Board Profiling

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I have a question to pose for all of you. We use BTU TRS ove... - Oct 18, 2002 by Sr. Tech

Sounds like you are a CM. In that case, I would suggest tha... - Oct 18, 2002 by monkey

I agree with Monkey. We are a CM and profiling is a way to C... - Oct 18, 2002 by mike m

Many times the board may look the same but incases there cou... - Oct 18, 2002 by CAL

The world of the CM isn't alway's a happy one and the proble... - Oct 19, 2002 by JohnW

Sr. Tech

#22009

Board Profiling | 18 October, 2002

I have a question to pose for all of you. We use BTU TRS ovens for all of our SMT reflow. Anyone that has had any experience with these ovens knows that they are large and the have a lot of " thermal mass" Which means to me that they are very stable even when loaded up.

My question is: Should it be necessary to profile every single new assembly that comes in the door? I have been able to demonstrate time and time again that if you take a very thin lightly populated board and a very large thick densely populated board the profiles are almost identical. But some people insist that every board has to be profiled.

What are you experiences with this ? Should I profile everything. It just seems like a waste of time to me.

Thanks in advance.

Sr. Tech

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monkey

#22020

Board Profiling | 18 October, 2002

Sounds like you are a CM. In that case, I would suggest that you do profile every new product that comes through the door as a way to cover your a** to your customers.

In the offchance that your customer requests to a see a copy of your oven profiles for their product, you'd best have one on hand to show them. Paperwork paperwork paperwork...

It's true that oven profiling is redundant for pcbs of similar densities, but necessary as a way to prove that you are using the ideal process for the product. And really, profiling doesn't take that much time - run a quick one during shift change and you're all set.

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mike m

#22027

Board Profiling | 18 October, 2002

I agree with Monkey. We are a CM and profiling is a way to CYA. If we allowed operators to make decisions on when to and when not to you could end up in a bad spot.

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CAL

#22035

Board Profiling | 18 October, 2002

Many times the board may look the same but incases there could be subtle differences that could cause your process to go out of process limit. With boards that look alike you still need to consider: Solder paste (Is key to the reflow profile) component density multi layers (including ground planes) board composite (fr4, teflon) and even color.

I agee with the "Profile each board" concept

Cal

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JohnW

#22044

Board Profiling | 19 October, 2002

The world of the CM isn't alway's a happy one and the problem is that some one else is alway's paying your wages, that soemone else beign the customer so you really have to do what they say. The board profilign one is a constant one round our place and with customers from time to time as well. We take the approach that you need to profile every card, why?, well a lot of it is the good old CYA but what CAl say's is also true. I have 2 cards at the moment from the same customer, they are the same base material, same size even use 95% of the same components and weigh almost the same. Thermally though they're totally different because inside one has 10 layers the other 14, one has 3 ground planes, the other only 2 and one of them is more biased to 1 half of the card and so forth. I think you can safely have band's of starting profiles but you do need to tweek each one to fit the card your doing.

John

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