Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.

Profile board usage

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Profile board usage | 25 October, 2007

Is there a standard to specify how many times a profile board can be used? if No, then could I say that it depends on the actual board appearance (discoloration,delamination etc.) then it's time to replace a new one. Thanks in advance for sharing.

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Profile board usage | 25 October, 2007

It's all by feel and looks. Too many variables to tell you exact number of times. Most profile boards are set up to perform initial profile and then repeatability at a set period after that. So changing boards will alter the t-couple and skew your repeatability. I have one that's 8 years old and goes through several ovens every month. If you need something that is very robust and just needed for repeatablility, think about a ceramic board. Use your original profile board as the initial set-up, then run the ceramic board. Now you have the correlation between the two boards and can use the ceramic one for a long time - if you don't break it.

But since there is a reply now, I'm sure someone will counter point and say there is a standard that specifies a board can only be sent through the oven 18.675 times.

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Profile board usage | 31 October, 2007

I only ever change board when the board layout is changed. I too have boards that are, well, not so pretty. but they work for profiles. Wayne

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Profile board usage | 2 November, 2007

Is your data scewed in any fashion? If not the board is fine. If the cosmetics are an issue, write a procedure to have them changed out based on the criteria you choose (testing results, cosmetics etc.). This will be essential if your company is ISO certified or equivilant. I think the gentleman who suggested the ceramic boards should cure your problems...

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Profile board usage | 9 November, 2007

Thank You Guys for all your input.

The reason I raised this case that it was our customer challenge us on the physical outlook of the profile board rather than its functionality no matter the profile curves looks good. Yes, we have a procedure to describe that in every 'nth times used we have to replace. but, in many cases before we reached to that point the board already looks very bad and it's no joke to make a new one everytime based on the cosmetic appearance as the pcb and components itself are pretty expensive. even, we are allowed only to use the actual board and component.

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Profile board usage | 9 November, 2007

I am in the R&D department at KIC. We have been making thermal profiling equipment for 20+ years. A standard circuit board is made from FR4 fiberglass. A typical solder reflow profile, whether leaded or unleaded, takes the board above the "glass transition temperature" of the FR4. This causes the board to lose a little mass each time it is profiled. Boards that have been run many times will be significantly lighter and will have different thermal properties. I suggest you compare the weight of the profiled board to the weight of a fresh one. If the difference is more than 5%, it is probably time to make a new golden board. I noticed a lot people recommending ceramic boards which do not get lighter over time. PCK

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Profile board usage | 10 November, 2007

Well now.......there you have it.

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