Plated Through Hole printed circuit boards (PTH PCBs) are used in many applications because they are easy to fabricate, reliable, and durable. The main manufacturing process is the same as other circuit boards, but with a few differences.
In this article, we will explain what PTH PCBs are and how they work. We’ll also discuss some of the advantages of using them in your products.
Plated-Through Hole PCB
What is PTH in a PCB?
PTH stands for “plated through hole”, and it’s a type of printed circuit board (PCB) that has holes in the middle of the board that connect to copper traces on the bottom side. PTH boards are used in applications where you need to make connections between two points on the same side of the PCB.
It’s made up of an insulating substrate, which is usually fiberglass-reinforced epoxy glass laminate, with a metal layer deposited on top. The metal layer has holes drilled through it so that components can be mounted to the surface. This type of PCB is also known as “thru-hole” or “through-hole.”
This type of PCB is great for beginners because it makes it easy to assemble your first circuit—you just need a soldering iron and flux, two tools that can be purchased at most hardware stores. But even advanced users will prefer this type of board because it’s faster than other methods when you have lots of connections to make or need to solder large components on the back side of a board.
PTH in a PCB
How Does PTH Work in a PCB?
If you’ve ever seen a printed circuit board, you’ve likely seen the holes in it. These holes are called plated-through holes (PTH). They’re also sometimes referred to as “vias.”
These holes allow for easy interconnectivity between different layers of the PCB and increase its flexibility. They’re also used to mount components and make connections between those components and other parts of the board.
The most common types of PTH boards are single-sided, double-sided, and multilayer. Single-sided PCBs use only one layer of copper for the traces that connect components, while double-sided PCBs have one layer of copper on both sides. Multilayer PCBs have multiple layers of copper, which means they can handle high frequencies better than single or double-sided circuits.
PTH and NPTH
PTH and NPTH Comparison
You may be wondering, “What’s the difference between plated through hole and a non-plated through hole? Is one better than the other?”
The PTH and NPTH through holes are two different types of through-hole components. They both have their own advantages and disadvantages, and choosing one over the other will depend on your project’s needs.
Plated Through Hole
Plated Through Hole (PTH) is a manufacturing process in which a via hole is drilled through the board, and copper is electroplated inside so that the copper connects pins on opposite sides of the board. This allows for a much easier soldering process than non-plated through holes.
PTH involves drilling a hole through the board, which is then plated with copper and filled with epoxy resin. This method creates a strong, stable connection between the solder and the copper traces on the board, but it is more expensive than an NPTH connection because of all the extra steps involved.
Non-Plated Through Hole
In contrast, an NPTH connection involves placing conductive epoxy around a drilled hole and filling that space with molten solder. This provides a less-stable connection between components than PTH, but it’s much less expensive and also makes sure that there’s no extra material in your board’s design.
NPTH is a type of through hole that does not have a plating layer. This means that NPTH holes can be made in non-conductive materials such as aluminum, ceramic, or plastics. NPTH holes are often used for vibration dampening, heat transfer, and molding components.
Steps on PTH PCB Process
In order to make a plated through-hole PCB from your PCB layout, you have to go through the following steps.
Step 1 – Alkaline Degreasing
Alkaline degreasing is the first step in any PCB process. This process uses a solution of sodium hydroxide and water to remove oils, greases, and other contaminants from the surface of a printed circuit board.
The cleaning process involves submerging the board into the alkaline solution for about three minutes, then removing it and rinsing it with deionized water. After this step, the PCB is dried using compressed air or nitrogen gas.
Step 2 – Microetching
In the second step, we begin the process of creating a micro etching on your PCB. This is where we create a pattern that will be used as an etch mask during the next step.
To do this, we use a laser to burn away areas of your PCB that you don’t want etched away. The laser can be controlled in such a way that it burns only through the copper and leaves other parts of the board intact. This gives you a very fine-grained control over where your etch mask will be created, which is essential for making sure you get a clean final product with no shorts or other problems.
Step 3 – Preimpregnation
In this step, the copper is covered with a protective coating of resin and then heated to cure the resin and make it insoluble in water or other solvents. The object of preimpregnation is to prevent copper corrosion during subsequent processing steps and to provide good adhesion between the copper and dielectric layers.
The preimpregnation process uses a UV lamp to expose the whole PCB in an oven at room temperature, creating an even coating of resin on all surfaces of the board.
Step 4 – Activation
This process is done by sanding the copper layer with a fine-grain emery paper, followed by a thorough cleaning of the board. The activation is done to remove any oxides on the surface of the copper and prepare it for soldering.
Step 5 – Peptization
This process is the fifth step in the plated through hole PCB manufacturing process. This process uses a mixture of chemicals to remove any remaining photoresist from the board. The resulting chemical solution is then washed off using pure water, which is then dried by means of a blower.
The goal of this step is to remove all traces of photoresist from the board, so that it can be processed further and made ready for plating.
Step 6 – Electroless Copper Plating
After the plated through-hole PCB manufacturing process, the board is ready to be electrolessly copper plated. This process creates a conductive layer that will allow for soldering of components and interconnects.
In electroless copper plating, the PCB is immersed in a solution of copper sulfate and other chemicals. This is a chemical reaction that results in the deposition of copper on the surface of the board.
This process also helps improve corrosion resistance, which is especially important for electronics that will be exposed to moisture or high-humidity environments.
Things to Consider when Drilling PTH
Drilling plated through hole in a printed circuit board can be a daunting task, especially when you are not sure of the procedure. In this article, I will discuss some of the considerations that you should keep in mind when drilling plated through holes in printed circuit boards.
Edge Clearance – 0.009″
When drilling a plated-through hole in a printed circuit board, this should be at 0.009” to ensure that the drill bit doesn’t catch on the plating. This is especially important when using a drill press, as the force from the drill can easily cause a chip to break off and short out your board.
Hole Size – 0.006″
When drilling plated through hole in a printed circuit board, this should be 0.006″. This is because it’s the most common size for the boards and components in use today, but also because it provides enough room to accommodate parts with a wider range of diameters.
Annular Ring Size
Annular Ring Size – 0.004”
This is the clear area around the drill hole, and it is important to take this into consideration when drilling plated through holes in a printed circuit board. The annular ring size should be at least 0.004” larger than the bit diameter to allow for adequate cutting and to prevent chipping of the plating edge during drilling.
Component’s Insertion Type on a PTH PCB
The radial insertion type is used to attach components to a printed circuit board by inserting the lead of the component into a plated through hole.
The radial insertion type is the most common in printed circuit boards. It allows for the maximum amount of contact between the component and its pads. This makes it ideal for components with a high current density or ones that generate heat.
An axial insertion component is placed into a plated through-hole printed circuit board by inserting the component with its lead wires in the same direction as the circuit traces on the printed circuit board. The terminal is inserted in the direction of the axis, which is perpendicular to the surface of the PCB.
Axial components include LEDs, capacitors, fuses and resistors. These components have leads that extend from one end of their bodies and terminate in pins or terminals at their other ends. These leads are inserted into holes in a printed circuit board along the same axis as their bodies. Axial components can be surface-mounted or mounted in sockets.
Odd Form Components
These components are designed to be inserted into a plated through-hole printed circuit board (PCB). They feature a square or rectangular shape with one flat side, and they may have one or more corners on their opposite side. Odd Form components are used in applications where space is limited and there is no room for the component to be placed sideways.
In this type of insertion, you manually push the component through the board until it comes to rest in its correct place. This is a slow process and can be difficult to do on printed circuit boards that are crowded with other components.
PTH PCB Advantages
When you’re looking for a way to make your circuit boards more efficient, you can find a lot of options. But what are the plated through-hole printed circuit board advantages?
Larger Annular Rings
This is the main advantage of a plated through-hole printed circuit board. The annular rings, which are the outer circumference of all holes, are larger on a plated through-hole printed circuit board than on a non-plated through-hole printed circuit board. This makes it easier to solder components to the board and creates a stronger connection.
PCB with an annular ring is that it can better protect the circuit board from mechanical damage. Since the annular ring is thicker than the surrounding plate, it has a stronger mechanical strength, so it can better resist external force and pressure.
Lower Hole Density Per Square Meter
In a printed circuit board, the holes are the paths that allow electrical current to flow from one side of the board to another. The more holes per square meter, the higher its conductivity and the more easily it can transmit data.
The lower the density of holes per square meter, the better conductivity will be in your printed circuit board. This is because there are fewer gaps between holes and therefore less resistance for current to flow through.
Plated through-hole printed circuit boards are more durable than non-plated through-hole PCBs. The holes are larger, and the plating is thicker than on other boards, so it is more resistant to damage.
Through-hole components are typically used for electronic projects. They are soldered into holes and parts may be placed on top of them. Through holes can be round, square, rectangular, or any other shape.
The shape of the holes determines how much material is removed from the board during drilling and plating, which affects the strength of the finished product.
PTH PCBs are most commonly used in the mass production of industrial products, as they are quite affordable, easy to manufacture, and can be produced in large batches. PTH PCBs can also be manufactured with large-scale equipment and a high volume of throughput.
If you do the research and shop around, you can get a printed circuit board of high quality. Without the proper research, though, you could end up with a subpar product, and that’s what we hoped to avoid with this article. If you’re in need of professionally made boards for your next project, give some of these companies a shot. They can produce a high-quality PTH PCB –something that businesses both big and small require.