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March 20, 2017

Soldering Station Calibration

To calibrate or not, that is the question. When our company purchased new soldering stations two years ago we were told that they do not require calibration. I believe that all soldering stations should be calibrated and re-calibrated after some point? Do you agree?

A.A.

Experts Comments

Most facilities will test soldering systems for repeatability others will calibrate. These are two very different topics and can involve many hours of discussion as well as time to achieve the desired end result.  

Repeatability is commonly called out by the MIL-Standards as well as the IPC standards and this is to ensure the soldering system meets its desired temperature and holds this temperature over the life of the system. For example, you turn on your iron on January 1st and after it stabilizes it measures 722F.

Six months later, you repeat your setup and re-measure the tip temperature in the EXACT same way, it needs to measure 722F +/- 10F. So if the temperature is within the accepted range, your soldering system is considered repeatable and you are operating within the protocol of the IPC or MIL-STD that you are contracted to. This test is repeated as often as called out in your facilities operating procedures and is your way to ensure a quality product is produced.  

Calibration is a much more time consuming process that involves matching the tip temperature to the displayed temperature of the soldering system. For example, you turn on your soldering system and set it to the same 722F, after the system stabilizes you measure the tip temperature, if it measures anything OTHER than 722F it is OUT OF CALIBRATION. At this point your technician would need to consult the manual for the correct calibration procedure for that model soldering system and adjust the output temperature to match the displayed temperature.  

After calibration, you would still need to make sure this / these stations are REPEATABLE to the protocol of the IPC or MIL-STD that your contracted to operate under for your facility.
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Edward Zamborsky
Regional Sales Manager
OK International Inc.
Mr. Zamborsky serves as one of OK's technology advisers to the Product Development group. Ed has authored articles and papers on topics such as; Low Volume SMT Assembly, Solder Fume Extraction, SMT Rework, BGA Rework, Lead Free Hand Soldering, Lead Free Visual Inspection and Lead Free Array Rework.
This is a great question and we just went through this question at the last APEX show in Las Vegas. Appendix A of the IPC-J-STD-001 has a requirement for calibration of the soldering irons. Based upon the new irons in the market and the heat generating techniques employed by the various manufacturers, it is more important to check the validity of the temperature of the iron as opposed to the calibration of the solder iron.

For example the specification called for the verification of the idle temperature. Based upon conversations with equipment manufacturers and members attending the meetings, who cares what the idle temperature is, it is only being used to extend shelf life of the tip and it cannot be measured simple because when it is mechanically measured a load is applied to the tip and that is not the idle temperature.  

Since the revision is in final review I cannot state the requirements exactly at this point, but the conceptual requirements is that we can determine what the temperature is and the iron can be measure to see its temperature variations when various loads are applied to the tip. These loads should not impact the physical temperature more than + 10 degrees C as mentioned below.  

This is the original information presented to the committee and it has since been modified somewhat through wordsmithing at the meetings. So keep check on the Rev F of the 001 document for the correct verbiage.

b. Temperature controlled soldering equipment should be able to demonstrate control within +/- 10C [+18F] of their operator selected or rated temperature when a minimal static load sufficient only for validation measurement is applied to the tip.

c. Temperature stability, defined as temperature degradation to peak recovery temperature shall be checked following multiple load, point-to-point soldering and shall not exceed the temperature control limits defined in Section (b).

d. Temperature stability, defined as temperature degradation to recovery overshoot shall be checked following multiple load point to point soldering and shall not exceed the limits defined in section (c).
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Leo Lambert
Vice President, Technical Director
EPTAC Corporation
At EPTAC Corporation, Mr. Lambert oversees content of course offerings, IPC Certification programs and provides customers with expert consultation in electronics manufacturing, including RoHS/WEEE and lead free issues. Leo is also the IPC General Chairman for the Assembly/Joining Process Committee.
Personally, despite what the manufacturer says, I would still verify that they are within tolerance at the desired setpoint, and do this periodically. Some station designs rely on the tip to "set" the temperature, and others have selectable temperatures. For the stations where the tip sets the temperature, each individual tip has its own characteristics, and in theory that is what you are verifying. For stations with selectable temperatures, the offset from the setpoint may still depend on the type of tip installed, and so when verifying, it should always be done with the same tip type.

For this type of station, a single-point verification is acceptable where the setpoint is rarely changed. For cases where a range of setpoints are used on the station, a two- or three-point verification may be desirable. I use the term "verification" because it may not be possible for the user to actually calibrate the system, only to verify whether it is within specification.
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Fritz Byle
Process Engineer
Astronautics
Fritz's career in electronics manufacturing has included diverse engineering roles including PWB fabrication, thick film print & fire, SMT and wave/selective solder process engineering, and electronics materials development and marketing. Fritz's educational background is in mechanical engineering with an emphasis on materials science. Design of Experiments (DoE) techniques have been an area of independent study. Fritz has published over a dozen papers at various industry conferences.
It really depends on the soldering station. Many stations today use a cartridge or powered tip design. There's nothing to calibrate on these units.  

On units that have adjustable temperatures, follow the manufacturer's recommended process for any calibration which might be needed.
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Kris Roberson
Manager of Assembly Technology
IPC
Kris Roberson has experience as a machine operator, machine and engineering technician and process engineer for companies including Motorola, and US Robotics. Kris is certified as an Master Instructor in IPC-7711 / 7721, IPC A-610 and IPC J-STD 001.
Yes I agree! Anything used in critical manufacturing processes can and should be calibrated. Calibration is often confused with, adjustment or maintenance.  

Calibration is NOT an adjustment of the equipment, although you may choose to adjust the equipment as the result of a calibration.

Calibration is a documentation process to record the fact that your equipment is performing as specified. It's like taking a "test" in school to see if you are learning the subject. This documentation process should be done on a regular basis, typically annually.
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Paul Austen
Senior Project Engineer
Electronic Controls Design Inc
Paul been with Electronic Controls Design Inc. (ECD) in Milwaukie, Oregon for over 34 years as a Senior Project Engineer. He has seen and worked with the electronic manufacturing industry from many points of view, including: technician, designer, manufacture, and customer. His focus has been the design and application of thermal process measurement tools used to improve manufacturing processes like: mass reflow and wave soldering, bread baking, paint and powder curing, metal heat treatment and more.
Most specifications have a tolerance for the soldering temperature which should be verified. At Trace, we calibrate annually at a minimum.
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Renee Michalkiewicz
General Manager
Trace Laboratories
Renee has been with Trace and an IPC member for 16 years. She has managed all military and commercial PB qualification and conformance testing and training, as well as product qualification and testing in the areas of solder pastes, fluxes, solder masks, and conformal coat. She is the chairman of the IPC Testing and the IPC-J-STD-004 Flux Specification Committees and the Vice Chairman of the Assembly and Joining Committee. She has published more than a dozen papers and presented at numerous electronics conferences.
A lot depends upon the type of station utilized. Is it a military application? If so there are different requirements.
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Jerry Karp
President
JSK Associates
Based in. Northern California since 1971. Founded JSK Associates in 1979. Actively involved in soldering, cleaning, chemistries. 30 years experience in EOS/ESD control.
When attempting to answer this question, I cannot bring up brand names so just let me say this: I would always validate the solder stations you are using at least once every two weeks using a good tip tester calibrated to NIST standards at a frequency no greater than every 6 months, no matter what brand the station is or what claims the vendor makes, documented or otherwise.

Some tip testers are much better than others in terms of repeatability and accuracy.

If the solder system's tip temperature is not +- 5 degrees from the set temperature or rated tip temperature, it should be calibrated. If the solder station cannot be calibrated to achieve the desired "set" temperature or the temperature the tip is rated at after trying more than one tip, then return it.

Never assume a brand new tip will always be at the rated temperature; test them prior to soldering on production CCAs. Do not be afraid to thoroughly evaluate other solder irons and tip testers. My experience has been that most if not all solder station vendors are happy to drop off a station and a few tips (and even a tester)  for at least a month-long evaluation.

There is a wide range of quality, cost, and accuracy amongst solder stations and their tips, and the correlation between price and quality is NOT directly linear.

Test the ability to come up to the desired temperature without overshooting, the ability to maintain the tip temperature when loaded (making contact with various masses) and remember that the J-STD-001 requires the station be accurate and repeatable to +- 15 degrees, if memory serves me.

Some of the best-known solder stations cannot meet this requirement. And some of the tips provided fail right out of the packaging, as in stone cold defective. Be especially aware that some "knockoff" tips can begin losing their plating after only a couple of weeks of normal use.

You can find the plating embedded in the solder joints! Not a good situation at all. So try one or two stations out thoroughly for a few weeks before making a large purchase, so there are no surprises later.
Richard D. Stadem
Advanced Engineer/Scientist
General Dynamics
Richard D. Stadem is an advanced engineer/scientist for General Dynamics and is also a consulting engineer for other companies. He has 38 years of engineering experience having worked for Honeywell, ADC, Pemstar (now Benchmark), Analog Technologies, and General Dynamics.
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