PCB 장착 구멍에 대해 알아야 할 모든 것

You may think PCB mounting holes are just plain holes. But there is more to them than you might see at first. Making them the right way is very important. It makes sure your PCB is strong and easy to put together. It also helps it work the right way. In this article, we will talk about the different kinds. We will talk about why they are so important. And we will talk about how to make them the right way in your PCB computer program.

What’s the Big Deal with PCB Mounting Holes?

So, what are PCB mounting holes? They are holes that are put into a circuit board. These holes are used to hold the board tightly to a case or another thing. I have seen many projects where people didn’t think about these holes until the end. This caused trouble later on. Good mounting holes are very important for making sure your board is strong and doesn’t move. They stop the board from moving around. They also stop it from shaking. Shaking could break the parts on the board or the solder that holds them. The holes also help when you are putting the board together. They make sure everything lines up in the right way.

Should My Mounting Holes Be Plated or Non-Plated?

One of the first things you have to decide is what kind of mounting hole to use. You can choose plated through-holes (PTH). Or you can choose non-plated through-holes (NPTH). This may seem like a small thing to decide, but it can make a big difference.

I have used both kinds of holes in my work. Plated holes have a thin layer of copper on the inside wall of the hole. This is very good when you need to connect the screws or bolts to your ground plane. This is for electrical grounding. This can help stop electrical fuzz, which is a big problem for circuits that work very fast. Non-plated holes are different. They are just holes with no copper inside. I use these when the screws should not touch any of the electricity in the board’s circuits. Remember, making non-plated holes can cost more. This is because it takes an extra step to make them.

How Do I Choose the Right Size for Mounting Holes?

Picking the right size for your mounting holes is very important. I always say, “pick your screw first!” The screw you use tells you how big the hole needs to be. You need to find the size of your screw. Then, make your hole a little bigger than the screw. This gives you a little extra space. That way, the screw does not crack the board. A popular choice for my projects is an M3 screw. This screw usually needs a hole that is about 3.2mm wide.

You need to think about more than just the hole. Think about the screw head too. Make sure there is enough room around the hole for the screw head. Also, make sure there is room for the tool you will use to make it tight. I learned this the hard way one time. I put a tall part too close to a mounting hole. Then I could not get a screwdriver in there!

Where Is the Best Place to Put Mounting Holes?

Where you put your mounting holes is very important. It’s just as important as their size. For a board that is shaped like a rectangle, I put a hole in each corner. This gives the best support. It stops the board from bending. It is also a good idea to keep the holes away from the edge of the board. A good rule is to keep the hole away from the edge of the board. The middle of the hole should be at least 3mm from the edge. This stops the board from cracking.

If your board is big, you may need more holes in the middle. This will stop it from bending. And make sure your holes match up with the case you are putting the board in. I use a 3D picture of the case in my PCB software. This helps me check that everything lines up.

What About Empty Space Around the Holes?

Empty space, or clearance, is the space you leave around your mounting holes. It is very important to do this. It helps you stay out of trouble. You need to make a “keep-out” area around every hole. This means you should not put any copper lines or other parts too close to the hole. I try to leave at least 3mm to 5mm of empty space around the hole.

This empty space stops the screw from touching a live copper line. If it touches, it can cause a short circuit. It also keeps nearby parts safe when you tighten the screws. Parts that break easily can be a problem. For example, ceramic capacitors. They are in danger if they are too close to a hole. The board can bend a little when you make the screw tight.

Can I Use Mounting Holes for Grounding?

Yes, you can, and it is often a smart thing to do! You can use plated mounting holes. You can connect them to your ground plane. This is a great way to make your board work better. When you put the board in a metal case with screws, the plated hole connects the board’s ground to the case. This can help protect your circuit from electromagnetic interference (EMI). EMI is electrical fuzz that you don’t want.

But you have to be careful. Usually, you should not connect the mounting holes to the signal ground. It’s better to connect them to a chassis ground. Sometimes it is best to only use one hole for grounding. This stops ground loops from happening. Ground loops can make their own noise problems. The best way to do grounding depends on what you are making.

How Do I Create Mounting Holes in My PCB Software?

Most computer programs for making PCBs make it easy to add mounting holes. For example, programs like Altium Designer or KiCad. You can often add a “pad” or a “hole” from the main menu.

Here is the way I usually do it:

• Add a Pad: I first add a pad where I want the mounting hole to be.
• Change the Settings: In the pad’s settings, I set the hole size to be right for my screw. I also set the size of the copper circle around the hole. This is called the annular ring.
• Plated or Non-Plated: I pick if the hole should be plated or not plated.
• Lock it in Place: When the hole is just right, I often lock it in place so I do not move it by mistake.

Some programs have ready-to-use footprints for normal mounting hole sizes. This can help you save time.

What Is an Annular Ring and Why Does It Matter?

The annular ring is the copper ring around a plated through-hole. The part’s leg, or the screw, connects to this ring. The size of this ring is important to make a good connection. A good rule for the smallest ring size is about 0.1mm (4 mils) wide.

A bigger annular ring can give better support. This is great for bigger parts. It is also good for boards that might shake a lot. Sometimes I use teardrop shapes. This is where the copper line meets the ring. This adds more copper. It makes the connection stronger. This helps stop cracks from forming.

What are Some Common Mistakes to Avoid?

I have made some mistakes over the years. I have also seen mistakes from other people who make boards. Here are some common mistakes you should try not to make:

• Not Following the Maker’s Rules: Always read the rules from the company that makes your PCB. Look for rules about the smallest hole size and the amount of empty space.
• Putting Holes Too Close to the Edge: This can make the board weak and can lead to cracks.
• Forgetting to Leave Space for Parts: Make sure you leave enough room for all your parts around the mounting holes. This is very important for tall parts.
• Wrong Grounding: If you do not think about how to do your grounding, you can have noise problems.

Final Thoughts on PCB Mounting Holes

It’s easy to not pay attention to something simple like a mounting hole. But I have learned that paying attention to these small things can save you a lot of trouble later. A mounting hole that is made well will make sure your PCB is safe and easy to put together. It will also make sure it works right every time.

기억해야 할 주요 사항은 다음과 같습니다.

• Always pick your screw first.
• Choose between plated or non-plated holes for your grounding.
• Put your holes in smart places to make the board strong.
• Always leave enough empty space around your holes for screws and tools.
• Think hard about how you will do your grounding.

If you remember these things, you will be able to make strong PCBs that work well. Happy designing