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Handling PCB assy's

I am wondering what the general concensus is for handling PC... - Oct 30, 2002 by

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Dan

#22200

Handling PCB assy's | 30 October, 2002

I am wondering what the general concensus is for handling PCB's. Do bare hands pose a problem for PCB assy's? Should operators who handle boards wear gloves?

Thanks for your input.

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#22201

Handling PCB assy's | 30 October, 2002

Dan

Generally it is a good practice. If we are doing PTH type assembly or "low end" assembly I would probably not worry, but many board finishes today such as white tin, gold and OSP mandate special handling. Oils from dirty hands can cause soldering issues especially on um BGA's and fine pitch parts.

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CAL

#22207

Handling PCB assy's | 30 October, 2002

Doug is right contaminates can be transfered from hands to boards easily.

I also know gloves are a good practice as some times people wear moisturizers and hand creams that can also cause issues.

Another thought is that you do not want people handling the PCB's (solder) anyways as it can be absorbed through the skin causing Big issues. We used to be required to have lead tests once a year. (no Joke)

Cal

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dragonslayr

#22223

Handling PCB assy's | 31 October, 2002

I used to take required lead blood tests every 3 months and when the lead content rose high enough I had to work in another area of the plant, away from the lead. What lead is in my body will always be there and is a potential to cause of nerve damage and internal organ problems as I get older. Take lead contact seriously and prevent future problems for yourself. On the brighter side, I have enough lead in my blood that my pencil is always hard!

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#22228

Handling PCB assy's | 31 October, 2002

Whoa, I have (for a long time) been under the impression that lead can only be absorbed via the mucus membranes, not through skin as in the hands. Did I miss something?? Not that I behave would much differently, other than donning gloves whenever I even touch a stencil or the printer controls. I simply believed that if you only get it on your hands, and you scrub it all off, you're safe.

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#22229

Handling PCB assy's | 31 October, 2002

?....naaahhhhhhhh. Never mind.

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dragonslayr

#22232

Handling PCB assy's | 31 October, 2002

Steve- I was once an auto body repairman in an automotive assembly plant. We used lead for dent filler instead of bondo. It was much faster to use. No cure time like a plastic filler needs. Lead was absorbed through my skin from hand filing the lead smooth. I breathed lead particles that were in the air. I wore a paper filter mask but that only kept out the big chunks.

Once again, I encourage all to take great precautions when handling a heavy metal that will cause you health problems.

In SMT, wear ESD safe textile gloves at a minimum. Latex finger cots over the gloves is better.

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CAL

#22236

Handling PCB assy's | 1 November, 2002

Lead Links- Only a small amount of lead can be absorbed through the skin, but nonetheless can be. Any cuts, abrasions raise the risk significantly. Also remember lead can be present on the skin and ingested, again a high degree of concern. From these postings exposure through inhalation to the soldering process is a higher degree of concern.....Thus proper ventilation.

http://www.epa.nsw.gov.au/leadsafe/leadinf3.htm

www.epa.gov/lead

http://www.osha-slc.gov/SLTC/lead/index.html

http://www.atsdr.cdc.gov/ToxProfiles/phs8817.html

Anyway the bottom line....best to be safe and wear gloves. Now are the workers latex sensitive?

Cal

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kenBliss

#22242

Handling PCB assy's | 1 November, 2002

Based on this thread

Shouldn�t the handling systems allow the worker to do what is needed on the board during the stated hand operation so the worker has minimal direct contact with it.

Now for the non sales pitch, sales pitch. Doesn�t it make the most sense to use the tray handling system method to lay bare boards on as well as partially assembly as well as assembled boards. This allows the operators to touch the board only once while they take it off the conveyor and put it in the tray then they only touch the tray to move it around. when they need to do an operation to the board they can do that while the board is in the tray. Minimizing touching, minimizing esd damage minimizing handling. sounds to me like a much safer and better way to handle PC boards and reduce lead contact.

Do you all agree with my thought process or are you mad because it sounds a little like a sales pitch, hey, I did not even put a link to the website.

Ken Bliss

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RDR

#22244

Handling PCB assy's | 1 November, 2002

Ken, Is it really possible to load P.T.H., handsolder SMT apply glue or whatever when a board is in a tray? I am trying to get a visual here. I may not understand what types of trays you are talking about.

Please contact me offline to discuss. I am interested in hearing what you have to say or show.

Russ

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#22245

Handling PCB assy's | 1 November, 2002

I guess I just don't see how it would benefit us any. We rarely remove a board from the conveyor unless it's coming out of an oven. And why would you put bare boards on a tray? Why not into a destacker that feeds your line, so only the edges of a stack of boards gets handled? I can see more benefit in a batch system than an inline system.

Also, it seems to me that the number of direct handling step involved with transfering a board from a conveyor to a bench and back again is the same whether you put it on a tray or not, unless you remove it from the tray to put it on a bench, in which case the handling actually doubles. The only benefit I see is where it's protected by the tray during transport, which would reduce stress on soldered connections (if they've been reflowed) and reduce ESD concerns somewhat.

To answer your last question, I didn't think it was particularly sales pitch-ish, and I wasn't worrying about it.

It's Fri. 4:00p.m. and there's a Red Hook down the street with my name on it, folks. Have a weekend........

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Ken Bliss

#22246

Handling PCB assy's | 1 November, 2002

Hi Russ

I have customers doing all those things all the time in the trays, I would be glad to talk off line. I tried to email you but it did not work, please email me your phone number or call me.

Ken Bliss 510-490-8401 kbliss@blissindustries.com

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blnorman

#22251

Handling PCB assy's | 4 November, 2002

We manually handle boards all the time (repair, clean misprint solder paste, etc.). The workers know to handle with gloves, but it's a rarity that they do. We also use hand lotions in the plant, and a couple of times, lotion residue has shown up on boards. It's hard to enforce safety issues, when line supervisors are being hammered to meet production.

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CJN

#22255

Handling PCB assy's | 4 November, 2002

This is what pisses me off in this industry today. It seems the operators are in charge of the whole process. Management and supervisors are too afraid of lawsuits to lay down the rules and enforce them. If your procedure states and I am sure everyone�s does, that �Latex Gloves Must Be Worn Whenever Handling Solder-Paste� that does Not mean whenever the operator feels like it. If they do not listen, first offence verbal, second offence written warning and third offence show them the door. The procedures are there for their safety and mine.

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erikb

#22256

Handling PCB assy's | 4 November, 2002

As a rule handling PCB's with bare hands is acceptable provided that there is sufficient esd protection as well. It is a good rule of thumb however to provide your inspectors or assembly people with finger cots or cotton gloves to keep the product clean. Finger cots and gloves must be changed if contamination occurs. Solderabitity can be a problem due to oils in the skin but generally speaking it is not a problem

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kenBliss

#22258

Handling PCB assy's | 4 November, 2002

Hi Steve

I understand your point, the comments on the thread of which are slightly off of the original posted question but it still is handling. Handling is handling. If you pick up a board from one conveyor just to put on another conveyor that is one issue, but most of the time in bare board as well as assembly if you take the board off the conveyor most people are doing something manual to it while it is laying on a bench. The tray concept is to lay the board on the flat tray right from the conveyor. then do any and all manual work on the board while it is laying in the tray. If and when it needs to go back on the conveyor you carry the tray over to that area and then pick up the board and put it on the conveyor. In my experience most people can fit 2-4 or more boards on a single tray very safely. You virtually eliminate ESD issue, Solder on your hands issue, minimal requirement to wear gloves etc etc.

Steve your quote �The only benefit I see is where it's protected by the tray during transport, which would reduce stress on soldered connections (if they've been reflowed) and reduce ESD concerns somewhat�

This alone is huge don�t you think, along with the other things I noted. It is just a better way to do things during manual processing and handling of PC boards.

Yes you can solder, glue, screw, snap together assemblies in the tray and one size pretty much fits all.

Ken Bliss

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blnorman

#22289

Handling PCB assy's | 6 November, 2002

I agree whole heartedly. Unfortunately in the different industries I've worked (garment, appliance, aerospace, and now electronics) this is a common issue. These procedures are in place for product reliability as well as safety.

I trained at the OSHA institute in Des Plaines and we looked at a press that had every known safety device on it. The instructor told us to take a good look, cause in industry, each of the safety devices will be disabled at one plant or another.

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