Silly question: Soldering temperatures?

[StubbornGreek]

Here is a shot of what I'm referring to:

Well exactly. That is the ceramic compound. You cannot open that. besides why would you want to inspect that ? What do you think you will be able to see ? it either works or it doesn't. If it doesn't -> garbage can.
There is no 'inspection' that can be done. Apart from maybe cracks in the ceramic element. The soldering irons that i use  (WSP80 and MT1500) you cannot even remove the cermic part it is cast in the steel sleeve.

Have you not found (aside from outright quitting on you) that these elements 'degrade' over time and therefor produce less heat (and more importantly produce it less rapidly and maintain it for shorter periods)?

[TriodeTiger]

Well exactly. That is the ceramic compound. You cannot open that. besides why would you want to inspect that ? What do you think you will be able to see ? it either works or it doesn't. If it doesn't -> garbage can.
There is no 'inspection' that can be done. Apart from maybe cracks in the ceramic element. The soldering irons that i use  (WSP80 and MT1500) you cannot even remove the cermic part it is cast in the steel sleeve.

Although the element I will probably not need to be concerned with for a long while, the FX-888 manual does explain for maintenance that you can perform to check resistance of the heating element at room temperature to get a guage of its condition.

1. Heating element resistance (red): 2.5-3.5 Ohms
2. Sensor resistance (blue): 43-58 Ohms

This is perfectly normal. That is the border between the iron coated tip and the chrome plating where solder will not stick and that protects the core from oxidation.[...]

I am glad I am not doing anything wrong. It feels like hitting something with your car, except there is no feedback, so you've no clue if something is wrong yet.

i didnt try wider wicks then 2.2mm but with a little solder on the tip it makes wonders. ohh and its only a 40 watts tip

Looking at my solder wick, there was previous solder globbed on from when I used it with my 40W fixed.

It's some supercheap DX (DealExtreme) stuff - goot wick, 2.5mm an claims to have RMA flux, at least "RMA" is the only Latin writing on it other than width/length.

Unsure why it did not adhere solder really at all on pcboard joints with my Hakko, probably am using it wrong, although I can't say getting better wick is a bad thing here even if.

[free_electron]

Elements degrading over time ? That is nonsense . its a piece of tungsten or wolfram wire encapsulated in ceramic.

And even if they would degrade ( which they don't  ) : a properly controlled station will still reach the correct temperature as it is a closed loop regulation system.
As for 'holding heat' that is pure thermal mass induced. Unless you start shaving down the ceramic element you do not modify the thermal mass.
So this is nonsense.

[StubbornGreek]

Elements degrading over time ? That is nonsense . its a piece of tungsten or wolfram wire encapsulated in ceramic.

And even if they would degrade ( which they don't  ) : a properly controlled station will still reach the correct temperature as it is a closed loop regulation system.
As for 'holding heat' that is pure thermal mass induced. Unless you start shaving down the ceramic element you do not modify the thermal mass.
So this is nonsense.

Hmm, good info, thanks. I hadn't thought about it in those terms.

Now that I think about it, aside for dead elements, I've only changed out one working unit and that may have been premature.

[IanB]

Elements degrading over time ? That is nonsense . its a piece of tungsten or wolfram wire encapsulated in ceramic.

It's likely that wire will over time oxidize at the surface and acquire a thinner conductive cross section. In turn its resistance will increase and it will produce less power for the same voltage applied. Lower power will increase the recovery time and reduce the ability to sustain the tip temperature. The feedback loop will compensate with longer on periods, but this will only go so far. At some point the heating element will need replacing to maintain performance.

[TriodeTiger]

I've considered some form of degradation over time that would reduce effectiveness of the core, seeing how they list the resistivity to look out for in their mini-manual as a maintenance step.

[saturation]

There was a similar discussion here:

https://www.eevblog.com/forum/general-chat/soldering-iron-calibration/msg89543/#msg89543

The right temperature in many studies ~ 330-375C or a mid point of ~ 350C.





If you have a look at the PACE videos here:

https://www.eevblog.com/forum/general-chat/basic-soldering-lessons-from-pace/msg108029/#msg108029

A lot of recommendations are still relevant, but up to ~1990s, folks were less keen on regulated iron temperatures in relation to good hand soldered joints:  technique and heat time using a >= 30W iron mostly mattered.  A lot of later studies showed that post production damage can be reduced by using regulated irons.  Its now an IPC standard.  The studies were statistical, looking at damage to 1000s of items assembled and repaired.  But, for low volume production, you could use an unregulated iron using 1980s style technique and take your chances.   

The whole point of regulated irons, and therefore also setting temp limits is to put statistics in your favor, particularly considering its a one-sized fits all recommendation ranging from large passives, to SMTs.

If you change to a tip with a thermal mass different from the base tip were the station was calibrated, the iron has to be re-cal'd or you can estimate a fudge factor as Hakko mentions in its tip charts, or use a self-calibrating station.   This is because the Hakko FX888 or 936 thermocouple is not actually at the tip, but at the base, so actual tip temp and station readout are slightly off relative to the size of the tip.

If you find you adjust a station above 350C, be sure you have the right sized tip, it could be too small or the tip is damaged, not conducting heat properly, its simply out of cal, or you need a larger iron.  It maybe OK for occasional work, but you will be stressing your station when you do it.

http://www.hakko.com/english/maintenance/topic_ondo_2.html

Replacing worn $6 tip will reduce wear on the $20 ceramic heater.  All this hinges on checking the station calibration periodically.

[free_electron]

If you change to a tip with a thermal mass different from the base tip were the station was calibrated, the iron has to be re-cal'd or you can estimate a fudge factor as Hakko mentions in its tip charts, or use a self-calibrating station.   This is because the Hakko FX888 or 936 thermocouple is not actually at the tip, but at the base, so actual tip temp and station readout are slightly off relative to the size of the tip.
[/quote

wow.. Major design flaw ...

[saturation]

Ceramic heaters eventually degrade, otherwise we'd all have wonderful lifelong heater elements! The imbedded wire wears out, changes resistance with age so it gradually no longer gets as hot, so you'll have to recal the station to gets the equivalent heating output using more current from the station.  YMMV with how long it takes, overall durability and whether the chemistry of the ceramics assist in degrading the heaters.

http://www.docstoc.com/docs/49903413/Ceramic-Heater---Patent-6265700

Elements degrading over time ? That is nonsense . its a piece of tungsten or wolfram wire encapsulated in ceramic.

Now that I think about it, aside for dead elements, I've only changed out one working unit and that may have been premature.

Its a 15+ year old design [ Hakko 936], but the good news its proven itself despite the flaw; all stations that use similar methods where thermocouples are not actually in the tip suffer the same problem, yet they are all IPC compliant because the change in temp, or offset, is still within their specs.

If you change to a tip with a thermal mass different from the base tip were the station was calibrated, the iron has to be re-cal'd

wow.. Major design flaw ...

[T4P]

If you change to a tip with a thermal mass different from the base tip were the station was calibrated, the iron has to be re-cal'd or you can estimate a fudge factor as Hakko mentions in its tip charts, or use a self-calibrating station.   This is because the Hakko FX888 or 936 thermocouple is not actually at the tip, but at the base, so actual tip temp and station readout are slightly off relative to the size of the tip.
[/quote

wow.. Major design flaw ...

No it's not, you get the flexibility of turning down the temps.... if like a pad is very lift-prone, i like it so i'm not worried.
At least the tips don't cost me much until you get to the fx-951 tips where the heater is in the tip and the temp probe is on the tip itself ...
Okay, if my 936 (clone lol ...) breaks i'm getting a FX-951 (clone lol ...)

[saturation]

This is probably a bottom line rule of thumb, turn heat down as far possible while still getting your solder time to 2-3 seconds per joint.  For small pads I get away with 260C in the high summer months, and 300C in the winter.  You can set it anywhere you like and avoid going over 350C,  for the reasons mentioned.

As free-electron said there is no reason to get into wasteful habits even if the parts, tips and heaters, really don't cost much.  But by following the simple rule above and checking the tip temp with eutectic solder so you know where the 350C point is in your analog station, you can prolong your tips and heater life, and substantially reduce the risk of thermal injury to your components.

you get the flexibility of turning down the temps....