Electronics Assembly Knowledge, Vision & Wisdom
Are Gloves Required for PCB Handling?
Are Gloves Required for PCB Handling?
How important are gloves when handling circuit boards prior to wave soldering or reflow soldering? The Assembly Brothers, Phll Zarrow and Jim Hall review the topic and provide insight.
Board Talk

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Board Talk is presented by ITM Consulting
Phil Zarrow
Phil Zarrow, ITM Consulting
With over 35 years experience in PCB assembly, Phil is one of the leading experts in SMT process failure analysis. He has vast experience in SMT equipment, materials and processes.


Jim Hall
Jim Hall, ITM Consulting
A Lean Six-Sigma Master Blackbelt, Jim has a wealth of knowledge in soldering, thermal technology, equipment and process basics. He is a pioneer in the science of reflow.
Transcript

Phil
Welcome to Board Talk. We are the Assembly Brothers, Phil Zarrow and Jim Hall of ITM Consulting, and we're here to answer your questions on SMT processes, equipment, materials, procedures, and anything else you have on your mind. What have we got today, Jim?

Jim
We've got a question about printed circuit board handling from Bob W. in San Diego, California.

At present, our operators and technicians do not wear gloves when handling PCBA's. Now I heard that this is not a good practice and we will get in trouble. How do you guys weigh in on this issue?

Phil
Weigh in on this issue? Where's my soapbox? Bring out the soapbox. Here we go. Weigh the issue? Oh, man. Okay, calm down. Okay, here we go.

We consider best practices, in other words something that should be employed world class, that anyone coming in contact with a board assembly, prior to final soldering, should be wearing gloves or finger cots, period, no exceptions.

Jim
That means even the quality assurance supervisor who comes over to look at a board, don't just pick it up off the rework table. Put on gloves or finger cots.

Phil
The reason for this is because your fingers have oil and dirt, what we commonly call contaminates, and these can be transferred to the board and the result will be poor wetting, weaker solder joints, voids, and a host of other fun things.

Jim
Remember they're contaminates, and fluxes in your wave soldering machines do not reliably remove contaminants. If you get contaminants on those soldering surfaces, you're asking for possible problems.

Phil
You would think this would be common sense, yet per our audits the manufacturers who are actually doing this are in the minority. Most manufacturers really can't seem to be bothered. I don't know if it's bother or what else do you think, cheapo?

Jim
Cheapo and they're not tracking their defects. The same thing we talk about all the time. That was no joke about a quality control manager coming over after the first side of double-sided reflow and picking up a board to inspect it to show us something with her fingers touching the bottom side of the board which was then going to be flipped over and stencil printed and reflowed.

Phil
We see this kind of nonsense in CEM's and OEM's, alike, but probably one of the most important pieces of industry lore comes from our good buddy, Terry Munson at Foresight.

In a previous life, when we got to know Terry way back in the days of yore, he had established himself as the contamination and cleanliness expert at a very large, metropolitan automotive electronics company.

Terry conducted a very interesting test when he was at this company. What he did was he made various cleanliness and contamination tests on circuit boards built on a line and he conducted a run of tests on the boards produced on the morning shift.

Then, using the same line, same boards, same materials, same product, and same operators, he basically tested the same cleanliness examination test on boards built after lunch.

This is something that came to be called the Lunch Hour Effect because what Terry observed was that the levels of contamination on boards built after lunch went up by several magnitudes and again, for the obvious reasons.

People don't always practice best hygiene. Probably this is the same reason you shouldn't eat peanuts in a bar, but in this case, it's something that gets transferred to your boards.

The number of people that are actually using gloves and finger cots are far and in between. This is a practice everybody should be doing and people feel, "Well, I'm getting adequate results."

But again, the question is, are you getting zero defects? We believe that over time, as Jim mentioned, if you're actually tracking your defects and you employ this practice, you will see an improvement. I can guarantee it and, of course, Terry's data backs that up, too.

Now, of course, if you are wearing gloves and finger cots, wear them properly.

Jim
We've seen some seemingly unbelievable things, particularly in rework areas, where people wearing their gloves have cut out the fingers where their fingers touch the board in order to get better feel and control over handling the boards, defeating the exact purpose that they're wearing gloves for in the first place.

This doesn't speak much to the training integrity of that kind of facility because people are wearing gloves but they obviously have no perception of why they're wearing them.

Phil
Which underscores another important facet that you should not only tell people what to do, you should tell them why they're doing it. Knowledge is wonderful and knowledge is power.

Reader Comment

Total disregard for ESD concerns is a major fault in this dissertation. Gloves are a problem as they create a barrier to ESD grounding. With due respects to Phil & Jim , you are overlooking the factor of an insulated surface in contact with the PCB.. A properly grounded operator may add oil, etc to the PCB but once the cleaning process is completed this is a non issue.. ESD damage is not.. The damage can be latent or catastrophic created by the operator wearing insulated gloves.. I think the brothers need to expand their concepts of what can cause PCB damage.

Jerry Karp
Reader Comment

There is no doubt in my mind that quality companies making quality products must, must, must use gloves when handling their PCBs. Terry Munson is absolutely correct: contamination kills PCBs, and there is no contamination more troubling than fingerprints. Consider the fact that there really are only three types of contamination. There are (a) organic contaminates like grease and oil, (b) inorganics like the corrosive halites in fluxes and the salt in persperation, and (c) insoluble particulate like fine dust or hair. Fingerprints are the only common source of contamination that contains all three types.

This makes removing fingerprints a challenge, so it is far better to simply never let them get on the boards to start with. One additional reason this is a compelling issue is because most boards today are made in "no-clean" environments. Obviously, any fingerprints left on the boards will remain to cause corrosion and other problems for months or years to come. Modern solvent cleaning systems can remove fingerprints expeditiously - unlike aqueous systems - but for many boards the expense of cleaning can be avoided by simply using inexpensive gloves and changing them often. It's the old "ounce of prevention" theory.


Mike Jones, MicroCare Corp.
Reader Comment

I would not use a company that did not enforce the use of truly ESD-safe nitrile gloves when handling room-temperature CCAs.

Period. The story about ESD gloves being 2kv generators is completely false. Obviously the operator was not grounded, or the gloves were not truly ESD safe. I have tested many gloves and found several brands that were excellent, assuming the operator is grounded also (wrist strap/foot strap or both when seated).


Richard Stadem, General Dynamics Mission Systems
Reader Comment

The gloves are good for the PCB before the reflow. However, the contractor have taken your words and changed the last 35 years their experiences on chip and wire assembly line from this year! You know what, all kind ESD damages to the GaAS based devices due to ESD gloves.

It has been tested that over 2KV ESD voltage is generated when a finger touches a PCB even the operator is perfectly grounded. As the matter of fact, it has been documented the ESD glove is number 1 ESD killer among 23 SED damage causes, http://www2.evaluationengineering.com/archives/ArchiveWrapper.aspx?file=1102esd.htm.


River Huang, WanTcom Inc, USA
Reader Comment

In our company (Schoeller - Electronics GmbH, Germany), we have been producing PCBA's more than 40 years for various applications. (Medicine, Aircraft, HF Applications) During this time, we had problems with fingerprints on sensitive inner layers or flexible base materials that have been adversely affected during the production process.

Very sensitive surface finishes (ENIG / el.Silver / el. Thin) need to protect against Fingerprints. For this reason, Schoeller- Electronics GmbH employees need to use rubber gloves when they are handling PCBA's or part of them.


Ralf Barth, Schoeller- electronics GmbH, Germany
Reader Comment

I work in the mobile phone industry and we have been wearing gloves for about 10 years now. At first, we hated the gloves as they were very uncomfortable. We tried various types/styles of gloves, and in the end, the whole industry agreed on the same glove.

Cotton Gloves are useless as the glove needs to fit the hand for comfort and usability - so it must be flexible. Plus for phones, gloves must be ESD Safe.

Our gloves are nylon/polyester mix with carbon filaments making them both comfortable and ESD dissipative. For grip, the finger tips are coated in polyurethane. No leakage of oils from staff to product. In summary, they are the perfect glove. But yes, of course you must change them regularly. And you must follow IPC rules on PCB handling whether you wear gloves or not.


Lindsey Robertson, SBE (UK) Ltd, UK
Reader Comment

I too support board handling by the edge only, gloves not required except for HSE barrier protection for the operator using past/flux.

In places I have seen gloves used they are not replaced at regular intervals and hence are generally "Bogin" to use a Scottish term!


Matt N-stott, Scotland & China
Reader Comment

I have used many types of gloves within my job as a QA engineer/auditor as you typically wear whatever the site stocks. Well, I recently used gloves at a manufacturer that were wonderful. Cloth with rubber tips (I am sure more costly). Cloth...slippery, and sometimes transfer oils from the manufacturing site or body. Rubber...sweaty and can be too sticky and uncomfortable. Combined...marvelous, I wore them all day and was wishing I would have asked for a pair!! For what it's worth.

Les Beller, Echostar, USA
Reader Comment

Actually, I prefer to handle the boards by the edges. I've used gloves for stenciling - they seem to work best for me, but that's more of a health/safety issue to keep the paste off my hands.

But when loading & unloading the pick&place and oven, I've found that cotton gloves snag on board edges and rubber cots or gloves don't give good traction. In other words, if I were using gloves/cots I would probably be dropping a lot of boards. Just my 2-cents from actually running the equipment for many hours/days at a time.

I guess I also question how proper handling by edges could cause solderability issues on pads??? Seems to me good practice is good practice. Just wearing gloves isn't an improvement if they get dirty and you don't realize it.


Patrick Muldoon, JPD Controls, Inc
Reader Comment

When you recommend gloves, it reminds me of a study I did years ago where we noticed that eventually after a few hours use, human oils were saturating the cotton gloves and causing more defects than no gloves at all.

Cots, on the other hand don't allow oil to penetrate to the boards. So, if your going to recommend gloves, make sure they are not cotton, or change them frequently.


Gerry Cooper, Teledyne Printed Circuit Technology
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