Soldering How-To

[Neo2_000]

Should get my new Hakko in the next few days.

Problem: I have never used a Temperature Controlled Soldering Station before.

What temperature should I run it at to recap Mobos?

Any other tips I should know about?

TIA,
Neo.

[Topcat]

Re: Soldering How-To

For motherboards, I hit them hot and fast. Mine reads in Celsius, and I set it somewhere between 450-480 degrees C.

[willawake]

Re: Soldering How-To

it does depend on the tips you are using, some dont transfer the heat so good especially if they are thin. but generally i have it on full : 450oC which will minimise dwell time.

should really bring it down to 350oC for installing the caps but i am too lazy. no more than a few seconds of dwell time for that and all is well.

anything else? each to his own. you will develop your own technique with your new station and learn the best temperature settings. if it doesnt improve your technique significantly i would be suprised.

the temperature settings are useful when you need to work with components that must not be soldered above a certain temperature.

[Neo2_000]

Re: Soldering How-To

Just got my new Hakko and Wow, I'm completely lost. It will take some time and adjustment on my part before I get used to it.

I should explain that the only temperature control on my old Scope iron is my thumb. As long as it is pressed on the collar, power will surge through the tip. If I hold it down for say 10 seconds, the 3mm tip will glow bright cherry red and were I to hold it down long enough, I reckon it might just melt the copper tip completely although I have not put this to the test.

Lack of power was never an issue but you were never quite sure just waht the temperature was - and sometimes it was hot enough to do some serious damage.

In contrast, I am having difficulty generating enough heat with the Hakko but I feel completely safe and confident that I would have to do something extreme before I could endanger the motherboard. In the beginning, I was a bit worried about running it at full temperature but not any more. A greater concern would seem to be tip oxidization rather than mobo damage!

Like I say, it's gonna take soooome time to get a feel for it, but I am looking forward to it.

[willawake]

Re: Soldering How-To

the 3mm tip will glow bright cherry red

sounds way too hot

what is the difference between the thin tip and the standard tip for recapping. do you still have heat probs with the standard tip?

[Neo2_000]

Re: Soldering How-To

That was written about my old "Scope" soldering iron which has a 3mm wide pencil shaped copper tip. This iron is now history as far as Mobos are concerned.

Regarding my new Hakko: Beside the standard tip, I got a chisel shaped tip which was 1.6mm wide at the end. However, this proved to be a little too big and clumsy, so I went back to the standard conical tip and filed a tiny flat on it. Hakko make a standard tip like this which I originally was considering but the salesman steered me towards the chisel tip.

The conical tip proved to be handy for poking down PCB holes to clear them when de-soldering.

I picked an easy board for my first trial - one with relatively good quality soldered joints and it looks like my first successful recap with the Hakko because the Mobo seems to boot and behave impecably.

I experimented with several temperature settings trying to minimise the temperature while maintaining effective performance. Even at higher temperatures such as 400 - 450 degrees, I found that I had to dwell for considerable time on a few stubborn joints when desoldering before the solder would liquify so I could remove the old cap. I would guess around 6 second, although generally this was not typical.

This seemed to happen on the ground side lead so I am wondering whether the PCB tracks were responsible for soaking up the heat.

As for resoldering with the new iron, I chose a lower temperature of 350 - 400 degrees which seemed OK, but I sometimes had difficulty pooling the solder at the base of the joint. Need to work on my technique here or maybe work on the shape of the tip a bit more.

Nonetheless despite these teething problems, I had a successful outcome and hope to improve with time.

Any hints are most welcome.

[willawake]

Re: Soldering How-To

conical tip on my iron is not hot enough for motherboards. (salesman recommendation also....bastard salesmen )

[Neo2_000]

Re: Soldering How-To

What kind of tip do you use?

[willawake]

Re: Soldering How-To



standard chisel tip. the other two didnt get hot enough. you can see also that the standard tip is the shortest, this is important for heat transfer. i actually want something not so wide but i am gonna upgrade the whole station anyway.

[Neo2_000]

Re: Soldering How-To

Seems I was right about the PCB soaking up heat on some joints.

Just cleared another board of badcaps and it became obvious that on joints whch serviced fine PCB tracks, it was very easy to melt the solder, taking only a second or two.

By comparison, joints which were surrounded by large copper prints took for ever to melt the solder at 450 degrees. In fact, it took so long on occassions that I was concerned for the safety of the motherboard. But no obvious damage presented itself. The acid test of course is yet to come - will it boot?

All this is so opposite to the problems I experienced with my old Scope solderiing iron that my whole world has turned upside down!

Ever watched a SciFi movie where the reactor goes critical and the fuel rods melt right through the concrete foundations of the Nuculear, errrh - Nuculear (well you know what I mean - never could pronounce Nuclear!) power plant?

Well my Scope soldering iron can do that!

[AK0R]

Re: Soldering How-To

Ever watched a SciFi movie where the reactor goes critical and the fuel rods melt right through the concrete foundations of the Nuculear, errrh - Nuculear (well you know what I mean - never could pronounce Nuclear!) power plant?

Another member of the ignorant public; not that this industry has done much to educate them. All nuclear power plants operate in a critical state if they are not shut down. Definition of critical (as applied to nuclear power): a self-sustaining nuclear reaction, where power level is not changing. The "fuel rods melting through the concrete foundation" (also known as the China Syndrome, due to the supposition that the fuel would melt all the way through to China) scenario, while not impossible, requires multiple failures of redundant safety systems. People become even more concerned when they hear the term super-critical. That just means power level is rising, and not how fast (like speeding up in your car: do you have the acceleration of a VW Bug or a Saturn V rocket?).

[AK0R]

Re: Soldering How-To

Back on topic: I was having a terrible time getting the holes cleaned out on boards I was re-working. I would heat up the joint with a little fresh solder, work the old part out, and then spend several minutes trying to clean out the holes (needle, solder wick, etc.). My bulb solder sucker just could not pull the solder out. But, I noticed that it produced a nice puff of air when squeezed. So, I tried heating the hole with a little fresh solder and blowing the solder out (towards the iron). Bingo! Now, the holes are quickly nice and clean, allowing easy insertion of the leads on the replacement part. If there is any flash left on the component pad, it is easily removed with some solder wick.

[PeteS in CA]

Re: Soldering How-To

This seemed to happen on the ground side lead so I am wondering whether the PCB tracks were responsible for soaking up the heat.

Definitely. Copper makes a very good heatsink - whether an actual heatsink or a copper ground (or voltage) plane on a PCB.

[Rainbow]

Re: Soldering How-To

I clean the holes using mechanical sodler sucker. Some of them cannot be cleaned this way because of the big copper plates - so I use bulletin board pins then:

[willawake]

Re: Soldering How-To

woah! another technique....nice one Rainbow.

are they stainless though?

[arneson]

Re: Soldering How-To

Small Hat pins, also excellent for probing a hole.
When I was etching my own boards I used a mini Dremel with the apropriate size drill and, this was really crazy, drilled all the holes, sometimes thousands of them.

[Rainbow]

Re: Soldering How-To

woah! another technique....nice one Rainbow.

are they stainless though?

Probably not. But I don't heat it up when using these pins. I just push the tip of the pin (it must be sharp enough - not all of them are) through the hole, taking care not to damage anything. Usually, there is only a small amount of solder remaining in the hole (it's very good when you can see light through the hole but new cap does not fit because there is some solder remaining inside). But if the hole is full, it's harder to do (push from one side, then from the other, move it a bit, sometimes the pin tip bends or breaks).

[Neo2_000]

Re: Soldering How-To

I have pretty much solved this problem now.

Unfortunatley, The Hakko was not up to the job so I went back to much maligned Scope after all, having gained a new appreciation for it. But now I apply some careful techniques to avoid overheating. I have also modified the copper tip, fashioning it into a finer conical point like the Hakko.

First I preheat the motherboard as described in another post. Despite this amateur arrangement, this works remarkably well. If it a sunny day, leaving the board out in the sun for a while also works well.

To maintain temperature, I will keep a hot air stream from a hair dryer trained on the board throughout desoldering.

I am diligent to maintain careful control with the soldering iron temperature. I apply plenty of fresh solder to the joint within reason - more makes desoldering much easier.

I only make short duration contact for no more than a few seconds with the iron when desoldering, alternating between leads or even caps. This gives the bus and cap time to backup some heat, negating their heatsink effect and allowing the solder to melt in the joint without damage due to focused isolated heating.

If the joint is still stubborn I will not attempt to force it with the iron. I will apply more solder if necessary and focus the hot air stream on the joint till it is nice and hot - enough application almost always works.

Clearing the holes is the same. I use a stainless steel dental pick which I also preheat.

If despite all of this, one hole just refuses to clear (very rare) - I trim and tin the leads of the replacement cap and gently coerce it through the blocked hole.

Since adopting these measures my level of confidence in a successful outcome is very high and problems have all but vanished.

[kids]

Re: Soldering How-To

Ahhhh!!! Carefullyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy!!!!

If you want to broken copper hole, need one drilling-machine (1mm) I think!!!

[linuxguru]

Re: Soldering How-To

I tried yet another variant of the hat-pin/dental-pick method today, and it's very useful where there are traces all around the pin on the solder side.

I removed the capcitor in the usual way, with a standard spade-tip and gentle wiggling to free one lead and then the other. This left both holes clogged with solder, which I previously used to remove with the Radio-Shack bulb-type vacuum desoldering iron. The main problem is that the tip eroded rapidly, leaving the tip hole diameter too large to effectively remove the solder, especially when the hole is on a large copper ground or Vcc plane. To solve this, I used to apply additional 63:37 solder, heat the hole for about 5 seconds while keeping the desoldering tip tightly sealed against the hole, and then release the bulb. With luck, it would come clean on the 3rd or 4th attempt, sometimes after many more attempts. Invariably, this damaged the solder mask adjacent to the hole, which could be a problem when there were thin traces adjacent to the hole.

The new technique dispenses with the Radio-Shack bulb-type desoldering iron. It takes longer, but gives a clean hole with minimum collateral damage. I use a milliner's pin, widely available in the yarn/thread section of most supermarkets. The one I use ia about 20mm long and has a plastic bead on one end, to grip it - this bead is important. These are usually plated with nickel or tin (which are easilt wetted by solder - that's not good). So I used a fine emory paper to completely remove the plating - exposing the underlying steel, which doesn't wet that easily. If you get copper or brass below the nickel, try another brand of pin.

To remove the solder in hole, place the board *component side up* (or alternatively, clamp it so that both sides are accessible). Place the pin at the center of the clogged hole, holding it by the bead. Using the spade soldering iron, heat the pin as close as possible to the solder - it will melt. At this point, wiggle the pin in gently, keeping the iron on the pin. It will eventually go right through the hole. Keep wiggling it, and remove the iron. Now the solder will solidify, with the pin loosely stuck in the hole. If it's tightly stuck or the solder has wetted the pin, you won't be able to extract the pin - in this case you'll have to reheat it and extract it. The key to the method is that the solder must not wet the pin.

Now, using my fingers (or a small scrap of a paper towel), I rub off any solder on the pin that's stickin out on the *solder side* of the board - if it has not wetted the pin, this is easy. I do this until I can withdraw the pin gently from the component side. If necessary, reheat, withdraw the pin and repeat again (if there's excess solder).

If done carefully with the correct diameter pin, you'll have a clean hole with no damage to the adjacent solder mask or the walls of the hole. However, it takes longer than the vacuum desoldering method.

Re-soldering is performed in the usual way.