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

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SMT electronics assembly manufacturing forum.


Nitrogen for reflow

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#63955

Nitrogen for reflow | 17 March, 2011

I did some investigating and it seemed that getting a reflow oven with an inert atmosphere could be the answer to the inconsistant wetting issues that we are having with a leadfree DFN-10 on one of our products. Here's my question(s). It seems that creating an inert atmosphere for reflow requires a bucketload of gas. Is the benefit enough to outweigh the cost of gas? How do you have the gas supplied, generator, portable tanks, permanent tanks or some other means? We're currently tweeking the stencil and thermal profile to see if that helps, just wondering how anyone reflows using N2 w/out major cost factors. Thanks, Shannon

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#63959

Nitrogen for reflow | 18 March, 2011

First thing try a different solder paste. All solder pastes are not created equal. Also if everything else on the board looks good then check the part. As far as nitrogen goes its about 4 bucket loads you need an external tank. I have seen some marginally better results with lead paste. I have not been able to see the difference on lead free it looks the same to me. It should be noted that because of the expense a lot of places start turning down the nitrogen flow until it probably is ineffective so it’s hard to tell.

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rem

#63963

Nitrogen for reflow | 18 March, 2011

I agree with the comments below. I see no difference with lead free. Across five reflow ovens our external nitrogen tank was about 14' tall and 7' round. I am with a different company now due to the great ole american "lets send product out of the country", but where I am now, I don't use nitrogen at all. I am using Indium 8.9. lead free.

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#63967

Nitrogen for reflow | 20 March, 2011

We have a Nitrogen Silo. Your going to want to be careful if you decide to use nitrogen, not only are the levels unstable most of the time but it can also cause your components to tombstone like crazy, especially if you run a lot of LED's. We run 24/7 about 150-200thousand panels a week. 99% of the time we turn the nitrogen off. I would suggest looking online to see which recipe you should use in your oven. Try a couple diff reflow profiles first.

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#64101

Nitrogen for reflow | 6 April, 2011

I have done the same thing. We are changing over to the Indium 8.9E solder paste. It prints great and the joints look great. Does not look like a lead free alloy. We have turned off the nitrogen.

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