The art of soldering iron calibration. OMG I love doing soldering iron calibrations!
I have had the true pleasure of worrying about this effort as a calibration technician. I have been asked to do the seemingly silly calibration of a glass ruler once a year, ( I might ask, "what could change").
A soldering iron is a simple item, but with varied applications deserving degrees of attention.
At a facility like Lockheed Martin, where space qualified and defense product is produced, attention to every detail is warranted.
The soldering iron has 2 features of interest.
1. Soldering tip temperature accuracy
2. Soldering tip residual mV AC/DC and ohms to GND, (0-5 expected)
These 2 items are related. A dirty soldering iron tip will cause intermittent performance
There are soldering irons with digital readouts and marked knobs with temperature values
Some soldering irons have no digital display or marked temperatures for the knob control
The temperature control feedback is within the soldering iron heating element, and there is some gradient loss between the control element and the actual tip. There are different types of tips, with the small fine tips having the most temperature loss to the tip. Developing a solder pool to measure the tip temperature is a wild estimate, which can with some skill be reduced. In many attempts it has become a written procedural practice to verify max temperature above 700 deg. F. in most cases to warrant range capability, and resistance to ground to comply with ESD issues standards. The effort required to achieve +/-5 deg. F. with a system which is best accurate with a digital display of +/-1 deg. or temperature marked knob with +/-3deg best setting ability exceeds reasonable efforts. The soldering iron would have to get a correction chart for tips used, (which some manufacturers actually supply), and a calibration conditional statement that the values achieved were with a tail-light warranty, because repeating the testing successfully is unlikely. Calibrating soldering irons in some cases is warranted, but should be restricted to only when really needed.
Recommended: I recommend a written procedure to include:
limits testing on all soldering irons to max temp. >700deg. F. and tip resistance <5 ohms.
Further efforts could be added to meet customer needs when requested or required.
This is a suggestion, and is in practice in the commercial calibration field.
IF regular testing is planned, then consider stocking a good collection of new tips, and heating elements to acheive good results. annual calibrations by service labs do little to better the soldering iron performance. The user of the tool is a very good source for awareness of tip issues in many cases.
I am offering a what if variance comment to relentless testing of a device which is user settable to desired performance. Similar to calibrating a garden hose shut-off valve. "ya just set it where you want it"
I am rambling, and sorry if this is off the track you desire. It is a good real world account. Thanks for reading it..........