Soldering Irons

[joechimp]

I did a search and there was only one thread that had mention of soldering irons but it was about capacitors and not the irons themselves.

My question is to those that use soldering irons on a regular basis to solder components on any electronic boards. What works on motherboards, I assume will work on other delicate electronics.
Specifically , Old cameras. I still use film SLR's and I have have several of the same model that don't work. One is like new and I need to disassemble it to fix it. This includes un-soldering several connections. They are extremely delicate and the least bit too much heat and POOF ! GONE !

Also I have a couple computer motherboards I want to experiment on before I try to fix another one I care about.

Someone told me that the cold soldering guns are best but on the other hand I have been told that they don't get hot enough to do anything. That statement doesn't make sense to me.

Googling has come up with various answers but I want to hear some hands on experience.

I will spend what I need to to get the proper equipment. Not like a $1000 but a reasonable price.

If any one could share Manufacturer, Recommended wattage, Cold Or hot solder. Variable heat or set heat. I would greatly appreciate it.

I think I know the proper solder to use but those recommendations would be helpful , as well, as flux and cleaning and any tips you are willing to share.

Maybe others will find use in this information too.

Thank you in Advance.

[chilly]

Very delicate situation joe,some boards have two or three tracks,the components was bathed with solder,most time's i have tried i cocked it up,the solder goes from bottom of board to top,ok i am old school,had a few successes with a solder pump using a 50 watt miniature tip.25watt can do it but tends to gouge the tracks.

[joechimp]

Very delicate situation joe,some boards have two or three tracks,the components was bathed with solder,most time's i have tried i cocked it up,the solder goes from bottom of board to top,ok i am old school,had a few successes with a solder pump using a 50 watt miniature tip.25watt can do it but tends to gouge the tracks.

Yes very delicate indeed. I assume I will be told that time and again. THere are many variables to what you want to do.
The motherboards are more complicated . The cameras require very little soldering or un-soldering. Perhaps I may get something just for the cameras.
Thank you

[Just17]

Get an iron which makes it easy to change bits when hot ....  and do it carefully or burn yourself  

You will need several bits of different sizes ....  the bigger ones for the heavier component legs and the smaller bits as the 'thickness' of the component legs gets smaller.

When taking out a component, it is usually because it is to be replaced, so the component itself is not going to be salvaged.
After making sure the component legs are not bent over, use a very light pliers (so it does not act as a heat-sink), to hold the leg, and apply solder and heat to the leg until the original solder begins to flow ....  at that point the leg can be withdrawn from the PCB hole, usually leaving the hole blocked.

Unblocking the hole can then be done at leisure.

Again, the idea is to apply fresh solder to the hole, so that all the solder flows, and then - depending on the PCB - you can use a solder sucker, to suck up the soft solder .....  or you can actually soften the solder and hit the board onto a surface that won't damage it, and the sudden stop of the board will cause the solder to fly out of the hole.

Again, you must choose the solder tip size (bit) to suit the application ......  for instance if the hole is in a ground plane, it might be large, and might have a lot of copper attached to it, making a heat sink ....  in that case a larger, hotter tip might be needed to over come the heat sink effect to get the solder to flow properly.

The difficulty is selecting the correct bit size for the particular job ......  that comes with experience.
Applying too much heat can cause the copper tract to lift off the board .....  a definite no-no.

As appears to be your intention ......  get a variety of old PCBs and practice removing components.
It will take quite some time to get reasonably proficient.

Even then mistakes are almost inevitable.

When you make a mistake on a test board, continue with similar sized components & holes, until you have it right.

When all the components have been stripped from a board, go back to the errors, and see if you can repair the mistakes.

A huge complication with modern PCBs is that they might be multilayer .....  and the layers are connected together by the 'lining' of the hole (through hole plating).
If you damage that plating, there is very little you can do to salvage things unfortunately.

Just some thoughts that came to mind .....  it has been a few years since I was involved in such things, but the basics haven't changed I guess .......  except for special instruction for surface mounted devices, and for ICs which are mounted through the PCB (there are special fittings for some soldering irons which will heat all the legs together) ....  but the cost of replacing the IC is usually not worth the risk of damaging the through hole plating, so cutting the IC body off and then removing the legs individually is most often the best approach.

Have fun! ........  and practice, practice, practice!  

[chilly]

Very nice Just17,the problem is damaging the tracks on multiple layer boards,i.e how hot is too hot to get through the hole,it takes a lot of skill and dexterity to replace an old power cap on a motherboard,god knows on the new one's  

It can be done,but i think most stuff is throwaway,like a part on a widescreen is just that "a part" a washing machine timer is a card,same for your top of the range cooker,all throw away parts.

[joechimp]

Thanks just 17. Very extensive information. I will heed your advice. I have done soldering in the past but it has been awhile. I might have better success with the cameras. No boards involved just wire connections. Albeit small ones, I suspect it will be easier and less hazardous.
I appreciate it.

[ThirdOfSix]

First, a physics lesson.

When heating ferromagnetic alloys (metals that a magnet will stick to), at some temperature called the curie point, the magnet will no longer stick to them.

Weller made a soldering station for years that utilized this effect to control the temperature of the iron.

In essence, it had a switch with a magnet in it that that would turn on a sixty watt heating element in the iron. When the soldering tip was installed in the iron, the switch would sense the alloy of the tip and turn on the heater. When the tip reached the design temperature which was determined by the curie point of the alloy of that particular tip the heater would shut off.

These irons were never the wrong temperature. They could use a very large wattage heater for the tip size without ever any chance of overheating the board being worked on. Because the heating element was very large for the tip size, they heated up very quickly and if the item being soldered  had a lot of thermal mass, it did not matter because it had plenty of reserve power.

These irons were the industry standard for many years/decades. Mine was made in the late fifties or early sixties and I can still get parts for it.

I think there are even tips of the right alloy to give the temperature required for the new solders.

I think a British company bought out Weller but still supports these soldering stations.

There are a lot of digital electronically controlled soldering stations out now complete with LCD temperature readouts.

The problem is that the temperature is only as accurate as the electronics and sensors. A lot of them are Chinese lookalikes that I would not trust if I did not have a way of checking the calibration.

The reason that I went into all of this is that on expensive electronic items, it is very easy to destroy the circuit boards unless you use a precisely temperature controlled iron.

To make matters worse, the new politically correct solders require an iron that is a hundred degrees or so hotter than the old solder required. An iron can be precisely temperature controlled but can still destroy a circuit board material if the heat is applied too long. This means that an iron that does not get hot enough to melt the newer solder can still destroy the circuit board if used improperly.

All the components and board materials are specified to work at a given temperature for a specific length of time only.

When working on such a board it is vital that the repair be done very quickly at the right temperature.

If someone uses  the wrong iron, they may be able to change the component but will have kept the joint at melting point so long that the board or other nearby components have been destroyed.

This is not a job for someone who is hesitant or has bad vision.

Given that you plan to work on items that may have any type of solder, and as stated above you absolutely must have a temperature controlled iron, I would buy one of the soldering stations with a digital readout electronic temperature control with about a sixty watt element and easily interchangeable tips.

I would avoid any spring loaded solder sucker irons. Most are not temperature controlled and they only work in certain situations. More often than not they have the effect of applying a jack hammer to your device.

I would buy a good selection of solder wick in several sizes and with flux for each of the common solders.

Also, a box of quality round tooth picks come in handy for cleaning solder holes that may end up partially plugged.

If you know of a source for high temperature highly flexible silicone tubing, it can be very handy to have one end in your mouth while using the other on the joint to blow the molten solder out of the hole.

Also, as I said in the other thread, some of the original low temp multicore lead tin solder comes in really handy to tin the joint that you are going to work on.

For some reason, even when using the "correct" solder, it is very difficult to get the iron to initially melt the solder on the joint enough to get good heat transfer from the iron. Applying just a dab of the old solder at the contact point of the iron and the joint makes the heat transfer very quickly and seems to lower the melting point of the new solder as it mixes with it.

The result is that you are able to make your repair very quickly without overheating the circuit board or nearby components.

The last time I was in Fry electronics, I think that the soldering stations that I am talking about sold for somewhere between one and two hundred dollars.

That is a lot of money but in the end it is cheaper than the repair on a ruined classic camera.

[ThirdOfSix]

I just Googled "Weller Curie point" and found this:

http://www.amazon.com/WTCPT-Temperature-Controlled-Soldering-Station/dp/B00004W463

This is indeed a lot of money but I would still rather have one of these than one of the glitzy Chinese knockoff digital readout units.

Mine went fifty years before I had to replace the thermostat switch.

Reminds me of the old days when you bought the most expensive tools once and expected them to last a life time.

Now, the "life time free replacement" tools are just the same cheap Chinese junk with an insurance policy tacked on for an extra ten to twenty dollars.

The folks at Sears don't understand at all when I complain about today's quality of their Craftsman tools. They just don't understand that a "free replacement" on a crappy tool that caused several hundred dollars worth of damage or injuries when it broke is not a bargain.

By the way, do not think that my comments about cheap Chinese tools is meant as an insult to the Chinese people who I happen to like.

I remember back when the purveyors of knock off junk here in the United States were contracting with Japanese companies for their junk when a reporter interviewed some Japanese workers who said something to the effect that only rich Americans can afford to use this stuff we make. Over here, tools  are only bought once per generation or two and have to last.

[Just17]

http://cpc.farnell.com/1/1/46352-wtcp-51-soldering-station-0053100399-cooper-tools-weller.html

This is the type of soldering station I had in mind when I posted, and to which ThirdOfSix referred above.

I used various versions of this type for many years, and at one time tried a couple of the 'new' (then) electronically controlled irons, which proved to be less than useless for the majority of the work required of them.

I still have one of this type in use after 30 years or more ....  with a few others 'put aside' which I have never had to dig out.

They had easy maintenance .....  very easy to replace wearing parts (heat degenerating some of the metal parts) ....  and heating elements.
I don't recall ever having a transformer failing.

I could not comment on the present build quality .....  but those older ones from the same manufacturer were rugged and long lasting, as well as being excellent at the job for which they were designed.

[Tony]

In these days of not so great 'Tools', make sure joechimp to buy an Soldering Iron with a heat control knob, (Variable Resistor) . So much great info here that's all I can add, except to practice with the Temperature on those old boards so you have some idea of what is a sweet position to set your Temp controller, so the solder is melting off in a controlled manner, not streaming off.

Good luck ! 

[russell.eberhardt]

Apart from the correct temperature iron it is important to use the correct grade of solder with surface mounted resistors and capacitors.  The wron solder will disolve the silver contact off the component.  The correct solder is already loaded with solder and will not absorb more.

Russell.

[ZX80Man]

All good stuff, 4 sure...
Just like to add:
Having a way to safely hold your work.
Maybe a flexible magnifying glass with a lamp in it. (you need to see the solder change states)
Sometimes you can repair a damaged trace by overlaying a tiny piece of buss wire. (good to have some around)
IMHO, I think that, sometimes, using just a little more heat with speed, is better than conserving on heat and having to hold the iron on a delicate piece so long that it destroys it.  I would compare the art to spray painting.lol (hold in one spot too long=oops)
Also, sometimes you can clip on a tiny heat sink, to stop heat from traveling to a risky area.
Just thought I'd add my 2 cent worth to the very good info above, Dan

[efc321]

For a decent soldering station at a good price try a Hakko 936 or Hakko FX888. The Hakko 936 can be found on Ebay used for a good price. At work the solders used to keep theirs set to 700 deg F.  That is what I keep mine at home set to.  We now use much more expensive soldering stations now a days with the event of ROHS.  Sometimes the boards are even preheated before being worked on.  But for a good all around home use soldering station the Hakko 936 still gets the job done.   Get several different size tips including a very large chisel tip.  Remember that sometimes you have to add more solder to "WET" the area for the desoldering braid to work.  Liquid flux seems to work good with desoldering braid.  Also try a Edsyn DS017 Deluxe Soldapult Desoldering Pump or similar instead of buying a desoldering gun station.   Remember to keep your sponge damp not wet. 

Have fixed many a remote control car (the kind that goes over 55 miles an hour and jumps more than twenty feet) and laptop mother boards with these tools.   Oh and don't forget the heat gun.  Yes the correct solder and flux is a must but so is a good soldering station.  Not weller or a radio shack special.

[joechimp]

Wow, what a wealth of information. I am so glad I asked this question When someone else does a search for soldering , they will find everything they need to know in this thread.
It is sure helping me.

Thank you to all who helped out in this thread.

Just 17, THirdOfSix, you both were certainly in depth in your suggestions. In conjunction with  , chilly, Tony, russell, ZX80Man , efc321 ,  I can't go wrong. I have many choices and techniques to choose from.

Again, it is about as good as I could get. 

[ThirdOfSix]

joechimp,

I just reread your original post and find that I must comment on one item you mentioned so as to prevent a future reader from causing a disaster.

You mentioned "cold" soldering irons.

Please, never never never and I repeat, NEVER, use one of those on electronic repairs!

They work by passing a large current through the metal of the item being soldered thus causing it to heat up. The actual temperature developed is dependent on a number of factors. It will not be controlled and can be anywhere from lukewarm to a blinding flash of plasma.

If the two contacts of the tip happen to contact the two sides of the joint being soldered, they can send a current through the external circuitry of the device being worked on thus destroying the item that you are attempting to repair.

If you were to apply that tool to a multilayer circuit board, you could cause the metal runs inside the board to disintegrate just like the filaments in a flash bulb.

That cold soldering technology was designed for use on structural items like jewelry or water pipes etc.

Please, never even think about using such a thing on any electronic system.