Introduction

hello. It's phi.

I finally received the PCB board that I designed the pattern last time (Fig.1).
This time, it is finally mounted on the board that arrived!
I thought, but I stumbled in the previous stage, so I will introduce the episode.

Continuity check

A PCB board with painstaking pattern design.
I think it's fine, but just in case, I did a continuity check first.

First, check continuity between VIN and GND!
“Pi”
I thought I heard it wrong, so I asked again.
“Pi”

I am conducting.
It's a so-called short. (It is a such a fool…!!)

why did you shoot

I was quite upset by the unexpected short circuit, but I know that electricity doesn't lie, so I will deal with it calmly.

Let's look at the layout first.
I checked the positions of wiring, lands and vias one by one.

Then, the via (the part surrounded by the red circle in Figure 2) directly connected VIN and GND.
It was a really stupid mistake, but I'm glad I noticed.
What were you doing when you were designing the layout?

Now that we know the cause, we just have to deal with it.
I thought it would be better to stop the electricity before the via as shown in Fig. 4 so that VIN and GND are not connected.

However, I suddenly thought.
“How am I supposed to turn off the electricity?”

Why not just break the via part out of the PCB board first? I thought.

When you actually try...
The PCB board is very hard and I can't break it with my own strength.

After that, I kept thinking about how to turn off the electricity, and found one way.
"Scrape without breaking"

The board this time has two layers, and if you scrape the upper layer with a file, the electricity should be turned off (Fig. 5)!

“Can you really cut it??”
I was half in doubt, but I tried it for the time being.

Then...

I deleted it (laughs)
It's a little painful, but I can't help it. .

Never mind continuity check!
“...”
No sound = insulated.

"I did it! Insulation success!!"

The short is now resolved. Analog FAE only analog.

I was happy for a short while...

I was very happy to have resolved the issue.
I thought for a moment...

Senior: “Why did this problem occur?”
Me"···"

I'm at a loss for answers.

I realized that there are temporary solutions to fix the problem (which I was happy with) and fundamental measures to prevent the problem from happening again.

Fundamental measures

For a fundamental countermeasure, we deeply investigated the cause of the problem.

What caused the problem
・Believing that the pattern layout that you designed is correct.
・I didn't check every corner

I considered the following as a countermeasure.
・Have someone else look at it (double check)
・Create a checklist

At the end

I was able to overcome the stumbling block I introduced this time by "grinding the PCB board".
The most important thing is not to make such mistakes in the first place.

I felt that it was important not only to solve the problem, but also to take measures to prevent the problem from happening again.

Next time, I would like to move on to evaluating DCDC converters. looking forward to!