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PCB for SMD soldering practice

starLED

Member
I have bought for 5 Euros PCB for SMD soldering practice.
I got PCB (90x60x1.6 mm) and bunch of SMD resistors, capacitors, LED's and couple of IC's.
PCB will be a rotating LED's if I can solder everything without making Chernobyl out of it. :nailbiting:
Wish me luck!
IMG_20210106_165800.jpgIMG_20210106_170125.jpgIMG_20210106_165807.jpgIMG_20210106_170002.jpg
 

JimB

Super Moderator
Most Helpful Member
Enjoy the adventure!

JimB
 

starLED

Member
Here are first components soldered.
I have soldered first and third column, first are 1206 resistors, third are 0805 resistors.
1206 resistors are soldered without flux, 0805 with flux.
I always firstly add solder to right pad, then put resistor, and then add solder to left pad.
I had problems with right pad joints, when I put resistor and heat up solder, often I leave spike, when using flux it's better. I don't know is it because of too much solder, or because pencil iron tip.
Left joints are much better.
Judge and give verdict of my work, before I proceed to next columns. :eek:

IMG_20210107_182919.jpg
 

throbscottle

Well-Known Member
Looking ok so far, though you've got a bit too much solder on most of them. Possibly you need thinner solder - I use 0.5mm. You might need to run your iron a little hotter too.

Solder with lead in it is massively easier to solder than the lead free sort, and KISS makes a good point that I didn't know (not least because there's a bit of a US/UK divide with the 2 main alloys). It's worth buying good quality solder too if you are going to do a lot of soldering - it's easier to use.
 

JimB

Super Moderator
Most Helpful Member
In my SMD adventures I have standardised on 0603 size components.
I use 0.5mm 60/40 tin/lead solder.
I also use extra flux, a gel type called "Chipquik" which come is small squeezy tubes.

When soldering a resistor, I put a small dab of the flux on both pads,
I then tin one of the pads,
hold the resistor in place using tweezers (self gripping type are easiest to use for this),
heat the pad with the solder and let it re-flow and join the resistor.
Then I apply the iron and solder to the other pad to complete the fitting of the resistor.

To allow my ageing eyes to see what is happening, i use a video camera and a monitor to see close up.
It takes a bit of practice to get used to the lack of stereoscopic vision and not looking directly where I am pointing the soldering iron.
The story of my camera/monitor is here:

JimB
 

throbscottle

Well-Known Member
Gave up using tweezers for holding them down. I use a fine knife tip. Less chance for wobbles to reach the part. Me Too on the 0603! Though i use whatever's in my board-pull collection, so sometimes I get smaller or larger parts. The 0603 pads I use will take them all. Same process here, too.

Illuminated magnifier is great. However I've started needing to wear spectacles too in recent years.
 

starLED

Member
What solder are you using?
I used 1.0 mm 60/40 lead solder and 30W iron.

Looking ok so far, though you've got a bit too much solder on most of them. Possibly you need thinner solder - I use 0.5mm. You might need to run your iron a little hotter too.
I agree, I have to buy 0.5 mm solder.
I used 30W, I think maybe 40W would be a better choice.
I also tried with 60W, but it gets way too hot, I managed to solder something quickly, but still there is too much heat.
 

starLED

Member
When soldering a resistor, I put a small dab of the flux on both pads,
I then tin one of the pads,
hold the resistor in place using tweezers (self gripping type are easiest to use for this),
heat the pad with the solder and let it re-flow and join the resistor.
Then I apply the iron and solder to the other pad to complete the fitting of the resistor.
I used same procedure, but I encountered problem.
I often can't align resistor horizontaly with PCB, maybe tweezers are the problem.
Perhaps I should use this procedure:
1) put the flux on pads
2) hold the resistor in place
3) put solder on tip
4) solder both pads.
 

throbscottle

Well-Known Member
No never solder anything that way! If you do I will come to your house and beat you around the head with a screwdriver!

The procedure should always be clean, tin and wipe the tip, then heat the pad and component lead, and apply solder to them direct. Often you need to start it off applying solder to the iron at the same time, but never ever use the iron to take solder to the joint! Then just keep going until you need to clean again - usually due to build up of solder on the tip.

Of course that's fine for through hole connections, or solder tags, which don't need you to hold them together whilst you solder them. SMDs don't have that advantage...

Basically, you need to grow an extra arm. Do that and you'll be just fine ;)

No really, Jim has the best way. Tack one end to the tinned pad just to stop it moving, then solder the other end, then solder the first end properly.

Extra flux helps but is optional. It makes more difference if you have cheap solder. If I'm going to use flux I kind of wave it in the general direction of what I'm soldering, so it knows I mean business. If it's' really troublesome I think about actually putting some flux on the joint. If thinking about it doesn't work then I'll use a slight smear of the stuff.

A 30w mains powered iron will be plenty hot enough! I used one for many years before going temp. controlled. I also have a 100W iron for those "difficult" situations...
Don't be tempted to use an extra fine tip. A standard bevel will do fine unless things get cramped. I have a selection of fine tips and never use them.
I was under the impression that "ChipQuick" was intended for desoldering. Oh well. I know it's out of my budget anyway. "Screwdriver" style tips are also good. Just find one you like and get good with it.

A selection of mostly good advice on soldering can be found on Quora.
 

KeepItSimpleStupid

Well-Known Member
Most Helpful Member
One key is non-magnetic tweezers. Cut off toothpick.. Large wooden swab.

Solder paste will make a huge difference.

When soldering NORMAL components with leads, it's customary to apply heat to the interface between the lead and the pad and apply solder to the pad and opposite the soldering iron tip.

63/37 is better than 60/40 for SMT work.
 

throbscottle

Well-Known Member
I tried solder paste once. Couldn't get on with it, gave up pretty quickly.
 

rjenkinsgb

Well-Known Member
Most Helpful Member
I've been using this stuff from ebay for the last couple of years - "Mechanic XG50" which is a 63/37 solder & flux paste.
There are numerous places selling it on ebay, just one example:

I use a small amount transferred to the PCB pads and sometimes also the component leads, hold the part down with a toothpick or cotton bud and either touch the joints with a clean iron or small components, or use a hot air gun for ICs. It flows very well and the bit of residue is easy to clean off with IPA.

It's also good for sheet metal work, joining the edges of tinplate or brass.
 

throbscottle

Well-Known Member
Hmmm, interesting. Doesn't solder paste go bad if you keep it too long?
 

starLED

Member
No never solder anything that way! If you do I will come to your house and beat you around the head with a screwdriver!

The procedure should always be clean, tin and wipe the tip, then heat the pad and component lead, and apply solder to them direct. Often you need to start it off applying solder to the iron at the same time, but never ever use the iron to take solder to the joint! Then just keep going until you need to clean again - usually due to build up of solder on the tip.

Of course that's fine for through hole connections, or solder tags, which don't need you to hold them together whilst you solder them. SMDs don't have that advantage...

Basically, you need to grow an extra arm. Do that and you'll be just fine ;)

No really, Jim has the best way. Tack one end to the tinned pad just to stop it moving, then solder the other end, then solder the first end properly.
I saw a bunch of YouTube videos where people solder SMD components, especially chips, by putting solder on tip and solder that way.
I know that's not recommended, I saw even some pro serviceman do it that way.
I know that objects for soldering need to be heated first in order to transfer solder, and I always did it that way.
 
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rjenkinsgb

Well-Known Member
Most Helpful Member
Doesn't solder paste go bad if you keep it too long?
It does not seem to.
I have a pot of that stuff on a bench that's been standing open with a couple of bits of heavy wire in it for applicators, for two years now & it's still OK for sheet metal or large joints.
It has thickened up slightly and I'd not use it for fine work, but due to the dust and likely bits of swarf etc. that it will have accumulated over time rather than just age.
 

throbscottle

Well-Known Member
I thought there's no difference.
I can't remember which one the word applies to, but one of them is a eutectic alloy and the other isn't. 60/40 has solidus and liquidus points at different temperatures, whereas 63/37 they are at the same temperatures. Each has advantages and disadvantages. I've never used 63/37 so can't comment. For a clearer understanding you could look at the phase diagram for each alloy.
I saw a bunch of YouTube videos where people solder SMD components, especially chips, by putting solder on tip and solder that way.
I know that's not recommended, I saw even some pro serviceman do it that way.
I know that objects for soldering need to be heated first in order to transfer solder, and I always did it that way.
You're not thinking of drag soldering, are you? That is the exception to the rule; you can even get specially shaped bits to do it. You definitely need extra flux if you do it. I never had any luck with the method except one time.
 
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