So surface mount it is

[paulca]

Found my first need for surface mount stuff.

I am building a binary clock and was planning on using 3x74HC595s to control the 16 or 17 LEDs (depending on whether I want 12 hour or 24 hour clock).

Then while watching the Back to the future Time circuits video from Dave I spotted the TLC59282.  A serial-to-parallel constant-current 16 channel LED driver.  It cuts my component count by about 18 parts.  No need for the 16 resistors or any of the 595s.  I can drive a 12 hour binary clock straight off it.

Downside is... it's only available in SMD.

So I bought 2 chips, expecting to kill at least one and 5 adapter boards.

Deep breath, I wonder how this goes on my first attempt to solder SMD.  Although I did order two of those SMD practice boards, so maybe I should start there.

[daqq]

Deep breath, I wonder how this goes on my first attempt to solder SMD.

Good luck!

But don't be afraid of it, it's pretty simple after some practice. Soldering SMDs is unavoidable these days, you might as well start now.

[max_torque]

i've always found soldering SMD to be easier and faster!

The only downside is that you can't just stick the parts into a solderless breadboard, but buy some of those "DIP adapter" boards (small pcbs with 0.1" headers down each side, and a footprint for a SOIC or whatever in the middle) and even that becomes easy 

[paulca]

Deep breath, I wonder how this goes on my first attempt to solder SMD.

Good luck!

But don't be afraid of it, it's pretty simple after some practice. Soldering SMDs is unavoidable these days, you might as well start now.

So tack and drag.  The tacking I get, I'm less convinced the dragging is as easy as people like Dave make it look. 

Also without a microscope it will be tricky to verify/inspect the joints.

[Photon939]

Make sure you use lots of external flux, it helps a ton on preventing solder bridges when you're hand soldering SMD

[phil from seattle]

SMD is pretty much unavoidable these days. The good news is it's not that hard to hand solder a lot of SMDs.  Avoid small pitch stuff but 1206s, 805s, SOICs, TSSOPs and so on are quite easy by hand if you have a reasonably good, fine tipped soldering iron. I think they are a lot easier and faster than through hole components. You might want to get some sort of magnifying visor or similar, depending on how good your eyesight is. A stereo microscope is great but not absolutely necessary.

If you want to take it to the next level, learn about reflow. It's pretty amazing to watch your components line up by themselves when they hit the right temperature.

[tooki]

Deep breath, I wonder how this goes on my first attempt to solder SMD.

Good luck!

But don't be afraid of it, it's pretty simple after some practice. Soldering SMDs is unavoidable these days, you might as well start now.

So tack and drag.  The tacking I get, I'm less convinced the dragging is as easy as people like Dave make it look. 

Also without a microscope it will be tricky to verify/inspect the joints.

With decent flux and the right tip, drag soldering really does work that easily. It’s incredibly satisfying!!

[paulca]

I actually bought a flux pen recently, not used it much in anger yet.

I seen Dave was using only 260*C on the iron, is that right?  Sounds a bit low.

[JacquesBBB]

Look to the video of these guy.
The are the best I  could find on the web.



One could not say enough that the flux is essential.

Another very nice ingredient when you go to very small pitch ( 0.5 mm) is the binocular. But this is more expensive than the flux.

[tautech]

Deep breath, I wonder how this goes on my first attempt to solder SMD.

Good luck!

But don't be afraid of it, it's pretty simple after some practice. Soldering SMDs is unavoidable these days, you might as well start now.

So tack and drag.  The tacking I get, I'm less convinced the dragging is as easy as people like Dave make it look. 

Also without a microscope it will be tricky to verify/inspect the joints.

Any of the magnifying headsets is all you need. I'm in my late 50's and I wear them all the time for any soldering.

To confirm others recommendations: flux, flux, flux !
I too have only recently got a flux pen and it sure helps and saves time not having to go over joints again. 

[paulca]

So I use a manicure/nail light for soldering, but it's only 4x.

If I set my phone on the lens, it's fairly stable and I can get to this with a little digital zoom.


In fairness without the phone my eye sees things like that, just the way the lenses interact the phone doesn't get the full effect of the nail light lens.  If I moved the phone away from the lens it might, but then I'd have to hold it.

[Electroplated]

Not related to your project as such but.......

I remember years ago having to face soldering SMD for the first time, it filled me with dread thinking about damaging parts and pcb's so what I did was dig out a few SMD boards from my junk pile, removed a few assorted chips and practiced re-soldering them back.

Plenty of flux and solder wick at hand and just practice, this way your not wasting valuable parts while you gain experience.

--

[paulca]

I do have an old computer motherboard.  It's never going to work again because it wouldn't give me my heatsink I wanted so I asked the pliers to provide persuasion.   

[Electroplated]

I do have an old computer motherboard.  It's never going to work again because it wouldn't give me my heatsink I wanted so I asked the pliers to provide persuasion.   

A motherboard will do, so long as your aware that using a heatgun to remove chips for 'training' often melts anything plastic in the area, fumes can be bad enough but hot plastic on the skin is even worse !

--

[janoc]

I do have an old computer motherboard.  It's never going to work again because it wouldn't give me my heatsink I wanted so I asked the pliers to provide persuasion.   

A motherboard will do, so long as your aware that using a heatgun to remove chips for 'training' often melts anything plastic in the area, fumes can be bad enough but hot plastic on the skin is even worse !

--

Uff, beware - the plastic is the least of your problems!

The components on these are often glued down and the fumes from the glue when heated up can be horrible. I had one laptop board which was producing something comparable to hydrochloric acid fumes when desoldering parts - extremely unpleasant stuff, I was wheezing for a good while afterwards. You do want to have some sort of ventilation/fume extractor when doing this. Normal flux fumes are Chanel No 5 compared to it.

And avoid heating any electrolytic caps - they love to go KABOOM when cooked with the heat gun.

[phil from seattle]

I think it took 2 or 3 chips to get a decent feel for soldering SMDs.  But even my first was successful so don't be afraid. Maybe do a SOIC breakout board first.

[janoc]

I think it took 2 or 3 chips to get a decent feel for soldering SMDs.  But even my first was successful so don't be afraid. Maybe do a SOIC breakout board first.

Yeah, or one of those toy SMD soldering kits - I think Velleman sells some. You will soon discover that if it has "legs" or accessible pins you will be able to solder it no problem, even very small pin pitches.

Now QFNs, CSPs and BGAs are a different story. QFNs are still mostly doable with a bit of care by hot air, the last two are really hard to do reliably without solder paste and some way of doing reflow.

[phil from seattle]

Yeah. LGAs as well.  I use a toaster oven and monitor the temperature. Works pretty well. QFNs, LGAs.  I've heard of people doing BGAs in a toaster oven.  I've never gotten reliable results from hot air.

[schmitt trigger]

Fortunately, Youtube literally has dozens and dozens of SMD tutorials.
Spend a lazy afternoon watching some of them, and you will avoid many rookie mistakes.

[Simon]

I could never get small SMD stuff done with an iron but SOIC is ok, stencils make life a breeze and actual paste is a good first step, if your board has a solder mask and you don't overdo the solder it will look after itself under hot air/infrared oven. Stencils from chinese PCB makers are very cheap so if your having boards made then just tick the box for unframed stencils.

[paulca]

Well, I did get one of the cheapo kits today.

Brace yourself, it's ugly.

I can see it's doable.  The chips I have had delivered are SSOP-24 and a little more forbidding looking.

Also, since you mention QFN and VQFN, when I am looking for DC/DC converters that supply both a boosted +12V and -12V for my audio project they all seem so be absolutely tiny little MSOP or VQFN chips   I suppose MSOP is probably achievable?  What do you think?

Oh... I do have a bottle of Isopropanol in the post and a small brush to clean things up.

Question... how do you stop the little "nipples" of solder plucking up when you remove the iron?

... and yes, the kits comes with a SOP-16 chip with 16 legs and... a SOP-16 area with 14 pads.  WTF?

[Simon]

If it's you first hand soldering it's good, like I say nothing more gleeful than watching components right themselves! under hot air or in the oven.

[paulca]

Never trust the flux in solder wire. Always add more. No need to go to the other extreme like Louis Rossmann does, but you do need to add some flux.

I was using a flux pen.  I found it made things easier.  I also found it was better to apply a little after the chip is in place so the pins are coated too.  The side of the chip I did this went easier than the side I didn't.  The first with only flux on the pads the pins all joined together, luckily they unjoined with a few delicate pokes of the iron.

I think I will keep hunting for a DC/DC dual supply creator in a more sensible package.  I could end up with a boost and a second inverting boost though to avoid micro sized packages.

VQFN is the package the 16u2 on the Arduino UNO board isn't it?  Not a hope in hell of soldering one of them with an iron!

[phil from seattle]

Paul, you are doing fine. Just because they aren't perfectly aligned doesn't mean they won't work. And MELFs are a royal PITA anyway.  Anything with a lead sticking out is hand solderable.

MSOP is harder to solder with small pad design. With larger pads, it can be easier, but I only do absolutely small designs, so I can't say much about it.
QFN should be easy if you have some solder paste and a hot air gun or hot plate (or if your mom doesn't care if you cook your board with her dinner in the same oven).

Or go to a thrift shop and buy a second hand toaster oven. I see them all the time for $10-20 USD.  I highly recommend reflow for QFNs.

[paulca]

Do you think the guy who made those diodes round has a little giggle to himself every night?

EDIT:  I googled MELF.  Mostly End up Lying on the Floor

[janoc]

Question... how do you stop the little "nipples" of solder plucking up when you remove the iron?

Not enough flux, possibly iron too hot (burning off flux too quickly) or too cold (causes solder to not melt sufficiently). Also make sure you use a proper tip - do not use a conical tip, even though you may think you need a thin tip for the small pins! Conical tips have hard time transferring heat and then you get issues.

Normally adding flux to such "pointy" joint and touching it with an iron should fix it right away.

[paulca]

Not enough flux, possibly iron too hot (burning off flux too quickly) or too cold (causes solder to not melt sufficiently). Also make sure you use a proper tip - do not use a conical tip, even though you may think you need a thin tip for the small pins! Conical tips have hard time transferring heat and then you get issues.

Normally adding flux to such "pointy" joint and touching it with an iron should fix it right away.

Thanks for the tip.

I was using one of these (sorry didn't intend the pun):

[tautech]

Not enough flux, possibly iron too hot (burning off flux too quickly) or too cold (causes solder to not melt sufficiently). Also make sure you use a proper tip - do not use a conical tip, even though you may think you need a thin tip for the small pins! Conical tips have hard time transferring heat and then you get issues.

Normally adding flux to such "pointy" joint and touching it with an iron should fix it right away.

Thanks for the tip.

I was using one of these (sorry didn't intend the pun):

Those hoof tips are pretty good for universal work and preferred for drag soldering. I've got one but prefer to use a 2.4mm chisel that's fine enough for down to 0805.

Your SMD first attempt is good and you'll get better with practice. Don't be scared to work with a hotter temp as it reduces the dwell time spent on the joint......you'll work it all out. 

[JacquesBBB]

Question... how do you stop the little "nipples" of solder plucking up when you remove the iron?

Put more flux and use less solder. This may help.

Your tip is good. Clean it and bring it close to the join to suck the solder excess.

[agehall]

Question... how do you stop the little "nipples" of solder plucking up when you remove the iron?

Put more flux and use less solder. This may help.

Your tip is good. Clean it and bring it close to the join to suck the solder excess.

+1. You can never have too much flux. And buy some good stuff! Once I bought some of the flux that Louis use I was 200% sold on it. It is sooooooo much better than flux pens and the quickchip flux I used before.

[paulca]

I'm using Chemtronics Flux.  I was soldering at 260*C.  Dwell time to get the flow with the component in place was about 2-3 seconds.  Should I try 280 or 300?

[tautech]

I'm using Chemtronics Flux.  I was soldering at 260*C.  Dwell time to get the flow with the component in place was about 2-3 seconds.  Should I try 280 or 300?

Yep.
It's a tradeoff of reducing dwell time, not flashing the flux off before the joint has been completed and not exposing parts to too much thermal stress or lifting pads. For active components have a look at datasheets to get some idea of what heat and time they're designed to handle and still have 100% operation.
Practice heaps on passives before you get into lots of actives.
You should get the heart rate down and with increased confidence to the point you look at pretty much any SMD and tell yourself, yep I can do that....easy. 

[tautech]

Have a look at Dave's vid of soldering the SMD's on his Nixie clock project:
https://www.eevblog.com/2017/06/02/eevblog-997-how-to-solder-surface-mount-components/

[paulca]

How "defacto" is having a hot air gun?

I know it will make my heatshrink tidier as I currently use a lighter, which often leaves black residue and it's too easy to set fire to the heavier/large stuff

I assume the $10 / £5 China guns are likely deadly or useless, but the $40-50 / £30 dollar range with temp control and various nozzles are they worth it?  I don't want to spend hundreds of $!

[tggzzz]

For my experiences of how I came to love[1] SMD, see https://entertaininghacks.wordpress.com/category/homebrew-pcbs/

[1] hyperbole obviously. But in some ways I prefer them to PTH.

[tautech]

How "defacto" is having a hot air gun?

I know it will make my heatshrink tidier as I currently use a lighter, which often leaves black residue and it's too easy to set fire to the heavier/large stuff

I assume the $10 / £5 China guns are likely deadly or useless, but the $40-50 / £30 dollar range with temp control and various nozzles are they worth it?  I don't want to spend hundreds of $!

They're not so useful for assembly/populating, more so for rework and you can get away with a handyman unit if they have a smaller nozzle and not too much blast/flow.
I have a cheapish dual rework station and for population I use the pencil in favor of hot air. Rework is where you use both. TBH I've never used the various IC tips that came with it.

Get some old PCB's out of any buggered domestic appliance to practice on to learn what's possible and what's not.

[paulca]

Get some old PCB's out of any buggered domestic appliance to practice on to learn what's possible and what's not.

It's odd, I looked around my house and found nothing I could take apart to harvest and play with.  I'm sure it's there right in front of me, but I haven't yet got that mind set of seeing unused and unloved stuff as salvage.

I have an air conditioner that needs repaired but that is highly unlikely to need SMD work.  It's most likely cap or relay failure.

I have a laptop battery BMS board I could try dismantling, it has a few SMD chips I could try and remove, but alas I can't test I get them back on correctly.  I assume removing them without a hot air fun (or chip quick) is difficult.

It might be worth buying some cheapo 74HC SMDs from china and some adapter boards, at least I can test the chips work after I solder them.  Before I start on the actual chips I want to use in my project which were about £3 each + adapter boards.

[janoc]

Get some old PCB's out of any buggered domestic appliance to practice on to learn what's possible and what's not.

It's odd, I looked around my house and found nothing I could take apart to harvest and play with.  I'm sure it's there right in front of me, but I haven't yet got that mind set of seeing unused and unloved stuff as salvage.

Look around your street. I am not sure how it is in UK but here people put old appliances in a pile next to the trash bins once or twice monthly for collection. It is pretty common to find old printers, TVs, computers and what not there every month. If you don't mind getting your hands dirty it can be a cheap way to get hands on some interesting parts (especially from those printers) and a ton of cheap electronics to practice both your soldering and repair skills on.

Also a local recycling center or a charity shop could be a way to find something usable.

[schmitt trigger]

MELFs have been around for the longest time....I saw them being used in commercial products in the mid-1980s.

If I remember correctly, MELFs evolved from the thru-hole small signal counterparts, which usually came in the glass DO-35 package. For instance the ubiquitous 1N4148 diode.

Semiconductor manufacturers who were making DO-35s in very high volumes naturally evolved into a similar, but leadless, package.

[janoc]

How "defacto" is having a hot air gun?

I know it will make my heatshrink tidier as I currently use a lighter, which often leaves black residue and it's too easy to set fire to the heavier/large stuff

I assume the $10 / £5 China guns are likely deadly or useless, but the $40-50 / £30 dollar range with temp control and various nozzles are they worth it?  I don't want to spend hundreds of $!

Hot air is mostly for rework and disassembly as taking off an SMD chip without it is almost impossible without destroying either the chip or the board (or both). Passives can be sometimes removed with an iron (make a blob of solder and/or heat both sides with the side of the tip) but larger components with many leads are difficult, even if you use some special solder (like Quick Chip). Solder sucker and wick are almost useless for reworking SMD components.

I have the cheap Atten 858d that Dave has reviewed here:


It wouldn't do for reworking huge BGAs but for desoldering smaller chips, reflowing poor joints or crooked components and heatshrink it is perfect. And if it dies I will just get a new one because it was so cheap.

I had one of those Ayoue combo-stations with soldering iron and hot air in one before but I didn't like that - the thick hose from the pump was constantly getting in the way on the bench even though it is a tool that isn't used that often. The Atten doesn't have a hose but only a thin cable to the handle. Both the heater and a fan are in the handle, there is no pump there, so it is easy to put away when not needed, taking up almost no space.

However, if you decide to buy one of the Attens, verify the wiring before turning it on - there are many clones and copies around and some are dangerously miswired, with the metal case not being earthed and/or the metal nozzle being live.

[phil from seattle]

How "defacto" is having a hot air gun?

I know it will make my heatshrink tidier as I currently use a lighter, which often leaves black residue and it's too easy to set fire to the heavier/large stuff

I assume the $10 / £5 China guns are likely deadly or useless, but the $40-50 / £30 dollar range with temp control and various nozzles are they worth it?  I don't want to spend hundreds of $!

I've had one for about 10 years. It cost me around $70 and works fairly well.  You want heat and flow control.  I like having it but don't find it to be a must have. About 90% of it's use is for heat shrink. The biggest problem with hot air - it's very easy to have collateral damage. I suppose that's due mostly to bad technique but good technique seems to be elude me.  And reflow with hot air? I've done it but find it tedious - a lot easier and much more controllable to do the board in my toaster oven. It's opt for a hot plate before using hot air.

[janoc]

Re collateral damage with hot air - use some aluminium foil/capton tape to cover anything you don't want to heat around the target area. Yeah, I have melted/scorched few things too before I have learned this

Re reflow - while hot air can be used to solder an entire board (I think Dave shows that in one of his SMD tutorials)  it is tedious, indeed. It is more for reflowing/correcting specific components - e.g. because you have soldered it crooked or the part doesn't have accessible leads (QFN ...).

Hotplate/skillet/oven are good but given the mess and the short life/complicated storage of solder paste, I rarely bother. That makes sense only for people populating a lot of boards. For one offs with reasonable amount of components hand soldering is perfectly fine.

[bson]

Get all kinds of SOIC and 0.5/0.65mm SOP to DIP adapters off eBay.  Dirt cheap and handy for breadboarding.  Then practice soldering things like op amps, I2C EEPROMs and other inexpensive parts to them.  You get practice and end up with parts handy for breadboarding.

[paulca]

So I ordered 4 74HC4067 multiplexers in SSOP-24 format, plus 4 DIP adapter boards.

These can serve as an easily testable IC so I can verify my soldered SMD ICs work.  They were only £1 each.  Although the actual chip I want to use, the LED Driver 74HC is only about £2.50.

The multiplexers might come in handy.  I picked a chip that was cheap, the same package, but might also be of use to me.

[tggzzz]

Have you got a local hackspace/makerspace?

My local one has many surplus ICs that could be used for experiments, plus people would be willing to offer guidance that stopped you going down blind alleys.

[paulca]

Have you got a local hackspace/makerspace?

I just googled that and there is one pretty much next door to where I work Mon and Fri.  They share the premise with lots of different genre of hacker/maker/artsy groups, so the tricky part is working out when the electronics folks are there.  I'll maybe ping them on FB.

[tggzzz]

Have you got a local hackspace/makerspace?

I just googled that and there is one pretty much next door to where I work Mon and Fri.  They share the premise with lots of different genre of hacker/maker/artsy groups, so the tricky part is working out when the electronics folks are there.  I'll maybe ping them on FB.

Many will have open or social evenings. Apart from that it might be hit and miss.

[phil from seattle]

Hotplate/skillet/oven are good but given the mess and the short life/complicated storage of solder paste, I rarely bother. That makes sense only for people populating a lot of boards. For one offs with reasonable amount of components hand soldering is perfectly fine.

Shelf life of the Kester Sn/Pb paste syringe I'm using is at least one year - I've had it that long and don't store it in a fridge though my basement doesn't get very hot. About $15 USD. So not a tragedy if I have to buy one every year.  I do QFN and LGA packages so reflow is my only choice. If you can stick to SOICs, TSSOPs and similar leaded packages then reflow isn't required. Though, there is something very satisfying baking a PCB and watching the components self-align.

[paulca]

How hot does the oven need to go for reflow?  Does getting a bit gravy on it harm anything?

[phil from seattle]

Gravy, yes, I'd think it would. Don't know about butter though...

Reflow profiles are available. Pb/Sn typically has a melting point at 217C.  There are reflow oven controllers out there but I just use a thermocouple+DMM and watch the time. The actual times aren't super critical but there is a max temp you can't exceed. Also, there is a 60-90 second limit for the parts at the highest temperature.

I start by preheating the oven to like 75C, let the board dry out there for about 3 minutes, then run it up to 150C or so (turn if off when it hits 150, it continues up to about 165), let it sit in the 165 area until 2 minutes has passed and then turn the oven back on for 225. When it hits 217, I turn the oven off.  At that point the paste melts. I start timing when the temp hits about 190 to make sure I don't go more than 90 seconds in the reflow temperature zone. Then I pop the door open to allow cooling. My latest CP2102N PCB (QFN28 part) came out perfect using that technique.

[phil from seattle]

by the way, the trick to getting temps right is to sense the temperature at the PCB. Lots of reports about burned PCBs where the thermocouple is hanging in the air.  I have a metal plate that the PCB sits on and has the thermocouple directly attached.

[schmitt trigger]

If Sn63 Pb37 solder is employed, its melting point is actually lower: 183C or 361F.

[paulca]

I assume a normal fan oven heats too slowly?

[phil from seattle]

If Sn63 Pb37 solder is employed, its melting point is actually lower: 183C or 361F.

yes, you are right, I'm using lead free.  principal is the same, though.

@paul, I don't bother with a fan (I assume you mean convection) as it works just fine. I'd be concerned about blowing small parts right off the board.

[janoc]

Hotplate/skillet/oven are good but given the mess and the short life/complicated storage of solder paste, I rarely bother. That makes sense only for people populating a lot of boards. For one offs with reasonable amount of components hand soldering is perfectly fine.

Shelf life of the Kester Sn/Pb paste syringe I'm using is at least one year - I've had it that long and don't store it in a fridge though my basement doesn't get very hot. About $15 USD. So not a tragedy if I have to buy one every year.  I do QFN and LGA packages so reflow is my only choice. If you can stick to SOICs, TSSOPs and similar leaded packages then reflow isn't required. Though, there is something very satisfying baking a PCB and watching the components self-align.

You either got lucky or that was a very good paste and the syringe was airtight. Normal shelf life of solder paste is something like 6 months, refrigerated. Possibly even less if you don't buy a syringe but a little dose/bottle because it is more practical for stenciling than syringes - those are rarely airtight and the paste dries out quickly due to large surface area being exposed.

[phil from seattle]

Even if it only keeps for 6 months, I don't see it as a huge cost item. The jars do dry out fast and I like the syringe better. I just squirt out a little paste on the stencil and spread it. Cap is off the syringe for maybe 5 seconds.

[paulca]

I was kinda referring to using my kitchen oven.  Anyway  It just sounds like too much hassle for my needs.

Anyway, my Rolson magnifying visor arrived.  Nice.  With the maximum lenses in I can actually read the SOIC-8 Eproms that arrived.

Of course as is fate's playful little game is, the SOIC-8 chips arrive, but the SSOP-24 adapters arrive.  The SSOP-24 practice ICs and the SOIC-8 adpaters are still in the post.

[janoc]

I was kinda referring to using my kitchen oven.  Anyway  It just sounds like too much hassle for my needs.

Don't. Getting solder paste (even lead-free) near anything used for food is a bad idea.

If you want to do reflow soldering in an oven, get a small electric one or an electric skillet and use them only for this. Both can be  had cheaply.

[paulca]

So after practising with two SOP-8 EEPROMs which handily had test sketches for Arduino on the internet... they both worked, I tried the SSOP-24 chip!

It did not go easily.  I got quite a lot of bridging had to get the solder wick out, but a bit of patience, poking and dabbing and a little dob of flux and ... it WORKS!

Excuse the focus, but my phone camera doesn't like me using a magnifier lens with it.


I also found some surgical alcohol wipes I had lying around which are basically lint free Isopropanol alcohol wipes.  Which allowed me to clean it up a bit.  I discovered that water an an electric toothbrush doesn't work LOL  Poor chip.

[paulca]

A somewhat better shot:

Almost looks like there is too little solder, but I'm fairly certain they are secure and continuity is in order.

[janoc]

Good job! 

Don't worry about bridges - just add more flux and drag the solder away from the chip with a clean tip.

Solder wick is a bit dangerous - if you aren't careful and it sticks to the joint, you could easily tear off a pad or even a pin on your component. Use that only as a last resort when you manage to drop a really big solder blob somewhere.

For cleaning the flux - most fluxes don't really need to be cleaned, except for aesthetic reasons or if you are worried about leakage (not a problem in 99% of cases). If you don't have isopropanol then normal denatured alcohol works fine, it may just leave a bit of white residue, depending on what it was denatured with.

[tautech]

Paulca
The looooong pads on that PCB make soldering a small IC a breeze.
Remember this if/when you get to do a PCB layout !

Altium for example offers 3 standard SMD footprint types for passives; High Density (shortest/smallest), MD and Low density; longest/biggest. For hand soldering I always select the low density footprint.
I also find it useful to print on paper any layout and physically check components fit.

[myf]

Hello,

I want to solder one simple wire on a circuit with small smd.

I'm quite sure I'll break the circuit if I use wire solder and iron solder. I will get a solder bridge or I'll unsolder one small smd component.

I see video about smd soldering but I don't understand what "magic paste" I must buy.

Can I use this one :
https://www.ebay.fr/itm/10ML-Flux-Pen-PCB-Soldering-Reflow-Solder-Tool-Applicator-Brush-Head-No-Clean/282010097209

Or do you propose an other product.

Do I put very few paste on the wire and on the smd contact, and then I put the hot iron solder on it ? Or do you propose an other way ?

Have a nice day !

F. from France

[paulca]

Are you soldering the wire onto the leg of an IC or onto a random location?

Both are possible, though onto the wire of an IC would need very steady hands.

If however you took your wire, put a tiny bit of solder onto your iron tip and touched both to the end of a surface mount resistor with a good bit of flux for a second it would most likely connect fine without disturbing the resistor terribly.

[myf]

Thank you very much for your answer !

I want to solder this wire on a leg of a smd resistor and, at the other end of the wire mount a Dupond isolated connector.

This solder will not be on the leg of a multi-legs IC, nor on the track (or piste) of the PCB. 

Can I only use my solder iron with the previous flux-pen solder (found on ebay at 2eur = USD 2) ? or must I use other products ?

Have a nice day !

F.

[phil from seattle]

I think you are soldering the wire to a resistor that is already soldered onto a PCB. If that is correct then here is how I do it:
- Shape the end of wire to have the most contact area.
- Tin the wire (apply solder to the end of the wire)
- Apply flux to the point where you will solder.
- Place the tinned wire where you want to solder it.
- Put soldering iron on the tinned wire until the solder melts both on the wire and the PCB.

Some things to consider. Solid core wire is easier than multistrand.  But it is stiffer and makes it easy to put stress on the PCB pad. Easy to lift/break the pad so be careful. If you are doing this for testing/debuging/scoping, a different approach is to solder a very short piece of solid core wire and then use a clip to hook up to the short wire.

[paulca]

So things have progressed.

It's still not perfect, but when a practice board or adaptor works after soldering I always feel I'm mastered it, but every time I do a new practice board or adaptor it presents new chalenges and I learn a few things.

I also got an Andostar microscope.  This is my first attempt soldering using only it.  I'm persevering though it seems more difficult than solder with the jewellers visor. at about 20x.  Part of is the lack of distance perception, the larger part is the coordination required.  I'm sure the later is practice, so... I'm persevering to see if it get's easier.

Things tried and lessons learnt as per the video ... bridges don't come out with hot air, but the iron will kill them quick.

[tautech]

Really nice work, thanks for sharing !

Never would I've thought to use paste like that for fear of bridging but I plainly see if you get the bead not too large it works just fine. 

[paulca]

Yea, when you get the bead wrong bridges are  problem, but...it can be extremely satisfying removing the bridges. 



This is removing the bridges on network resistors when I applied a bit too much solder paste.  An experienced solder'er will see ahead of time the build up and the need to clean the tip with a copper ball more often, as you see me doing eventually.   If after each bridge clear I cleaned the iron this would have taken much less time.  It's part about transfer to the iron and part about distributing the extra to the other pins.  Spread it.  If you can't spread, clean the tip and try again.... only them consider solder wick.

With the microscope you can then review for solder balls and poke them away with the tweezers.  Note; they survive an electric tooth brush with iso-propynol!

[FrankE]

SMD is far less faff once one has the equipment tools, consumables, glass and a little practice.

[paulca]

SMD is far less faff once one has the equipment tools, consumables, glass and a little practice.

Glass?

Though totally agree, the right solder, the right heat, flooding things in flux, good magnification all makes a huge difference.   

It seems the rule is... if you have  a problem then more flux and a freshly clean tip.

EDIT: No need for the microscope, though it does make pretty videos.  A jeweller visor is more than enough.

BTW, none of these videos are edited, they are realtime, unedited, that's how long it took me.

[tautech]

SMD is far less faff once one has the equipment tools, consumables, glass and a little practice.

Glass?

Though totally agree, the right solder, the right heat, flooding things in flux, good magnification all makes a huge difference.   

It seems the rule is... if you have  a problem then more flux and a freshly clean tip.

EDIT: No need for the microscope, though it does make pretty videos.  A jeweller visor is more than enough.

BTW, none of these videos are edited, they are realtime, unedited, that's how long it took me.

Bingo !

BTW, what width Hoof tip are you using ?

[paulca]

I think it's 2mm.  It's a TS100 with a TS-BC2 tip.

[FrankE]

SMD is far less faff once one has the equipment tools, consumables, glass and a little practice.

Glass?

.

Microscope, loupes, magnifiers or whatever other lensing arrangements one prefers.

[dkonigs]

Good luck finally getting into SMD! I always used to shy away from SMD myself.  The last time I was doing hobbyist electronics, I'm not sure it was a popular thing for hobbyists yet. A few months ago I did my first big project in ages, and I still went out of my way to avoid SMD completely.

Now, something has changed. Probably the discovery that many modern components are SMD-only, and the eagerness to try something new. So for the project I'm currently working on, I decided to finally go ahead and just embrace SMD everywhere.

My first real attempt at SMD soldering was tacking a VSSOP chip to a breakout board, using a gigantic DeWalt hot air gun. It was only after this that I discovered that chip actually came in a slightly larger package. Doh!

After that, I bought myself a more appropriate hot-air gun (similar-looking to the Atten), which was much easier to use.
Over the course of this project, I've managed to solder a lot of SMD components to various breakout boards. I'm no longer scared of it. Just a pair of good tweezers, 5x and 10x loupes, and the hot air gun. (I should really get myself a microscope at some point too.)

The only time I've really had trouble was when I run across a component whose footprint isn't available in the common catalog of breakout boards. The one I ran into with this was a UFDFN. I eventually found a "close enough" breakout board, but it took a whole evening of attempts to get it contacting all the pins correctly.

Now I'm looking forward to doing full-board reflow for the actual PCB. Will likely use an oven or hotplate of some sort. (Got a ReflowR on-order, hope it eventually ships.)

[paulca]

Now, something has changed. Probably the discovery that many modern components are SMD-only, and the eagerness to try something new. So for the project I'm currently working on, I decided to finally go ahead and just embrace SMD everywhere.

Yea, it was one IC that nudged me towards SMD.  It only came in SSOP-28.  I had to have a go.  At first I was reserved to actually soldering the breakout board into a project and remaining 99% THT.

But then I bought some practice boards and found it was perfectly possible to solder even 0603 with a basic magnifying lens, a jewellers visor made that even easier.

This inspired me to give paste and hot air a go.  Again this seemed to make things easier.

When laying out a PCB in KiCad I put the SSOP-28 into the board SMD and then placed a THT 100nF decoupling cap on it's power pins.  It looks ridiculous. The "tiny" cap towers over the chip like a 1980s car phone beside a Samsung Galaxy.  The ATMega in DIP 28 looks even worse. 

I have a long term project to make an audio box which at present count will have something like 9 opamp ICs.  I had bought 10 x DIP-8 chips for the project, but doing a quick layout in a PCB editor it's going to end up 6" square with THT.  Making it SMD will half the boards size.

The only thing that hangs off the move to SMD, slowing it down is of course breadboards.  It means to prototype a circuit you either have to have the same chip in DIP + associated THT passives or a breakout board. 

Someone needs to come up with an innovative way to mount SMD onto breakboards.  There are the little "jaw clamp" things for chips but they are large and expensive.  Someone needs to come up with something smaller that is integrated into the breadboard.  I can see the trouble is the number of different packages.  A row of SSOP connection points running up the middle of the breadboard would work, until you had an SOIC or FQP.