So surface mount it is

[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.