What to do with Zig-Zagging TC Readings?

What’s wrong with this picture?

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 profile.  You can easily do this with the profile you just ran.  Look what happens, you go from a far out-of-spec profile of 126% PWI to a far in-spec profile of48% PWI.

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.


‘Hot’ Blog!

Today we added a link to ProfilingGuru.com, a new blog launched by the good folks at KIC Thermal. As the name suggests, the blog — and it’s really more informative than that — covers tips on profiling.

You may recognize the names behind it: Mike Limberg, who has been kicking around our industry for some 20 years between Intel, Seika USA and KIC. He estimates he has worked on on hundreds, if not thousands, of production lines.

His partner in crime is the funny and energetic Brian O’Leary, Americas Sales Manager at KIC. Brian has worked for KIC and Sono-Tek, and the pair teamed up on the recently published 2009 Profiling Guide, an entertaining and informative guide for the reflow process.

Check it out.