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Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.

Topside Heat on Board

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Topside Heat on Board | 29 May, 2006


What method does everyone use for measuring the heat on the topside of the board in a Wave- we are currently using temp stickers. If the Flux is activated at between 110-120 degrees Celcius does this mean that the topside should read around 90 degrees?


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Topside Heat on Board | 30 May, 2006

Temp stickers work fine but a temp profiler gives you more useful data. The topside temp depends on the type of flux you use Look at the flux spec sheet or ask your flux supplier.


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Topside Heat on Board | 30 May, 2006

Howdy Marc, Check with your flux vendor, they should have a data sheet with what you need. Baring a wave rider or other profiler, I use a laser thermometer (They're cheap.)and It gets me close to where I need to be on our assemblies. I usually check after preheat 1 and after preheat 2. For example I use Kester 920CXF and they recomend a top side temp of between 180F-220F. Hope this helps. Jay

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Vince Whipple


Topside Heat on Board | 2 June, 2006

Marc, Topside temperature is one of the most critical parameters for a successful solder process. Temp stickers are OK to use but won�t tell you the temperature in tight areas. The temp gun like Jay suggested is what I use as a quick indicator. (Raytek MT is the one I have and cost me about $50)

The temp that the flux manufacturer is referencing is a reading taken just before the board makes contact with the solder. So your 110-120 degrees is just before the solder contact and the reading is on the top side.

As Patrick said, the best tool to use is a profiler. It works by attaching thermocouples to your board at multiple areas and then gives you a picture of temp over time for each location. The following is a link that shows the profile output from a profiler:

(or you can get an idea as to delta t by using the 2 readings like Jay does and then doing the math. If you have SMT, get a profiler though.) In our training classes we recommend the use of a profiler regularly and the temp gun for quick checks. And I can�t stress enough how important the temperature is to a successful process; especially for a no clean process!

Good Luck, Vince Whipple, Sono-Tek.

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