ESD Practices for PCB Assembly and Repair

hi my name is Normand muir and welcome to this session on basic concepts of electrostatic discharge or ESD I am a master instructor for Jai standard which deals with process control 610 which deals with specifications on how everything should be placed on an electronic circuit board 77 11 21 rework and repair 620 wires cables and harnesses and sixty twelve which is board fabrication what we're going to be talking about here again is on ESD and it's basic concepts and what we need to know to protect our workspaces as technology has progressed in our world parts have gotten smaller and smaller because we want our equipment to do so much more look at the original cellphones they were called bricks very large items now look at them they're very small and we can do a lot more with them well in order for us to do all this we had to go from through-hole to surface mount so things have gotten smaller and smaller and that means more sensitive to a static electricity or any other unwanted electrical energy so we're going to talk about this and I hope you enjoy this says we're going to talk about here is the causes of the VSD strategies to minimize the SD operating procedures to minimize ESD in our workspace as a student you'll be able to define ESD and explain its causes will understand how products they handle can be damaged by ESD in our workspaces and will understand the consequences of not controlling ESD in our workspaces so this is what you're going to get out of the next 30 minutes to 45 minutes we're going to be talking about all this information and educate you better especially in your work environments whether it's a big facility like ours or even larger than ours or just two or three people in working in one area especially when you're working on cell phones because that's popping up everywhere and they're not aware of static electricity and we're trying to get you educated on that knowledge so what is ESD that's the first thing we got to define it's electrostatic discharge is the sudden discharge of static electricity energy between two objects the key word here was sudden but we can also talk about rapid either or it happens so fast that it's already done when you go and walk across that carpet and grab that doorknob you're discharging immediately okay it happens look at lightning another thing happens so quick you don't even know it sometimes you hear the noise and it's like you start looking for the lightning it has already occurred at nighttime it's more visible than it is before so we're going to be talking about these and the cause and effects so causes first one to objects rubbing against each other friction your hands rubbing together like this can cause static electricity remember when you were a child you grabbed that balloon you put it on your head and you rub it really hard and you put it up on the ceiling and it stuck that was the charges connecting to each other you got positive and negative charges okay so was connecting to itself but if you notice your hair started going up also the other one is two objects separating in today's world when we buy magazines you it's more prevalent there it's because the pages are stuck together you get a magazine it's about this thick but as time progresses and you start looking through it it gets a lot thicker almost double in size that's because these pages are stuck together with static electricity because it's going through that printing press so fast and then you're separating so you're creating that static electricity and here's another example of it here is showing up you separating tape it's a pretty neat little thing to see okay what happens here is many charges you got a high potential and you got a low potential so what is happening you get they're trying to balance each other okay so you got all this energy up here and very little down here so what it's trying to do is go to equal just imagine like in hoover dam you've got a dam here very large dam right then right behind me is all this water and then you look on the other side there's just a trickle going down through there or if I open up them flood dams what happens this water comes down this water comes up doesn't it well that's what you're doing here so you've got to be very careful about these high potentials and low potentials you want to keep everything at an even keel okay since the smallest electrostatic discharge the human body can feel is about 2,000 volts just imagine that you are generating minimum where you can feel and here it is 2,000 volts very very little didn't it you don't even realize that but like it says here we can generate over 25,000 volts 25 well we get electronics and components that operate less than 4 volts and you're hitting it with 2,000 volts or voltage that you don't not even aware of it can cause issues in the electronic circuits so you got to be very careful you got to be very cautious you got to wear a lot of not a lot you got to wear a smock like I am maybe a wrist strap some heel straps something to protect that environment and we're going to talk about some more of these things as we go along also so here is a nice example of electrostatic discharges as it passes through a circuit look at it it's eroded right here well hot what happened that energy came through there and it doesn't have to blow the circuit completely up it can degradation otherwords caused some damage that we call latent damage doesn't happen right here now that it's bad but as time progresses that energy keeps hitting it it keeps the roading at it and then guess what one day your cell phone doesn't work your game system doesn't work your television doesn't work these are the things that can occur from just as a little bit of damage just think of this as waters rushing through a little area and if it keeps rushing to it it stays the same but if I add more energy to it it starts your roading the side start caving in doesn't it well that's what happens to static electricity it's that same concept so consequences of not taking care of this is waste what do you mean by waste look at it higher product cost unhappy customers well how do I get all this it's very simple one you didn't use your ESD strap right you do something right you grabbed ahold of that circuit board coming off the line and you caused damage well guess what you've got to rebuild that board now or fix it so new board new parts oh that's man-hours that's equipment cost that's energy cost hmm higher product cost now because you're not paying attention oh I'm sorry you didn't get your product out on time because you had to rework it or fix it so now your customers not happy why because they didn't get the product on time we all know this if we have our cars worked on or anything like that we expect it back in a timely manner and if we don't what happens we get irritated with that customer don't we or how about at a restaurant when we order a food and it takes forever to get there and you sit there and wait and wait and your conversation and it's coming to a wall or your food finally arrives you're teaching because it didn't get there on time so that's what we're looking for so non-conductive materials data diskettes vinyl binders safety glasses we have to have them in our workspaces a lot of times but make sure that you wear them properly and that you wear your wrist straps and in a great environment to work in plastic pins how about highlighters a post-it notes these are a lot of things that we see in our environment and we got to be careful with Oh scissors we have to cut things once in a while so we've got to be careful with that also so this is what we're talking about all these items they're insulators oh we got to have our morning cup of coffee you know so you got to watch out for these in your environment because they can generate but they store static electricity too so you got to be careful with that conductive materials this is all your metal products right you got tweezers you got pliers in your work environment a part of your ballpoint pen is metal how about the conductors on the circuit board or metal nuts bolts and screws laying around or all metal what happens here is the energy passes through it it doesn't slow down and keeps on going it travels on and that's what we have there that is conductive materials partial conductors did you realize that you are a partial conductor you can store energy but it dissipates out too you stand up water and grab a hold of something electrical see if it doesn't pass through you to ground that's going to be a conductor right you've grabbed in a Christmas time or any other time grabbing a plug out of an outlet and slip and you grab a hold of the two ends while they're still then you get shocked don't you okay but you can store that energy to charge field what do we do here what do we mean charge fields how can we create a charge very simple is how do we avoid loose-fitting clothing what do you mean Oh remember that rubbing that movement that goes around okay that can cause static electricity or generate it keep PSD since advices at least 12 inches away from your clothing why because remember this moves around and stuff but I got the jacket on instead where materials made of cotton but remember if you're wearing cotton a lot of times people iron we'll have them start stuff well that defeats the purpose of the cotton and creating static electricity when I was in the Marine Corps that was one things you know you had to be pressed up really nice every day so we had to start our uniforms so they look nice and crisp well guess what we were defeating the purpose of a yes D program because our clothing is made of cotton so it can breathe a lot easier but that's what we have to do we're anti-static static dissipative shoes or heel straps when you're walking around in your work space will show you these later in the video wear wrist wraps when seated no unauthorized objects or materials inside the static free boundary remember what we showed you if they don't need to be in if you don't need that coffee cup in there don't bring it in there one of the biggest violators I see now is people with cell phones you become tech Sambas you have to keep in contact or somebody constantly why who knows it's just your mental thought now that's what you have to do okay iPod I got to listen to my music okay well what's that case made out of plastics okay Kenneth store static electricity yes so you got to be careful in your workspace again eliminate unnecessary non conductive materials inside the static your boundaries if they don't need to be there don't bring them in bottom line avoid friction producing activities brushing your hair wiping yourself off stuff of this nature these can cause static electricity so let's try to prevent them from our work areas humidity in ESD 30 and 70% we've got to watch out for these in accordance with Jay standard zero zero one you want to maintain between 30 and 70 percent in your workspace it's in section for the standard itself okay this is something I didn't make up they've got enough case studies to prove this anything below 30 percent in some companies it's complete work stoppage okay because what happens is humidity increases as static electricity increases as humidity decreases as humidity increases static electricity decreases very simple so you've got to start monitoring a below 30 percent because become point components become more sensitive because there's less moisture in the environment now when it's above 70 percent you've got to look at two is moisture sensitive devices a lot of the components that are made of plastics are very sensitive to moisture a prime example in our surface mount is one of the big ones is the chip capacitors moisture gets inside that ceramic little guy and when you hit it with an iron and as small as it is that that evaporates in other words it turns into a vapor that expands right it can care a core fracture the inner layers and you're not even aware of it Yury replace the part that won't even what caused it it was you hitting that iron with it and it happens just like that so be very very careful okay here's some of the examples look at these work at the worker at the bench walking over violin look at this vinyl car vinyl flooring 12,000 volt that's a lot of voltage coming to custody but as humidity increases the 65 to 90 percent look at it drop to 250 so you got to watch that humidity in our workspace how can we help prevent some of this in our workspace static-free solutions it comes in a lotion it comes you can actually get it as a towelette and you wipe everything out down a lot of people do it on a daily basis some companies do it two or three times a week it depends on what you want or they just alleviate all that and use these things called air ionisers and what this does and the good ones you want that produces positive and negative charge is constantly going out so what are you doing there can't be a high potential there can't be a low potential it's all got to be the same because you're constantly put in the same amount out there so it's keeping everything even now isn't it and air ionizers are great a lot of companies do use them draining off the charge how can we do this does this system work well that we have been talking about talking about that we're going to talk about wrist straps ESD mats are heel stuffs will this work well let me see works for conductors yes because you keep into the ground potential zero so it's straight shot to it partial conductors if I put a wrist strap on like I'm wearing right now that's part of my smock okay yes it works so non conductors air ionisers work well with it but if I just ground it mmm it could actually store it okay for a little bit of time especially like on our star foam cups and stuff like that hmm it's held in check draining off that charge okay how do we do that first off one of the easy ways I don't have to own a smock I can wear a wrist strap just like this and I put it on and it snapped into place right here and this in believe it or not would be attached to a mat this mat is something like this it's an esd-safe mat it's got a mesh barrier in its all to ground it's got a 1 mega ohm resistor in line with it and all I would do now it's just come over here and snap it into place something like that and then now I keep all my equipment materials on this esd-safe mat and then I don't have any issues whatsoever should not have okay that's another way to do it nice dissipating mats wrist straps but if I don't want to wear ERISA because if you notice this gets in the way a lot of times so companies will buy smocks like this one that has it built into it so all I have to do now is just snap it right here right there and then I plug it in now I can do whatever I want I don't have to worry about anything whatsoever because I'm at a ground potential of zero I can keep working in doing what I want like I said it has a 1 mega ohm resistor it actually allows you to dissipate it slowly not rapidly how often do we test it it depends on your company's requirements minimum is usually once a day and all you do is just plug it into a system and you test it no big deal with that I go to companies on prime example I was in Penang Malaysia teaching several years ago and to get in for their doors to open you put the plug the wrist strap into the tester and then do everything is right the doors open well believe it or not mine didn't work there's like how you rotate your wrist around and stuff and that could be intermittent issues but it still wasn't working so what I had to do is take this lotion that they have esd-safe lotion like a hand lotion type material and I wiped it all over my arms in my hands and I did it again guess what the doors open for me so that's what you got to look for stuff of that nature and a lot of companies there is companies out there to get in to work you have to do this get into that workspace like I just talked about you have to be ESD safe so these are one of their failsafe ways to do it ok wiggle the wrist up when testing again like I said it could be intermittent the heel straps these are great little items of interest okay they're nice okay got little velcro got a little tap and this goes around the foot your shoe fits into right into here just like so then you've got this this goes in between your sock and the and your shoe on the inside so you push this all underneath that moisture and everything will create a path and then you put this down there now you keep this is hitting the floor all the time okay as you walk okay very simple now one of the things about these that I see people doing a lot of times is they don't they take them they walk outside they take their coffee breaks they take their cigarette breaks or like today it's very nice out they want to take a little bit of a walk because it's getting off the wintertime spring is here feels so nice out there so what do they do they get dirt and contamination on here so now when you're touch walking on that esd-safe flooring is guess what it doesn't work it's not creating a path anymore so that's why you should never wear these outside or off an esd-safe floor now you can also instead if you don't want to buy these and use these you can also have esd-safe shoes they are available in the market okay says the smock is the next thing buttoned up completely - all the way buttoned up as you can tell they do come up higher if you want to buy that kind with the nice little collars and everything like that this says not rolled up you don't want them all the way up in here or over the top of your clothing because it's not protecting anything says contact skin or ground strap that's what you want it to do static dissipative protective materials the surfaces will absorb the discharge at a rate which will not harm it in other words it's just charges slowly you don't want it to happen too fast and that's what we're talking about so we've done that part no problems whatsoever now we've got a candidate and transport these things okay we have totes that we can use make sure they're completely closed and everything is inside of it they're nice clean and not dirty because dirt if you get this dirty and there's contamination on here it could actually create a path and guess what static electricity can get inside and cause damage so we want to be very careful with that okay bags that's what we're talking about - if we get this nice ESD safe bags how do we know that is very simple as our bag will indicate with some type of marking on it for this one here and I'll bring it up closer for you so you can see it as you can see right here that it says attention static sensitive device see it's got the little halo around it means that's protecting everything inside of it okay now when you're transporting anything around the area you should always put it inside the bag okay yeah this is a little bit larger bag than what you would probably normally use but you can put it inside of there fold it up make sure it's completely secured and now can be transported anywhere you want inside the facility or out to your customer it does not matter okay what a lot of them will do this is a static bag now you have your anti-static bags it's like this pink poly stuff okay it's used for cushioning and protection now this will not generate static electricity but electricity will be allowed to pass through it so a lot of times they'll put that in there they'll seal it up and then they will put it inside of the bag itself and then seal that up and now it can go off to the customer just like that some of the handling and transportation rules it says here first off keep the device on a static dissipative surface keep it on that mat until you're ready to put it inside of that bag makes it very easy keep all leads on there to remember it says never slide in ESD sensitive device over any service member sliding causes static electricity and we don't want to cause that never handle the ice seized by its leads if it's done you want to keep it on that mat remember oils and acids from your neck anywhere else couldn't cause static electricity not what it will do though it will contaminate the leads and prevent a good quality solder joint a lot of people said well I rub my neck and stuff like that and that'll cause static electricity that's not true it's the oils and acids on the back your neck that causes the issue okay avoid rapid friction producing activities in other words you don't need to comb your hair dust yourself off or anything in your workspace you can walk away from that remember if you're brushing your hair because you want somebody to notice you they've already noticed you in the workspace they still notice you in the break area the same way okay minimize handling is these sensitive devices if you don't need to touch it leave it alone always use clean static dissipative containers we explained to you earlier why always make sure the device is completely inside the closed container because if it's not it's not protecting anything whatsoever come on think about this let's grab that board real quick we want to take it down to Billy right down the thing he's I got a component needs replaced so what do you do you do this I call it the Taco Bell carry because you wrap it around it like this this is not being protected whatsoever and you go down there so anything it's ESD sensitive on there could be a walking path something is plastic its Roberts a nonconductor hmm I'm going to discharge into the component so don't do it like this again put it inside the bag to transport it from point A to point B okay never see on the SD bag by stapling it closed you're poking holes in it now is there protecting anything that's like trying to fill a bucket up with full of water and it's got a lot of holes in it is it going to key it's going to take you a lot longer and it might not ever fill up so think of it that way never leave a device on top of static dissipative container again put it inside always use only easy since improved tapes I have seen so much of this I've seen people using regular scotch tape I've seen people putting post-it notes on top of circuit boards because they want to make sure that we know which part has to be replaced well guess what static electricity causes issues never play static plastic pocket travelers on or near container remember it's a nonconductor it's an insulated it is storing static electricity so keep them out of the workspace always use cars designed for ESD sensitive devices because some people use like rubber mates and stuff of that nature and they're got all the things on well guess what that's got wheels that are turning in it it's causing static electricity the static electricity is coming up them legs going to that tabletop guess where your board is on top of that tabletop so it's getting all sorts of electrical day going on so always check to see that the card is grounded and that all shelves are in complete contact with the frame and then that is touching the floor that way everything is ESD safe all ground potential of zero as you're transporting it what I hope you've enjoyed this and it says here you got any questions if you have any questions contact us here at best my name is Norman Muir and like I said I work for best incorporated as a master instructor we can answer your questions and if I'm not here there's several other people another one would be James Barnhart he is another master instructor Francisco he's another one of our instructors here we got a lot of people in the back that a supervisor could discuss this with you about ESD programs so I hope you've enjoyed the last 30 minutes of our program and again be esd-safe and thank you

Channel: SolderingGeek

Views: 33,277

Keywords: ESD Training, EOS training, static control training, static awareness training, IPC static control training, IPC ESD training, IPC EOS/ESD certification, electrostatic discharge, esd, static, esd training, electrostatic, discharge

Id: IZS_jqYONXc

Length: 28min 47sec (1727 seconds)

Published: Tue May 26 2015