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Selective solder N2 consumption

Selective solder N2 consumption

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Hey all, We recently purchased a second hand EBSO SPA-400 se... - Aug 24, 2020 by kyleh04

yes Once I was using dewers of liquid N2 and recommended swi... - Aug 25, 2020 by Stephen

On a small, single stage RPS machine I was going through a d... - Aug 25, 2020 by dontfeedphils

Yes, this consumption rate is normal for a high purity N2 pr... - Aug 25, 2020 by LarryD

We didn't use the machine regularly. The dewars would only b... - Aug 25, 2020 by Stephen

I agree with the other posters. A bottle will last a day top... - Aug 26, 2020 by DWL

Great! Thanks a lot for the help Definitely nice when everyo... - Aug 26, 2020 by kyleh04

One thing about liquid N2 is while it is safe, only let trai... - Aug 26, 2020 by Stephen

I hacked machine to only spend nitrogen when solder pump is ... - Aug 31, 2020 by bukas

> I hacked machine to only spend nitrogen when <BR... - Sep 03, 2020 by kyleh04

i did it like this. red wire form Y1 valve is connected by r... - Sep 04, 2020 by bukas

kyleh04

#85511

Selective solder N2 consumption | 24 August, 2020

Hey all, We recently purchased a second hand EBSO SPA-400 selective. Other than the normal pain of a used machine, everything seems to run OK. We ran some preliminary tests, with really bad results. There were tons of shorts and icicles. The only nozzles that we had were these really big jet nozzles.

We just received some proper smaller wetables, and are hoping that will solve most of our issues. I do have a concern with the N2 consumption however. The machine is spec'd to use 1.5m3 per hour. Our biggest bottle we can buy (compressed N2, not liquid) is around 300 ft3. 300ft3 is 8.5m3. Each bottle of N2 costs us around $80.

At this consumption rate, we would go through over a tank a day. Is this normal? When we were doing our testing, we only used around 0.25m3/hr due to a limitation of our flowmeteter.

So, is this an expected rate to use, and could too little N2 cause our defects? I know people suggest using generators to save costs, but I hear a payback period of a little over a year. At this rate, we would go through a lot more than the cost of one in a year.

We are using lead-free SAC305.

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Stephen

#85512

Selective solder N2 consumption | 25 August, 2020

yes Once I was using dewers of liquid N2 and recommended switching. I tried using air to the machine so the sensor would let the machine run. Boards went from good to a two inch icicle covering a large area. We went to a wall mounted single stage filter at 99.9% (IIRC). I could see the difference going to a lower N2 purity. But the boards were ok. Here we have a 2 stage generator that we use for our conformal coating machine. You will want a two stage generator. They can generate a higher purity with less input air.

And technically it is too much oxygen, not not enough N2.

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dontfeedphils

#85514

Selective solder N2 consumption | 25 August, 2020

On a small, single stage RPS machine I was going through a dewar (not sure on the capacity differences between what you're using and a dewar) every 6-9 business days running normal 8 hours shifts.

Side note, I'd suggest trying out SN100C alloy over SAC305 for many different reasons.

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LarryD

#85516

Selective solder N2 consumption | 25 August, 2020

Yes, this consumption rate is normal for a high purity N2 process. We switched to a generator and had a payback of about 7 months. The bigger improvement than cost reduction though was in process consistency. When we were switching bottles we were also making program changes to reduce defects. What we didn't know is that this was really due to variations in N2 purity not a machine or process problem. Once we started using the generator these changes completely went away and the process is much more stable.

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Stephen

#85517

Selective solder N2 consumption | 25 August, 2020

We didn't use the machine regularly. The dewars would only be good for a month or two whether you used it or not. The nitrogen evaporates and discharges. The first day we forgot to warn afternoon shift. As far as I know nobody had to change their pants.

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DWL

#85526

Selective solder N2 consumption | 26 August, 2020

I agree with the other posters. A bottle will last a day tops, A dewar should last a week or two. Dewars have a limited shelf life as the liquid nitrogen will vent even if your aren't using it. My experience is with ACE machines.

Bottles are really only good if you only run your machine few times a month. Dewars are cheap but kind of a hassle. if you only need nitrogen for one machine, a generator might pay for itself pretty quickly.

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kyleh04

#85528

Selective solder N2 consumption | 26 August, 2020

Great! Thanks a lot for the help Definitely nice when everyone is in complete agreeance. I do think going to liquid nitrogen, then a generator makes sense. Currently we aren't planning on using the machine daily, so we'll probably hold off until we are utilizing it more frequently.

On a good note, we did tsome test boards yesterday, and they turned out absolutely perfect! We had a new wetable nozzle, used the correct amount of nitrogen, and also tuned the preheat time. What a difference having a proper process makes!

Couple of follow up questions:

1) The SAC305 is what we had in the pot, and have addition wire for it. (We did an analysis on the solder, and it is acceptable). I do hear a lot about SN100c for selective. Are the main reasons cost and less likely to eat away at the pot? I assume we will switch when we use up what we have here.

2) What are some brands/models for the N2 generators? Also, some ballpark pricing if you know that as well.

Thanks!

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Stephen

#85530

Selective solder N2 consumption | 26 August, 2020

One thing about liquid N2 is while it is safe, only let trained personnel near it.

I believe if someone got their hand frozen on the side, it is not coming off until the dewer is completely empty and warmed up.

And make sure management understands that the dewers go empty on their own and will probably take a day to deliver.

The nitrogen generator we have is from 1clickSMT. It works well, we currently use it on our conformal coating machine after we got rid of the selective solder machine we were using. No idea for the cost but not hugely expensive.

Compressor companies are also making nitrogen generators but so far those are nowhere even close to what you need.

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bukas

#85552

Selective solder N2 consumption | 31 August, 2020

I hacked machine to only spend nitrogen when solder pump is on, this made about 80% save when you count in frame change, fluxing and operator slacking

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kyleh04

#85591

Selective solder N2 consumption | 3 September, 2020

> I hacked machine to only spend nitrogen when
> solder pump is on, this made about 80% save when
> you count in frame change, fluxing and operator
> slacking

Hah! I was thinking of doing just that. What'd you use to trigger the solenoid? The pump relay?

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bukas

#85600

Selective solder N2 consumption | 4 September, 2020

i did it like this. red wire form Y1 valve is connected by relay when pump is started.

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