not for everyone.A "doofus" or tool for holding smt parts in place while trying to solder them helps.There have been very simple ones that work well and are easy to make. I use a steelcookie sheet for a work surface for building my smtprojects. The low sides make it easier to work but still keep the parts somewhatcontained. I purchased a cheap machinists magnetic tool/dial holder and set it on the cookie sheet.The tool has setable articulating arms so I canposition the arm over the part. In the hole for the end arm that normally holds the machinistmicrometer I use a knitting needle that fits the hole and the clampallows me to put the needle on the part with a little pressure and hold it while soldering.Others use a wooden chop stick or evena toothpick. Blue tack has been suggested but I find that to be too big for most parts.I see suggestions to, for example, place a smt ic with several pins and then melt a blob ofsolder and drag that blob across the pins on each side of thedevice. I have never like that method. For one thing, it reminds me of the old throughhole part days where we were always chastized and told not tomelt the solder onto a joint but to heat the joint and let the joint melt the solder.Also once you have dragged the blob across all the legs you them have toget rid of that extra blob. It always stroke me as a good way to create solder bridgesand bridges are not always easy to remove from smt parts once you get them!One method suggests using a big solder tip that covers several pins of a part. Thismight be ok but I have always bought the 1/64" round tips for mysoldering iron and soldered each pin of even quad flat pack ic's...with the help of my microscope.As you can see, there are a lot of different methods for soldering surface mount parts. You will have to find themethod and tool(s) that works best for you.73WA7DUY

author: tggzzz
author_rank: Super Contributor
timestamp: August 17, 2017, 07:43:35 am
content: I'm 60, and until a couple of years ago I shared your concern about SMD; now I prefer them to PTH and find 0603/0.5mm pitch components are no problem.Best way of soldering many small components at once is to use solder paste and "skillet" method. Well, actually I modify it by using a saucepan with a couple of mm of sand in the bottom. The sand acts as a buffer, spreading heat, preventing hotspots, and slowing down the rise in temperature (measured by a point-and-shoot non-contact IR thermometer) so that the temperature profile can be controlled by turning the knob on the gas ring. I have access to a toaster reflow oven at the local hackspace, but have never bothered to use it.For methe best way of seeing the little darlings is to use a £20 head-mounted visor, e.g.https://www.maplin.co.uk/p/lightcraft-headband-magnifier-a87unThat allows me touse my normal glassesinstantly re-position the viewing angle for maximum effect - just move my headquickly have more or less magnification depending on what I'm looking athave a useful distance between magnifier and PCB/iron/tweezersuse them for peering into dodgy old scopes etc at very odd angles and on the floorYou might like to considernottaking components out of their strips and rehousing them in something neater: consider what happens when you drop one container, let alone several!

author: KL27x
author_rank: Super Contributor
timestamp: August 17, 2017, 12:48:44 pm
content: For populating a board like what you posted, try this:1. Dab liquid rosin flux over the all the pads.2. Use a vacuum pickup tool to pickup each resistor and drop it over the pads. The flux will make the components stick, so they won't disappear into the ether if you bump the board or sneeze. Continue until all resistors are placed.3. Put the board under the microscope.4. Use a soldering tip which can hold/control a large bead of solder. (Anything but a pointy conical, but 2-3mm CF/BCF is probably best.5. Lay some solderwire out over a flat surface.6. With tweezers, align and hold the component in place over the pads6.5 If you get the part stuck to the tweezers funny, stick the iron to the tweezers to heat up the flux, to help the component fall off so you can try again.7. Pickup some solder onto the tip of the iron, as needed.8. Dab one of the pads of the resistor until solder flows and forms a joint9. Before letting go of the component, use the tweezers on the component you just tacked to center the next component in the FOV.10. Repeat 6-9 until all the resistors are tacked.11. Set down the tweezers, flip the board, and zip up the other end of each resistor.If you have the right kind of tip, you can do a lot of joints without reloading. Under the microscope, this has a major advantage of being able to stay "in" the microscope for several joints without having to look away to get more solder. I reckon 3mm CF is as good as it gets, if you have the space to maneuver it. The combination of pad size and amount of tip loading/angle/maneuvering will control the amount of solder that is deposited on the board. As for loading the tip, the 2.5-3mm CF tips are pretty forgiving. But to fine tune the bead is a bit of an art. If I get too much, I just flick the bead off onto a flat surface which is coated in old flux residue (this happens naturally as you use it as your solderwire pickup board, which I call this my "rosin board"). Because the board is coated in flux, the bead of solder breaks up into little balls. Then you can pick up a lesser amount than you had before. (If you splatter a bead onto a non-fluxed surface, it will turn into a pancake).If you manage to touch a non-fluxed part of the PCB while soldering, you might lose part of your solder bead. Pick it up with the tweezers and deposit it back onto the iron tip. If you try to pick it up with the iron, you will just leave another string of solder. The flux is what makes this work.

author: tooki
author_rank: Super Contributor
timestamp: August 17, 2017, 01:05:19 pm
content: Quote from: Southerner on August 17, 2017, 06:20:12 amThe reason -- and the only reason, really -- for not carrying solder to a joint on the iron is flux, or rather the lack thereof. (You don't want the flux to burn off before it has a chance to act on the work, and when flux-core solder is applied to the iron tip, the flux burns off practically instantly.)In drag soldering, applying flux is mandatory, and the reduction in surface tension thanks to the flux is what stops solder bridges from forming. Additionally, remember that* moltensolder flowstowardsheat, so the excess solderwantsto stick to the tip, not the work. (No idea where you got the idea that removing solder bridges from SMT parts is hard; it's super easy. Flux, flux, flux!)*Edit: insert here: "absent larger forces". Hyperlink also added.

author: alanb
author_rank: Frequent Contributor
timestamp: August 17, 2017, 01:34:25 pm
content: I'm also relatively new to using surface mount. My most useful tool for soldering is a cocktail stick to hold the component onto the board whilst heating with the soldering iron.

author: KL27x
author_rank: Super Contributor
timestamp: August 17, 2017, 01:58:44 pm
content: QuoteAs far as this part goes, this is what for you have the rosin flux and vacuum pickup tool. With a vacuum pickup tool, you can't fling the part anywhere. And once it's on the fluxed pad, there's only one way to lose it. 99% chance you will find it by turning over your soldering hand to look at the part of your hand that touches the bench.Even if I'm placing $0.0003 resistors, I am careful to not place extra parts on the board. For example, if I have 8 resistors, and on the last one, my pickup tool gets two, I will not just drop them both on the board. I will take the time to set them down and pick up just the one. Because this is faster than trying to get rid of the extra part once it touches flux. You have to stop and wipe the part off your tweezers (on a paper towel or something). You can't lose the damn thing if you tried.

author: tautech
author_rank: Super Contributor
timestamp: August 17, 2017, 05:41:30 pm
content: Quote from: KL27x on August 17, 2017, 12:48:44 pmSimple and practical.QuoteIf you don't........then you haven't laid out the PCB with thought of how you might populate it.This can make a PCB next to impossible to populate and solder by hand and then reflow becomes the only option.It can't be stressed enough for a layout newbie.........do the layout with thoughts of hand population AND rework especially when prototyping.It's much different to TH layout, that is you can't flip the PCB to get to solder joints.

author: jmelson
author_rank: Super Contributor
timestamp: August 17, 2017, 08:19:09 pm
content: Well, I've been doing surface mount assembly for 20+ years. I can do 0805 parts just fine without vision aids, but for long sessions I use a magnifying hood to prevent something that happens to my vision after long sessions of close-up viewing. For anything smaller than 0805, and for ICs, transistors, etc. there's NOTHING like doing it under a stereo zoom microscope. Some models don't have enough working distance. Mine has about 6" working distance, which allows plenty of room for hands and soldering irons to get under it.My system is to put a dab of solder onto one pin of the passives, and a corner pin of the ICs. Hold the part with bent-nose tweezers and touch the iron to the pad with the solder. Once it has solidified, double check the alignment, then solder the remaining pads. I add two pieces of tiny heat shrink to the tweezers where my finger tips hold it, to make it less slippery.I've done this in production for about 10 years before getting a P&P machine. I still do a lot of this for prototype and rework. For fine-pitch stuff, tiny solder (.010" or .015" diameter) is a big help.For high density chips, there is usually enough solder on the HASL PC board to make a joint. I apply GC liquid flux with a wire along the line of leads, and then use a tiny soldering tip to relow them. If the joint doesn't look good, I add a tiny dab of solder to it. I do the above scheme, but with a dab of solder on two corner pins first. If alignment is not good, I can"walk" the chip into alignment before fluxing and soldering the rest.Jon

author: KL27x
author_rank: Super Contributor
timestamp: August 17, 2017, 09:06:02 pm
content: QuoteThis isn't technically true. Once molten, solder acts by a few simple laws of physics. It will "flow towards heat" in the sense that surfaces which are wettable and hot enough to keep the solder molten will suck up some solder. But it doesn't in ay way follow a temp gradient. For instance, if you use solder wick, the solder will wick away from the tip, no problem.When you are soldering a joint on a soldermasked board, all wettable surface of the board and iron are quickly covered. Once that is finished, the remaining factors which govern where the solder ends up (as long as flux is sufficient and doesn't run out) are mostly down to surface tension and gravity. This is why tip selection is such a big thing with SMD. If you use a tip that holds a large bead, you can just imagine it as a large pcb pad. Between the small pcb pad and the large pcb pad, the large one will end up with more of the solder. Perhaps enough so that it can share solder to a lot of smaller pads without a noticeable change.Yes, you can solder just about anything with a fine, pointy conical tip. But this is the last tip I use for soldering anything. In the case of a pointed conical tip, the bead will natural suck up, away from the tip due to larger surface area at the base of the cone. If you consider the total surface area of bead + wettable iron surface, the surface area is smaller when the bead is higher up on the tip. This is fine when you are adding solderwire with your other hand, but in a lot of SMD soldering you don't have that luxury. And even when feeding solderwire, you will notice that periodically you may have to wipe or fling excess solder off the tip, because the bead can grow out of control. It only gets bigger and bigger until it manages to either touch something it shouldn't, or it gets big enough that gravity trumps surface tension and it drops down to the tip and falls off in a huge blob. If you use a tip that can share its solder reservoir back to the board, you have a huge advantage. Hoof/chisel/knife/CF/spoon tips have a better ability to both give and take. The tinned-face only tips are especially efficient. The closer you can keep the solder to the tip/board, the better. Gravity and surface tension are working together, rather than in polar opposition in a binary struggle that ends up "bad," one way or the other. You don't really care to suck solder far up the tip, you just care what amount gets left on the pad.A lot of us grew up with "don't use the end of the tip, use the side." This is thru hole mentality. With SMD, only a handful of tips can be used like this (BR bent conical, perhaps). With SMD soldering, you will be using just the tip (insert joke). This one reason why IMO, knife tip is mo betta than chisel tips for SMD. (In addition to the angle, one of the main differences between a knife and a chisel is that a knife tip has chrome plating covering the sides, leaving only the tip as wettable. Kinda like the difference between a CF and a C.) Yes, knife tips are huge. In fact, between the two styles of iron I have, the knife tips average 1/4". This is not a problem for most SMD work, because the components are so flat. Slightly angling the tip will keep it flat enough to work and yet clear surrounding parts in a lot of your SMD applications (such as the board that is pictured).

author: KL27x
author_rank: Super Contributor
timestamp: August 17, 2017, 11:05:28 pm
content: QuoteI'm a scientific type. I like to use exact language. I don't care how conventional it may be for someone famous to inaccurately describe something.In the case of the protoboard, you're seeing wicking effect. Because the board has no soldermask. Yes, you can move the tip around to avoid reaching reflow temp on areas you don't want to be wetted with solder. You are also moving a huge portion of the surface area (the tip of the iron) in this equation. On a soldermasked board, the entire wettable area of pad will quickly be wetted, and solder has nowhere else to go in order to try to minimize its surface area. Temp gradient has nothing further to say on the matter.Besides. Have you never seen Dave solder?

author: KL27x
author_rank: Super Contributor
timestamp: August 18, 2017, 12:56:59 am
content: No, I didn't.The capillary action is over once the surface is wetted. What you're describing is only affecting large areas/plane of copper, or solid metals like in welding/brazing/soldering jewelry. Yes, if there is part of the metal that is not hot enough to liquefy the brazing/soldering material, it will not be able to have any capillary action. Because it's not a liquid.When you solder a board like OP has posted, the entire pad will be above the melting temp of solder. The entire solder bead will be fluid. And the entire wettable surface will be covered. There are no capillaries left to have capillary action. What determines the amount that sticks with the iron vs what stays on the pad is primarily left to surface tension and gravity. It doesn't matter if the board is on a preheater and set at 350C. Unless you are using tiny tip on large exposed pad/plane, you're not concerned with Italian-dude-phenomenon.*ok, I was curious and looked. I think you're making a strange connection to even bring it into the thread. Different fluids have different surface tension. They have example of alcohol and water. So what that has to do with solder? In soldering you have solder and flux, but the flux doesn't mix with the solder. It is not soluble in solder. It just drips off the solder and pools around the edges of the joint. There's no reason for the hotter part of the solder bead to have higher surface tension than the cooler part, as long as the entire bead is molten. Please connect just one dot for me.

author: KL27x
author_rank: Super Contributor
timestamp: August 18, 2017, 01:26:38 am
content: QuoteMaybe you're starting with a false assumption, here. I have never heard anyone use this Margoni effect in the way you are trying to make a square peg fit a round hole.QuoteIt's drawn towards the surface area of the iron. Once that filet between pin and iron wicks in, the iron becomes part of the surface area of the bead. The bead naturally wants to make the smallest surface area possible, which now includes all hot enough parts of the pad/pin and soldering iron tip. If you take two soldering iron, one set for 300C and one set for 400C with identical tip shape, and you put one on each side of the pin, what do you think will happen? Do you think the COM of the bead will be pulled towards the hotter iron?Glass of water/alcohol sitting unmolested is different from solder for other reason, too. Even if flux or a second fluid with a significant evaporation rate was soluble in the solder, the solder bead isn't sitting in a static environment. There is a very hot spot on one end, and heat sinks on the other end. And there are convention currents in the bead. It is going to get mixed up.

author: mrpackethead
author_rank: Super Contributor
timestamp: August 18, 2017, 01:30:22 am
content: Like anything SMT Hand soldering is a set of skills that is learned, but perfected by practice.. there was a time i woudl not have ever dreamed of hand soldering 0402 parts, or 0.4mm pitched IC's.. thats routine and normal.. When i first started, a 1.27mm SOIC seemed 'impossible'. I'm now doing 0201 parts..Theres a technique and process for everthing.. the big thing is *never* give up!

author: KL27x
author_rank: Super Contributor
timestamp: August 18, 2017, 02:02:16 am
content: QuoteSo this is a fact in your mind? And you have researched it to your satisfaction? I find this statement curious.QuoteTry this. Take the lead and fully coat it with solder, so it's all wetted. Fix it in a vice so it stays perfectly horizontal. Put a solder blob anywhere you want on it, fully melting the solder and lead above melting temp. Let it cool. Now use IR heat on one end or the other to make it move.

author: KL27x
author_rank: Super Contributor
timestamp: August 18, 2017, 02:05:20 am
content: QuoteI'm not hiding anywhere. I think you prefer it if I did. I am not arrogant. When someone says something that is illogical, I sometimes point it out.You hide behind fancy-pants-phenomenon, apparently without enough understanding to realize it does not support your argument.

author: KL27x
author_rank: Super Contributor
timestamp: August 18, 2017, 02:39:32 am
content: Quote from: KL27x on Today at 12:02:16 PMQuoteQuote from: KL27x on Today at 12:02:16 PMQuoteAgain, I ask you to connect some dots, here.QuoteThis is a thought experiment which is meant to be fairly obvious the expected outcome.QuoteAnd for real world experiment, I already gave you one. You actually believe the hotter iron will pull a solder bead towards it? (COM, btw, is me using acronym for center of mass). You would actually bother doing this if you had two identical irons? Again, I think the outcome will be pretty obvious.QuoteDismissing Margoni effect and not understanding how it is applicable, here, are two different things. I claim the latter. I claim ignorance of your full argument. It does not make sense to me. You make too many assumptions on my understanding of what you know (or what you think you know).Please, don't take it personally. I could care less.

author: KL27x
author_rank: Super Contributor
timestamp: August 18, 2017, 03:12:51 am
content: QuoteWot?QuoteI understand how people would think what you do. Probably because people have been saying things like this since the beginning of time. I thought the same thing 10 years ago. But it doesn't hold up to deeper reasoning.Here's my explanation (excerpted from my reply #24 in this thread, in case you want to read the whole thing):QuoteIn case you are not getting it, this essentially means surface tension is beating gravity. I will be happy to dissect it and connect the dots in case you are missing a logical leap, here or there.

author: KL27x
author_rank: Super Contributor
timestamp: August 18, 2017, 03:41:55 am
content: Here is a 1 minute way to see this for yourself. I just did this.Take 2 wooden Q tips. Sharpen one to a nicely tapered point.Take the pointy stick and coat it with mineral oil, then put a little drop on and point it straight down. Watch the bead form at the tip. Now, because the surface tension to weight ratio of mineral oil is lower than for molten solder, it WILL actually make it to the tip. But tilt the tip 45 degrees, and watch what happens.Do the same with unaltered Q-tip.

author: nugglix
author_rank: Regular Contributor
timestamp: August 18, 2017, 04:40:33 am
content: Thanks for derailing this way to useful thread.

author: ez24
author_rank: Super Contributor
timestamp: August 18, 2017, 04:59:17 am
content: .

author: KL27x
author_rank: Super Contributor
timestamp: August 18, 2017, 08:54:23 am
content: QuoteThis is so weird, because I find it irritating when someone directly contradicts me and cites vague stuff that is supposed to explain things, but it doesn't. And I don't know why it is arrogant to question that? Socially erudite, perhaps. Arrogant? You just said you're not a physicist or an expert; you said you did a quick google search, essentially. So why are you offended if I question your reasoning?QuoteThis part is not clear to me. I don't know why you think actual scientists/physicists (or soldering experts) are using Maragoni effect to explain that solder is drawn towards heat. You keep stating "facts," but all you did was link a Wikipedia article on Maragoni effect???QuoteIf it explains why a liquid bead on an inverted cone will defy gravity and behave just like a soldering iron, all while in absence of a temperature gradient, why do you need to invoke Maragoni effect (which you admit you don't even understand how it furthers your cause) to explain what needs no further explanation? Worse yet, how do you credit the temp gradient and/or Maragoni effect for producing a result that you just stated is going to happen in absence of temp gradient, anyway? If you think the temp gradient between the base of the tip and the point is doing this, you could touch the very tip of the iron onto an ice cube to see if the bead climbs higher. But this is dumb; we know it won't.*edited, (sorry)QuoteI'm not trying to belittle you. I'm trying to understand what you see or experience or understand (or think you understand; and again, this is not belittling you.. you admit you aren't a physicist and don't seem to have thought things all the way thru, perhaps?) that makes you come to the conclusion you hold so strongly with so little supporting evidence.I hope this is not overly offensive. People tend to get irritated and defensive when you question their beliefs. But this is soldering we're talking about. Not politics, race, religion. This is pretty close to science.

author: KL27x
author_rank: Super Contributor
timestamp: August 18, 2017, 10:09:42 am
content: As I have stated, I have once upon a time held similar vague belief as you. But at some point I gave it some thought. And I came to a more comprehensive understanding with fewer inconsistencies.So when someone like you comes along, I have to wonder. Is this me ten years ago? Or am I still missing important pieces of the puzzle? If I find my understanding is in error, I will be glad to learn something. Hence, I question.

author: sasa
author_rank: Regular Contributor
timestamp: August 18, 2017, 11:56:51 am
content: Quote from: alanb on August 17, 2017, 01:34:25 pmLiving true!I use similar to hold 0805 parts in order to prevent turn over vertically when touch with chisel tip, then drag soldering iron to join and solder to bubble at dedicated end, then it is trivial to solder opposite side...My favorite way to solder TQFP100 is to use chisel tip as well, scotch tape to fix chip, quite a bit of liquid flux, then make small blob on top of tip and in one press solder 4 or 5 pins at once. No shorts, no desoldering wick, no overheating...Thanks to John Gammell, this was (and still is) my favorite video for "Professional SMD soldering":

author: KL27x
author_rank: Super Contributor
timestamp: August 18, 2017, 08:50:23 pm
content: Re John Gammel vid, yes this vid changed everything for me, too.After seeing this vid, I noticed he uses C3 orCF4CF3 more than any other tip in his drag soldering. He also states in this vid:"T15-CF3 an amazing multipin drag soldering tip." So when he says this, and he doesn't say this about any other tip, I of course listen and buy it. Then buy all the other CF tips. And they change everything.*edited for typo.

author: mrpackethead
author_rank: Super Contributor
timestamp: August 19, 2017, 08:05:39 am
content: The right tips are everything. I'm about to put a second iron on my desk so i can have one of each ready to go.

author: Old Don
author_rank: Regular Contributor
timestamp: October 03, 2017, 11:08:47 am
content: After soldering multiple SMD diodes to a board you discover that all will be reversed from the desired direction.

author: xani
author_rank: Frequent Contributor
timestamp: October 03, 2017, 03:53:29 pm
content: Quote from: Old Don on October 03, 2017, 11:08:47 amAnd after checking one with smd probe tweezers just to be sure you will discover that leads were backwardBut hey, at least SMD components dont hurt as much compared to DIPs if you stomp barefooted on them

author: tautech
author_rank: Super Contributor
timestamp: October 03, 2017, 07:21:07 pm
content: Quote from: Old Don on October 03, 2017, 11:08:47 amALWAYS have an orientation maker on the PCB for all polarised parts.In the overlayoras copper...K, +, dot (pin1) etc. as needed.

author: KL27x
author_rank: Super Contributor
timestamp: October 03, 2017, 10:01:27 pm
content: I discovered SOT23 dual diodes. They are about as cheap as they come, even if you only need one of the pair. You will never solder them on backwards. You have a new problem to tackle, though. Whenever you drop a SOT, it lands upside down.but if you use SOT23 transistors, you already have this problem.

author: Old Don
author_rank: Regular Contributor
timestamp: October 04, 2017, 01:02:49 am
content: Quote from: tautech on October 03, 2017, 07:21:07 pmDo you really look at those things?

author: xani
author_rank: Frequent Contributor
timestamp: October 04, 2017, 12:58:48 pm
content: Solder one leg then beep it with multimeter.Solder another and do it again just to avoid any quantum SMD tunnelling (also called "I swear I've already checked that one")

author: Southerner
author_rank: Regular Contributor
timestamp: March 10, 2020, 05:56:15 am
content: Quote from: sasa on August 18, 2017, 11:56:51 amThe video says to use the T15-CF3 tiphttps://www.hakkousa.com/products/soldering-iron-tips/t15-series/t15-cf3.htmlfor drag soldering but the list of irons it fits is pretty small:Hakko FM-206 3-Port Soldering Station (FM2027 Handpiece)Hakko FM-204 Soldering StationHakko FM-203 Soldering StationHakko FX-951 Soldering StationHakko FM-202 Soldering SystemHakko FP-102 Soldering StationHakko FP-101 Soldering StationI was hoping it would fit my Chinese 936 clone and the Chinese Aoyou 701A+ rework clone but am not willing to spend $37 usd in the hopes it might fit. Has anyone used that tip on any of the Chinese clones?Thank you.

author: HobGoblyn
author_rank: Unknown
timestamp: March 10, 2020, 08:43:34 pm
content: Hehe I take it the person KL27X is debating with, has had their posts removedvery weird trying to follow thread, but is three years old.OP has it perfect. I replaced a camera in friends iphone in December, tiny screw in my tweezers, next second it pings about a foot off the table, onto laminate flooring, never to be found.First smd repair a couple of weeks ago, 4 port SATA pci xpress card in my PC, port 3 wouldn't work. Looked fine under naked eye, under microscope a capacitor was clearly misusing. I replaced it with an 0805 which was about twice the physical size, took me about 30 mins to solder it in place, had it half over the pads and dragged solder to each side.Worked perfectly, but trying to place under a microscope, then get iron in place etc, takes some getting used to.

author: Southerner
author_rank: Regular Contributor
timestamp: November 27, 2022, 09:18:36 am
content: Quote from: tooki on August 17, 2017, 01:05:19 pmI got it from personal experience. Your mileage may vary.

author: tooki
author_rank: Super Contributor
timestamp: November 27, 2022, 06:28:20 pm
content: What’s the point in replying 5 years later?!?