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Tips on Cooking Both a Perfect Thanksgiving Turkey and a PCB

November 23, 2011 by Profiling Guru Leave a Comment

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Why does it take half a day to cook a Thanksgiving turkey?  The answer is simple ― you have 20 lb of bird that simply cannot just be nuked in a microwave like last night’s dinner.  If not properly thawed, prepared and monitored, you either have an overcooked, dried-out bird or worse: Salmonella. Strangely enough, as you will see in a moment, PCBs are not that much different.

Let’s say you skip the thawing process and in your haste stick a frozen bird in the oven.  What happens?  The bird may look properly cooked on the outside, but as soon as you try your skill with the carving knife, you either hit bedrock or the inside is completely raw. OK, I will admit I speak from personal experience on this one (please do not bring this up with my wife).  Are PCBs any different?  Well, your reflow profile has a preheat phase, with the purpose of bringing your PCB to temperature. In other words, the entire mass of the board with all its components is gradually brought to equilibrium. If you do not do this, you run the risk of thermally shocking your components when they hit reflow and peak.  Thawing your bird and preheating your PCB ― you have the same objective in mind.

So, for the vast majority of us, we really have no idea when the turkey is fully cooked until getting an internal reading. A PCB is no different. On the surface, both might look great, but upon closer inspection, you discover some components have defects due to improper reflow or, for that matter, when you cut into a turkey that is still pink it really hits home that you aren’t cooking a TV dinner.

turkey-in-Spec_SM01

Because of this, as we all know, a 20 lb turkey requires a thermometer. I will concede that some of you use the old “poke the bird and check for pink until done” trick. Let’s assume you are not as skilled, like me, for example. Would you seriously cook a turkey by relying solely on the oven’s temperature reading on your stovetop?  Of course not, but why do some of you profile your PCB by relying on your reflow oven’s reported readings? Are either situation that much different?  Actually, yes. Your nice self-contained turkey cooking oven is more of a steady state, but there remains a large difference between what is reported by the oven and the internal temperature of your turkey. In contrast, your PCB is exposed to anything but a steady state environment because it rides on a conveyor through different heated zones with blowers, extraction systems and both ends of the oven even open to the elements!  For this reason, any oven manufacturer will adamantly tell you to profile and with regularity. Alright, you may have learned how to cook a turkey in your Mama’s kitchen and, in fact, be skilled at not using a thermometer; however, I doubt any serious SMT manufacturer would take a similar approach, checking your PCBs regularly for “doneness” in your reflow process.

What about placing the fate of your Thanksgiving feast on the cheap-o plastic pop-up indicator that likely came with the turkey? Do not laugh. How many of us use the trailing wires that came with the reflow oven?  Now to be fair, both work in principal; otherwise, you would have the likes of Purdue Farms with food poisoning lawsuits on their hands, but they only give you ballpark readings in many cases. By design, the turkey is going to be a little overdone and dried out.  Your PCB, on the other hand, cannot afford to be a little overdone or it is simply OUT of spec.  You can get by with eating the overcooked turkey … the gravy and mashed potatoes are there to make up for less than a perfectly cooked bird. But your PCB will not be as forgiving.  Trailing wires, never mind being cumbersome to use, have a tendency to kink and stretch, which compromise their readings.  They also are susceptible to 50 or 60 cycle noise from some reflow oven environments, further questioning their accuracy in some cases.

So you want to cook the perfect bird. Who doesn’t? So you pony up for a stainless steel large-dial meat thermometer to accurately read the internal temperature of your 20 lb bird. You also pony up for a KIC Explorer with Navigator because you want to create the perfect deep-in spec reflow profile. It will not only tell you the specific temperature of the joints of your $500 BGAs, but it also will find a balance that does not overcook them or any of your other temperature-sensitive components on the PCB.  No pop-up indicator profiler needs to apply since the KIC Explorer with Navigator will go the extra mile and tell you not only if you are in-spec but how DEEP in-spec your profile is, along with what can you do to improve the profile in minutes, if not seconds.  Now do you know of any turkey thermometers that can do that?

So when you prepare your Thanksgiving turkey, and as you pause to give thanks, consider applying the same care and consideration that you have given to your family’s feast as you do to your PCBs.

Happy Thanksgiving – Profilingguru

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Filed Under: Featured, Improve, Reflow, TC's Tagged With: AOI, BGA, BGA Profiling, ceramic packages, cost-based tools, electronics manufacturing services, energy efficiency, flip chip, maximize throughput, Process monitoring, Process Window, profiling, profiling software, Reflow, reflow oven, reflow ovens, reflow process, reflow profiling, SMT, SMT and standards, SMT Reflow, soldering, SPI, surface mount technology, Thermal Management, thermal process, thermal profiling, thermocouple attachment

Reducing Reflow Product Changeover Time

November 7, 2009 by Profiling Guru Leave a Comment

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2009 Presentation at SMT Long Island on how to reduce the changeover time from one reflow profile recipe to another.  If you ever opened up your reflow oven to dump all its heat to lessen downtime, this 4 min video is for you!!!

To view the complete video series (click here).

To subscribe to my Podcast for iTunes (click here).

https://profilingguru.com/podcasts/Product_Changeover.m4v

Podcast: Play in new window | Download (Duration: 3:40 — 16.9MB)

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Filed Under: Improve, Podcasts, Process Window, Reflow Tagged With: AOI, BGA, BGA Profiling, ceramic packages, cost-based tools, electronics manufacturing services, energy efficiency, flip chip, maximize throughput, Process monitoring, Process Window, profiling, profiling software, Reflow, reflow oven, reflow ovens, reflow process, reflow profiling, SMT, SMT and standards, SMT Reflow, soldering, SPI, surface mount technology, Thermal Management, thermal process, thermal profiling, thermocouple attachment

Increasing Reflow Oven Throughput

November 6, 2009 by Profiling Guru Leave a Comment

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2009 Presentation at SMTAI San Diego on how to increase reflow oven throughput without sacrificing quality profiles in the process.  After you watch this 3 min video you will learn an easy method of increasing throughput on your reflow oven for a particular profile in 20 mins or less.

To view the complete video series (click here).

To subscribe to my Podcast for iTunes (click here).

https://profilingguru.com/podcasts/Increased_Throughput.m4v

Podcast: Play in new window | Download (Duration: 3:00 — 13.6MB)

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Filed Under: Improve, Podcasts, Reflow Tagged With: cost-based tools, efficiency, electronics manufacturing services, profiling, profiling software, Reflow, reflow oven, reflow ovens, reflow process, reflow profiling, SMT, SMT and standards, SMT Reflow, surface mount technology, Thermal Management, thermal process, thermal profile, thermal profiling

Getting your Profiler Deeper within Specification

November 4, 2009 by Profiling Guru Leave a Comment

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2009 Presentation at SMTAI San Diego on how and why you need to drive your reflow profile deep within specification.  After you watch this 8 min video you will never take profiling for granted again!

To view the complete video series (click here).

To subscribe to my Podcast for iTunes (click here).

https://profilingguru.com/podcasts/Deeper_in_Spec.m4v

Podcast: Play in new window | Download (Duration: 8:10 — 39.9MB)

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Filed Under: Improve, Podcasts, Process Window, Reflow Tagged With: cost-based tools, efficiency, electronics manufacturing services, profiling, profiling software, Reflow, reflow ovens, reflow process, reflow profiling, SMT, SMT and standards, SMT Reflow, surface mount technology, Thermal Management, thermal process, thermal profile, thermal profiling

What to do with Zig-Zagging TC Readings?

November 2, 2009 by Profiling Guru Leave a Comment

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What’s wrong with this picture?

Profile Lose TC

Well if you have ever used Kapton tape to attach a thermocouple, you have certainly seen your share of profiles like this!

So what, it is a perfectly good profile, right?  Yes, but no.  I had a customer who was using KIC’s Navigation (auto prediction) to help create a better “deep in-spec” profile.  The only problem, they were trying to optimize on a TC reading that was bouncing literally all over their PCB.   Navigator is an awesome tool, but it can only work with what you feed it.  If you feed it garbage, it will give you garbage.  In their case, it was trying to find them a new solution where literally every time the board was run the bouncing TC that was attached (or I should say was not very well attached) with Kapton was giving false readings.    Navigator would give a different solution based on what the TC was reading at that given time.   It is like try to put post-it notes on the ocean.

Solution is very simple, eliminate the TC reading from your graph.  You can easily do this with the profile you just ran.  Look what happens, you go from a far out-of-spec of 126% PWI to a far in-spec of 48% PWI.

Profile Lose TC2

So you saved your hard work this time, but you are after all one thermocouple reading short.  You added that TC to your profile for a reason.  Next go around, do yourself a favor and use a better material for attachment, such a conductive double side aluminum tape, which by the way, a recent study from RIT proves it a superior attachment method aside from sticking to your PCB much better.

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Filed Under: Improve, Measure, Process Window, Reflow, TC's Tagged With: cost-based tools, efficiency, electronics manufacturing services, profiling, profiling software, Reflow, reflow ovens, reflow process, reflow profiling, SMT, SMT and standards, SMT Reflow, surface mount technology, Thermal Management, thermal process, thermal profile, thermal profiling

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