What tool or technology do you reach for most often as an engineer?

Soldering Iron, a pity i don't do well and i allways have to throw to the trash all the things i tried to repare

Hi Xarly,

Here are some soldering tips.

Use an iron that is 20 or 25 watts max. The tip must be tended to continuously. I tin the tip and brush it with a clean steel brush every 10 to 15 minutes. Some techs like to brush the tip with a wet sponge. if you get excess solder on the tip brush or shake it off. If you shake it off be careful not to hit your skin or clothing. If your tip has dark spots or black spots keep cleaning it and retinning it. If you can't get it to the point where you can tin all of it, buy a new tip. Make sure you do not have dirt or grease on the brush that you use to clean the tip. Never use the tip to burn wood or melt plastic. Use a good quality multi core solder. The care and preparation of the tip is the most important part of soldering. The next step is the preparation of the spot to be soldered. Wires should be clean. Many parts nowdays come in strips with masking tape. All foreign glue, tape, material must be removed from the wire. I sometimes use a 600 grit wet/dry paper to clean the wires. If I am soldering to a pad or connector I make sure it is clean. In some cases I will tin the wire and the connector before I solder them together.If I am soldering two wires together I will tin both wires, position them next to each other and heat them to melt the tinning together. When I was originally taught to solder they said to always make a good mechanical connection before soldering. This is incorect. The best procedure is to seldom make good mechanical connection first. If the solder is properly heated and allowed to cool it will have a smooth shiney surface and will make as good a connection alone as having made a good mechanical connection first. When you make a solder joint you place the two things to be soldered in close proximity. Place your clean tinned soldering tip against the joint. Do not try to heat the joint itself. Slide the solder between the tip and the joint. It will melt when it touches the solder tip. The melted solder will heat the joint and as the joint comes up to temp the solder will flow by adhesion into the joint. As soon as the solder flows remove the tip as we do nort want to over heat the junction. The longer your tip has a solder bridge between it and the joint the longer heat will have to travel up wires to potentially damage your parts. The shape of your solder tip is specific to different jobs. A long skinny tip is good for small tight connections but it will not conduct enough heat to the soldering site if the joint is too large. On the other hand a chisel or blunt tip will conduct enough heat to solder a larger joint but might not fit into a tight space or a small site. These are the techniques that I have found to work well and give good results. Now all you have to do is practice. If you want to unsolder things send me a note and I will give you some tips on this too.

John

Hi John,

First of all thanks for all the tips, i have a 30W soldering iron, an friend of mine helped me a few years ago with my iron, he sanded my iron tip because the tip was so bulky and the solder don't flowed propertly, i usually clean the tip with a sponge (that comes with my soldering kit also with a support for iron and two claws like a helping hand), the base of my problem is for example, trying to joint two wires, first i place every wire into my soldering iron support then i tin everything, the iron and all the wires, when all is tinned, i try to place a wire on top of the other and when is placed what i think is correct pick up the iron and heat it up, but when the solder appears to be melted and the junction maked, i retreat the iron and the wires pops out and i get like "aw, man" after 5 or 6 retries i get so tired that i gets in rage and trow everything to the trash so that's all my problems

Use an iron of 20-25 Watts max? Maybe for budget irons, but I'm using an 80Watt Weller both at work and at home (down to 0402 SMD's),  and that works perfectly. Most important part of a soldering iron is the temperature control. With a good 80 Watt station, the termperature is very constant. With a crappy 25 Watt iron the temperature drops immediately when you touch a large surface.

To met, the most important for soldering is:

- pre-tinning leads of what you want to solder

- keep your tip clean (lower the temperature of your iron when you're not using it for a while)

- Do NOT grind the tip if you have a decent one. You'll be ruining its surface

- solder is also working as a heat guide; if your soldering work is getting 'lumpy' , just add some solder so heat is transferred better to the component. Use Litze to remove excess afterwards.

As victor has said below finding a temperature controlled iron will make your life much easier...

You now have something that people can either buy or contribute to for Birthday/Xmas or whatever ...

Mark

I think I have to take exception here with John, to solder modern small surface mount parts effectively you NEED a temperature controlled iron. You can buy a nice one (last I bought was an Ersa iCon Pico) or try your luck with a cheapo Chinese one, like this (£36) from E14:

Image is for illustrative purposes only.
Please refer to product description

 

Manufacturer:

TENMA

Order Code:

2064549

Manufacturer Part No:

21-10115 UK

You may find similar things cheaper elsewhere but E14 do have a range of bits for it.

The other thing you need for surface  mount chips is flux - I use

 

Future 315 Low Residue No Clean Flux 125ml Spray Bottle

 

 

Order Code:

87-0720

 

from Rapid Electronics. Don't use that gunk that comes in pens !

And as V said, never file your bits !

(and use solder with lead in it !)

MK

Hi Michael,

I stand corrected. I learn something new everyday. It is because I am stuck in the past a little and resisting having to work with surface mount technology. I have been soldering for 55 years and now I have to learn to do it all over again. Xarly is trying to solder two wires together and I am hoping that they don't discontinue all the through the board components. Tell me, is tip maintenance still needed on the temperature controled solder irons? How is it possible to prototype with the surface mount components? For a flat out beginner would you recommend a temperature controled iron or would you still get your feet wet with a simple iron? Thanks for your insights, guess I will put one of those new fangled temperature controled irons on my birthday list.

John

Hello John,

Go for the temperature controlled iron for anything/everything. The Ersa one I mentioned is very nice but a bit pricey  - I've used  a few cheapo ones and they have been OK.

I prototype on pcbs - I hardly ever use through hole parts except for bodging or where necessary for power/mechanical reasons. You can get prototype (2 layer or 4 layer) pcbs very cheaply and quickly from one of many pcb pool type services. I use PCBTrain but there are others. If you have more time and less cash you can make your own boards but I haven't done so for many years now.

Most modern chips (micros, switching power regulators etc) just don't work on breadboard,stripboard or with though hole caps and Rs. Analogue bits might work Ok but none (few) of the nice modern chips come in through hole packages.

One day I'll try to make  a video of hand soldering a surface  mount board:

Here's a picture of one I did last week:

All hand soldered with an iron except for the little PSU switcher on the left beside the inductor which was flowed on a  hotplate (becasue it has several pads underneath).

MK

Nice work.

I'm presuming you did the Hot Plate bit first?

I'm sure there would be great interest in doing something like that and how a novice can do similar work.

Even just soldering the 3 chips feeding the sockets would be useful to a number of people.

I bet that if element14 were to send you one of these (Tenma smd rework unit part No 2062633) you could do a really good video and more people might buy one to use.  element14Dave

mark

Nice work.

I'm presuming you did the Hot Plate bit first?

I'm sure there would be great interest in doing something like that and how a novice can do similar work.

Even just soldering the 3 chips feeding the sockets would be useful to a number of people.

I bet that if element14 were to send you one of these (Tenma smd rework unit part No 2062633) you could do a really good video and more people might buy one to use.  element14Dave

mark

Yes, definately do the hot plate bit first - otherwise all the other bits wriggle about and get cooked

I've never really been into the hot air torches except for removing bits from boards.

MK

except for removing bits from boards.

Unless you are starting form scratch, then removing and then replacing is probably when most of us 'get our feet wet'

Presumably you have a commercial hot plate, or did you steal and hack the wife's one.??

Mark