Narrow down by specifying conditions
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This is Sasaki in charge of power supply dock technology.
In this column, I would like to introduce some examples of problems related to power supplies that I encountered multiple times during various customer support sessions.
We received a call from a customer designing an FPGA development board, saying, "I would like to consult with you about the high rate of defective boards returned by specific users."
Was it because I was busy with problems? ?
What kind of symptoms are you returning?
In the manufacturer's analysis report of the device in which the problem occurred, the result was that it was destroyed by ESD (*).
*ESD: Abbreviation for Electro-Static Discharge
ESD? Is the board ESD safe?
No. Since it is an FPGA development board, I believe that the engineers handle the board while taking ESD measures such as antistatic wristbands.
Is that so. But engineers don't always wear antistatic wristbands (laughs).
I think you should do something about it.
indeed.
However, since it is a development board and the number of shipments is small, it is not realistic to obtain and implement ESD countermeasure parts.
First of all, I would like to include a warning in the manual that says, ``Please take precautions to prevent static electricity.''
I think that's good.
But why are there so many returns from specific customers?
That's the question.
One reason is that the customer handled the board without antistatic measures.
Also, the customer may have a static constitution.
Do you have an electrostatic constitution?
It seems that there is.
Some people say that if your eating habits are disturbed or stress builds up, your body will oxidize and static electricity will easily build up. Also, be careful if you have dry skin.
Is that so. It's amazing how stress can affect you.
Come to think of it, semiconductors are designed to withstand up to 2,000V as an ESD countermeasure so that they won't break even if people touch them, right?
So why did someone touch it and break it this time?
I'm guessing you're applying more than 2,000V when you're probing or using solder.
When a person directly touches a semiconductor, it discharges through the high resistance "skin". However, if the object (metal piece) to be probed is passed through, the electricity accumulated in the body will be discharged when the resistance value is zero, so it may exceed 2,000V and damage the semiconductor.
Even in the summer now, the air conditioner is working and the environment is dry, so static electricity can occur regardless of whether it is summer or winter.
I see.
First of all, I'd like you to thoroughly wear an antistatic wristband.
The point of this time
・Thoroughly implement ESD countermeasures when handling boards (antistatic wristbands, etc.)
・Keep your body and mind healthy to avoid unnecessary problems.
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