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

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Nozzle size

Tony

#21436

Nozzle size | 6 September, 2002

Question: I am going to start placing 3mm x 3mm plastic smt leds and want the absolute lowest errors caused by the nozzle either dropping or allowing the part to shift. Would a 2.5mm nozzle be too big for the 3mm part. My logic is that the more surface area the better but would I be better off with a smaller nozzle?

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Stephen

#21510

Nozzle size | 12 September, 2002

What type of machine are you using? We have a panasonic MPA placing LED's. I would have to check which nozzle we are using. Despite the odd shape we don't have problems with them. And don't forget that parts can shift in the oven. Usually for the better but not always.

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Tony

#21511

Nozzle size | 12 September, 2002

I amusing a Fuji CP3. The part data seems to be the easiest part for me, 3x3 square. I went with the 2mm and had LOTS of dropped parts. A 1.3mm worked MUCH better, between 1 and 2% loss. My only problem now seems to be profiling the oven. The specs on the leds calls for a very tight profile. Well..... never a dull moment.

Thanks for the response, I can always use the opinions of others.

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Stephen

#21512

Nozzle size | 12 September, 2002

It's been years since I worked with a Fuji. I only once resorted to the undocumented part class 255 (or whatever they call it) and that was when I was working midnight shift. The smaller nozzle working better than the larger nozzle makes me wonder about the pocket size in relation to the component. I've seen components with lots of room to move around. At one place, with a certain component, when the operator had to change that part she would shake the available reels, and not use the loudest ones. Don't know if dayshift also did the same or if they got stuck using the reels with the oversize pockets. (actually smaller parts) I believe there is a standard for such things, and if anyone could point us in the right direct, I would appreciate it. Also what about head speed? Have you played with slowing it down. I'm trying to remember do you have control over nozzle up and down speed on a Fuji CP?

How many zones does your oven have?

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Tony

#21513

Nozzle size | 12 September, 2002

There seems to be less play in the pocket than with other parts i've loaded. I was assuming the large nozzle would work better but for reasons unknown to me it didn't. I also tried a 1mm and had parts all over the machine (can you say hand place 100+ leds). The 1.3 is working fine. I slowed the cam to 50%. That may bee too conservative but considering the cost of the parts I would rather start way low and work up after the bugs are worked out. Who knows, I might just stay at 50, It's not like I have many other jobs right now....

I use a BTU HPI5 with 10 zones. I can work out a good profile that falls within the specs on a blank board but I know when I place a black board, 315mm X 175mm in the oven loaded on one side with 45 misc parts and the other side with 770 leds, the temp on those leds is going to be WAY different than the surface of the blank board.

Do you think if I put a thermocouple on the under side on an unbaked led loaded board it would give be a fairly accurate reading? Would it be better or worse to put the thermocouple on the led side on the very edge (as not to disturbe the unsoldered leds)? The company I am buiding these for want the temps recorded like every 2 hours to ensure we stay within the limits. What a pain.

Unfortunatly I am the only employee in the SMT department and so one else in the company knows much about the technology at all. This forum and general net hunting is about the only way I can learn this stuff.....

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sales

#21514

Nozzle size | 12 September, 2002

Hi Tony, as you might guess, a Nozzle Mfg. has stepped into this conversation. Having worked with many small, mid-size, and Fortune 500 companies for almost 15 years we have seen many "parts" pick up challenges. We were the first to offer "Compliant" tips for Fuji nozzles, others have followed of course. We would suggest looking at using a tip with the "Compliant" or "O-ring" type of tip making your parts pick with minimal errors. And yes...we can help you with that. Visit our website at http://www.nozzlesupply.com. We also offer custom/special nozzle services as well as "re-tipping" and Windmill repair. thanks, hope we can help you... NSC(Nozzle Supply Company)

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Stephen

#21532

Nozzle size | 13 September, 2002

I guess no one at ECD reads this forum. They make a clip-on thermocouple prob. Where I used to work we had 3. At first I thought they were very awkward to set up. But once you practise a bit and get used to the right hand thread tightening screw in left hand thread sleeve, it's easy to set up. they are a bit pricey but it sounds like they will be well worth it to you. Usually I would reflow a board, then clip the probes on and send it through the second time. It sounds like you might need to get permission to do this. I am assuming you won't have a populated scrap board to use. Occasionally there would be tension on the probe and the component would get shifted in the oven.

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Tony

#21535

Nozzle size | 13 September, 2002

Hey Thanks! Yep, they are pricey but I think it would be a worth while expense to safegaurd $250,000 worth of leds! I will tell the powers that be and see if I can squeeze out some cash.

If I scrap one loaded board could I use it for profiling 20 to 25 times. I know the board would be usless but would the temps be an accurate representation of a board reflowed once?

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