[SOLVED]How do you solder component leads on PCB

Thread Starter

Pushkar1

Joined Apr 5, 2021
416
Hi All,

Whenever I'm doing soldering, I make a big mess of it. I've seen lots of videos that show how to do it. but still my soldering joints doesn't looks good

How do you solder component leads on PCB to make good joint's.

1625740261496.png
 

rsjsouza

Joined Apr 21, 2014
335
The videos above are great. Just a few highlights:

Be sure the soldering iron is warm enough. Before soldering, melt some solder on the tip and see if it melts quickly when in contact with the tip (it may need cleaning in case it does not do that). After that, remove the excess solder on the tip (it tends to create a bubble of solder) so this does not excessively accumulate on the part/pad. In larger pads and pins (thick wires, connectors, etc) the excess solder on the tip will be beneficial as the thermal mass is larger, but in general it is not.

To solder wires to terminals, potentiomenters, pads, etc. make sure to apply a thin coat of solder to the wire before trying to solder the two together. This greatly helps with a successful connection, especially because of the larger thermal mass.

Make sure the soldering iron has a tip shape that touches both the pin and the pad and make sure there is a good contact between them - as the movie #6 says, these places you need to heat. When I was beginning to solder, it was quite common for me to get frustrated as the solder was never melting.

Make sure the solder is touching the pad and the terminal, not the soldering tip. When I was beginning to solder, it was quite common for me to melt solder away as I was touching it on the tip instead on the junction.

Having a clear visualization of the soldering joint is critical. I had a perfect eyesight but, as I got more *ahem* "experienced", I started to lose sight of the nearer objects and the quality of my soldering started to decrease sensibly. I then realized I needed reading glasses and a loupe (or more than one, depending on the usage). Well worth the investment if you are around that critical age.

Keep some old boards and old parts around to practice. It is fundamental to keep doing it until you get really good with the more expensive and critical parts.

Good luck in your journey! It is long but surely worth it!
 

MrChips

Joined Oct 2, 2009
24,651
As with everything it takes repeated practice.

It would be a good idea to use 63/37 Sn/Pb solder when starting to learn how to solder.

Your soldering iron tip is too large. Get one with a finer tip.
Make sure the tip is clean and coated with a thin layer of solder, a procedure called “tinning”.

Heat the joint and then bring the solder to the joint.
 
What solder ally are you using?

The flux might not be suitable?

The component leads look too oxidized.

Your tip is definately too oxidized.

A temperature controlled iron surely helps with lead-free solder.

I think you have the right idea. Use a solder with the flux in the core. The tip should be tinned and usually iron clad.
Heat the pad and the lead and push the lead of the component. Sandwich solder, lead&pad, iron and apply solder to the lead.
 

MisterBill2

Joined Jan 23, 2018
9,905
First, the point of the soldering iron MUST be tinned, so that melted solder will stick to it. The other comments are valid as well. But if the tip of the iron is not tinned it is almost impossibe to produce a satisfactory solder connection. And the photo does not show a tinned tip.
 

Thread Starter

Pushkar1

Joined Apr 5, 2021
416
Thanks all for giving a great suggestions

@rsjsouza Thanks for detail Discription

What solder ally are you using?
Soldering Iron https://robu.in/product/25-watt-led...MIs6LgztLT8QIVkH4rCh1FaAGfEAQYASABEgI4-vD_BwE

Soldering wire https://www.electronicscomp.com/sol...MItui9t9bT8QIVBMWWCh1uwgIlEAQYAyABEgL7m_D_BwE

Avoid lead-free solder if you like nice, shiny solder joints.
sorry I don't understand what it means can you explain for me.
 

MrChips

Joined Oct 2, 2009
24,651
1. Use tin/lead solder.
2. Don't use additional flux. Solder for electronics already has flux in the center core.
3. Clean the tip by wiping on brass wool.
4. Learn how to tin the tip.

brass wool to clean the tip then thin with fresh solder. Wipe off excess solder. (I use a damp sponge to wipe off the tip.) The tip itself should be shiny silver, not black. Hold the soldering tip at the joint for at least 3 seconds while you apply fresh solder.
1625755587313.png

1625756014292.png

For regular thru-hole components I use a tip with 0.031" diameter. I switch to 0.015" for SMD.

0.031" (0.80mm) conical tip
1625756305830.png

0.015" (0.38mm) conical tip
1625756411171.png
The two tips shown above are specially coated and for use with Weller soldering stations. Do not file the tips since filing will damage the protective coating.
 

DickCappels

Joined Aug 21, 2008
8,000
Solder that does not contain lead can be bought. It takes a higher melting temperature than lead bearing solder and the joints often look dull and defective. Avoid solders that are "Lead free", they will be labeled as such.
 

MrChips

Joined Oct 2, 2009
24,651
When learning how to solder, practice with tin/lead solder alloys first, tin/lead composition of 60%/40% or 63/37.
For personal use, you may continue to use tin/lead solder.

For commercial products you need to use lead-free solder. When repairing commercial products you are more likely to find that lead-free solder was used in the manufacture of the product. This will require that the solder iron be set to a higher temperature, 800°F instead of 700°F.
 

peterdeco

Joined Oct 8, 2019
415
For legal reasons, we have to use lead-free solder. After countless searches for a lead-free solder that doesn't chew up our soldering tips, doesn't flow smooth and doesn't look like a cold solder joint, we found it. The company name is KOKI Company Limited. It is a part of their Eco Plus series. It performs as well as lead solder. The one we use is SO3X7Ca-70M. It is manufactured in Japan and their MSDS lists their flux as a trade secret. It is available through distributors in the U.S.
 

Ian0

Joined Aug 7, 2020
3,785
For legal reasons, we have to use lead-free solder. After countless searches for a lead-free solder that doesn't chew up our soldering tips, doesn't flow smooth and doesn't look like a cold solder joint, we found it. The company name is KOKI Company Limited. It is a part of their Eco Plus series. It performs as well as lead solder. The one we use is SO3X7Ca-70M. It is manufactured in Japan and their MSDS lists their flux as a trade secret. It is available through distributors in the U.S.
I have 3 different Weller soldering irons, the good old TCP, a more modern WS81, and the most up-to-date WE1010.
The TCP bits oxidised in no time on lead-free solder, the WE1010 is a little better, but the WS81 bits last almost as well as they do on Tin-Lead.
I even tried some WS81 bits bought very cheaply from abroad on Ebay, and they also lasted well.

I find the RoHS regulations really annoying, especially as when our product is shipped it contains 1.6 tons of lead in its battery.
 

Audioguru again

Joined Oct 21, 2019
3,872
The solder shown from India does not say its metals or percentages of its metals.
The ad for the cheap soldering iron does not say it has controlled temperature then it probably gets much too hot which incinerates rosin in the solder and oxidizes the tip and wires.

I think only manufacturers must not use solder with lead in it. Hobbyists can.
 

dl324

Joined Mar 30, 2015
13,573
Whenever I'm doing soldering, I make a big mess of it. I've seen lots of videos that show how to do it. but still my soldering joints doesn't looks good
  1. Your soldering iron tip looks like it needs to be cleaned and/or tinned.
  2. Your tip is too big for what you're trying to solder.
  3. If the tip has a chisel point, you're holding it upside down.
When soldering, you need to use the tip to heat the pad and component lead. When they're hot enough, you apply solder to the lead/pad (not the iron tip). You remove the wire solder when sufficient solder has flowed to make a good joint (concave edges). Don't jostle the joint until the solder has cooled. Chances of making a cold solder joint are reduced if you use eutectic solder (e.g. 63/37).
 

Ian0

Joined Aug 7, 2020
3,785
Put a blob of solder on the tip, and watch it. It should say shiny. If it starts to look dull, grey and wrinkly, then the soldering iron is too hot. (If you look dull, grey and wrinkly, then that's just part of getting old)
 

Audioguru again

Joined Oct 21, 2019
3,872
Everybody on the other side of the world on You Tube videos carry molten solder around on the dirty tip or their soldering iron.
I have and use two hands to solder things. Maybe people over there have only one hand.
One of my hands holds the solder or a wire and the other hand holds and guides the soldering iron.
 

Yaakov

Joined Jan 27, 2019
3,769
Everybody on the other side of the world on You Tube videos carry molten solder around on the dirty tip or their soldering iron.
I have and use two hands to solder things. Maybe people over there have only one hand.
One of my hands holds the solder or a wire and the other hand holds and guides the soldering iron.
If they are recording on their phone the other hand may be occupied...
 
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