Archive for category Thermal Musings
Heat Flow Happens
Posted by Paul Austen in M.O.L.E. MAP, OvenCHECKER, OvenRIDER, Profiling, Reflow Oven Verification, Reflow Profiling, Thermal Musings, Thermal Profiling on May 24th, 2011
An often misunderstood concept is heat flow and how it can influence the temperature of the product being heated so here is Wikipedia’s definition of heat flow, followed by a discussion of our own on the subject.
Energy needs a conductor in order to flow
1) An energy difference between two objects.
and
2) There is a conductor to act as a bridge enabling the energy to flow.
Energy always flows through a conductor from an object of high energy to an object of low energy. In this illustration, the high-energy object is a moving hammer, the low energy object is the table and the conductor is a block sitting on the table.
When you hit the block with the hammer, the energy contained in the moving hammer is transferred to the block when it hits. Some is also conducted through the block and transferred to the table it is sitting on. However, because the block is not a perfect conductor, which is true for most things, some of the energy stays in block. That energy bounces between the molecules of the block like balls on a pool table.
Because the molecules rub up against each other, and there is friction between them, some of the moving energy of the hammer is converted to heat energy, which causes a rise in the block’s temperature. It all comes down to molecular motion in an imperfect conductor creating friction that raises its temperature. Therefore, temperature increase is a way of observing energy flow, and energy flow that causes a temperature rise is called heat flow. Read the rest of this entry »
Lead-free in Mission Critical – Failure Is Not An Option
Posted by Grant Peterson in Thermal Musings on August 19th, 2010
The following is an excerpt from an article by Grant Peterson, V.P. of Marketing & Sales at ECD, which discusses the use of lead-free in mission critical hi-rel applications. The article originally appeared on August 11 in SMT Online. The link at the end of this excerpt will take you to the complete online article.
Lead-free in Mission Critical – Failure Is Not An Option
A mission-critical industry can be defined as one in which product failure can be catastrophic: threatening life or critical infrastructure, causing unacceptable collateral damage, and resulting in liability for OEM and/or EMS. Generally included are the military/aerospace, aviation, medical, and automotive industries. To confidently use lead-free in those high-reliability applications, especially considering the EU drive to impose RoHS on some areas currently exempt, it seems prudent to step back and determine where we are, how we got here, and what remains to be done.
RoHS was implemented in the consumer sector before hi-rel industries for two reasons. First, consumer goods made up most landfills. But more importantly, it was initially assumed the lifespan for items like cell phones would give us approximately ten years to encounter and solve any lead-free related problems before moving into mission-critical areas. Life span, however, was greatly overestimated. Cell phones, computers, etc. are now replaced sooner and with greater frequency than originally anticipated. With this reduced time frame, we have neither seen the full extent of lead-free reliability problems, nor developed means to fully combat those we have. Can we really proceed to mission-critical areas with full confidence? Click here to go to the full SMT Online article.
MOLE® Thermal Profiler Calibration – Why and When?
Posted by Paul Austen in Thermal Musings, Thermal Profiler, Thermal Profiling on July 26th, 2010
MOLE® Thermal Profiler Calibration – Why and When?
Calibration of electronic measurement instruments is a necessary process, even though most electronic equipment is very stable and somewhat “resistant” to the effects of environment and changes due to aging.
Q: So why calibrate if my MOLE is “in spec” every time I send it in for calibration?
Because calibration is not so much an adjustment process but rather a proofing process that shows, over time, that your MOLE has been in calibration and thus should remain in calibration, because you have a track record to prove it. Documented history of a MOLE’s performance is the only way to claim your MOLE is in calibration at any given instant.
Most good labs will tell you that when your MOLE is calibrated, it is compared to standards , typically standards that have traceability to NIST, and if it is shown to be measuring within its specified accuracy they will not make any attempt to “adjust” it. Only if it is “on the edge,” which usually means it is getting to the last 10% to 20% of the specified accuracy limit, will they make any adjustments. Your MOLE may still be “in spec” and thus “in calibration,” when the lab received it, but getting close, so they will adjust it closer to the middle of the spec. range.
If it is out-of-spec when received by the lab, then a red flag goes up and calls into question every measurement made since the last calibration! The lab will tell you how far out of spec it is, and you can decide if its measurements during that time affect the quality of the measurements made more than can be tolerated, or if they are “close enough” to still be acceptable.
Q: So, when should the MOLE be calibrated?
The number one best time to calibrate the MOLE is on a regular time-based interval, which is recommended once a year. However, there are other events which may cause you to want to seek calibration at other times of the year, such as:
- When the MOLE is subjected to rough treatment like a fall to the floor,
- When your MOLE is accidently “over heated” ,
- When you are starting a new product introduction and you are characterizing an oven and new assembly to find the right recipe,
- When a new customer’s contract stipulates you use equipment that has been recently calibrated,
- When your in-house quality program requires a calibration interval.
Getting your MOLE calibrated is easy and we want to make sure you are always making the highest quality temperature measurements.
MOLE Talk
Posted by Paul Austen in Thermal Musings on June 28th, 2010
Yes I know, I’m ripping off the Car Talk radio program name, the truly funny call-n show where two well educated brothers have the best of fun giving advise (correct for the most part) to their call-in victims about everything from car repairs to personal relationships. If you’ve not heard the program, find your local NPR radio station and check it out. And also, I’m following on the heels of Board Talk, a web based collection of questions and answers by two respected members of the electronic assembly community who do a nice job (in a “Car Talk” like format) of answering many common questions submitted by followers of the Circuitmart web based electronic assembly resource.
So why take the risk of being yet another abuser of the “Car Talk” theme? Well because I have been asked this question many times: “Why did you call it a Mole?” Call what a Mole?
You know the M.O.L.E. ® Thermal Profiler, that pocket sized 6-channel temperature measurement logger used to see if you are getting the right temperature to your solder joints without overheating your thermally sensitive components (J-STD-075) in reflow or wave soldering machines.
There is a mouth full! Well, to answer this question I thought I’d take a look at the many really cool things a Mole can be. Here are a few:
A Mole of any substance shall have the same number of atoms, molecules, ions, or other elementary units, as the number of atoms in 12 grams of carbon. That number is: 6.0225 × 10^23, AKA: Avogadro’s number. So if you want to calibrate your scale, simply pile up 602,250,000,000,000,000,000,000 atoms of carbon and you’ll have 12.001 grams.
An annual celebration of the date and time represented by the numbers 6.02×10^23 or October 23 from 6:02 a.m. to 6:02 p.m. There is a cool web site in honor of this important number in the world of chemistry and physics. Check it out.
A small gray burrowing mammal, that is for the most part blind, although they probably can tell night from day. Moles tunnel through dirt and eat small worms living mostly underground. Moles can be found in most parts of North America, Asia, and Europe, although there are no moles in Ireland.
What do you call a Mole’s baby? Yes, a Pup. A female Mole is called a sow and the male is called a boar. And if you have more than one Mole you have a “company” of Moles.
A benign skin tumor found on human skin appearing as a small, sometimes raised area, with darker pigment.
A Mexican sauce made from chili peppers, other spices, and chocolate. However, it’s pronounced “Mole-Ay” and I often take service calls from Spanish speaking customers who say they have a “Mole-ay” that is due for calibration. I recommend this dish at your favorite Mexican restaurant. However, there are many different ways to make it so if you don’t like it at one restaurant, don’t be afraid to try it again at another.
A spy who has worked their way into an organization or country for the purpose of getting information. Wasn’t there a TV show?
A pier, jetty, or junction between places separated by water. I did not know this could be called a Mole until today.
A complete line of stage and production lighting products made by the Mole-Richardson Co I’m into theatrical lighting so naturally I’d know about this one.
OK, so this has been fun. Can we get on and just answer the question, “Why did you call it a MOLE?” Taking from the best parts of the many uses of the word Mole, we grabbed the following:
- A Mole crawls through tunnels.
- A Mole secretly spies on the goings-on of something or someone without detection
- A Mole of something is a number that starts with the number 6 (6.02…)
- A Mole is a delicious Mexican sauce. OK, we took nothing from this possible definition of Mole.
Put these together and you get an instrument that goes through the dark tunnels of many different thermal processes, measures the temperature of that process without disturbing it, and does it in 6 (or 3, or 20, since the original naming of the brand) locations of that process. Only a M.O.L.E. ® can do that. So that is why we called it a Mole. So what does the acronym M.O.L.E. stand for?
M = Multichannel – more than one temperature measurement input
O = Occurrent – events that happen (or occur) at the same time
L = Logger – a recording instrument
E = Evaluator – one who makes a judgment, as in the “OK” button on the new V-M.O.L.E. and MEGAM.O.L.E.
IPC Government Relations
Posted by Grant Peterson in Thermal Musings on April 16th, 2010
We’ve just returned from APEX in Las Vegas, where we had a chance to participate in the IPC Government Relations Committee’s Open Forum. For your information, an annual opportunity to gain insight, or get your voice heard, is upcoming.
Capitol Hill Day, scheduled for June 9-10, 2010 is just around the corner. If you’ve ever wanted a chance to voice your company’s concerns related to trade policy, RoHS regulations, counterfeit parts, or any other weighty matter, IPC makes it easy for you.
They can set up appointments ahead of time with many Representatives or Senators and often even send someone from IPC with you. It’s being held in conjunction with the IPC “Executive Market and Technology Conference: High-Reliability Electronics and the Future of American Electronics Manufacturing“. One can go to either Capitol Hill Day, or the Conference, or both.
Seems like a good way to get your voice heard. Check it out at the links above, or for more information you can contact Ron Chamrin, IPC manager of government relations at: email:RonChamrin@ipc.org or +1 703-522-0225. He invites inquiries, and the effort just might be worth your while.
VP Marketing & Sales, ECD
Recent Comments