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Paste printing fine pitch components

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#71221

Paste printing fine pitch components | 12 October, 2013

Has anyone had success using a DEK Proflow printhead with fine pitch components (~.2mm pitch). I have been told that squeegees are the way to go for fine pitch. What other major factors play a role in successfully printing fine pitch. Print speed, paste pressure,stencil thickness,ect.

Thanks, gm

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#71225

Paste printing fine pitch components | 14 October, 2013

Hi,

1. the top thing here is the good stencil design. When you go to small apertures there are certain requirements you have to follow to design the right stencil. Your ratio should be > 0.5 if you use electroformed stencil or > 0.8 if you use laser cut. 2. Always use fresh paste 3. Uses the right printer parameters for your paste(for example Alpha likes fast release of the stencil from the board - in DEK this is called separation speed) 4. Cleaning cycle is very important - you should have a good clean after each board for fine pitch. On my DEKs I have the option for the cleaner to vibrate while cleaning- it is very useful.

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#71227

Paste printing fine pitch components | 14 October, 2013

Yes, I agree with Evtimov. It's more about aperature reduction and type than it is the type of machine. Aspect and and Area Ratio are very important. Take a look at this page I found on the internet http://www.qualiecocircuits.co.nz/stencil-technology-other-aspects.htm

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#71228

Paste printing fine pitch components | 14 October, 2013

Thanks for the replies. I have just ordered the IPC Stencil Design Guidelines manual.

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#71234

Paste printing fine pitch components | 15 October, 2013

See if you can get a sample of Dek's Nano Protek. We use it on all our fine pitch stencils. I'd say it's kind of like car wax for the aperture walls. They operators really like it a bug me every day to order more if we run out.

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#71238

Paste printing fine pitch components | 16 October, 2013

I heard it works well on Chrome Rims for your car too. Swag, I'm not at all suggesting that your operators have discovered this and this is why you keep running out and have to keep ordering it :-p

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#71248

Paste printing fine pitch components | 17 October, 2013

Hey SWAG, any idea where that Nano Protek goes, that you have to replace it? (and I am not talking about polishing up wheels) Is it being scrubbed off of the stencil during the print process, and over time it must be replenished?

Sorry a bit off topic, but your comment had me thinking... (yeah, I know, mark the time and date)

'hege

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#71249

Paste printing fine pitch components | 17 October, 2013

I've used the Nano Protek product in the past and it is fantastic, worth every penny for those small aperatures. It's just like a wax and yes it works great on rims ;)

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#71252

Paste printing fine pitch components | 17 October, 2013

But where does it go, that it needs to be refreshed or replenished on the stencil? Does that "just like wax" product wind up in my solder joints, no matter how small the percentage, and would it then qualify as a contaminant? I heard there are some (nano)coatings that are baked on during the production of stencils, and some are wiped onto the stencil by the end user. Those wipe on products I worry about just a little, as in, where does it go that it needs to be replenished on the stencil? I think that bears some thought. Maybe someone with expertise on these coatings can chime in, maybe recommend a white paper or something? 'hege

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#71254

Paste printing fine pitch components | 18 October, 2013

Hege,

the Nano coating goes on the opposite of the squeegee side of the stencil. I don't know if the cleaning paper is able to remove it little by little with the time, but I never refreshed my stencils with Nano coating and they work just fine. However I don't run big quantity products...

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#71255

Paste printing fine pitch components | 18 October, 2013

I believe it's mostly worn off through cleaning solvents and the slight abrasion during the under stencil cleaning process. I couldn't say whether or not it's ever in a state that would allow it to transfer to the PCB though.

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#71256

Paste printing fine pitch components | 18 October, 2013

Nano coating = Rain-X = Snake oil

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#71264

Paste printing fine pitch components | 22 October, 2013

Yes, car rims (and brass tubas)! You finally helped me get to the bottom of this expensive issue. We fired the culprit. It's the same guy that was using the ultrasonic stencil washer to clean car parts on night shift. It might be snake oil, I don't know - the guys swear by it. I don't think rain-x is snake oil because when I put in on my windshield, it makes it different although I don't know if the droplets of water coming off the windshield like stars at warp speed in front of the Starship Enterprise is good for equilibrium while driving.

We only use it one time per stencil. We are very high mix processing many new builds per week, many with fine pitch so that is why we go through so much.

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