Hello everyone! My name is Dmitry. I am glad to see you all again on my youtube channel
"Electronics Manufacturing Technologies". In this video, we will talk with you
about measures to prevent the occurrence of static charges in electronics manufacturing.
I will divide the video into two parts. In the first part, I will talk about the basic equipping approaches that should be taken by almost all enterprises.
In the second part, I will talk about the internal ESD infrastructure.
What and how it works, about principles, about approaches .... I think it will be interesting for you! Don't switch! Go!
Electronics Manufacturing Technologies
Part One. In it, I laid down the basic conditions that should be in all enterprises that
are related to electronics or printed circuit boards.
The first is the climate. By climate, I mean humidity, which should be 45-50% in all rooms
where components are stored, warehouses and production facilities.
The next part of the climate is temperature.
This is also an important factor. Many treat him with disdain, and he is very important.
The temperature in all rooms should be 21-25 degrees Celsius. Why not higher and why not lower?
Not worth it below, because it will be cold for the staff and there is no point in doing it,
because it does not affect anything else, except for the well-being of people. This must be remembered.
Why not higher than 25 degrees? - Because the higher the temperature,
the worse the solder paste retains its shape on the printed circuit board after the printer.
If you do not have a surface mount line and you are forced to first apply solder paste on several tens
or hundreds of printed circuit boards ... Somewhere you lay them out with solder paste. They lie for a while.
And at high temperatures, the print of the solder paste from the aperture, which you made on the polygon of the contact pad, the
print will lose its shape - the solder paste will blur from high temperatures. Therefore, no higher than 25 degrees. Desirable.
And the second point of Part 1 is Grounding.
Many of you rent space for your production facilities and few pay attention to
how the grounding is carried out on your sites.
Connection principles and approaches are different. There is a common grounding throughout the building. This is not very suitable for the electronics industry,
because you are very dependent on various incidents
that can happen due to the fault of your neighbors. That is, if someone breaks something, then these impulses will occur
throughout the entire grounding network. It is not very pleasant, it is not very good, especially for you.
On the contrary, it is necessary to prevent such incidents and therefore for such cases it is advisable,
if possible, to make your own ground loop outside. That is, outside of the general, create your own ground loop.
Agree, find areas, equip.
Make your grounding and connect your premises there. I know and understand perfectly well
that it is not always possible to make an outer contour. Sometimes there is simply no place to physically place it.
Therefore, it is imperative to think over protective measures against any incidents from the outside so that the neighbors do not cause problems.
It is also important to create the conditions and infrastructure in the workplace where manipulation of printed circuit boards and electronics takes place.
This will be the second part.
The first person to fight static charges in production is an anti-static floor.
It consists of a resistive coating and a spark that has fallen into it, in principle, cannot immediately go to the ground,
to which the antistatic floor is connected. A spark cannot, in principle, be formed,
because this coating very slowly conducts electricity through itself. In fact, it is a resistor.
A spark cannot be generated if it hits the floor covering. The spark will gradually drain.
Next, anti-static footwear comes into play. This is important.
The shoes have a resistive material and the spark will not pass through the shoes with lightning speed.
Be sure to check the markings on the shoes for the ESD badge. This means that the shoes are antistatic.
And we already have two resistances. The first resistance is the flooring. The second resistance is shoes.
In the floor 1 megaOmm minimum and on shoes 1 megaOmm.
The more such layers, the slower the charge will drain. Do you understand?
1 megaohm is the minimum value for antistatic protection. This is not endless growth -
up to two or three megohms is quite possible.
Antistatic shoes work when a person is moving. Surface friction occurs and charges are generated.
The next stage in the fight against static is clothing - robes, gloves and hats.
Well, caps protect the cleanliness of the room. So that nothing falls from our heads.
Gloves have a dual function. The first function is resistance.
The spark will not pass through them. The second function is the aesthetics of work.
So that your greasy fingers do not leave marks anywhere. It is very important.
Electronics doesn't like fat, because it will also have to be washed. Well, ethics ... you can't leave fingerprints on devices.
It's ugly, you shouldn't do that. The task of the robe is one of the most basic.
If there is no robe, then any charges accumulate in some locations,
in parts of our body.
The robe, since it is current-conducting, has a silver thread sewn into it, there are many threads,
and thanks to this, the charges do not accumulate in one place, they are distributed.
This facilitates the movement of charges down - into the feet - into slippers - into the floor. This allows you to get rid of the uppermost accumulations of charges,
where they have accumulated, so that they go away faster - for this you need a robe.
The second function of the robe is to prevent sparking.
That is, from your body, no matter what you touch something or someone, a spark will not arise through the robe.
A robe, gloves and a hat should also be in the arsenal of a person
who works in a room where electronics are produced.
We are on an anti-static floor. This is evidenced by the copper sticking out of the floor.
There are still repairs going on, but I'll just explain to you. My slippers also conduct
static electricity through themselves. They have a resistance of 1 megaohm.
The robe, also antistatic, also conducts electricity through itself.
Distributes all the charge evenly throughout the body and allows it to move faster from the upper body down -
to the feet - to the slippers - to the floor. The charge appeared on the shoulder, I walk, the
charge moves, new charges appear ... Gradually, they flow down through the slippers and onto the floor.
There are no charges left on me, because all the charges from me immediately go to the floor through the robe and through the slippers.
Therefore, it makes no sense to make an antistatic floor when you do not have special shoes,
when there is no special clothing that will facilitate leakage.
Leakage of charges without sparking into the floor. And then into the ground, into the circuit, into the ground.
There is no point in having an antistatic floor if you don't have everything else done.
This is a complex of various measures, ranging from wristbands in the workplace,
grounded soldering irons and other equipment. This also applies to clothing, slippers, grounded equipment,
so that no one is electrocuted, that no one is discharged onto the circuit boards, and that your circuit boards are safe.
The next item is one of the most basic is the table.
This is where PCB manipulation takes place.
This place must be protected as much as possible. How it's done? - the person must first wear an
antistatic wrist strap. I have one here. An ESD wrist strap is worn on your wrist
and connected to an ESD outlet. The first resistance is in the cord itself.
It says 1 megaohm here. The bracelet is connected to an outlet, where there is also resistance on each line.
You can connect a bracelet, a mat that is on the table,
some additional device, equipment with which you work to the outlet .
The equipment also has pins that can also be connected to an outlet.
It also turns out two levels of protection - the first level is in the 1 megaOmm bracelet and the second level is directly in the socket
where the bracelet is connected. The outlet also has a resistance of 1 megaohm.
It turns out at least 2 megaohmma. The charge drains off even more smoothly.
You will probably think that you have complicated everything too much, but in fact it is done once, it is done efficiently.
and we forget about it, we work every day, we do the same procedures,
nothing changes, and at the same time all these small things with protection, all these small nuances preserve our products.
When talking to some electronics manufacturers, I often hear
that they have never encountered static electricity problems. Never suffered.
Not a single board was harmed. With what it can be connected? I have identified three explanations for myself.
The first explanation is that the printed circuit boards that are manufactured do not have components at risk,
or that the board uses components that are protected from static electricity.
Therefore, the board does not suffer. The second explanation I found was the
wrong definition of the defect. That is, the manufacturing does not even consider that the PCB
could stop working due to static electricity. - Due to the fact that the static has damaged it.
It's not even considered! Anything can be considered ...
a PCB defect, a component defect, an assembly defect, anything but static electricity.
It just isn't being considered. As if this problem doesn't exist.
And if the devices produced are cheap enough, then they just put it aside.
Then they repair it, change the component and no longer remember.
The third explanation, which is also probably, I lowered it to the very bottom, but it also has a place to be ....
Many productions are quite miniature. Very small rooms. And a lot of people work in them.
Really! I have been to such industries where there is a very large number of people per unit area.
They exhale so much air that the humidity inside the room is high enough.
Due to the high humidity, there is no accumulation of static charges on surfaces.
They flow down to open earthing switches: batteries, pipes, ventilation ...
These are all open earthing switches and static charges move through humid air in them.
The phenomenon of humid air definitely takes place and therefore such industries may not face the problem of static.
Then the question arises - why build anti-static protection at all?
If we approach production correctly, then we must guarantee the protection of
our products from the appearance of static charges, and it is all these measures that I described in this video that
allow these guarantees to be provided. Hope this video was helpful to you. Be sure to put your thumbs up!
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